Vat Lieu Hoc Dai Cuong-Bai Giang 3

8/3/2019 Vat Lieu Hoc Dai Cuong-Bai Giang 3

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CNG NGH v

KHOA HC VT LIUI CNG

Mng tinh th trong chtrn

NguynThNgc AnhEmail: [email protected]

T: 01247907676
mailto:[email protected]:[email protected]


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Ti sao li phi nghin cuCu trc tinh th

Trong s cc loivt liu, loi c cutrc tinh th chim t l rt ln vthng mang cc tnh cht rt adngph thuc vo kiuspxp ccnguyn t:

Ccvtliuccptil dngchtrn

Tnhchtccvtliulin quantrctipncutrc tinhthca chngL tinhthhocl khng tinhth

Cc tinhthncht(camtnguynt thnhphn) v cc tinhthhpcht(gmnhiunguynt thnhphn)

Cutrc v kchthccc tinhth,

cc binhtH S Phm K Thut Hng YnKhoa C bn Hng Yn 2011


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Cht rn: n tinh th, a tinhth, v nh hnh, gi tinh th

cc cht n tinh th, cc hiung ca s sp xp cc nguynt trong tinh th thng d dngquan st mt cch v m, do hnhdng t nhin ca tinh ththng phn nh cu trc spxp nguyn t

Cc sai hng tinh th nh hng

rt r rt ln cc tnh cht vt lv ha hc ca vt liu. Cc kinthc v cu trc tinh th l rtquan trng hiu r v cc saihng trong tinh th

HtBinht

H S Phm K Thut Hng YnKhoa C bn Hng Yn 2011
http://upload.wikimedia.org/wikipedia/en/0/03/Galvanized_surface.jpg


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Cu trc ntinh th

Cu trc vnh hnh



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Cu trc Tinh th

Tinh th l s sp xp tun hon trong khng gian ca ccnguyn t hoc phn t, cc nhm nguyn t hoc phn t

S sp xp tun hon lp li theo c 3 chiu khng gian

Trong iu kin l tng, c th to n tinh th, trong ttc cc nguyn t trong cht rn u trong cng mt cu trc

= +

Cu trc tinh th = Mng tinh th + C s



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Cu trc Tinh th

Cu trc tinh th = Mng tinh th + C s

Hoc



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Gi Tinh th - Quasicrystals



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Gi Tinh th - Quasicrystals

Gi tinh th l mt dng tnti khc bit ca cht rntrong cc nguyn t spxp dng nh l u nnhng khng c s lp li

c cp ti v nghincu ln u tin bi DanShechtman nm 1982

Hu ht cc gi tinh th thuc cho thy u l hp

kim ca Nhm (Al-Ni-Co, Al-Pd-Mn, Al-Cu-Fe), mt scc hp kim khc gm c(Ti-Zr-Ni, Zn-Mg-Ho)

T Gi tinh th c dng ch cc mu c trt t xanhng khng tun hon

Cc vt liu c cu trctun hon c nghincu nhiu. Cn t quan tmti cc vt liu gi tunhon(quasiperiodic) hocbt tun hon (aperiodic)



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a hnh v th hnh

Mtsvtliu c thtntinhiuhnmtloicu hnhtinh th - cgi l tnhahnh(polymorphism)

Nuvtliu l mtchtrn cng mt nguyn t -cgi l c tnh th hnh,tnh khc hnh (allotropy)

Mt v d cho c tnh thhnhl nguyn t carbonc thtnti nhiudngnh kim cng, than ch,carbon nanotubes, C60, C70

v carbon v nh hnh



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Tnh d hng Cc chiu khc nhau trong mt

tinh th c s xp xp khcnhaudn n khc nhau vmt s tnh cht vt l v hahc

V d cc nguyn t dc theocnh ca FCC cch xa nhauhn so vi hng cho

D hng v i xng trongkhng gian dn n d hngv nhiu tnh cht c bn

Trong a tinh th, s nhhng cc ht l hon ton

ngu nhintnh cht ca vtliu l ng hng Mt s vt liu c cc ht vi

chiu u tin



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Tnh ixng i xng l mt trong nhng tnh cht quan trng ca tinh

th, n th hin hnh dng bn ngoi,cu trc bn trongcngnh cc tnh cht

Tnh ixngca tinh thcctrngbi cc yuti

xng. Miyu tixng tngngvimtbini hnhhc xc nh mt h thng im, ng, phn t,... ttrng lpvi chnh mnh trong khng gian

12H S Phm K Thut Hng YnKhoa C bn Hng Yn 2011
http://en.wikipedia.org/wiki/File:Asymmetric_(PSF).svghttp://en.wikipedia.org/wiki/File:Asymmetric_(PSF).svghttp://en.wikipedia.org/wiki/File:Asymmetric_(PSF).svg


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Tnh ixng Nhngyutixng quan trng l:

- Tm ixng (k hiu C): bng php nghcho qua tm ccims trng nhau- Mt chiugng (k hiu P): bng php phn chiu qua mtmtphng cc mts trng nhau

- Trcixng (k hiu L): cc ims trng nhau bng cchquay quanh trcmt gc , n=2/gi l bccatrcixng(n= 1,2,3,4,6)

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a1

a2

a3

b3

b2

b1

C

P

a1

a2

a3

b1

b3

b2



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c s

cs (nv) l mt cch spxpca ccnguyn t trong khng gian ba chiu,nu ta lpli n th n schimy khng gian v stonn tinh th.

Kch thc v hnh dng ca c s c xydng trn c s:- 3 vector n v: a, b, c tng ng vi 3 trc x,y, z theo 3 chiu khng gian.- Modun a, b, c ca 3 vector n v l kch thcca c s, cn gi l hng s mng

- Cc gc , , hp bi cc vector n v ivimicu trc tinh th,tntimt nv

quy c, thng c chn mng tinh thc tnh ixngcao nht. Do tnh ixng,tmt cstnhtin theo ba chiu trong khng

gian scmtmng tinh th 14H S Phm K Thut Hng YnKhoa C bn

Hng Yn 2011


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M t Mng Tinh thCC LOI VT LiU V S SP XP NGUYN T

H S Phm K Thut Hng YnKhoa C bn

Hng Yn 2011


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5 Mng Tinh th hai chiu

a

ba b, 90

a b, = 90

a

b

a = b, = 90

a

a

a b, = 90

a

b

a = b, =120

a

a

Mng nghing

Mngchnht

Mngchnhttm mt

Mnglc gic

Mng vung


Hng Yn 2011


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Cc Mng Tinh th c bnMng Bravais (Bravais Lattice)

Cch chn cc vct a1, a2, a3ca mng Bravais c tnh i xng cao nht ca h m tinh th c

xp vo

c s gc vung ln nht hoc s cnh bng nhauv s gc bng nhau nhiu nht c th tch nh nht ( nguyn t, c s)

Nu khng th ng thi tha mn c 3 yu t trn th chncc vct a1, a2, a3theo th t u tin 1, 2, 3Chc 7 dng c s c th dng lp y khng gian

mng tinh th


Hng Yn 2011


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Mng Tinh th ba chiu:7 h tinh th 14 mng Bravais

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Lpphng

Bnphng

Trcphng

Lc gic

Ba phng

Mt nghing

Ba nghing


Hng Yn 2011


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Tinh th l s sp xp tunhon trong khng gian cacc nguyn t hoc phnt, cc nhm nguyn t

hoc phn t S sp xp tun hon lpli theo c 3 chiu khnggian

Trong iu kin l tng, c

th to thnh n tinh th,vi tt c cc nguyn ttrong cht rn u trongcng mt cu trc

Ba nghing

Mt nghing

7 h tinh th14 mng tt Bravais

Tm y



Hng Yn 2011


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Trc phng(Trcthoi)

Su phngLc gic

Tm y =Tm cnh

Tm khi Tm mt



Hng Yn 2011


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Tinh th l s sp xptun hon trong khnggian ca cc nguyn thoc phn t, cc nhmnguyn t hoc phn t

S sp xp tun honlp li theo c 3 chiukhng gian

Trong iu kin ltng, c th to thnhn tinh th, vi tt ccc nguyn t trongcht rn u trong cngmt cu trc

Ba phng

Bn phng

Lp phng



Hng Yn 2011


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Mng Tinh th ba chiu7 h tinh th

Th tch cc mng Bravais c tnh nh sau


Hng Yn 2011


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S nguyn t trong mt cs

1 nguyn t c s

2 nguyn t c s

4 nguyn t c s

6 nguyn t c s

Lp phng n gin Lp phng tm khi Lp phng tm mt Lc gic xp chtSimple cubic SC Body-centered cubic BCC Face-centered cubic FCC Hexagonal close-

packed HCP


Hng Yn 2011


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H s xp cht APFtrong tinh th

H s xp chtnguyn t(H s lp ynguyn t) APF


Hng Yn 2011


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Nt mng Da trn c s ca h to c th xc nh (k hiu, nh s) cc

nt mng, phng, mt tinh th Nt mng tng ng vi cc to trn 3 trc Ox, Oy, Oz chn

c t trong du mc vung [x,y,z] Gi tr m biu th bng du - trn ch s tng ng, v d trn t s

tng ng vi trc Oy c gi tr m l [x,y,z]

25H S Phm K Thut Hng YnKhoa C bn

Hng Yn 2011


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Chs Miller ca phng(chiu) trong Tinh th

Chs Miller chiucamtng trong mng tinh th c th xc nhcnu bit 2 nt mng m phng i qua. K hiu bng [uvw]

Do tnh quy lut trong sp xp nguyn t m cc phng song song vi nhauc tnh cht hon ton ging nhau, nn sc cng ch s phng ly theophng i qua gc to O.

Ba ch s u, v, w l ba s nguyn t l thun vi to ca mt nt mng nmtrn phng song gn vi gc to nht : Bng cch vng song songving qua gcta. Chs Miller cang l tacaimutin m ngi qua. Nutacaim l u, v, wth chschiucangs l [uvw].

Theo quy cngi ta dng tp cc s nguyn nhnht [1], [112], [224] chcc chiutngngngi ta dng [112]

Cc chs m c k hiu c gch ngang trn u [112]

Cch xc nh ba ch s v chiu trong tinh th


Hng Yn 2011
http://upload.wikimedia.org/wikipedia/commons/a/af/Indices_miller_direction_exemples.png


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Ch s Millerca chiu trong Tinh th

1. Vc t c di thch hpct sao cho i qua gchta. Mi vc tuc thdchchuyn trong mng tinh th m khng lm n thay inuvn duy trs song song

2. Xc nhchiu di ca hnh chiu vc t ln 3 trc: thango theonvca csa, b v c

3. B 3 s ny c nhn hoc chia bi cng mths (quy ngmus) rtgn chng vb ccs nguynnhnht

4. B 3 chsc cho vo trong mc vung khng phn cch biduphy [uvw].Rt gnb cc s nguyn u, v, wtngngvi hnh chiu theo cc trcx, yv z

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Cch xc nh ba ch s v chiu trong tinh th


Hng Yn 2011
http://upload.wikimedia.org/wikipedia/commons/a/af/Indices_miller_direction_exemples.png


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Chs Millercachiu trong Tinh th Vector nh hnh vi qua gchta, do khng

cnphitnhtin. Hnh chiucavect ln cc trc x,y, vzlnlt l a/2, b, and 0c, cxcnh , 1,and 0theo thng sca cs (tc l khi chiuxunga, b, v c). Quyngmus ccs nyvbnhnhtca ccs nguynbng cch nhn michs

vi cng gi tr2.Kt qu l cc s nguyn 1, 2, v 0,scng trong ngoc vung [120]

Cc hng [100], [110], v [111]trong mt cbn trong tinh th

Cc hnh chiu

Quy ng mu s, rt gn

t trong du ngoc

Cc bc thc hin nh sau


Hng Yn 2011


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Chs Millerca cc mt trong Tinh th

Cc ch s h, k, lc xc nhnh sau:- tm giao imca mt phngtrn 3 trc theo

th t Ox, Oy, Oz- xc nh dion thng t gcto n ccgiao im, ri lycc gi tr nghicho

- quy ng mu schung, ly cc gitr ca t s, chnh l cc ch sh, k, l ca mtphng cn tm


Hng Yn 2011


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Chs Millerca cc mt trong Tinh th

Chs Miller camt A (403)

Quy ngmus, rt gn 4 0 3

Nghcho 2 0 3/2

imcttrcta 1/2 2/3

Mt (A)x y z

Chs Miller camt B (112)

Quy ngmus, rt gn 1 1 1

Nghcho 1 1 2

imcttrcta 1 1 1/2

Mt (B)x y z


Hng Yn 2011


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Ch s Millerca cc mt trong Tinh th

Trnh by cc hmt (a) (001),(b) (110), v (c) (111) ca ccmt trong tinh th

H S Phm K Thut Hng Yn

Khoa C bnHng Yn 2011

Ch Mill hi t h


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Chs Miller cachiu trong hsu phng

Ch s Miller trong h su phng c bn trc to Ox, Oy, Ou vaOz, trong ba trc u tin nm trn cng mt mt phng. K hiubng (hkil). Ch s th ba i (ca trc Ou) c quan h vi hai ch s uh, k (Ox, Oy) nh sau: i= -(h+k)


Khoa C bnHng Yn 2011


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Chuynth 3 chs sang h 4 chsu, v, wu, v, t, w

a1a2z

a1a2a3z

Chs Miller cachiu trongh su phng

u'= a1= 1

v'= a2= 1

w'= z= 1


Khoa C bn

Hng Yn 2011


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Chs Miller camt trong hsu phng

t trong dungoc (111)Quy ngmus, rt gn 1 -1 1

Nghcho 1 -1 1

imcttrcta 1 -1 1

Mt x y z

a1 a2 z

Mt song song vi

trc a3i= 0


Khoa C bn

Hng Yn 2011


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Xc nh ch s phng Millertrong cc hnh sau

37H S Phm K Thut Hng Yn

Khoa C bn

Hng Yn 2011

Mill


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Xc nh ch s mt Millertrong cc hnh sau


Khoa C bn

Hng Yn 2011 38


Quy ngmus, rt gn 0 -1 1

Nghcho 0 -1 1

imcttrcta -1 1

Mtx y z


Quy ngmus, rt gn 0 -1 2

Nghcho 0 -1 2

imcttrcta a -1b c/2

Mtx y z

X h h Mill


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39H S Phm K Thut Hng Yn

Khoa C bn

Hng Yn 2011

X h h t Mill


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40H S Phm K Thut Hng Yn Hng Yn 2011

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Vat Lieu Hoc Dai Cuong-Bai Giang 3