Crystals yog lub cev muaj zog nrog cov duab geometric tsis tu ncua. Cov qauv nyob rau hauv uas txiav txim hais nyob rau hauv yog hu ua ib tug siv lead ua lattice. Cov ntsiab lus ntawm qhov chaw ntawm cov khoom uas lawv oscillate yog hu ua cov nodes ntawm cov siv lead ua lattice. Tag nrho lub cev no tau muab faib ua monocrystals thiab polycrystals.
Dab tsi yog ib qho crystals
Single crystals yog ib qho siv lead ua uas siv lead ua lattice muaj qhov kev txiav txim meej. Feem ntau ib leeg siv lead ua muaj qhov zoo li niaj zaus, tab sis qhov no tsis yog qhov yuav tsum tau ua thaum txiav txim siab hom siv lead ua. Feem ntau cov minerals yog ib tug crystals.
Daim ntawv sab nraud yog nyob ntawm qhov kev loj hlob ntawm cov khoom. Nrog kev nce qeeb thiab qhov sib npaug ntawm cov khoom siv, cov khoom siv lead ua muaj qhov raug txiav. Nyob rau nruab nrab ceev, qhov txiav tsis yog pronounced. Ntawm qhov siab crystallization tus nqi, polycrystals uas muaj ntau cov crystals loj hlob.
Classic piv txwv ntawm ib qho siv lead ua yog pob zeb diamond, quartz,topaz. Hauv cov khoom siv hluav taws xob, ib qho crystals, uas muaj cov khoom ntawm semiconductors thiab dielectrics, yog qhov tseem ceeb. Alloys ntawm ib tug crystals yog yus muaj los ntawm kev nce hardness. Ultrapure ib leeg muaju muaj tib yam khoom tsis hais keeb kwm. Cov tshuaj muaj pes tsawg leeg ntawm cov zaub mov nyob ntawm qhov kev loj hlob. Qhov qeeb ntawm cov siv lead ua loj hlob tuaj, qhov zoo tshaj plaws ntawm nws cov muaj pes tsawg leeg.
YPolycrystals
Ib leeg muaju thiab polycrystals yog tus cwj pwm los ntawm kev sib cuam tshuam molecular siab. Ib qho polycrystal muaj ntau lub pob zeb ib leeg thiab muaj cov duab tsis zoo. Lawv qee zaum hu ua crystallites. Lawv tshwm sim raws li ib tug tshwm sim ntawm kev loj hlob ntawm ntuj los yog loj hlob artificially. Polycrystals tuaj yeem yog hlau, hlau, ceramics. Cov yam ntxwv tseem ceeb yog ua los ntawm cov khoom ntawm ib qho muaju, tab sis qhov ntau thiab tsawg ntawm cov nplej, qhov kev ncua deb ntawm lawv, thiab cov ciam teb yog qhov tseem ceeb heev. Nyob rau hauv lub xub ntiag ntawm ciam teb, lub cev yam ntxwv ntawm polycrystals hloov loj, lub zog txo.
Polycrystals yog tsim los ntawm crystallization, hloov pauv hauv cov hmoov crystalline. Cov zaub mov no tsis tshua ruaj khov dua li cov muaju ib leeg, ua rau muaj kev loj hlob tsis sib xws ntawm cov nplej.
YPolymorphism
Ib leeg muaju yog cov khoom uas tuaj yeem muaj nyob hauv ob lub xeev ib zaug, uas yuav txawv ntawm lawv lub cev. Qhov no hu ua polymorphism.
Tib lub sijhawm, cov khoom hauv ib lub xeev tuaj yeem ruaj khov dua li lwm qhov. Thaum ib puag ncig hloov pauv, qhov xwm txheej yuav tshwm simpauv.
Polymorphism yog ntawm cov hauv qab no:
- Reconstruction - lwj tshwm sim rau atoms thiab molecules.
- Deformation - tus qauv hloov kho. Compression lossis stretching tshwm sim.
- Shift - qee lub ntsiab ntawm cov qauv hloov lawv qhov chaw.
Crystal cov khoom tuaj yeem hloov pauv nrog kev hloov pauv tam sim hauv kev muaj pes tsawg leeg. Cov piv txwv classic ntawm polymorphism yog kev hloov pauv carbon. Hauv ib lub xeev nws yog pob zeb diamond, hauv lwm qhov nws yog graphite, tshuaj nrog cov khoom sib txawv.
Qee hom carbohydrate tig mus rau hauv graphite thaum rhuab. Kev hloov pauv ntawm cov khoom tuaj yeem tshwm sim yam tsis muaj deformation ntawm cov iav siv lead ua. Nyob rau hauv cov ntaub ntawv ntawm hlau, kev hloov ntawm ib co Cheebtsam ua rau lub ploj ntawm magnetic zog.
Crystal zog
Txhua yam khoom siv hauv cov cuab yeej siv niaj hnub no muaj lub zog kawg. Ib qho alloy ntawm nickel, chromium thiab hlau muaj zog tshaj plaws. Kev ua kom muaj zog ntawm cov hlau yuav txhim kho cov khoom siv tub rog thiab pej xeem. Kev hnav tsis kam ntxiv yuav ua rau lub neej ua haujlwm ntev dua. Vim li no, cov kws tshawb fawb tau kawm txog lub zog ntawm ib leeg siv lead ua tau ntev.
Ntshiab ib leeg muaju yog cov muaju uas muaj qhov zoo tshaj plaws siv lead ua lattice, muaj qee qhov tsis xws luag. Nrog rau qhov txo qis ntawm qhov tsis xws luag, lub zog ntawm cov hlau nce ntau zaus. Tib lub sijhawm, qhov ntom ntawm cov hlau tseem yuav luag tib yam.
Ib leeg siv lead ua nrog cov lattice zoo tshaj yog tiv taus cov neeg kho tshuab kev ntxhov siab txog qhov melting point. Tsis txhob hloov nrogsij hawm. Feem ntau, xws li ib tug crystals muaj ib tug xoom dislocation. Tab sis qhov no yog ib qho kev xaiv. Lub zog tau piav qhia los ntawm qhov tseeb tias microcracks yog tsim nyob rau hauv qhov chaw uas muaj ntau tshaj plaws ntawm dislocations. Thiab nyob rau hauv lawv qhov tsis muaj, tsis muaj qhov chaw rau cov kab nrib pleb tshwm. Qhov no txhais tau hais tias ib leeg siv lead ua yuav kav mus txog rau thaum qhov pib ntawm nws lub zog dhau lawm.
Artificial single crystals
Loj hlob ib leeg muaj peev xwm ua tau nyob rau theem tam sim no ntawm kev tshawb fawb. Thaum ua cov hlau, yam tsis hloov nws cov muaj pes tsawg leeg, koj tuaj yeem tsim ib qho siv lead ua uas muaj cov npoo siab ntawm kev nyab xeeb.
Muaj 2 txoj hauv kev paub txog kev tsim cov khoom siv lead ua ib leeg:
- super siab thiab hlau casting;
- cryogenic siab.
Thawj txoj kev yog nrov rau kev ua cov hlau teeb. Muab qhov purity ntawm cov hlau thiab nce siab, cov hlau tshiab yuav maj mam tshwm sim uas muaj cov khoom zoo ib yam, tab sis muaj zog ntxiv. Nyob rau hauv tej yam kev mob, nws muaj peev xwm yuav tau txais ib tug siv lead ua ib tug zoo tagnrho lattice. Nyob rau hauv lub xub ntiag ntawm impurities, muaj peev xwm hais tias cov siv lead ua lattice yuav tsis zoo tagnrho.
Nyob rau hauv cov hlau hnyav, nrog nce siab, cov txheej txheem ntawm kev hloov cov qauv tshwm sim. Cov siv lead ua ib leeg tseem tsis tau tig tawm, tab sis cov khoom tau hloov pauv.
Cryogenic casting yog raws li kev tsim cov kua cryogenic. Crystallization tsis tshwm sim nyob rau hauv lub zog ntawm lub magnetic teb. Daim ntawv semi-crystalline dhau los ua ib qho siv lead ua tom qab raug hluav taws xob.
pob zeb diamondthiab quartz
Cov khoom ntawm pob zeb diamond yog raws li qhov tseeb tias nws yog cov khoom siv nrog atomic crystal lattice. Kev sib txuas ntawm atoms txiav txim siab lub zog ntawm pob zeb diamond. Nyob rau hauv tas li ntawd, lub pob zeb diamond tsis hloov. Thaum raug lub tshuab nqus tsev, nws maj mam hloov mus ua graphite.
Crystal qhov ntau thiab tsawg sib txawv. Synthetically zus pob zeb diamond muaj lub ntsej muag lub ntsej muag thiab saib txawv ntawm lawv cov counterparts. Cov khoom ntawm pob zeb diamond yog siv los txiav iav.
Quartz muaju muaj nyob txhua qhov chaw. Cov ntxhia yog ib qho ntawm feem ntau. Quartz feem ntau tsis muaj xim. Yog tias muaj ntau qhov tawg hauv lub pob zeb, ces nws yog xim dawb. Thaum lwm yam impurities ntxiv, nws hloov xim.
Quartz muaju yog siv rau hauv kev tsim cov iav, tsim ultrasound, hauv cov khoom siv hluav taws xob, xov tooj cua thiab TV. Qee hom yog siv rau hauv cov hniav nyiaj hniav kub.
qauv ntawm ib lub ntsej muag
Metals nyob rau hauv lub xeev cov khoom muaj ib tug crystalline qauv. Cov qauv ntawm ib qho crystals yog qhov kawg ntawm kev sib hloov atoms. Qhov tseeb tiag, qhov kev txiav txim ntawm atoms tuaj yeem cuam tshuam vim qhov cuam tshuam thermal, mechanical lossis lwm yam laj thawj.
Crystal lattices muaj nyob rau hauv 3 hom:
- tungsten yam;
- tooj liab;
- magnesium yam.
Daim ntawv thov
Cov khoom siv dag zog ib leeg yog lub sijhawm kom tau txais cov khoom siv nrog cov khoom tshiab. Daim ntawv thov cheeb tsam ntawm ib leeg muaju yog loj heev. Quartz thiab spar tau tsim los ntawm xwm, thaum sodium fluoride tau cog qoob loo.
Monocrystals yogcov khoom siv hauv optics thiab electronics. Quartz thiab mica yog siv hauv optics tab sis kim. Nyob rau hauv cov khoom siv dag zog, koj tuaj yeem loj hlob ib leeg siv lead ua, uas yuav txawv ntawm purity thiab lub zog.
Pob zeb diamond yog siv rau qhov xav tau lub zog siab. Tab sis nws yog ntse synthesized nyob rau hauv dag tej yam kev mob. Peb-dimensional single crystals yog zus los ntawm melts.
