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1. O V E R V I E W P o i n t d efe ct s : s o l u te at o m s (st r e ng t h , c ond u ct i v i ty) L i n e d efe ct s : d i s l o c a t i on s ( p l ast i c d ef o r m a t i on ) S u r face d efe c ts: ext e r n al s u r face (c r yst al s h a p e) V o l u m e d efe c ts: v o i d s, i n c l u s i o n s (f r act u r e) DEFINITION & Classification of Defects solid solution nonstoikiometri

2. Larutan padat = campuran homogen berwujud padat yang terdiri dari satu atau lebih zat terlarut dalam pelarut.

3. An ideal crystal can be described in terms a three-dimensionally periodic arrangement of points called lattice and an atom or group of atoms associated with each lattice point called motif: Crystal = Lattice + Motif However, there can be deviations from this ideality. Th es e d e v i a t i o n s a r e k n o w n a s C R YS T AL D E F E C T S . DEFINITION Berdasarkan dimensinya, terdapat 4 jenis cacat kristal yaitu cacat titik, cacat garis, cacat bidang, dan cacat ruang.

4. POINT DEFECTS Intrinsik defects : Occur in pure substances: Schottky defects and Frenkel defects Extrinsik defects Due to impurities: Substitutional solid solutions and Interstitial solid solutions

5. Point Defects I ntrin s ic de f e c t s Vacancy Self-interstitial E xtrin s ic de f e c t s S ub s titutional impurity I nte r s titial impurity

6. Vacancy  Missing atom from an atomic site  Atoms around the vacancy displaced  Tensile stress field produced in the vicinity

7. Impurity Interstitial Substitutional  SUBSTITUTIONAL IMPURITY Foreign atom replacing the parent atom in the crystal E.g. Cu sitting in the lattice site of FCC- Ni  INTERSTITIAL IMPURITY Foreign atom sitting in the void of a crystal E.g. C sitting in the octahedral void in HT FCC- Fe

8. Frenkel defect Schottky defect Cation vacancy + cation interstitial Cation vacancy + anion vacancy

9. Intrinsik Defects - Frenkel Often a vacancy and interstitial occur together - an ion is displaces from its site into an interstitial position. This is a Frenkel Defect (common in e.g. AgCl) and charge balance is maintained. Frenkel defects can be induced by irradiation of a sample

10. Extrinsic defects (due to impurities) Impurities or dopants in a solid are any atom(s) of a type that do not belong in the perfect crystal structure (see ‘extrinsic semiconductors’) The host crystal with impurities is called a solid solution Substitutional solid solutions Impurity atoms occupy the same sites of the host atoms Impurities "substitute" for the host atoms Interstitial solid solutions Impurity atoms occupy interstices in the host crystal structure Impurities usually have a small size compared to the host atoms

11. Gambar. Struktur paduan: kuningan dan baja Ada dua jenis paduan ( alloy ) yaitu paduan tersubtitusi dan paduan sisipan. Paduan tersubstitusi, contohnya kuningan (sekitar sepertiga dari atom tembaga telah digantikan oleh atom seng). Paduan sisipan, Misalnya, baja merupakan paduan dari besi dan karbon.

12. Impurity defects Cationic Ca instead of Na in NaCl B instead of Si in SiO 2 Anionic O instead of Cl in NaCl O instead of N in GaN Ch a r g e n e u t r a l i ty m u st b e maintained. T hu s, i f a s ub st i t u t io n a l i m p u r i ty h as a d i ffe r e n t c h a r g e t h an t h e s ub st i t u t ed i on , a no t h er d efe ct ( o r d efe c ts) m u st b e p r es e n t to b a l a n ce i t ou t. No n - st o i c h i o m e t r y o ften results.

13. Impurities must satisfy charge balance Ex: NaCl Substitutional cation impurity initial geometry Substitutional anion impurity O 2- anion vacancy Cl - Cl - O 2- impurity resulting geometry I M P URI T I E S

14. LINE DEFECTS (DISLOCATIONS) P l a s t i c de f o r m at i o n s by S li p Edge Dislocations Screw Dislocations Mixed Dislocation TUGAS: Jelaskan pengertian LINE DEFETS diatas beserta dengan gambarnya , kumpulkan setelah selesai jam Metalurgi diatas meja Pak Andika

15. Mechanism of plastic deformation in crystals: dislocation glide , or slip of atomic planes (atomic planes move one by one via the formation and movement of dislocations, rather than all the planes move simultaneously)

16. Burgers vector Johannes Martinus BURGERS Burgers vector Burger’s vector

17. 9 1 2 3 4 5 6 7 8 9 A closed Burgers Circuit in an ideal crystal S 1 2 3 4 5 6 7 8 F 9 8 7 6 5 4 3 2 1 1 1 1 1 2 1 3 1 4 1 5 16 1 6 1 5 1 4 1 3 1 2 1 1 1 9 8 7 6 5 4 3 2 1

18. 1 2 3 4 5 6 7 8 9 1 1 1 12 1 2 3 4 5 6 7 8 9 S 1 3 1 4 1 5 16 RHFS convention F b 9 8 7 6 5 4 3 2 1 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Map t h e  sa m e Burgers circuit on a real crystal

19. D e f ini t io n s T he bo u nd a ry pla n e a c ro s s w hi c h s h e ar o c c urs is t he glide plane T he bo u nd a ry line t hat s ep a ra t es s lipp ed ( red ) a n d u n s lipp ed re g io n s is t he di s lo c a t ion line or a x is l T he dire ct ion and m ag ni t ude of s lip = Burg er ' s v e c t o r , b b is in ge n eral a la tt i c e v e c t o r , s o t here is no long ran g e m i s m a tc h be t w een s lipp e d and un s lipp e d pla n es If b is parallel to l dislocation is ' screw ‘ I f b is perpendi c ular t o l di s lo c a t ion is ' edge ' glide p l an e σ b σ l

20. Edge and Screw Dislocations Perfect crystal lattice Edge dislocation: “extra plane” S c rew di s lo c a t ion (di s t or t ion of t he crystal) b l b l

21. Motion of Edge d i s l o c a t i o n Conservative (Glide) Non-conservative (Climb)  For edge dislocation: as b  l  Climb involves addition or subtraction of a row of atoms below the half plane positive climb = climb up → removal of a plane of atoms negative climb = climb down → addition of a plane of atoms Motion of dislocations On the slip plane Motion of dislocation  to the slip plane

22. Edge Climb Positive climb Removal of a row of atoms Negative climb Addition of a row of atoms

23. Let’s look at the atoms in a perfect crystal

24. 20 5 1 15 5 10 15 19 “Edge d i s l o cat io n ” = T Let’s look at the atoms in a realistic crystal

25. “glide”edge dislocations

26. “glide”edge dislocations

27. ? “glide”edge dislocations

28. “glide”edge dislocations

29. “glide”edge dislocations

30. “glide”edge dislocations

31. “glide”edge dislocations

32. “glide”edge dislocations

33. “glide”edge dislocations

34. “glide”edge dislocations

35. “glide”edge dislocations

36. “glide”edge dislocations

37. “glide”edge dislocations

38. “glide”edge dislocations

39. “glide”edge dislocations

40.   Atomistic mechanism of climb

41. b l b || l    SCREW D I S L O C A T I O N S

42. Mixed dislocations  b  l  b Pure Edge Pure screw

43. Mixed dislocations have edge & screw c o m pon e n t s Orien t a t ion of line w . r .t . f ault v e c t or b Mixed Dislocations varies along dislocation t op v iew

44. PARTIAL DISLOCATIONS

45. Defects Dimensionality Examples Point Vacancy Line 1 Dislocation Surface 2 Free surface, Grain boundary Volume 3 Voids, Inclusions, Precipitates

46. t h e SURFACE DEFECTS Imperfections, such as grain boundaries, that form a two- dimensional plane within crystal. classifications free surface twin boundary stacking faults grain boundaries

47. VOLUME DEFECTS voids inclusions p re c i p i t a t es Three-dimensional defects in solids Volume defects play an important role in corrosion mechanisms Always involve a second phase Porosity (solid – vapor) Inclusions (solid – solid) Precipitates (solid – solid) Cracks (solid – vapor)

48. E x t e r na l Internal Free surface Grain boundary Stacking fault Twin boundary Interphase boundary Same ph a s e D if f ere n t phases

49. free surface If bond are broken over an area A then two free surfaces of a total area 2A is created Area A Area A B r o k e n bonds Surface grooving where grain boundaries intersect free surfaces leads to surface roughness, possibly break-up of thin films

50. A r e a A Area A n A = n o . o f s u r f a c e a t o m s p e r unit area n B = no. of broken bonds per surface atom  = bond energy per atom A B 2   1 n n  S ur f a c e e n e rgy per unit area If bond are broken over an area A then two free surfaces of a total area 2A is created B r o k e n bonds

51. Su rf a ce e n e r gy i s a n i so t r o p i c S ur f a c e e n e rg y d e p e n d s o n t h e orientation, i.e., the Miller indices of the free surface n A , n B are different for different surfaces D i ffu se I n t erf a ce At high T, metal surfaces tend to be rough, diffuse F re e Surfa c e s of M e t a ls Su r f a ce t e n s i o n ( σ ) l o w e s t for low-index planes

52. free surface

53. twin boundary (plane) Essentially a reflection of atom positions across the twin plane Twining is very common in minerals (result of phase transition during cooling) Twinning is an important deformation mechanism Sn, Mg, high-N austenitic (FCC) steel, Cu at low T

54. (c) 2003 Brooks/Cole Publishing / Thomson Learning Formation of twin (b) may be caused by application of stress to the perfect crystal (a)

55. (c) 2003 Brooks/Cole Publishing / Thomson Learning Figure (c) : A micrograph of twins within a grain of brass (x250)

56. Twin: coherent vs. incoherent ( P o r t e r & E a s t e rl i ng - fig . 3 . 1 2 / p 1 23 )

57. stacking faults su r face defec t s Stack close-packed planes in wrong sequences Create extra or missing plane inside the crystal It may occur during crystallization from the melt or solid state, solid state processes or recrystallization, phase transition, and crystal growth, and deformations.

58. – For FCC metals an error in ABCABC packing sequence Intrinsic : Remove a plane (C) Extrinsic : Insert an extra plane (A) A B C A B C A B C A B C A B C A B C A B C A B C A B A B C A B C A B C A B C A B C A B A C A B C A B C A B C A B C A B C A B C

59. Intrinsik : menghilangkan bidang C Extrinsik : Memasukkan bidang tambahan A Kristal sempurna A A A B B B C C C A A A B B B C C C A A A B B B A C A B A C C B A A C B B A C C B A A C B B A C C B A C B C A B C A B C A B C

60. grain boundaries See Figure : The atoms near the boundaries of the three grains Grains and grain boundaries in a stainless steel sample. ( Cou r t e s y D r . A . D e a r d o .) Grain Boundary Grain 2 Grain 1 A g r a i n b o u n da r y is a boundary between two regions of identical crystal structure but different orientation

61. Grains : individual crystals Grain boundaries : zones between any two grains regions between crystals transition from lattice of one region to that of the other slightly disordered low density in grain boundaries high mobility high diffusivity high chemical reactivity

62. Grain Boundary: low and high angle One grain orientation can be obtained by rotation of another grain across the grain boundary about an axis through an angle If the angle of rotation is high, it is called a high angle grain boundary If the angle of rotation is low it is called a low angle grain boundary

63. (c) 2003 Brooks/Cole Publishing / Thomson Learning The low angle grain boundary is produced by an array of dislocations, causing an angular mismatch θ between lattices on either side of the boundary. An array of dislocations causing a small misorientation of the crystal across the surface of the imperfection. Low-angle grain boundary

64. H i g h - a n g l e gr a i n b o u n d a ry A s i m p le h ig h - a n gl e boundary where two crystals meet High-angle boundaries are likely sites for chemical segregation

65. Grain Boundary: tilt and twist One grain orientation can be obtained by rotation of another grain across the grain boundary about an axis through an angle If the axis of rotation lies in the boundary plane it is called tilt boundary I f t h e a ng l e o f r o t a t i o n i s p e r p e n d i c u l a r to the boundary plane it is called a twist boundary

66. Tilt-twist character If cos -1 ( b )=0°, boundary is pure twist; If cos -1 ( b )=90°, boundary is pure tilt. n  ˆ b

67. Twist B o unda r y   g n ˆ Grain A Grain B Grain A Grain B o u n d a r y n ˆ Grain B Tilt B o unda r y   g   (hkl) 1 (hkl) 2 Twist angle

68.    Butiran 1 Butiran 2 Batas kemiringan A  B C b  sin  2 h 2 b  tan  h A t au  2 2 h b A B C

69. Edge dislocation model of a small angle tilt boundary   Grain 1 Grain 2 Tilt boundary A  B  C  2 2 h b A B C s i n b   2 h 2 h b  t an  Or approximately

70. volume defects voids (porosity) holes in the materials Voids are small regions where there are no atoms, and can be thought of as clusters of vacancies inclusions inclusions particles of foreign matter embedded in the solid

71. precipitations Every impurity introduced into a crystal has a certain level of solubility, which defines the concentration of that impurity that the solid solution of the host crystal can accommodate. Impurity solubility usually decreases with decreasing temperature.

72. the crystal will become supersaturated with that impurity once it is cooled down. A c r y s t a l u n d e r s u ch s u p e r s a t u r a t e d c o n d i t i o n s s eek s a n d a c h i e v e s equilibrium by precipitating the excess impurity atoms into another phase of different composition or structure. P R E C I P I T A T E S Impurities cluster together to form small regions of a different phase volume defects If an impurity is introduced into a crystal at the maximum concentration allowed by its solubility at a high temperature,

73. Precipitates are considered undesirable because they have been known to act as sites for the generation of dislocations Precipitates induced during silicon wafer processing come from oxygen, metallic impurities, and dopants like boron

74. Effect on Mechanical Properties via Control of the Slip Process Strain Hardening Solid-Solution Strengthening Grain-Size Strengthening Effects on Electrical, Optical, and Magnetic Properties Importance of Defects Defectoscope Detect fine surface defects The system can detect flaws as fine as 30 microns on polished surfaces Electron microscopy Optical microscopy Defectoscope

75. S e l a i n d i k l a s i f i k a s i k a n b e r d a s a r k a n d i m e n s i n y a , c a c a t kristal juga diklasifikasikan berdasarkan stoikiometriknya. Berdasarkan stoikiometriknya, cacat kristal dibagi m e n j a d i du a k a t a go r i , y a i t u c a c a t s t o i k i o m e t r i k d a n cacat nonstoikiometrik. Cacat stoikiometrik diakibatkan faktor temperatur sehingga atom/ion pindah meninggalkan posisi normalnya menghasilkan cacat kekosongan & / cacat sisipan  tidak mengubah rumus kimia suatu senyawa Cacat nonstoikiometrik diakibatkan oleh sebagian kecil atom hilang atau ketambahan atom pengotor ke dalam kisi yang tidak sempurna  dapat mengubah rumus kimia suatu senyawa. Contoh NaCl 0,95

76. Cacat kristal nonstokiometrik dibagi menjadi tiga: Ca c at k e l e b i h a n l o gam / cacat pusat F / cacat pusat warna Cacat kelebihan logam pada Zn 1+x O Cacat kekurangan logam Cacat ketidakmurnian ( Impurity defect )

77. Larutan padat ( solid solution ) Larutan padat adalah campuran homogen berwujud padat yang terdiri dari satu atau lebih zat terlarut dalam pelarut. Pelarut ( solvent ) mewakili unsur atau senyawa yang ada dalam jumlah terbesar. Terkadang, atom pelarut juga disebut atom host . Zat terlarut ( solute ) digunakan untuk m e n u n j u k k an u n s ur a t au s e n y a w a y a n g a d a d a l am k o n s e n t r a s i k e c il .

78. Gambar. Atom pengotor sisipan dan substitusi pada larutan padat Cacat titik ketidakmurniaan ditemukan pada larutan padat, dimana ada dua jenis: substitusi dan sisipan. Untuk jenis substitusional, atom terlarut atau pengotor menggantikan atom pelarut

79. Jawablah soal-soal berikut dengan benar! Tuliskan macam-macam cacat kristal berdasarkan dimensinya! Kenapa besi oksida (FeO) dapat mengalami cacat kekurangan logam? Bagaimana cara membuat kristal NaCl yang mengalami cacat kelebihan logam? Apa yang dimaksud larutan padat? Apa perbedaan larutan padat substitusional dan larutan padat sisipan? Apa perbedaan Cacat Frenkel dengan cacat Schottky? Tuliskan macam-macam cacat kristal nonstokiometrik! Untuk kristal KCl dan KI, manakah yang lebih mudah mengalami a) Cacat Frenkel; b) Cacat Schottky

80. R e f e r e nsi Bu ku a j ar k i m i a z at p a d a t , bu ku r efe r e n si l a i n n ya , a r t i kel i l m i ah dll

81. Untuk lebih memahami materi ini silahkan baca di buku kami / yg lain: PPT ini digunakan untuk mempermudah pembelajaran, kebanyakan saya ambil dari berbagai literatur buku dan PPT (terutama yg berbahasa Inggris) dan dari buku Kimia Zat Padat, Samik dkk. Mau ebook buku Kimia Zat Padat, silahkan klik https://bit.ly/ebookKZP / 085731160005

82. Daftar Isi buku Kimia Zat Padat, Mau ebooknya, silahkan klik https://bit.ly/ebukuKZP / 085731160005

83. T E R I M A K A SIH