CneKaHMe OAHOKOMnOHeHTHblX CMCTeM

 

Harpes nopowKosoro TeJJa BbI3bIBaeT B HeM onpe.u.eJJeHHbi e 113Me­ HeHl1.H, CJJy)l(aUJ,11e XapaKTep11CTl1 KOH cmOOllU npou,ecca cneKaHl1.H.

,lJ,ocTaTO'IHO O'leBl1.llHO, 'ITO.llOJ])KHbl 6bITb 06beKT11BHbi e npl1'111Hbl (11x npl1H.HTO Ha3bIBaTb 06UJ1Cyu.1,11e CllJlbl) TaKl1X 113MeHeHl1H, a 11X pea­ JJ113au,m1 11 KOHKpeTHbl H pe3yJJbTaT 3aBl1C.HT OT Toro, KaK npOl1CXO.lll1T

nepeMeUJ,eH11e semecTBa B HarpesaeMOM nopowKOBOM TeJJe, T. e. KaKo­ BbI MexaHU3Mbl MacconepeHoca. B npou,ecce Harpesa npo11cXO.ll.HT noA3Y­ itecmb 11 peKpucmOJ1J1ll30ll, UR 11acT11u., a TaK)l(e (B 6oJibWl1HCTBe cJJy11a­ es) ynAomHeHue nopowKosoro TeJJa.

 

CTaAMM cneKaHMR

 

 

Bcio CJJO)l(HYIO nocne.u.osareJJbHOCTb npou,eccos, npo11cxo.u.Hm11x np11 Harpese nopOWKOBOfO Tena, 06bI'IHO crnpaIOTCH pa3.U.eJJl1Tb Ha CTa­

.ll.1111,.llJJH Ka)l(.llOH 113 KOTOpblX MO)l(HO.llOCTaTO'IHO TO'IHO yKa3aTb.llBl1-

)l(yUJ,11e c11JJbI 11 Ha1160JJee cymecTBeHHble MexaHl13MbI MacconepeHoca. Xorn TaKoe.u.eneH11e y.u.o6Ho, HO OHO B JHa1111TenbHOH Mepe ycJJOBHO, TaK KaK B 3aBl1C11MOCTl1 OT Ha'laJJbHblX CBOHCTB nopOWKOBOfO Tena 11 ycnos11i1 cneKaHl1H KaK11e-To HBJJemrn 6y.u.yT npo11cxo.u.11Tb nocJJe.u.o­ BaTeJJbHO 11)]11 0.llHOBpeMeHHO, nepeKpbIBaH 0.llHY 11n11.u.a)l(e HeCKOnb­ KO CTa.lll1H.

)J.nH cneKaeMOfO nopOWKOBOfO TeJJa xapaKTepHbl HeKOTOpble reo­

MeTp1111ecK11e 3neMeHTbl (p11c. 21 8), onpe.u.eJJHeMble noHHTl1HMl1 «WeH-

Ka», «Me)l('laCTH'-IHb H KOHTaKT», «1130Me'fPl1llecKa.H nopa» 11 np.

51.E. fery311H Bb1llen11JJ TPl1 npl1HU.11Ill1aJJbHO OTJ111llHbIX COCTO.HH11H nopowKosoro Tena B npou.ecce ero ttarpesa, K)l(.lloe 113 KOopbIX co­ orneTcrnyeT onpeneneHHOH crnn1111. Ha nep6ou (Ha11anbH011) crnn1111

np011CXO.lll1T np11neKaH11e nopOWl1HOK (11aCTl1U.) K npyr npyry, co­ npoBO)l(.llaIOllleec.H yBeJJ11'1eH11eM nJJOUJ,a.lll1 KOHTaKTa Me)l(.lly HHM11; Ka)l(lla.H 11acT11u.a coxpaH.HeT CTPYKTYPHYJO 11H.ll11BHllYMbHOCTb, T. e. rpa­ Hl1U.a Me)l(lly HHM11 coxpaHHeTC.H 11 c HdlcoxpaH.HeTC.H noH.HT11e «KOH­

TaKT Me)l(lly qacT11u,aM11». Ha 6mopoil cTan1111 nop11cToe TeJJo MO)l(eT

6bITb npencrnBJJeHO B 811.lle COBOKYilHOCTH.llByx 6ecnop.H.ll0'1HO nepe­ Me)l(aJOUJ,11XCH cpa3 - cpa3bI semecrna (11acT11U.bI) 11 cpa3bI «nycTOTb» (nopbI); Ha 3TOH CTa.ll.1111 cpopM11poBaH11e JaMKHYTbIX nop eme He 3a­ KaH'll1BaeTC.H, a KOHTaKTbl Me)l(lly qacT11u.aMH e 11cqe3aJOT 11 rpaHl1- U.bl Me)l(lly H11Ml1 OKa3bIBaIOTC.H pacnoJJO)l(eHHbIMl1 npo113BOJlbHO, BHe CBH311 c Ha'laJJbHbIM pacnono)l(eHl1eM rpaH11U. Me)l(lly 11CXO.llHblMl1 no­

pOWl1HKaMl1. Ha mpembell CTa.lll111 B nopoWKOBOM Tene B OCHOBHO

11MeIOTCH Jll1Wb JaMKHYTbie 1130nl1pOBaHHble nopbl, 1111cno 11 06m1111 06beM KOTOpbIX MOryT yMeHbWaTbCH. 0rMeTl1M, 'ITO.lla)l(e 3Tl1 BeCbMa yKpynHeHHbie TPl1 CTa.lll111 He MOryT 11MeTb qeTKOfO pa3rpaHl1'1eHH.H: 3aMKHYTbi e (113on11poBaHHbi e) nopbl BC'fPe'laIOTC.H B peaJJbHOM no­ pOWKOBOM Tene Ha paHHeH CTa.lll111 Harpesa (Hanp11Mep, eme np11 cpopMoBaHl111 3afOTOBK11), a HeKOTOpbie Ha'laJJbHbie KOHTaKTbl Me)l(lly 11acT11u,aM11 coxpaH.HIOTC.H snJJOTb no TPeTbei1 crnn1111 cneKaHl1.H.

Ll,nH 6onee nernnbttoro aHaJJ113a npou.eccos, conposo)l(llaIOUJ,11X

HarpeB nopoWKOBbIX Ten, qaCTO Bb.lleJJ.HIOT weCTb CTa.ll11H cneKaHl1.H

I) pa3s11T11e 11 so3Hl1KH0BeH11e c nocneny10m11M pa3Bl1Tl1eM CBH3e11 Me)l(lly 11acT11U.aM11; 2) o6pa30BaHl1e 11 pOCT «WeeK» Me)l(qaCTl1'1HblX KOHTaKTOB; 3) 3aKpbITl1e CKB03HOH nop11CTOCTl1 B nopoWKOBOM TeJJe;

4) ccpep011.lll13aU,11H nop; 5) ynJJOTHeH11e no­ pOWKOBOfO Tena 3a C'leT yca.llKl1 11Jon11poBaH­ HblX nop; 6) yKpynHeH11e (Koanecu,eHU.11.H)

nop.

Pa36umue C6Jl3etl Me)l(lly 11acT11U.aMH Ha1111-

HaeTCH cpa3y c HarpeBOM nopoWKOBOfO TeJJa, a

T. e. Ha caMOM paHHeM 3Tane cneKaHl1H. 3TO - n11cpcpy3110HHbl H npou.ecc, np11BO.llHUJ,l1H K

 

Pttc. 218. ct>parMeHT nopowKoBOro TC!la ao (a) H nocJie

(6) ttarpesa H J:lBYX'IUCTll'IH<UI MO,llC)lb cncKaHHH (6): a - pa.llHYC 'laCTHllbl; p - pam1yc «WCHKll»; X - paattyc CC'ICHHH o6paJylOUlCroCSI KOHTaKrn; )' - noJJOBtlHa

BCJll1'111Hbl c6JllllKCHHH UCHTpOll •1aCT11U 8

o6pa30BaHHIO H pa3BHTHIO Me)l(l.laCTH'-IHblX rpaHHU H, CJie,llOBaTeJibHO, yeeJIH'IeHHIO npO"IHOCTH H 3JieKTponpOBO,llHOCTH nopOlllKOBOfO TeJia. PeJyJihTaT 3TOH CTll,llHH - BOJHHKHoBeHHe «llleeK», T. e. nepeMbI"leK Me)l()ly "laCTHUaMH (nopOlllHHKaMH).

Poem «llleeK» KOHTaKTOB - ecTecTBeHttoe npo.aomKeHHe npouecca

Me)l("laCTH"IHOfO CB.ff3b1BaHm1; ero He06XO,llHMOe ycJIOBHe - nepeHOC BeIUeCTBa B o6JiaCTb Me)l("laCTH"IHOfO KOHTaKTa, KOTOpblH MO)l(eT 6b Tb ocymecTBJieH c noMOIUblO pa3Hb X TpaHcnopTHbIX MexaHH3MOB, Bbl-

3bIBaIOIUHX HJIH He Bbl3blBaIOIUHX ynJIOTHeHHe npH cneKaHHH. nopOlll­ KOBOe TeJIO CTaHOBHTC.ff 6oJiee npO"IHblM H 3JleKTponpoBO,llHb M. B Ka­ KOH-TO MOMeHT npHKOHTaKTHbl H yroJI Me)l()ly "laCTHUaMH (nepBOHa­

l{aJibHO eeCbMa OCTpbIH) npHTYnJIHeTC.ff HaCTOJlbKO, "ITO Me)l(JepeH­ Hbie (Me)l(4aCTH4Hble) rpaHHUbl Ha"IHHaIOT nepeMeIUaTbC.ff H HX nep­ BOHa"laJibHOe pacnoJio)l(eHHe HapylllaeTC.H. CneKaeMoe nopolllKOBoe

TeJIO no CTpyKType npH6JIH)l(aeTC.ff K COCTO.HHHIO, KOTOpoe 51.E. fery-

3HH HaJBaJI coeoKYnHoCTbIO.aeyx 6ecnop.H.ll04HO nepeMe)l(aIOIUHXCH cpa3 semecTBa H nyCTOTbl. 06bI4HO C"IHTaIOT, "ITO pOCT «llleeK» npOHC­ XO,llHT,llOBOJlbHO 6bICTpO H xapaKrepH3yeT Ha"laJibHbIH 3Tan cneKa­ HH.ff, KOTOpblH MO)l(eT OKaJaTbC.ff JaKJIIO"IHTeJibHbl M (HanpHMep, npH cneKaHHH nopOlllKOBb X aHTH<l>PHKUHOHHblX HJ)leJIHH). 0.aHaKO 3Ta CTll,llH.ff MO)l(eT npO,llOJI)l(aTbC.ff H BO epeM.H 6oJiee n03,llHHX CTll,llHH cne­ KaHH.ff, nepeKpbIBa.H HX.

301cpblmue CKB03Hoii nopucmocmu (nopOBbIX KaHanoB) HBJI.HeTCH

pe3yJihTaTOM pOCTa «rneeK» H npHBO,llHT K no.HBJieHHIO H30JIHpOBaH­ Hb X rpynn nop HJIH,lla)l(e OT,lleJibHb X nop. npH 3TOM 06IUHH (cyMMap­ Hb H) o6'beM nop B nopOlllKOBOM Telle yMeHblllaeTC.H H npoHCXO,llHT ero ynJioTHeHHe (yca,uKa). facTo cneKaHHe JaKaH•meaIOT Ha 3TOH cTa­

.llHH.

CcjJepouiJu3au,Ufl nop, KaK H npe,llh.llYIUaH CTa.llHH, CBHJaHa c poc­ TOM «llleeK»: semecrno c HeKOTOpblX Y"laCTKOB nosepXHOCTH nop ne­ peMemaeTC.ff B o6JiaCTb Me)l(l{aCTH"IHOfO KOHTaKTa, a CaMH nopbl (KaK

HJOJIHpoeaHHbie, TaK " coo6ma10mHec.H) oKpyrnHIOTCH, npHo6peTa.H ccpepH"IHOCTb. lpH,llOCTaTO"IHO)J)IHTeJlbHOH H30TepMH4eCKOH Bbl,llep)l(­ Ke H Bb COKOH TeMnepaTYpe cneKaHH.ff BnOJIHe B03MO)l(H0 nOJIY4HTb H)leaJibHble ccpepH"leCKHe nopbl. 3Ta CTll,llH.ff oco6eHHO Ba)l(Ha B CB.ff3H c BJIH.ffHHeM nopMCTOCTH Ha MexaHM"leCKHe CBOHCTBa nopOlllKOBb X MaTepMaJIOB H H3,lleJIMH, H3-3a 4ero Ha npaKTHKe cneKaHMe,llOBO,ll.ffT HMeHHO,llO 3TOH CTll,llHH.

YcaiJKa u3011upoeaHHblX nop - o.aHa HJ HaH6oJiee Ba)l(HbIX CTa.llHH

cneKaHH.ff, Tpe6y10ma.H BblCOKHX TeMnepaTYP H,llOCTaTO"IHO 60JiblllOH

)J)IHTeJibHOCTH Bb,llep)l(KH (HanpHMep, HeCKOJlbKO COTeH "laCOB) npH

M30TepMH4eCKOM Harpeee. ToJibKO ee JaeepllleHMe MO)l(eT npHBeCTH K nOJIY4eHHIO 6ecnopMCTOf0 (KOMnaKTHoro) nopOlllKOBOfO reJia, HO qaCTO 3TO OKa3bIBaeTC.ff 3KOHOMH4eCKH HeUeJiecoo6pa3HblM HJIH npaK­

TH"leCKH He,llOCTH)l(HMbIM.

YKpynHeHue (Koa.11ecu,eHU,Ufl) nop JaKJIIO"laeTCH B pocTe KpynHh X nop 3a C"leT yMeHbllleHHSI pa3MepoB H HC4e3HOBeHH.ff MeJIKHX, H30JIHpO­ BaHHblX nop. 06ma.H nopHCTOCTb npM 3TOM coxpaH.HeTCSI HeHJMeHHOH, a q11cJ10 nop yMeHbrnaeTCH npM yeeJIM"leHHH MX cpe.aHero pa3Mepa. YnJIOTHeHMe nopornKoeoro TeJia Ha TIOH CTa.aMM cneKaHMH He npo11c-

xo.a11T.

 

14.1.2.,QBMlKY°-'Me CMnbl cneKaHMH

 

B HCXO,llHOM COCTOSIHHH (.ao Harpeea) nopOlllKOBOe TeJIO npe,llCTaB­ JISleT co6oif CHCTeMy, y.aaneHHYIO OT COCTOSIHHSI TepMO,llHHaMMl{eCKOfO

paBHOBeCHSI O,llHOBpeMeHHO no MHOfHM napaMeTpaM. 3To CB.H3aHO npe)l(,lle ecero c HaJIH"IHeM CHJlbHO pa3BHTOH CB060,llHOH noeepXHOC­ TH OT,lleJibHb X nopolllHHOK (Me)l(cpa3Ha.H noeepXHOCTb pa3,lleJia eeme­ CTBo-nycTOTa) H nosepXHOCTH Me)l()ly,llHCnepCHb MH 3JieMeHTaMH HX CTpYKTYPbl (pa3BeTBJieHHa.H ceTKa Me)l(KpHCTaJIJIHTHb X rpaHHU, MHKPOnOJIOCTH BHyTpH nopolllHHOK H.ap.), a TaK)l(e c.aecpeKTHOCTblO caMOH KpHCTaJIJIHl{eCKOH CTpYKTYPbl semecTBa.

IlpH: Harpese ceo6o.aHaH 3HeprHH nopornKosoro TeJia.llOJI)l(Ha no­

HH)l(aTbCH Ja C"leT H3MeHeHHH B CHCTeMe, CTpeMSIIUHXCSI KaK MHHH­

MH3MpOBaTb nosepXHOCTH mo6oro BH,lla, TaK H yMeHblllHTb KOHUeHT­ paUHIO MHKpOHCKa)l(eHHH B 3JieMeHTaX CTpyKTypblnopOlllHHOK.

Ilpouecc npeepameHMH nopolllKOBoro KOHfJIOMeparn B nJIOTHOe TeJIO MO)l(HO paccMaTpMBaTb KaK aHaJIOf XHMH' eCKOH peaKUHH H xa­ paKTepH30BaTb TepMO,llHHaMM"leCKHM ypaBHeHHeM nOHH)l(eHH.ff CB0-

6o;LlHOH 3HeprnH /J.F:

!J.F = !J.H - T · !J.S, (14.1)

r.ne !J.H H /J.S - HJMeHeHMe TenJiocq.nep)l(aHHSI H 3HTpOnHH CHCTeMbl COOTBeTCTBeHHO.

TaK KaK npM cneKaHMH o.nHocpaJHOH CHCTeMhIHe npo11cxo.nMT Ja-

MeTHoro HJMeHeHHSI ee XHMH"leCKOfO COCTaBa, Heo6XO.llHMOe)J)I.ff npe­ BpameHHSI MCXO.l(HOH nopMCTOH MaCCbl B nJIOTHOe TeJIO noHH)l(eHH: CB060.l(HOH 3HeprnH noJIHOCTblO CB.H3aHO c yMeHbllleHHeM CB060.l(HOH noeepXHOCTH, ceoifcTBeHHOH cneKaeMOMY nopolllKOBOMY reJiy. YMeHh­ rneHMe nJIOIUa.l(H noeepxHOCTH COOTBeTCTByeT yMeHbllleHHIO.l(OJIH noeepXHOCTHOH 3HeprnH B o6meii (cyMMapHOH) CB060.llHOH 3HeprHH

 

CHCTeMbl..l(pyrHMH CJIOBaMH, HarpeBaeMaH Macca Bemecrna TIO,lJ,Bepra­ eTCH H3MeHeHHHM, CTpeMHlll.HMCH MHHHMH3HpOBaTb B HeH CB06o.n.­

HYJO TIOBepxHOCTb. c 3TOH TQqKH 3peHHH MO)l(HO paCCMOTpeTb mo6y10

s - TIJIOlll.a,lJ,b 3TOH noBepXHOCTH pa3,lJ,eJia.

L(aBJieHHe !l.p MO)J{HO HaHTH H3 YCJIOBHH MHHHMyMa TepMO,lJ,HHaMH­

qeCKOfO TIOTeHUHaJia d<I> = 0 npH + v2 = const:

H3 rneCTH OTIHCaHHb X Bbillie CTa,lJ,HH H y6e,lJ,HTbCH, qTo Ha KIDK)J,OH H3 HHX npoHCXO,lJ,HT yMeHbllieHHe TIOBepXHOCTH; qeM 60Jibllie cyMMapHaH

!l.p = p1

- p2

= aJ dS/ dV). (14.5)

TIJIOlll.a,lJ,b TIOBepXHOCTH H KOHUeHTpaUHH.n.ecpeKTOB B HCXO,lJ,HOM no­

pOllIKOBOM TeJie, TeM 60Jibllie H.D.BH)l(}'lll.He CHJibl.D.JIH BCex CTa,lJ,HH npouecca ero cneKaHHH.

L(pyroii no.n.xo.n., TO)J{e OCHOBaHHb H Ha repMO,lJ,HHaMffqeCKHX npHH­ UHnax, Be,lJ,eT K 6011ee «MeXaHHqecKOH» KOHUeTIUHH.D.Blll.HX CHJI

cneKaHH5(. TipH,lJ,OCTaToqHo Bh COKHX TeMnepaTYpax.D.JIH rnep.n.oro TeJia B CBH3H c Bb COKOH TIO,lJ,BH)l(HOCTblO aTOMOB MO)l(HO cqHTaTb, qTo no­ BepXHOCTHaH 3HeprHH 3KBHBaJieHTHa TIOBepXHOCTHOMY HaTH)J{eHHIO,

T. e. CHJie, CTpeMHlll.eHCH yMeHhllIHTb TIJIOlll.a,lJ,b TIOBepXHOCTH H TIOHH- 3HTb H36bITOK 3HeprHH, CBH3aHHblH c BeJIHqHHOH TIOBepXHOCTH. B CBH- 3H c,lJ,HcnepCHOCTblO HarpeBaeMOH nopOllIKOBOH MaCCbl K cneKaHHIO npHMeHHMbl KJiacc11qecKHe TepMO,lJ,HHaMHqeCKHe ypaBHeHHH KanHJI­ JIHpHOCTH, CBH3b1BaJ0111.He TIOBepXHOCTHOe HaTH)J{eHHe, KpHBH3HY no­ BepXHOCTH H BHYTpeHHee.n.aBJieHHe.

MexaH11qecKoe paBHoBecHe Ha rpaHHUe.D.Byx cpa3, pa3.n.e11eHHh X HeTIJIOCKOH TIOBepXHOCThlO, MO)l(HO oueHHTb ypaBHeHHeM JlaTIJiaca.

HcKpHBJieHHe noBepxHoCTH 03HaqaeT H3MeHeHHe noBepxHoCTHOH 3HeprHH, TaK KaK npOHCXO,lJ,HT H3MeHeHHe TIJIOlll.a,lJ,H TIOBepXHOCTH. c

HaJIHqHeM HCKpHBJieHHOH TIOBepXHOCTH pa3,lJ,eJia CBH3aHa CHJia HJIH

noBepXHOCTHOe (Me)J{cpa3HOe).n.aBJieHHe !l.p, 51.BJIHIOlll.eecH pa3HOCTblO

.n.aBJieHHH p1H p2Ha rpaHHUY pa3.n.e11a co CTOpOHhIcoorneTCTBYJOlll.HX cpa3:

 

(14.2)

PaBHOBec11e cpa3 He npe.n.noJiaraeT paBeHCTBa.n.aBJieHHH co cTopo­

HhI KIDK)J,OH H3 cpa3 H ocymecTBJIHeTCH, Kor.n.a B HHX 6Y.D.YT paBHbl TeMnepaTypbl (Tl = = T) H XHMHqecKHe TIOTeHUHaJihI:

µI(P p T) = µ2(P2• T) = µ npH +"'2 = const, (14.3)

r.n.e H "'2 - 06beMblcocymecTByIOlll.HX cpa3; µI H µ2 - XHMHqecKHe TIOTeHUHaJiblcpa3.

TepMO.D.HHaMHqecKHH noTeHUHaJI CHCTeMhI c yqeTOM rpaHHqHoii 3HeprHH HMeeT BH.D.

(14.4)

r.n.e a.1,2 -y.n.eJihHaH TIOBepxHOCTHaH 3HeprHH Ha rpaHHUe pa3,lJ,eJia cpa3;

YqHThrnaH, qrn.D.JIH KIDKJJ.OH ToqKH noBepxHocTH Me)J{cpa3HOH

rpaHHUhl cnpaBe,lJ,JIHBO BhJpa)J{eHHe

dS / dV = (l/R) + (I/), (14.6)

r.n.e RI H - rnaBHbJe pa.n.HYChl KPHBH3Hhl, ypaBHeHHe (14.5) MO)J{­ HO nepen11caTh:

!l.p = Pi - P2 = a.1,2[(1/ RI) + (1/)] y[(l / RI) + (1/)], (14.7)

r.n.e y - TIOBepXHOCTHOe HaTH)J{eHHe (cHJia, CTpeMHlll.aHCH yMeHbllIHTb TIJIOlll.a,lJ,b TIOBepXHOCTH), KOTOpoe.D.JIH TeMnepaTyp cneKaHHH npHMepHO

COOTBeTCTByeT a.1,2' T. e. y a.1,2"

qaCTHblH CJiyqaii ypaBHeHHH (14.7).D.JIH ccpep11qeCKOH TIOBepXHOC-

TH, Kor.n.a R1= = R:

!l.p = 2a.1 / R 2y/ R. (14.8)

MexaHHqecKoe paBHOBecHe Ha Btterntteii noBepxttoCTH «llieHKH» (pHC. 218):

PT = Pn - y/[(l/p) - (l/x)], (14.9)

r.n.e pT -.n.aBJieHHe (ttanpH)f(ettHe) B rnep.n.oM TeJie (qacTHUe); p " -

.n.aBJieHHe co cTopOHhInophI. TipaKTffqeCKH Bcer.n.a x«a, a p«x H ypaB­

HettHe (14.9) npHHHMaeT BH,lJ,:

(14. IO)

Be11Hq11tta y/p npe.n.crnBJIHeT co6oii pacrnrnBa10111.ee ttanpH)J{ett11e, CTpeMHlll.eecH C,lJ,BHHYTh (paCTHHYTh) KpaH «llieHKH» B CTopotty nophl, a p " ecTh.n.aBJieHHe ra3a B nopax, npenHTCTBYJOlll.ee pacrn11peHHJO «rneii­

KH». Ec1111 pacrnrHBa10111.ee ttanpH)J{ettHe npeo611a.n.aeT tta.n. p ", TO KOH­

TaKT MO)J{eT paCTH, T. e. Me)J{cpa3HOe.n.aBJieHHe co CTOPOHbl rnep.n.oii cpa3bl H eCTb.D.Blll.aH cHJia npouecca pOCTa Me)J{qacTHqHblX KOHTaK­ TOB. B 6oJihllIHHCTBe c11yqaeB nopHCTOCTh cneKaeMoro nopornKoooro

TeJia B nepHO.D. poem '«UleeK» HBJIHeTCH OTKpblTOH H oen11q11Ha Pn 3K­

BHBaJieHTHa.n.aBJieHHJO aTMoccpephIcneKaHHH (npaKTHqecKH 0, 1 MTia), a pa.n.11yc p 06h1qtto oqetth MaJI. Tio3TOMY B ttaqane cneKaHHH c11e.n.yeT

O)J{H,lJ,aTb 3HaqHTeJihHOH.D.Blll.eH CHJibl -pT; Otta TeM 60Jibllie, qeM Bb llie noBepXHOCTHOe HaTH)J{eHHe H MeHbllie pa3Mep «UleHKH». c poc-

 

 

TOM «llleHKH» H yBeJmqeHHeM pa,aHyca p 3Ta.llBHxyIUCUI CHJia yMeHb­ rnaeTCH.

B rn6JI. 50 npHeeaeHbIHeKoTOpb1e JHaqeHHH y/p.

MexaHHqecKoe paeHoeecHe Me)l(tj:>aJHb X aaeJieHHH MH HJOJIHpo­ eaHHOH ctj:>epHqeCKOH nopbl pa,aHyca r Bb pa)l(aIOT KaK

pT = pn - 2 y/ r, (14.11)

rae eeJIHqHHa 2y/ r npeacrnBJIHeT co6oi1 HanpH)l(eHHe, CTpeMHIUeecH

a.n,pyraH CBH3aHa c HepaBHOBeCHOH KOHUeHTpaUHeH BaKaHCHH B6JIH-

3H H30fHyTOH noeepXHOCTH.

.Il.aBJieHHe napoB eemecTBa Hat(BOfHYTOH noeepXHOCThlO «llleHKH» H BhinYKJIOH noeepXHOCThlO qaCTHUhl MO)l(HO Bhlpa3HTh ypaBHeHHHMH (14.12) H (14.13) COOTBeTCTBeH HO:

(14.12)

YMeHblllHTb noeepxHOCTb nopbI nyreM yMeHbllleHHH ee pa3Mepa; B

p- - Po = 2yVo,

(14.13)

CJiyqae 2y/ r>pn yca,aKa nopbl B03MO)l(Ha H ee.l(BHxyIUeH CHJIOH HBJIH­

eTCH eeJIHqHHa -pT, KOTOpyIO MO)l(HO paccMaTpHBaTb KaK C)l(HMaIOIUee HanpH)l(eHHe,.n,eiiCTBYJOIUee Ha Me)l(QJa3HYJO rpaHHUY co CTOpOHblTBep­

.n,oro TeJia B o6JiaCTH, OKpaIOIUeH nopy. lpe.n,noJIO)l(HTb eeJIHqHHY

Pn B Ka)l(.l(OM OTL{eJibHOM CJiyqae oqeHb TpY.llHO. c O.l(HOH CTOPOHbl, B

peJyJibTaTe yeeJIHqeHHH TeMnepaTypbl npH Harpeee, yMeHbllleHHH

o6beMa nopbl, o6pa3oBaHHH napoB BO.llblB CBH3H c BOCCTaHoBJieHHeM OKCH.nOB Ha noeepxHoCTH nopbI, HcnapeHHH eemecTBa H npoqHx tj:>aK­

p 0 RTa

rae p -.n,aeJieHHe napa eemecTBa Ha.a HJOfHyTOH noeepxHoCThIO; Po -

.n,aBJieHHe napa eemecTBa Ha.ll nJioCKOH noeepxHoCThIO; - o6beM aToMa HJIH MOJieKYJihleemecTBa qaCTHUbl B TBep.n,oM COCTOHHHH; R -

raJOBCUI nocTOHHHaH.

IlpeHe6peraH eeJIHqHHOH 1/x, KOTopaH MHOfO MeHbllle 1/p, ypaB-

HeHHe (14.12) npHHHMaeT BH.l(

ropoe 3Ta eeJIHqHHa MO)l(eT 6bITb > 0, 1 Mila. C.n,pyrow cTopoHhI,

BCJieL{CTBHe B03MO)l(HOfO OKHCJieHHH qaCTHU cneKaeMOfO eemecTBa,

.n,HtjJQ:>yJHH raJOB H3 nopbl H apyrnx npHqHH tJ,aBJieHHe ra3a B 3aMKHY­

- p - Po =- yVo -· Po RT p

(14.14)

TOH nope MO)l(eT 6b Tb < 0, 1 MOa. OrMeTHM, qro 6oJiblllaH eeJIHqHHa

-pT BilOJIHe B03MO)l(Ha H paccMaTpHBaeMaH.ll,BHxyIUaH CHJia 6y.n,eT yee­ JIHqHeaTbCH c B03pacTaHHeM 3HaqeHHH noeepXHOCTHOfO HaTH)l(e­

HHH H yMeHbllleHHeM HaqaJihHOfO pa3Mepa nophl.

KpHBHJHa noeepxHOCTH qacTHUhI H «rneHKH» onpe.n,eJIHeT cyme­ CTBOBaHHe eme L{Byx.llBHxyIUHX CHJI cneKaHHH, OL{Ha H3 KOTOph X - OTJIHqHoe OT paBHOBeCHOfO tJ,aBJieHHe napa Ha,a TBep.n,h M eemecTBOM,

 

p, MKM   OoeepXHOCTHOC HaTlDKeHJ.le y,)lJ.IH/CM       0,001 49,5 98,7 197,5 0,01 5,0 10,0 19,8 0,1 0,5 1,0 2,0 1,0 0,05 0,1 0,2 10,0 0,005 0,01 0,02 20,0 0,003 0,005 0,01

T a 6 JI H u a 50. 3na'leHHJI y/p, KI'/MM2,B 38BHCHMOCTH OT BeJIH'IHH y H p

.Il.aBJieHHe napa.Ha,a BOfHyTOH noeepXHOCThlO «llleHKH» MeHbllle

(p<po), a Ha,ll BhinYKJIOH noeepXHOCThlO qacTHUbl 60J1hllle (p>po), 4eM Ha.Ll n11ocKoH noeepxHoCThIO. AHaJIOfH4Hhie paccy)l(.l(eHHH cnpaBeMH­ BhIH LlJIH JII06hIX.upymx noeepxHocTeH pa3Hoff KpHBH3Hhl. On11caHHaH

pa3HHUa B.uaBJieHHH napOB eemecTBa Ha.Ll noeepXHOCTHMH pa3JIH4- HOH KpHBH3Hhl COJ.n,aeT.l(BHxyIUyIO CHJIY MexaHH3Ma ero nepeHOCa qepe3 ra30BYIO tj:>aJy. 3Ta.llBH)l(YIUaH CHJia yeeJIH4HBaeTCH c B03pacTa­ HHeM JHaqeHHH noeepXHOCTHOfO HaTH)l(eHHH H KpHBH3Hbl noeepXHO­

CTH H yMeHblllaeTCH Ha npOTH)l(eHHH cneKaHHH.

<t>opMyJibl (14.12)-(14.14) He co.n,ep:>KaT MaCCbl 4aCTHU H, CJie.l(O­ BaTeJihHO, MOfyT 6hITh npHMeHHMhl K 4aCTHUaM, Macca KOTOpblX paB­ Ha HYJIIO, T. e. K y3JIOBhIM eaKaHCHHM B KpHCTaJIJIH4eCKOH perneTKe

eemecTBa. Ha 3TO enepBhie o6paTHJ1 BHHMaHHe EJI. n11HeC, KOTOphlM

LlJIH oueHKH OTKJIOHeHHH KOHUeHTpaUHH BaKaHCHM OT paBHOBeCHOH

H3-3a KpHBH3Hhl Me:>Ktj:>a3HOH rpaHHUbl npeL{J]O:>KHJI ypaBHeHHH LlJIH o6JiaCTH «llleHKH» (14.1 5) H BbmyKJIOH noeepXHOCTH 4aCTHUbl (14.16):

(14.15)

(14.16)

r.ne c - KOHUeHTpaUHH BaKaHCHH B npHKOHTaKTHOM o6JiaCTH eew,e­ CTBa B6JIH3H «llleHKH» HJIH BbinyKJIOM noeepXHOCTH 4aCTHUbl; co -

paBHOBCCHaH KOHUCHTpaUHH BaKaHCHH, co =e-E,lkT (E - 3HepmH

o6paJoeaHHH yJJioeoH- eaKaHCHH; k - nocToHHHaH EoJIUMaHa); npH TeMnepazype nJiaBJICHHH eemecrna co o6billHO COCTaBJIHeT BeJIHllHHY

He Bblllle 10-3-10-4, a npH KOMHaTHOH TeMnepazype nopH.LJ;Ka 10-1s.

TaKHM o6pa30M, cymecrnyeT paJHOCTb (rpa.LJ;HCHT) KOHUCHTpaUHH BaKaHCHH Me)l(,l(y paJJIHllHbIMH no pacnOJIO)J(CHHIO B o6beMe noporn­ KOBOfO TeJia noBepXHOCT5IMH H Me)l(,l(y noeepxHOCTHMH pa3HOH KpH­ BHJHbl. 3ToT rpa.ri:HeHT KOHUCHT)JaUHH BaKaHCHH npe.LJ;CTaBJIHeT co6oH

.LJ.BHIUYIO CHJIY.ri:ml>ct>YJHOHHoro TpaHcnoprn eemecrna. Ha nporn­

)J{CHHH cneKaHHH 3Ta.LJ;BHIUaH CHJia YMCHbrnaeTCH, TaK KaK y6b1Ba­ CT rpa.ri:HeHT KOHUCHTpaUHH BaKaHCHH Me)l(,l(y paJJIHllHblMH yqaCTKa­ MH nopOlllKOBOfO TeJia.

.lJ.Hct>cl>YJHOHHbIH TpaHcnopTHbl H MexaHHJM MO)J{CT 6b Tb CBHJaH eme

c O.LJ;HOH.LJ;BHIUCH CHJIOH, onpe.ri:eJIHCMOH HepaBHOBCCHOCTbIO KOH­

UCHTpaUHH BaKaHCHH c B6JIH3H HJOJIHpoeaHHOH cct>epHllCCKOH nopbl pa.ri:Hyca r:

(C - C0)/C0 = 2yV/ k Tr. (14.17)

B TBep.ri:oM eemecrne B6JIHJH paccMaTpHBaeMoH nopb1 KOHUCHTpa­ UHH BaKaHCHH c Bblllle paBHOBCCHOH (pHC. 219) H TeM 60Jibllle, lleM

MeHbllle paJMep nopbI. CJie.LJ;oBaTeJibHo, Me)l(,l(y o6JiacrnMH cneKaeMo­ ro nopornKoeoro reJia, Y.LJ.aJieHHbIMH OT noeepxHOCTeH MeJIKHX cct>e­

 

KOHUCHTpaUHH BaKaHCHH Me)l(,l(y rpaHHUaMH JepeH, HaXO.LJ.HIUHMHCH

no.LI. pa3HblMH no BeJIHllHHe HJIH JHaKY HanpH)J{CHHHMH, npe.LJ.CTaBJIH­ eT co6oH-.LJ.BIUYIO CHJIY MexaHHJMa nepeHoca eemecrna, CBHJaH­ HOro c npoueccoM.LJ.Hcl>cl>YJHOHHOH noJIJyqeCTH.

 

MexaHM3MbI MacconepeHoca

 

B HarpeeaeMoM nopornKOBOM TeJie BOJMO)J{Hbl cJie.LJ.yIOmHe Mexa­ HHJMbITpaHcnoprn eemecrna: nepeHoc llepeJ raJoey10 ct>aJy; noeepx­ HOCTHaH.LJ.Hcl>cl>YJHH; o6beMHaH.LJ.Hcl>cl>YJHH; BHJKOe TelleHHe; TelleHHe, BbIJbIBaeMoe BHelllHHMH HarpyJKaMH (rop51qee npeccoBaHHe, cneKa­ HHe no.ri: ii,aBJICHHeM H noii,o6Hble CJiyqaH).

BnepBbie (I949 r.) Jaii,aqy o epe­

MeHH6H JaBHCHMOCTH xop.LJ.bI x (pa.ri:H-

yca KOHTaKTa) pelllHJI)I(. KyqHHCKHH x2-t;M..o x5 -t;M=O x5-t;t.L..a

.LJ.JIH TJJCX MexaHHJMOB MacconepeHOCa

- o6beMHOH H noeepXHOCTHOH.LJ.Hcl>­ cl>YJHH, a TaK)J{e nepeHoca qepeJ raJo­ BYIO cl>aJy.,ll.JIH 3TOfO HM 6bIJIH HCnOJib­ JOBaHbl 4 MO.LJ.eJIH HJ KpHCTaJIJIHlleCKHX

TeJI: cct>epa- nJiocKOCTh; ii,ee cct>epbI, a 8

PHlleCKHX nop, H 3THMH noeepXHOCTHMH, a TaK)J{e Me)l(,l(y COCC.LJ;HHMH

nopaMH paJHOfO paJMepa TaK)J{e cymecTByIOT rpa.LJ;HCHTbl KOHUCHTpa­

UHH BaKaHCHH, onpe.ri:eJIHIOIUHe HanpaBJieHHe.LJ.Hcl>cl>YJHOHHoro nepe­ Hoca eemecTea.

. fpa.ri:HeHT KOHUCHTpaUHH BaKaHCHH MO)J{CT 6bITb TaK)J{e CBHJaH c

TeM, llTO BHYTJJH llaCTHU MC)J{JepeH­

KOHTaKTHPYIOIU HC B TOlJKe; CTep)J{eHb­

HaBHTaH Ha Hero npOBOJIOKa; nyqoK npoBOJIOK. KyqHHCKHH yKaJaJI, llTO B o6JiaCTb KOHTaKTHOfO neperneHKa Be­ meCTBO MO)J{CT nepeHOCHTbCH He TOJib­ KO BCJie.LJ.CTBHe TpaHcnopTa B o6beMe

x 1-t;M=O x 5 -t;t.L=O x 4 -t;M<FO

Hbie (MC)J{KpHCTaJIJIHTHbl e) rpaHH­

06pa3ua, HO H HHblMH TpaHcnopTHbl ­ z a e

• • • • •

•.•·.·••·••:a

• • •••••

• •• • ••

Ubl HaXO.ll;HTCH no.LJ. HanpH)J{CHHCM H KOHUCHTpaum1 BaKaHCHH c B6JIH3H

HHX OTJIHllaeTCH OT paBHOBeCHOH C:

C = C0 exp(cr V/k 7), (14.18)

MH nyrnMH - no ero ceo6oii,Hoi1 no­

eepxHoCTH H qepe3 OKpy)J{aJOIUYIO ra­ JOBYIO cpeii,y.

KHHeTHKa npHneKaHHH oii,Hocl>aJ­

HbIX qacTHU, KOHTaKTHPYIOIU HX B TOll­

 

P11c. 220. CxeMa pa31111'1HhtX Me­ xaHl13MOB B3lll1MHOro np11neKaHl1SI

TBCptl,bl X c<t>ep1111eCKl1X '!aCT11U, KOH­ TaKT11pyt01Ul1X np11 t = 0 B TO'!Ke (t.l -113MCHCHl1C paCCTOSIHl1H MC)l(­

• • f.LJ.e cr - HanpH)J{CHHe,.LJ.CHCTBYI01Uee Ha MC)J{JepeHHOH (Me)J{KpHCTaJI­

JIHTHOH) rpaHHUe (noJIO)J{HTeJibHOe

e cJiyLJae pacrnrnea10mero H OTJJH­ uaTeJibHoe B cJiyqae C)J{HMa10mero

Ke (pHc. 220), B npouecce HJOTepMH­ LJeCKOH BbI.LJ.ep)J{KH MO:>KeT 6bITb onHCa­

Ha ypaBHeHHeM BH.LJ.a

x"('r) = A(T)t HJIH x" - t,

llY UCHTpaMl1 'lllCT11U): a - BSl3Koe

TC'ICH11e; 6 -o6beMHaSI n11<1>lf>Y311SI,

He np11eonst1Uast K ycanKe; s - o6beMHtlSI n11<t>lf>Y311SI np11 HMl1'11111 CTOKa B o6JJaCTl1 KOHTaKTa; i! - no­

eepXHOCTHtlSI n11<1><Py311si; iJ - ne­

P11c. 219. CxeMa (a) 11 rpa<!>11K (6)

pacnpct1,CJICHl1SI HaKaHC11H B6JJl1311 nopbt

YCHJIHH). BoJHHKaIOIUHH rpa.LJ.HCHT

me n - noKaJaTeJib CTeneHH, JaBH­

CHIUHH OT KOHKpeTHOfO TpaHcnopTHOfO

peHoc BCIUCCTBtl '!epe3 raJOBYIO

lf>aJy; e - np11neKaH11e non BJJHst­ HHeM npH)l(HMtllOIUHX yc1111111i

MexaHHJMa nepeMemettHH eemecrna; x" (t) - HJMeHettHe pa,n,Hyca Me)l(qCTWIHOro KOHTaKTa BO epeMeHH npH H30TepMH'IeCKOM BbI,Uep)((Ke t; A(1) -QlYHKUHH, KOHKpeTHblH BH,ll, KOTOPOM JaBHCHT OT TeMnepa­

TYPbl cneKaHHH, reoMeTpHH npHKOHTaKTHoro yqaCTKa H Tex KOHCTaHT eemecrna, KOTOpb e onpe,LI,eJIHIOT OCHOBHOM MexaHH3M npHneKaHHH (TeMnepazypbInJiaBJieHH!f, TeMnepazypbIKHneHHH,,LI,ecpeKTHOCTH qa­ CTHU, COCTOHHHH noeepXHOCTH qaCTHU, XHMWi eCKOfO COCTaBa MaTe­ PHaJia H,LI,p.).

<l>opMyJia 04.19) c yqeTOM H3MeHeHHH pa,n,Hyca a caMOM KOHTaKTH­

pyiomeH: 'IaCTHUblMO)l(eT 6b1Tb JanHCaHa no-,LI,pyroMy:

 

x"

51.E. feryJHH noJiyqHJI ypaetteHHH, COOTBeTCTBYIOIUHe,LI,BYM npe­

,LI,eJibHblM CJiyqaHM:

a),ll,JIHHa ceo6o,LI,ttoro npo6era MOJieKyJI (aTOMOB) eemecrna 'A npe­ eocxo,LI,HT JIHHeHHbl H pa3Mep o6JiaCTH KOH,LI,ettcau;HH ('A» p, T.e. Ma­

Jlble,LI,aBJieHHH aTMoccpepb1 cneKaHHH):

x3/ a = (18/n)0•5 (µ/ R1) 1 •5 (8pof d2) t HJIH x3/ a - t, (14.22)

r,LI,e µ - Macca ttarpeeaeMoH: 11acTHUbI; d - nJIOTHoCTb eemecTea 11ac­ THUbI B KOH,LI,eHCHpoeaHHOM cpa3e;

6),ll,JIHHa ceo6o,LI,Horo npo6era MoJieKYJI (aToMoB) eemecrna MeHb­ we JIHHeHHOfO pa3Mepa o6JiaCTH KOH,LI,ettcau;HH ('A «p, T.e. 60JibWHe

-;;{t) = A'(T)t,

a

(14.20)

,LI,aBJieHHH raJOBOM aTMOCcpepbl cneKaHHH):

r,LI,e m -noKaJaTeJib CTeneHH, 3aBHCHIUeM OT KOHKpeTHOfO TpaHcnopT­

x5/ a

= {40yp08 /(n(6µR1) •

p']} HJIH x5/ a

- t, (14.23)

2 4 0 5 2

HOfO MexattHJMa nepeMeIUeHHH eemecTea.

IlpH yca,n,Ke ccpepH'IeCKOM nopbl JaBHCHMOCTb H3MeHeHHH ee pa­

,ll,Hyca OT epeMeHH 6y,LI,eT aHaJIOrH'IHOM.

llepeHoc «ew,ecmBa ttepe3 za30By10 <jJa3y. H,LI,eaJibHaH MO,LI,eJib,,LI,eMOH­

CTpHPYIOIUaH 3TOT BH,ll, TpattcnopTHOro MexaHH3Ma, npHBe,LI,eHa Ha pHC. 220, a. B CBH3H c JaBHCHMOCTblO ynpyroCTH napa Ha,D, noeepxHOC­

TblO OT ee KpHBH3Hbl, eemecTBo HcnapHeTCH c BbinYKJibIX yqacTKOB qacTHU H KOH,LI,eHCHpyeTCH Ha BOrHYTOM noeepxHOCTH KOHTaKTHbIX ne­ perneMKOB. 3TOT MeXaHH3M lJaCTO eme Ha3bIBalOT «HCnapeHHe- KOH­

,LI,eHcau;HH». Ott,LI,OJI)l(eH npHBO,LI,HTb K poczy «rneeK» H ccpepoH,LI,HJaUHH nop H 6y,LI,eT,LI,eMCTBOBaTb,ll,O Tex nop, noKa B nopolIIKOBOM TeJie co­ xpaHHeTCH 3aMeTHaH pa3HHUa B KpHBH3He Me)((,l(y OT,ll,eJibHbIMH yqaCT­ KaMH noeepxttocTH paJ,LI,eJia eemecrno- nopa. HanpaBJieHHbIM nepe­ Hoc eemecrna B 30HY Me)l('laCTH'IHOro KOHTaKTa npHBO,ll,HT K ynpo'l­ HeHHIO H yJiyqrneHHIO 3JieKTponpOBO,ll,HOCTH nopOlIIKOBoro TeJia, HO He MO)l(eT Bbl3BaTb H3MeHeHHe ero 06beMa, T.e. yca,LI,KY.

B JIHTeparype npHBO,LI,HTCH paJJIH'IHbie KOJIWiecrneHHbie JaBHCHMOCTII

KHHeTHKH poem «lIIeeK» no MexaHH3MY HCnapettHe- KOH,LI,eHcau;HH. TaK, ypaetteHHe KyqHHcKoro HMeeT BHLI.

0

x3/ a = (9n/ 2MR1)0•5 yp t HJIH x3/ a - t, (14.21)

r,LI,e M - MOJieKYiiHpHaH (aTOMHaH) Macca eemecrna; t - npo,LI,oJI­

)l(HTeJibHOCTb H30TepMHlJeCKOM Bb,LI,ep)((KH npH cneKaHHH.

Y EJI. IlHtteca attaJiom11ttoe Bbipa)l(ettHe,ll,JIH npHneKaHHH HMeeT BH,ll,.

 

x7/a3 - t.

r,LI,e 8 - napaMeTp KpHCTaJIJIH11ecKoi1 perneTKH eemecrna; p' -,LI,aeJie­ HHe raJa aTMoccpepbI cneKaHHH.

IlepeHOC eemecTBa qepe3 raJOBYIO cpa3y aKTHBHpyeTCH c yeeJIH­ lJeHHeM TeMnepazypbl (po 3KCnoHeHUHaJibHO pacTeT c TeMnepazypoii), napu;HaJibttoro,LI,aeJieHHH napa eemecrna H noeepxttocTttoro ttaTH)l(e­

HHH.

PaccMaTpHeaeMbIH MexaHHJM MO)l(eT HrpaTb cKOJibKO-HH6y,LI,b cy­ mecTeeHHYIO pOJib JIHlIIb,ll,JIH MaTepHaJIOB c OTHOCHTeJibHO BbICOKHM

,LI,aBJieHHeM napoe npH TeMnepazype cneKaHHH (He HH)l(e I-I0 Ila),

T.e. KOr,LI,a KOJIH'leCTBO nepeHeCeHHOfO qepe3 raJOBYJO cpa3y MaTepHaJia MO)l(eT 6bITb 3HalJHTeJibHbIM, JIH60,ll,JIH cneKaHHH MeTaJIJIOB c BOCCTa­ HaBJIHBalOIUHMHCH HJIH,LI,Hccou;HHPYIOIU HMH oKcH,LI,aMH. B nocJie,LI,HeM CJiyqae,LI,aBJieHHe napoe MeTaJIJia Ha,D, noeepxHoCTblO 11aCTHU nopornKa

npH Harpeee 6y,LI,eT 60JibWe, lJeM MOHO O)l(H,ll,aTb, HCXO,ll,H H3 ynpyro­ CTH napoe Ha,LI, noeepXHOCTblO KOMnaKTHOfO MeTaJIJia: B npouecce BOC­ CTaHOBJieHHH HJIH,ll,HCCOUHaUHH OKCH,LI,a BXO,ll,HIUHe B Hero aTOMbl Me­ TaJIJia BbICB060)((,l(alOTCH H o6Jia,D,alOT noBbIWeHHOH no,LI,BH)l(HOCTblO, 06Jier11aiomei1 HX nepexo,LI, e napoeyio cpaJy.

lloBepxHocmHaR ou</J<Py3ua. Ha cxeMe B03MO)l(H0f0 BJaHMO,LI,eMCTBHH

,LI,Byx conpHKaCalOIUHXCH ccpepH'leCKHX qaCTHU, HJIJIIOCTpHpyiomeH: H,LI,eaJIH3HpOBaHHbIM 3JieMeHT npouecca cneKaHHH (pHC. 218, 6), noKaJa­

HO, 11To nocJie ttarpeea H Bb,LI,ep)l(KH npH onpe,LI,eJieHHOM TeMnepazype OHM qepe3 HeKOTOpoe epeMH CpaCTalOTCH. IlepeHOC BeIUeCTBa B 3TOM CJiyqae npoHCXO,ll,HT K noeepXHOCTH o6pa3YIOIUHXCH nepeMbI'leK, KaK 3TO noKaJaHo CTpeJIKaMH, H qacTHLJ,bl c6JIH)l(alOTCH, Bbl3bIBaH o6myio yca,LI,KY eceii CHCTeMbI; yeeJIH'leHHe KOHTaKTHOH noeepXHOCTH H C6JIH­

)l(eHHe qacTHU (yca,LI,Ka) npH cneKaHHH no 3TOH cxeMe CBH3aHO c

 

 

noeepxHOCTHOH,UHcpcpyJHeH JierKono,UBIDKHblX a,n,cop6HpoeaHHb X aTO­ MOB (a,n,aTOMOB) H nepeMemeHHeM aTOMOB B TOHKOM.uecpeKTHOM no C(TpYKTYPe noeepXHOCTHOM CJIOe TOJIIUHHOH 8s. CTpH 3TOM HCXO,USIT HJ

TOfO, l.fTO nO,UBH)l(HOCTb noeepXHOCTHbl X aTOMOB JaBHCHT OT JaHHMa­

eMOfO HMH Mecm: HaHMeHee no,UBH)l(Hbl aTOMbl, Jie)l(aIUHe BHyTpH KOHTaKTHblX yqaCTKOB; JaTeM, B nopSI)lKe BOJpaCTaHHSI no,UBH)l(HOC­ TH, HJlYT aTOMbl Ha rpaHHuax KOHTaKTHblX yqacTKOB, aTOMbl B yrny6-

JieHHSIX H ena,D,HHaX noeepXHOCTH, aTOMbl Ha pOBHblX yqaCTKaX H, Ha­ KOHeu, aTOMbl Ha BblCTynax noeepXHOCTH. TaK KaK aTOMbl Ha KOHTaKT­ HblX yqacTKax MeHee no,aBH)l(HbI, o6Jia,aaSI MeHbIIIHM JanacoM ceo6o.u­ HOH 3HepruH, qeM Ha ecex JlPYfHX yqaCTKaX noeepXHOCTH, TO OT CB0- 60,UHblX, HeKOHTaKTHblX yqaCTKOB K KOHTaKTHblM nepeXO.UHT JHalfH­ TeJibHO 6oJibIIIe aTOMOB, lfeM B o6paTHOM HanpaeJieHHH. B peJyJihTaTe npOHCXO)lHT paCIIIHpeHHe KOHTaKTHOfO yqaCTKa c O)lHOBpeMeHHblM c6JIIDKeHHeM reoMeTpHl.feCKHX ueHTpOB conpHKacaIOIUHXCSI l.faCTHU,

T.e. npOHCXO.UHT yca,n,Ka.

0.uHaKo O.UHHM HJ rnaBHblX He,UOCTaTKOB paCCMOTpeHHOH cxeMbl SIBJISieTCSI TO, 'ITO B HeH He npe)lCTaBJieHa nopa - OCHOBHOH 3JieMeHT CTpYKTYPblpeaJibHOfO nopOIIIKOBOfO 6pHKeTa. CT03TOMY B JII060H CHC­

TeMe ynpomeHHOfO HJo6pa)l(eHHSI Heo6XO)lHMO noKaJaTb no MeHb­ IIIeH Mepe TpH conpHKaca10mHecS1 qacTHUbI(pHc. 218, a). Tor.ua He­ TpY.UHO JaMeTHTb, 'ITO l.fHCJIO aTOMOB, yxo)lSIIUHX c BbinYKJib X qacTeH

ceo60,UHb X noeepXHOCTeH nopbl, paeHO lfHCJIY aTOMOB, BXOMIUHX B meJIH, KOTOpble npHJieraIOT K KOHTaKTHbIM yqaCTKaM. CJie)lOBaTeJib­ HO, no)l BJIHSIHHeM noeepxHOCTHOH MHrpauHH aTOMOB nopa 6y)leT

ccpepOH)lHJHpoeaTbCSI (pHC. 218, 6), He HJMeHSISICb B o6beMe, H yca,n,Ka

6pHKeTa KaK peJyJibTaT noeepXHOCTHOH)lHcpcpyJHH npH H30TepMH­

HOCTHaSI.UH<t><t>YJHSI npHBO,UHT K yeeJIHlfeHHIO H COOTBeTCTBeHHO K

ynpoqHeHHIO Me)l(l.faCTH'IHblX KOHTaKTOB. 3TOT TpaHcnopTHb H Mexa: HHJM cneKaHHSI oco6eHHO 60JibIIIOe JHal.feHHe HMeeT B Hal.faJibHbIH

nepHO.U cneKaHHSI.

OpH JarpSIJHeHHH noeepxHoCTH paJJIHlfHoro po.ua XHMHlfeCKHMH npHMeCSIMH (oKCH,UaMH, MexaHHl.feCKHMH BKJIIOl.feHHSIMH UH T.n.), a

TaK)l(e Bb XO,UaMH Ha noeepXHOCTb.UHCJIOKaUHOHHblX JIHHHH, nepeHOC MaCCbl,Ua)l(e npH JHal.fHTeJibHOH,UHcpcpyJHOHHOH no,UBH)l(HOCTH a,n,a­ TOMOB He 6y.ueT HMeTb MeCTa. <l>HJHl.feCKH 3TO OJHaqaeT, l.fTO Ha no­

eepXHOCTH OTCyTCTByeT rpa,n,HeHT XHMHlfeCKOfO noTeHUHaJia (cpopMaJib­ HO Vµ = 0). 0pM 3TOM CJie,UyeT Yt.fHTbIBaTb, 'ITO HJ-Ja HaJIHl.fHSI Ha

noeepXHOCTH TaKHX «CTOnopOB», 3HeprHSI aKTHBaUHH npouecca MO­

)l(eT oKaJaTbCSI HaCTOJibKO BbICOKOH, l.fTO 6y.ueT COHJMepHMa c 3Hep­ rueH aKTHBaUHH o6beMHOH)lHcpcpyJHH. 0.uHaKO B TO)Ke epeMSI BeJIH­ l.fHHa K03cpcpHuHeHTa noeepXHOCTHOli)lHcpcpyJHH MO)l(eT cymecTBeH­ HO npeBOCXO)lHTb BeJIHl.fHHY K03cpcpHuHeHTa o6beMHOH)lHcpcpyJHH B CBSIJH c cymecTBeHHO 60JiblllHM JHal.feHHeM npe,U3KCnOHeHUHaJibHO­ ro MHO)l(HTeJISI, He JaBHCSIIUefO OT TeMneparypbl.

B o6JiaCTH 6oJiee BbICOKHX TeMnepaTYP B nepeHoce MaCCbI MOfYT

HrpaTb pOllb npHnoeepXHOCTHb e CJIOH, xapaKTepHJyIOIUHeCSI pa3l1Hl.f­ HOH cTeneHblO)lecpeKTHOCTH (npHl.fHHblKOTOpOH MOfYT 6bITb paJHbl­ MH, HanpHMep KpHBHJHa noeepXHOCTH, y.uaneHHe OT Me)l(cpaJHOli rpaHHUbl, nJIOTHOCTb.,UHCJIOKauHH, HaJIHl.fHe qepo,UHblX aTOMOB "

.up.) H COOTBeTCTBeHHO pa3lIHl.fHOH,UHcpcpyJHOHHOH no,UBH)l(HOCTblO B

HHX aTOMOB.

PocT KOHTaKTa e CBSIJH c nepeHocoM Macchino MexaHHJMY noeepx- HOCTHOH.UH<t><l>YJHH no 51.E. feryJHHY HMeeT BH)l

l.feCKOM cneKaHHH 6eJyCJIOBHO He MO)l(eT HMeTb MeCTO.

x7/ a3 = (28Dsy 8/ k 1)• HJIH x7/ a3

•. (14.24)

BMecTe c TeM e yeeJIHl.feHHH npolfHOCTH Me)l(l.facTHlfHOro cuenJie­ HHSI (OCHOBHOH npHJHaK cneKaHHSI) noeepXHOCTHaSI H npHnoeepx­ HOCTHaSI MHrpauHSI aTOMOB HrpaIOT oqeHb Ba)l(HYIO pOJib (3HepruSI aK­

THBaUHH HHJKa, a JHal.feHHSI Ko3cpcpHuHeHTOB caMo,aHcpcpyJHH Ds

BbICOKH), TaK KaK npOHCXO)lHT yeeJIHl.feHHe Me)l(l.faCTHl.fHb X KOHTaK­ TOB H 6eJ yMeHbllleHHSI CyMMapHOfO o6beMa nop. CToeepXHOCTHaSI)lHcp­ cpyJHSI aTOMOB BblJbIBaeT CfJia)l(HBaHHe noeepXHOCTH conpHKacaIOIUHXCSI lfaCTHU, 'ITO yeeJIHlfHBaeT HCTHHHYIO noeepXHOCTb KOHTaKTa H npH- 80,UHT K ccpepoH)lHJaUHH nop, a TaK)l(e o6ecnel.fHBaeT nepeMeIUeHHe aTOMOB c noeepXHOCTeH KpynHblX nop Ha noeepXHOCTb MeJIKHX (npH coo6ma10mHxcS1 nopax), T.e. e noJio)l(eHHe 6oJihIIIeH TepMO.UHHaMH­ qecKoH ycTOHlfHBocTH.

TaKHM o6paJOM, Ha ecex 3Tanax (cTa,D,HSIX) cneKaHHSI noeepx-

 

B Bbipa)l(eHHH (14.24) JlJISI noeepxHoCTHoro CJIOSI napaMeTp peIIIeT­ KH 8 no)lJle)l(HT JaMeHe Ha TOJIIUHHY CJIO 8s, B KOTOPOM,UHcpcpyJHSI

aTOMOB HMeeT MeCTO B Mepy BeJIHl.fHHbl K03cpcpHuHeHTa caMO,UHcpcpy­ JHH Ds; no KyqHHCKOMY l.fHCJieHHb H coMHO)l(HTeJih 28.UOJI)l(eH 6bITb JaMeHeH Ha 56.

OTMeTHM, 'ITO noeepxHOCTHaSI,aHcpcpyJHSI ol.feHh qyecTBHTeJihHa K

aTMoccpepe cneKaHHSI " ee COCTaBy, TaK KaK a,n,cop6UHSI Ha noeepXHO­ CTH HJ raJOBOH cpaJbl MO)l(eT cymecTBeHHO noBJIHSITb Ha BeJIHl.fHHbl y H

Ds

06oe.MHOR ou<f}(jJy3u11. B caMoM o6meM BH)le nepeMeIUeHHe aTOMOB e

06beMe qaCTHUbl (nopOIIIHHKH) npe,UCTaBJISieT co6oH: TpaHcnopTHbl H MexaHHJM, KOTOpbIH SIBJISieTCSI OCHOBOH MHOfHX npoueccoe, npoHC-

XOJJ;.SIIUHX B TBep,D,OM KpHCTaJIJIH' eCKOM TeJie, B TOM qHcJie H noporn­ KOBOM. <l>opMyJIHpOBaHHe H pa3BHTHe OCHOBHb X npe,D,CTaBJieHHH 0 MexaHH3Me,D,HQ>Q>yJHOHHOfO 6Jiy)K,[l,aHH.SI aTOMOB B KpHCTaJIJIHqecKOH

perneTKe CB.Sl3aHo c pa60TaMH 51.11. <l>peHKem:1: nepeMeIUeHHe aTOMOB

B KpHCTaJIJIHqecKOH perneTKe eCTb nocJie,D,OBaTeJibHOe 3aMeIUeHHe HMH BaKaHCHH, npHqeM K03Q><l>HUHeHT,D,HQ>Q>y3HH aTOMOB D CB.Sl3aH c pae­

HOBeCHOH KOHUeHTpauHeH BaKaHCHH co H K03Q><l>HUHeHTOM HX,D,HQ>­

<l>Y3HH D'eb pmKeHHeM

 

(14.25)

yKa3aHHbIX B Ta6JI. 51:

1. BowymOJ1 no6epxHocmb «1UeiiKu»-6blnyKJ10J1 no6epxHocmb itacmuu,.

BaKaHCHH,D,BC.SI H3 o6JiaCTH HX BblCOKOH KOHUeHTpaUHH e6m-t3H BOfHYTOH noeepXHOCTH «IIIeHKH» B o6JiaCTb 6oJiee HH3KOH HX KOH­

ueHTpaUHH B6JIH3H BbinYKJIOH noeepXHOCTH qaCTHU. IlpH 3TOM aTOMbl

,n,eHTC.SI e npoTHBonoJIO)l(HOM ttanpaBJiemrn. PeJyJibTaTOM 3Toro TpattcnopTHOro nYTH.SIBJI.SleTC.SI pOCT npHKOHTaKTHbIX yqaCTKOB, c<t>e­ pOHAH3aUHH nop. EcJIH aTOMb, «CTeKaIOIUHe» K eorHYTOH noeepxHo­ CTH «IIIeeK», H,D,YT JIHIIIb c noeepXHOCTH qacTHU, TO, KaK 3TO CJie,n,yeT

H3 paCCMOTpeHH.SI MO,D,eJIH H3 Tpex qaCTHU (pHC. 218, 6), He CJie,n,yeT

C yqeTOM BeJIHqHH C0= e-E, t kr H D' = D e -£, 1 kr (D

- TeMneparyp­

O)l(H,D,aTb yca,n,KH cneKaeMoro nopornKoeoro TeJia.

0 0

HO HeJaBHCHMa.SI eeJIHqHHa, E. - 3HeprH.SI aKTHBaUHH,D,BIDKeHH.SI aTo­

MOB HJIH BaKaHcHM:)

 

- oe - oe ' (14.26)

D - D -(E,+E,)t kT -D -E0 tkT

r,n,e £0- 3tteprn.SI aKTHBaUHH,n,H<t><i>YJHH.

OTMeTHM, qTo no HMeIOIUHMC.SI ouettKaM, eeJIHqHHa 3HeprHH 06- pa3oeattH.S1 eaKaHCHH E.,D,JI.SI 6oJibIIIHHCTBa MeTaJIJIOB cocTaBJI.SleT no­ P.Sl,D,Ka 1/3 OT 3HeprnH aKTHBaUHH,n,HQ>Q>yJHH £ •

HaJIHqHe H36bnoqHbIX BaKaHCHH (C > C) npHBO,D,HT K yeeJIHqe­

HHIO K03Q><l>HUHeHTa,D,H<l><l>Y3HH H, KaK npaBHJIO, K noHH)l(eHHIO ee

3HeprHH aKTHBaUHH £0.

,Un.SI onHCaHH.SI,D,HQ>Q>yJHOHHb X nOTOKOB aTOMOB HMeIOTC.SI,D,Ba ypae­ HeHH.SI <l>HKa:

m = -DS(oC/ox) (14.27)

2. Bowymaa no6epxHocmb «weuKU»-zpaHUU,bl 3epeH. BaKaHCHH,D,BH­

.SI qepe3 KpHCTaJIJIHqeCJ<YIO perneTJ<Y H3 o6JiaCTH KOHTaKTa K rpa­ HHUaM 3epeH, cymecTByIOIUHM BHyTpH qacTHU, r,n,e KOHUeHTpaUH.SI eaKaHCHH HIDKe. BaKaHCHH no ceTKe rpaHHU JepeH MOfYT Bb XO,D,HTb Ha ra6apHTHYIO noeepXHOCTb cneKaeMoro nopornKoeoro TeJia. ATOMhI,

,D,BHfa.SICb B npomeonoJIO)l(HOM HanpaBJieHHH,,D,OCTHraIOT npHKOHTaKT­ Hb X yqacTKOB, cnoco6crny.S1 pocry «IIIeeK» H cQ>epoH,D,HJaUHH nop. TaK KaK aTOMblMOfYT nocrynaTb OT BHeIIIHHX ra6apHTHb X noeepXHOCTeM:

 

T a 6 JI " u a 51. IlyrH AHciKllY3HH aroMOB H ee 3C1Hi>eKTW ope cneKaHHH nopOIDKOBblX Te.JI

 

J1CTO'IHHK H3fibITO'l­ HbJX BaKaHCHH CTOKH.ll.illl H36btTO'l­ HbIX BllKaHCHH   3<1xt>eKTbl OT,!l,H<lxt>YJHH aTOMOB     3•.     6' 7' 8'   BorHYTbie noeepxHo- CTH "weeK" To JKe   - " - noeepXHOCTb cQ>epH- 'leCKHX nop To JKe     - " - )].HCJIOK8UHH To JKe     rpaHHUbl JepeH BbmyKJibie noeepx- HOCTH 'laCTHU rpaHHUbl JepeH     )].HCJIOKaUHH noeepXHOCTH fioJiee KpynHbIX nop rpaHHUbl JepeH     )].HCJIOK8UHH rpaHHUbl JepeH noeepXHOCTH '18CTHU   rpaHHUbl JepeH PocT "weeK", cQ>epo11,a,11- JaUHll nop PocT "weeK", cQ>epo11,a,11- JaUHll H yca,a,Ka nop To JKe YKpynHeHHe (KOaJICCUeHUHll) nop YKpynHeHHe H yca,a,Ka nop To JKe     PocT "weeK", cQ>epo11,a,11- JaUHll nop PocT "weeK", yca,a,Ka nop

H

ac;at = D(a 2 c ax2), (14.28)

r,n,e m - KOJIHqecrno eemecrna,,n,HQ>Q>yH,D,Hpy10m ee e e,n,HHHUY epe­ MeHH qepe3 nJIOIUa,D,J<Y s npH rpa,n,HeHTe KOHUeHTpaUHH BaKaHCHH

oC/ox; 3HaK «MHHYC» 03HaqaeT, qTQ,D,HQ>Q>yJH.SI aTOMOB npoHCXO,D,HT B

crnpotty y6bIBaHH.SI HX KOHUettTpaUHH. OTMeTHM, qrn HaBcTpeqy no­ TOJ<Y aTOMOB,D,BH)l(eTC.SI paBHbIH HM no BeJIHqHHe (HO He Macce!) no­ TOK BaKaHCHH.

B rn6JI. 51 npHee,n,ettbIcee,n,eHH.SI 06 HCToqHHKax H36b T04HbIX ea­

KaHcHM: H MeCTaX (CTOKax), J<Y,D,a BaKaHCHH,D,BH)l(YTC.SI H r,n,e OHH «OCe­

,D,aIOT», a TaIOKe yKa3aHbl 3Q>Q>eKTbl, K KOTOpblM MO)l(eT npHBO,D,HTb 06beMHa.SI,D,HQ>Q>yJH.SI aTOMOB.

HH)l(e npHee,n,eHbI 6oJiee,n,eTaJibHbie xapaKTepHCTHKH cJiyqaee,

 

 

 

 

' CJIY'mll c'IHTaCTCll MaJioeepoHTHbIM.

 

cneKaeMoro nopOWKOBOro TeJia, CJie.uyeT npH3HaTb B03MO)l(HOCTb yca.u­ KH B pe3yJihTaTe TpaHcnoprn MaTepttaJia no 3TOMY nyrH. 0TMeTHM, 'ITO.UBH)l(eHHe aTOMOB B,UOJib rpaHHU 3epeH HBJIHeTCH.UHCP<f>Y3HOHHbIM

npoueccoM, O,UHaKo He MO)l(eT 6bITb o6bHCHeHO c no3HUHH BaKaHCH­ OHHoro MexaHH3Ma o6Metta, TaK KaK rpaHHUhI JepeH, CTporo roeopH, He HBJIHJOTCH KpHCTaJIJIH'leCKHMH TeJiaMH. TeM He Mettee C'IHTaeTCH,

'ITO Bblpa)l(eHHe (14.26),UJIH K03<f><f>ttutteHTa,Utt<f><f>y3HH cnpaBe,UJIHBO

",UJIH rpaHH'IHOH.Utt<f><f>Y3HH. B Ka)l(,UOM KOHKpeTHOM KpHCTaJIJIHlJeC­

KOM eemecTBe nptt onpe.ue11ettttoi1: TeMneparype Ko3<f><f>ttutteHT.utt<t>­

<f>yJHH no rpaHHUaM 3epeH 06bilJHO BbIWe K03<f><f>ttUHeHTa 06beMHOH CaMO,Utt<f><f>y3HH, XOTH no KpHCTaJIJIHlJeCKOH peweTKe BellleCTBa npH cneKaHHH MHrpttpyeT TaK)l(e 60JibWOe KOJIHlJeCTBO aTOMOB " KHHeTH­ Ka npouecca npttneKaHHH 'laCTHU 6y.ueT onpe.ueJIHThCH Hatt6011ee Me.u­ JieHHOH CTa,UHeH, T.e. o6beMHOH CaMO,Utt<f><f>Y3HeH.

3. BomymaR noaepxHocmb «U1eu1Cu»-OuCJ101cal(uu.. Il,tt<f><f>YJHOHHbi e

noTOKH no 3TOMy nyrH no CBOeH CYlllHOCTH " pe3yJihTaTaM MOfYT 6bITb onHCaHbl aHaJIOrHlJHO npe,UbI.UYllleMy CJiyqaJO, O,UHaKo ClJHTalOT­ CH MaJIOBepOHTHbIMH.

4. MeJ11Cue c</Jepu'lecKue nopbL-KpynHble nopbl. C yqeTOM JaBHCHMOCTH

KOHUeHTpaUHH BaKaHCHH OT pa.uttyca nopbl (l4.17), c11e.uyeT npH- 3HaTb HaJIHlJHe rpa.utteHTOB KOHUeHTpaUHH BaKaHCHH Me)l(,Uy noeepx­ HOCTHMH nop pa3Horo pa3Mepa. B pe3yJihTaTe.utt<f><f>YJHH qepe3 Kpttc­ TaJIJIH'leCKYJO peweTKY eemecTBO nepeHOCHTCH c noeepXHOCTH Kpyn­ HblX nop Ha noeepXHOCTb MeJIKHX, MeJIKHe nopbl HClJe3alOT (paCTBO­ PHIOTCH), a 6011ee KpynHbie yeeJIH'IHBaJOTCH B pa3Mepax; npH 3TOM

o6mtti1: cyMMapHbI H 06beM nop He MeHHeTCH, T.e. yca.uKa He HMeeT MeCTa.

5. C</Jepu'lecKue nopb1-2pam11{ bl 1epeH.. Il,Btt)l(etttte eaKaHCHH qepe3

KpHCTaJIJIH'lecKyJO peweTKY eemecTBa H.ua11ee no rpattttUaM K noeepx­ HOCTH MO)l(eT npHBO.UHTb K yca.uKe nop. EcJIH)l(e rpaHHUa BblXO.UHT K KpynHOH nope, TO CKopee c11e.uyeT O)l(H,UUTb yKpynHeHHH (KOaJiecueH­ UHH) 3TOH nopbl.

6. C</Jepu'lecKue nopbl-OUCJIOKat{uu.. Il,tt<f><f>yJHH no 3TOMY nyTH MO­

)l(eT npHBO,UHTb K TeM)l(e pe3yJihTaTaM, 'ITO " B npe,UbI.UYllleM c11yqae, O,UHUKO CUM 3TOT CJiylJaH ClJHTaeTCH MaJIOBepOHTHbl M. '

7 H 8. C11y'latt C'IHTaJOTCH MaJioeepoHTHbI MH.

9. fpaHUl(bl 1epeH. fpaHHUbl 3epeH MOfYT 6b!Tb " HCTO'IHHKUMH " CTOKUMH,UJIH BUKUHCHH B 3UBHCHMOCTH OT.UdiCTBYIOlllHX Ha HHX HU"­

npH)l(eHHHX. TeopttH Kpttna (BH3Koro TelJeHHH) no Ha6appo-XeppttHry OCHOBaHa Ha 3THX npe,UCTaBJieHHHX " MO.>KeT 6bITb npttMeHeHa K cne­ KUHHIO. Ha rpaHttuax, r.ue.ueticTByIOT pacrnrnea10mtte ttanpH.>KeHHH,

KOHUeHTpaUHH BaKaHCHH 6011ee BbICOKH B cpaBHeHHH co C)l(aTbIMH rpaHHUaMH..IJ,m1 cneKaeMoro nopOWKOBOro TeJia c CHJibHO pa3BHTOH ceTKOH rpaHHU 3epeH.utt<t><f>Y3HH aTOMOB no 3TOMY MexaHH3MY MO)l(eT npHBO.UHTb K pocry «WeeK» " yca.uKe nopoWKOBOro TeJia.

AHaJIH3HpyH npttee.ueHHYJO rn611ttuy B03MO)l(Hb X nyrei1.utt<t><f>yJHH, c11e.uyeT o6paTHTb BHHMaHHe Ha CJie,UylOlllHe MOMeHTbl:

a) eCJIH HCKJIIO'IHTb H3 paCCMOTpemrn lJeTblpe.UH<t><f>Y3HOH HbIX nyrH c yqaCTHeM.UHCJIOKaUHH, TO H3 OCTaBWHXCH nHTH CJiyqaeB, TpH CBH- 3aHbl c rpaHHUaMH 3epeH, 'ITO yKa3bIBaeT Ha HX cymecTBeHHYIO pOJib nptt cneKaHtttt;

6) npHHHTO ClJHTaTb, 'ITO c TO'IKH 3peHHH Macconepettoca no Me­ xaHH3MY o6beMHOH.Utt<f><f>Y3HH Hatt6011ee Ba)l(HblMH HBJI51IOTC51 CJiyqaH

l, 2, 4 " 5.

flO,UTBep)l(,UeHHe, 'ITO 06beMHaH.Utt<f><f>Y3HH HBJIHeTCH MeXaHH3MOM,

o6bilJHO KOHTpOJIHPYIOlll HM CKOpOCTb cneKaHH51 nopOWKOBblX TeJI, 6b JIO no11yqeHO MHOrHMH HCCJie.uoeaTeJIHMH, H3YlJaBWHMH KHHeTHKY

npMneKaHH51 lJaCTHU Ha MOUeJIHX, npM'leM BO MHOfHX CJIYlfaHX pe3yJib­ TaTbl 3KcnepMMeHTOB y.uoe11eTBop11TeJibHO coena.uaIOT c npe.ucKaJaH­ HhIMH no TeOpHH.

51.E. fery3HH npoaHaJIH3HpOBaJI,UBa B03MO)l(Hb!X BapttaHTa 06beM­

HOH.Utt<f><f>Y3HH npH np11neKaHHH.ueyx c<f>eptt'leCKHX lJaCTHU B 3aBH­ CHMOCTH OT CTpYKTYPhl o6JiaCTH KOHTaKTHOro nepewei1:Ka. B nepBOM H3 HHX CTOKOM H36bITO'IHbIX BaKaHCHH, B03HHKWHX B6JIH3H BOfHYTOH

noeepXHOCTH «WeHKH», HBJIHeTCH BhmyKJiaH noeepXHOCTb nopOWH­ HOK (T.e. npeunoJiaraeTCH, 'ITO Me)l(,Uy 'laCTHUaMH OTCYTCTByeT Me)l(Je­ peHHaH rpaHHUa, HanpMMep npH cneKaHHH CB060.UHO HaCbinaHHOro nopowKa) " pOCT nJIOllla.UH KOHTaKTOB He conpOBO)l(,UaeTCH C6JIH)l(e­ HHeM ueHTpOB 'laCTHU, T.e. ycauKa nopoWKOBOro TeJia OTCYTCTByeT

(pHC. 220, 6); 11,JIH 3TOfO CJiy'laH pOCT KOHTaKTa MO)l(eT 6b!Tb onHCaH

Bbipa)l(eHHeM

 

(14.29)

Bo BTOpOM eapttaHTe CTOKOM H36b TO'lHblX BaKaHCHH HBJIHeTCH rpa­

HHUa Me)l(,Uy npttneKUIOlllHMHCH nopOWHHKUMH " pOCT n11oma.uH KOH­ TaKTa conpoBO)l(,UaeTCH c6JIH)l(eHHeM ueHTpOB lJUCTHU (pHC. 220, 6).

Bb1pa.>Ketttte 11,JIH poem KOHTaKTa HMeeT BH.U

 

(14.30)

Ha pttc. 22 l no.uaHHhIM Ky'IHHCKoro npttee.ueHhICTpYKTYPhIKOH­ TaKTHbI X 0611acTeH, B03HHKUIOlllHX npH B3UMMHOM npttneKaHHH Meu­ HblX npOBOJlOK (l 050 °C, 50 '1), Kor.ua B o6JlaCTH KOHTaKTa eCTb CTOKH

 

 

PHc. 221. CrpyK-rypbl KOHTaKTHbIX 96nacTeil:, BOJHHKaJOIUHX npH BJaHMHOM npHneKaHHH Me,llHbIX npoBOJIOK

 

 

BaKaHeHH.B BH,l(e Me:)l<:JepeHHb X rpaHHU (pHe. 221, a) H Kor,n;a eTOKOB BaKaHeHH HeT (pHe. 221, 6). OrMe'leHo, 'ITO poeT IIJIOI.IJ;a,ll;H KOHmKT­

HOfO neperneH:Ka eonpOBO)l{,ll.aeTeSI e6JIIDKeHHeM ueHTPOB KOHmKTH­ PYJOI..UHX npoBOJIOK JIHIIIh B eJiyqae HaJIH'IHSI B ueM Me:)l<:JepeuuoH: rpa­ HHUhI.

OrMeTHM, 'ITO npH eneKaHHH qaeTHU, <i>opMa KOTOpbIX OTJIH'IHa

OT e<l>epH'leeKOH HJIH UHJIHH.n;pH'leeKOH, 3aKOH poem pa,n;1fYea nepe­ IIIeHKa x MOXeT OTJIH'laTbCSI OT npHBe,n;eHHOro Bb IIIe x 5 - t H, KaK

IlOKa3aHO 3KenepHMeHTaJibHO, eOOTBeTCTBOBaTb JaBHeHMOeTH x3 - t.

TaKoe BJIHSIHHe <l>oPMhIqaeTHU Ha JaKoH poem x MoxeT HMeTb MeeTo H B CJiyqae.n;pyrHX paeeMaTPHBaeMb X MexaHH3MOB Maeeonepeuoea.

B.R. lHHee npe.n;JIO)KHJI Bblpa)KeHHe, oueHHBaIOI.IJ;ee BpeMSI tn IlOJI­

HOfO He'le3HOBeHIDI («.n;H<t><l>Y3HOHHOfO» 3apaemHHSI) H30JIHpOBaH­

r

HOH e<l>epH'leeKOH nopbIHa'laJihHoro pa,n;lfYea, uaxoMmeH:eSI B o6De­

0

Me BemeeTBa, r.n;e HeT,n;pyrHX HeTO'IHHKOB BaKaHeHH, a HX eTOKOM SIBJISieTCSI ero BHeIIIHSIH ra6apHTHa.H IlOBepxuoeTb:

 

tn = (kT/(yyD)r. (14.31)

B mo6oH: MOMeHT BpeMeHH H30TepMH'leeKOH BbI,n;ep)KKH t npH ene­ KaHHH mKaSI H30JIHpOBaHHaSI e<t>epH'leeKaH nopa 6y,n;eT HMeTb pa,n;Hye

r, paBHb H

0

r3= ri -(6yDV I kT)t. (14.32)

 

Ha pHe. 222 noKaJaHhInoCJie,n;oeareJibHb e 3TailhIJanoJIHeHHH nopbI BemeeTBOM BeJie.n;eTBHe ee BaKaHeHOHHOro paeTBopeHHSI.

no R.E. fery3HHY H 11.M. J1H$IIIHUY.n;H<t><l>Y3HOHHblH MexaHH3M

napaMeTP a.

3aJie'IHBaHHH nop SIBJIHeTeH npeo6Jia,n;aIOI.IJ;HM, Kor,n;a 6e3pa3MepHb H eymeeTBeHHO MeHbIIIe e.n;HHHUbl:

a.=(iJ «1,

.190

PHc. 222. nocne.noaareJJbHbl e 3Tailbl JaJ1e'H1BaHID1 nopbl npH ee noaaKaHCHOHHOM pacTBOpeHHH B OKp}')l(aJOIUeH KpHCTaJIJIH'leCKOH cpe.ne

 

 

T.e. pOJib.n;H<l><l>Y3HOHHOro MexaHH3Ma B03paemeT Ha 003,ll;HHX eTa.n;HHX eneKaHHSI.

Ba3KOe mettenue. 0KoJio rneeTH.l(eeSITH JieT TOMY HaJa,n; H.11. <l>peu­

KeJib e<t>opMyJIHpoBaJI H KOJIH'leeTBeHHO peIIIHJI,n;Be Ja,n;a'IH, eBSI3aH­ Hbie e peaJIH3au;HeH npH eneKaHHH nopoIIIKOBOfO TeJia MexaHH3Ma Maeeonepeuoea nyreM BSI3Koro Te'leHHH: o JanJihIBaHHH HJOJIHpo­ BaHHOH nopblH 0 eJIHSIHHH,n;Byx eonpHKaeaIOI.IJ;HXeSI nopOIIIHHOK.

<l>yu,n;aMeHTaJibHoe IlOJIO)KeHHe ero TeopeTH'leeKHX npe,n;emBJieHHH

- aHaJIOrHSI Me)K,11,y BH3KHM re•1eHHeM aMop$Hh X Tell (npoHeXOM­ J..UHM no MeXaHH3MY uenoporoBOH IlOJI3yqeeTH nyreM KoonepaTHBHO­ ro nepeMeI.IJ;eHHSI aTOMOB B Mepy K03$$HUHeHm BH3KOeTH, HBJIHIO­

meroeSI KOHemHTOH BemeeTBa) H KpHeTaJIJIH' eeKHX BemeeTB,,n;JIH KOTOpbIX OHO mKXe SIBJISieTCH npoueeeoM uenoporoBOH IlOJIJyqeeTH, HO nepeMeI.IJ;eHHe aTOMOB He SIBJISieTCSI npoueeeoM KOOnepaTHBHbIM, a eeTb pe3yJibTaT He3aBHeHMbIX 3JieMeHmpHb X aKTOB (eKa'IK006pa3HbIX nepeMemeHHH aTOMOB) no,n; BJIHSIHHeM KanHJIJISlpHoro.n;aBJieHHSI, Bb 3BaHHOro KpHBH3HOH noBepxuoeTH qaeTHU HJIH paJJIH'IHeM HanpSI­

)KeHHH B o6beMe nopOIIIKOBOfO reJia no BeJIH'IHHe HJIH 3HaKY. npHpaBHHB pa60TY eHJI noBepxuoeTHOro HaTSIXeHHSI As { As =

= -y[d(S)/dt]} pa6ore.n;e<i>opMaUHH Av [ Av = 2ri(di:./dt)2 V, r,n;e di:./ dt ­

eKopoeTb.n;e<t>opMaUHH KOHmKTHPYIOJ..UHX qaeTHU; f. H 2 v -eooTBeT­

eTBeHHO OTHOeHTeJibHaSI.n;e<t>opMaUHSI H eyMMapHblH o6beM,n;Byx.n;e­

<t>opMHpyeMblX e<t>ep], noeJie eooTBeTeTBYIOJ..UHX npeo6pa30BaHHH no­ JiyqHM Bblpa)KeHHe,n;JISI oueHKH poem KOHTaKTa Ha nepBbIX eTa,ll;HSIX eneKaHHH (pHe. 220, a)

x2/a0= (3/2)(y/ri)t HJIH x2/a0 - t, (14.33)

r,n;e ao - Ha'laJibHb H pa3Mep e<t>epb; ri - K03$$HUHeHT BH3KOeTH BemeeTBa npH,n;aHHOM eoeTOSIHHH eTPYKTYPhI, B eBSI3H e qeM ri -!JI.

,llJISI IlOJIHOro eJIHSIHHSI.n;Byx KOHTaKTHPYIOJ..UHX e<t>ep (x ao) Heo6-

XO,ll;HMO BpeMSI tn, paBHOe

(14.34)

Ha PHC. 223 npHBe,lleH KHHOMOHTIDK, H306pIDKaIOIUHH BeCb npo­

uecc CJIHSIHHSI c<t>ep B pe)l(HMe BSl3Koro TelleHHSI.

L(Jrn IlOJIHOro 3anJibIBaHHSI H30JIHpOBaHHOH c<t>epHlleCKOH nopbl HallaJibHOro pa.uHyca ro, KOTOpblH 60Jibllle pa3Mepa 3epHa HJIH 6JIOKa, r.ue oHa pacnoJio.>KeHa, Heo6xo,llHMO epeMsi: tn, paeHoe

tn = (4/3)(ri/y)r0• (14.35)

Pa.uHyc r TaKOH nopbI e npouecce H3orepMHlleCKOH Bb,llep.>KKH t

paeeH

r = r0 - (3/4)(y/ri)t. (14.36)

Ha pHc. 224 noKa3aHbInoCJie.uoeareJibHb e 3Tanb13anoJIHeHHS1 nopbI eemecTBOM BCJie,llCTBHe.UH<i><l>Y3HOHHO-BSl3KOro TelleHHSI.

llpuneKaHue noiJ BJIUJlHUeM npuJ1CUMa10U{UX ycwmii. TelleHHe eeme­ CTBa, Bbl3bIBaeMoe BHeIIIHHMH Harpy3KaMH (pHC. 220, e), CBSl3aHO c

.ue<t>opMauHeit qacmu.

 

14.1.4. non3y'l8CTb KpMCT&nnM'l8CKMX Ten

 

51.E. fery3HH, nonyJisi:pHO H3Jrnrasi: <l>H3HlleCKYJO npHpo.uy SIBJieHHH, conpOBO)l(,llaIOIUHX Harpee nopOIIIKOBOro TeJia, c<t>opMyJIHpOBaJI CJie­

.UYI01Uee onpe.ueJieHHe: «CneKaHHe -.UH<l><l>Y3HOHHasi: noJIJyqecTb no.a eoJ.ueitcTBHeM CHJI noeepxHoCTHoro HaTsi:.>KeHHSI». TaKoe noHHMaHHe po.ucrneHHOCTH npoueccoe cneKaHHSI H noJIJyqecTH B03HHKJIO eme Y

51.H. <l>peHKeJisi:, a 3areM 6bIJIO paJBHTO e pa6ornx Ha6appo, XeppHH­

ra,.6JI. IlHHeca H KyqHHCKoro.

- eH rpy3 (Macca KOToporo 3aBe,llOMO MeHbllle TOH, KO­

Ha pHc. 225 npHee.ueHa cxeMa, HJIJIIOCTpHpy10masi: 31)' aHaJIOrHIO. B 6e3.ue<l>eKTHOM KpHCTaJIJie B <l>opMe UHJIHH,ll­

·pa, O,llHH KOHeu KOTOporo 3aKpenJieH, a K.upyroMy no.u­ Belll

-

TOpasi: MO.>KeT C03,llaTb Hanpsi:.>KeHHSI, npeBbIIIIaIOmHe crT

MaTepHaJia MOHOKpHCTaJIJia), HanpSl)l(eHHSI B JII06bIX.ueyx TOlJKax e o6'beMe KpHCTaJIJia coeepllleHHO O,llHHaKOBbl. Pa3- JIHllHSI B03HHKaIOT Ha noeepXHOCTH: K TopueBb M noeepx­ HOCTSIM KpHCTaJIJia npHJIO.>KeHblpacrnrHBaIOmHe, a K 60- KOBb M - C)l(HMaIOmHe Hanpsi:.>KeHHSI, C03,llaHHbie H no.u­

.uep)l(HBaeMb e rpy3oM, no.ueeII1eHHb M K KpHCTaJIJiy. Ta­

 

B ee flOJJOCTb

Pl!lc. 224. 3aJJet:fl!IB3Hl!le nopbic noMOlllblO.nttcl>cl>YJl!IOHHO-BHJKOro Tet:feHHH BellleCTBa

 

TpaUHSI BaKaHCHH no cpaeHeHHIO c paBHOBeCHOH noBb IIIeHa, a Ha 6oKOBb X noeepxHocrnx - noHH.>KeHa. CJie.uoeareJibHO,.UOJI.>KeH BOJ­ HHKHYTb (H B03HHKaeT!) HanpaBJieHHb H noTOK BaKaHCHH OT Topue­ Bb X noeepXHOCTeH KpHCTaJIJia K ero 6oKOBb M noeepXHOCTSIM (HJIH noToK aroMoB e npoTHBonoJIO.>KHOM HanpaBJieHHH). B pe3yJibTaTe KpH­ CTaJIJI YTOHlJaeTCSI (aTOMbIyIIIJIH OT 6oKOBOH noeepxHOCTH!) H Y.llJIH­

HSleTCsi: (aTOMblnpHIIIJIH K ropueBb M noeepXHOCTSIM!). 3'ro H ecTb noJI- 3YlJ:eCTb KpHCTaJIJia B CBSl3H C.UH<i><i>Y3HOHHb M MeXaHH3MOM vnepeMe­ meHHSI aTOMOB, KOTOpyIO Il03TOMY Ha3bIBaIOT.UH<l><l>Y3HOHHOH noJIJy­

lJeCTblO.

· CneKaHHe nopoII1Koeoro rena, co.uep.>Kamero H30JIHpoeaHHb e nopbI HJIH SIBJISIIOIUerocsi: npocTpaHCTBeHHOH KOHCTpYKUHeH, B KOTOpoit nepeMe.>KaIOTCsi: conpHKaca10mHecsi: nopoIIIHH­

KH H nycrorn (nopb1), conpoeo)l(,llaeTcsi: non­ JyqecTbIO eemecTea 3Toro TeJia. MexaHH3MbI

.ue<t>opMaUHH (non3yqeCTH) KpHCTaJIJIH­ qecKoro TeJia B o6JiaCTH,llOCTaTOlJHO Bb COKHX TeMneparyp cneKaHHSI MOfYT 6bITb pa3JIHll­ Hb MH. Bbl,lleJISIIOT HenoporoBbie MexaHH3MbI,

onpe,lleJISIIOIUHe.ue<t>opMHpOBaHHe npH CKOJib yro.uHo MaJib X HanpSl)l(eHHSIX cr, H MexaHH3- Mbl noporOBbie, npOSIBJISIIOIUHe ce6si: npH

Hanpsi:.>KeHHSIX cr, npeBOCXO,llSllUHX HeKOTOpoe

npe.ueJibHoe 3HalleHHe cr'. IlpH HenoporoeoM

MexaHH3Me.ue<t>opMHpoeaHHSI (cr < cr') KpHC­ TaJIJIHlJeCKOe TeJIO Be,lleT ce6si: no.uo6HO HblO­

Pl!lc. 225. HanpaBJJeHHb1e

TOHOBCKOH)l(H,ll,KOCTH, OTJIHlJaSICb OT Hee TeM,

noTOKH B3K3HCHH (- -)

 

 

KHM o6pa30M, B6JIH3H TopueBb X noeepXHOCTeH KOHUeH-

 

Pttc. 223. 0ocJJe,noBaTeJJbHOCTb KHHOKa,npoB, HJJJJIOCTpl!lpYJOlllHX CJIHHHHe BH3KHX ccj>ep

'ITO K03<l><l>HUHeHT TeKyqeCTH ero eemecTBa

JaBHCHT OT CTpYKTYPHOro COCTOSIHHSI TeJia H

MO.>KeT H3MeHSITbCSI BO epeMeHH.IlpH cr > cr' B036y)l(,llaIOTCSI noporoBbie MexaHH3Mbl, npH KOTOpblX IlOJI3yqeCTb MO.>KeT SIBJISITbCSI CJie,ll-

If 3TOMOB(-), B03HH­

K3IOUlHe Ha 6oKOBblX If TopueBblX nosepXHOCTHX MOHOKpHCT3JJJJ3 no.n BJJl!IH­

HHeM COJ.nasaeMbIX HanpH-

)l(eHHH

.

7 - 5582

CTBHeM nepeMemeHHH.llHCJIOKaUHH, conpoBmK,D,aiomerocH npeo,D,o­ JieHHeM paJJIHtIHOfO po,D,a npenHTCTBHH, npH'IeM O,ll,HOBpeMeHHO MO­

ryr,D,eHCTBOBaTb H HenoporOBb e MeXaHHJMb.

061.UHM npHJHaKOM Bcex MexaHHJMOB HenoporoBOH nomyqeCTH HBJrneTCH HanpaBJieHHbIH.llH<l><l>YJHOHHbIH flOTOK BaKaHCHH (HJIH, qTO TO)Ke CaMoe, flOTOK aTOMOB B npOTHBOflOJIO)l(HOM HanpaBJieHHH), KOTOpbIH BOJHHKaeT B npe,D,eJiax Ka)l(,ll,OfO HJ 3JieMeHTOB CTpYKTYPbl

HJ-Ja rpa,D,HeHTa KOHU,eHTpaU,HH BaKaHCHH (pHC. 226). 3TOT noTOK MO­

)l(eT npHBeCTH K HJMeHeHHIO <t>opMbl COOTBeTCTBYIOJ.Uero 3JieMeHTa CTpYKTYPhI6eJ HJMeHeHHH ero o6beMa. CymecrneHHbIM B 3TOM npo­ uecce HBJIHeTCH TO, qTQ HeO,D,HOpO,ll,Hbi e.llH<l><l>YJHOHHbl e flOTOKH B npe,D,eJiax OT,D,eJibHOfO 3JieMeHTa CTpYKTYPbl He COJ,D,alOT MaKpOCKO­ nHqecKOfO noToKa e Macwrn6ax Bcero nopowKoBoro TeJia.)l.e<t>opMH­ poBaHHe Bcex 3JieMeHTOB CTpYKTYPbI,T. e. KpHCTaJIJIHqecKoro noporn­ KOBOfO TeJia KaK ueJioro, HBJIHeTCH npoueccoM caMocornacoBaHHbIM B TOM CMblCJie, qTo Ha HX rpaHHU,aX paJ,D,eJia He BOJHHKalOT HapyweHHH CflJIOWHOCTH H HJMeHeHHe <t>opMbl,D,aHHOfO 3JieMeHTa CTpYKTYPbl Ja­ BHCHT OT HJMeHeHHH <t>opMbl 3JieMeHTOB, HaXO,lJ,HJ.UHXCH c HHM B He­

nocpe,D,CTBeHHOM coce,D,CTBe (pHc. 227). 3ToT npouecc no,D,o6eH,D,e<t>op­

MHpoBaHHIO COBOKYilHOCTH conpHKaCalOIUHXCH peJHHOBb X o6oJioqeK, JanoJIHeHHbIX necKOM, BCJie,D,CTBHe,ll,BH)l(eHHH (nepecblnaHHH) nec­ qHHOK B Ka)l(,ll,OH HJ HHX. CaMocornacoBaHHoe HJMeHeHHe <t>opMbI3Jie­ MeHTOB CTpYKTYPbl nopOWKOBOfO TeJia npHBO,ll,HT K HanpaBJieHHOMY

 

---- 2

 

Plic. 226. CxeMa A1t<txl>yJ1toHHblX noTOKOR BUKUHCltH (/) It UTOMOB

(2) R nOJllt KpltCTUJlJllt'lecKOM

o6paJue noA ttarpyJKoi! P11c. 227. CxeMa Aecl>oPM1tpoBUH1tll nOJ11tKp1t­ CTUJlJlw1ecKoro o6paJua BCJleAcrn11e n11<t><f>y­ J1tOHHO-BS1JKoro npeo6pa30BUHltll <f>opMbl 3CpeH, HUXOllllll\ltXCSI non BOJAeilcTBlteM HanplllKeHltll

a (McxaH1tJM Ha6appo-Xepp11Hra- Jl11<t>urnua)

nepeMemeHHIO HX ueHTpOB Tjf)l(eCTH, KOTopoe no,D,o6Ho nepeMeme­ HHIO MOJieKYJI npH reqeHHH BHJKOH)l(H,D,KOCTH. 11.M. JlH<t>llIHU noKa­

JaJI, qTo 3TOT npouecc,ll,OJI)l(eH conpOBO)l(,ll,aTbCH CKOJib)l(eHHeM KpH­ CTaJIJIOB (qacTHU),D,pyr OTHOCHTeJibHO,D,pyra. TaKHM o6paJOM, BHJKOe TeqeHHe KpHCTaJIJIHqecKHX TeJI npH MaJibIX HarpyJKax H.llH<l><l>YJHOH­ HOe nepepacnpe,D,eJiemi:e Bemecrna Ja cqeT rpa,D,HeHTa KOHUeHTpaUHH BaKaHCHH B 06beMe 3JieMeHTOB ero CTpYKzypbl - H,D,eHTH'IHb e npo­ uecCb, B OCHOBe KOTOpblX Jie)l(HT BaKaHCHOHHb H MeXaHHJM. lo3TOMY npHHHTO fOBOpHTb 0.llH<l><l>YJHOHHO-BHJKOM TeqeHHH (.llH<l><l>YJHOH­

HOH nomyqeCTH) nopOWKOBb X TeJI npH cneKaHHH, KOTOpoe HMeeT MeCTO npH BbinOJIHeHHH ycJIOBHH

'1'2»8/ L,

r,D,e 'I' - yroJI paJopHeHTHPOBKH coce,D,HHX KpHCTaJIJioB; npH 8/ L 10-4

yroJI 'I'.llOJI)l(eH 6b Tb > 1°; 8 - aTOMHh H,D,HaMeTp; L - JIHHeHHb H

paJMep KpHCTaJIJia.

PaccMoTpeHHh H MexaHHJM Ha6appo-XeppHHra-JIH<t>wHua OT­ HOCHTCH K H,D,eaJIHJHPOBaHHOMY KpHCTaJIJIH'IeCKOMY TeJiy, r,D,e ceTKa

«aMop<t>HJOBaHHbIX» rpaHHU HBJIHeTCH e,D,HHCTBeHHb M npHJHaKOM

HepaBHOBeCHOCTH, TOf,D,a KaK B peaJibHb X nopOllIKOBblX TeJiaX HMeeT­ CH JHaqHTeJibHOe KOJIHqecrno O,ll,HHOqHb X KpaeBb X,ll,HCJIOKaUHH, He­ KOHCepBaTHBHOe,ll,BH)l(eHHe («nepenoJIJaHHe») KOTOPb X B noJie Ha­

npH)l(eHHH MO)l(eT cymecTBeHHO onpe,D,eJIHTb KHHeTHKY nomyqeCTH. c

3THM, BH,ll,HMO, CBHJaHa 3KCnepHMeHTaJibHO Ha6JIIO,D,aeMaH HeyCTaHO­

BHBWaHCH flOJIJyqeCTb B pe)l(HMe HenoporoBOfO,D,e<t>opMHpOBaHHH H ee JaBHCHMOCTb OT npe,D,b CTOpHH o6paJua.

0KoJio TpH,D,UaTH JieT TOMY HaJa,D, M.<I>. 3rn6H H P.A. <l>eppaJIJia