This document provides an introduction to solid state physics presented by Dr. Dattu Joshi. It discusses the aims of solid state physics, including understanding the properties of solids based on the interactions between atomic nuclei and electrons. It describes crystalline solids as having a regular repeated atomic pattern and discusses different types of solids including crystalline, polycrystalline, and amorphous materials. The document outlines several topics that will be covered related to crystal structure, diffraction, imperfections, and bonding in solids.

1. Introduction to SOLID STATE PHYSICS A Random Walk Dr. Dattu Joshi Applied Physics Department Faculty of Tech. & Engg. The M S University of Baroda Vadodara-390 001 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

2. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

3. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

19. CRYSTAL STRUCTURE Elementary Crystallography Typical Crystal Structures Elements Of Symmetry 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

21. Crystal Structure matter 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

25. Crystal Structure ELEMENTARY CRYSTALLOGRAPHY 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara SOLID MATERIALS CRYSTALLINE POLYCRYSTALLINE AMORPHOUS (Non-crystalline) Single Crystal

34. Crystal Structure CRYSTALLOGRAPHY What is crystallography? The branch of science that deals with the geometric description of crystals and their internal arrangement. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

38. Crystal Structure CRYSTAL LATTICE What is crystal ( space ) lattice? In crystallography, only the geometrical properties of the crystal are of interest, therefore one replaces each atom by a geometrical point located at the equilibrium position of that atom. Platinum Platinum surface Crystal lattice and structure of Platinum ( scanning tunneling microscope ) 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

41. A two-dimensional Bravais lattice with different choices for the basis 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

45. Crystal Structure Types Of Crystal Lattices 1) Bravais lattice is an infinite array of discrete points with an arrangement and orientation that appears exactly the same, from whichever of the points the array is viewed. Lattice is invariant under a translation. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Nb film

47. Crystal Structure Translational Lattice Vectors – 2 D A space lattice is a set of points such that a translation from any point in the lattice by a vector; R n = n 1 a + n 2 b locates an exactly equivalent point, i.e. a point with the same environment as P . This is translational symmetry . The vectors a , b are known as lattice vectors and (n 1 , n 2 ) is a pair of integers whose values depend on the lattice point. P Point D(n1, n2) = ( 0 ,2) Point F (n1, n2) = (0,-1) 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

49. Crystal Structure Lattice Vectors – 3D An ideal three dimensional crystal is described by 3 fundamental translation vectors a, b and c . If there is a lattice point represented by the position vector r , there is then also a lattice point represented by the position vector where u , v and w are arbitrary integers . r’ = r + u a + v b + w c (1) 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

50. Crystal Structure Five Bravais Lattices in 2D 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

53. Crystal Structure 2D Unit Cell example -(NaCl) We define lattice points ; these are points with identical environments 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

54. Crystal Structure Choice of origin is arbitrary - lattice points need not be atoms - but unit cell size should always be the same . 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

55. Crystal Structure This is also a unit cell - it doesn’t matter if you start from Na or Cl 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

56. Crystal Structure - or if you don’t start from an atom 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

57. Crystal Structure This is NOT a unit cell even though they are all the same - empty space is not allowed ! 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

58. Crystal Structure In 2D, this IS a unit cell In 3D, it is NOT 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

59. Crystal Structure Why can't the blue triangle be a unit cell? 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

60. Crystal Structure Unit Cell in 3D 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

61. Crystal Structure Unit Cell in 3D 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

62. Crystal Structure Three common Unit Cell in 3D 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

65. Crystal Structure Primitive and conventional cells of FCC 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

66. Primitive and conventional cells of BCC Primitive Translation Vectors: 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

67. Crystal Structure Simple cubic (sc): primitive cell=conventional cell Fractional coordinates of lattice points: 000, 100, 010, 001, 110,101, 011, 111 Primitive and conventional cells Body centered cubic (bcc): conventional  primitive cell Fractional coordinates of lattice points in conventional cell : 000,100, 010, 001, 110,101, 011, 111, ½ ½ ½ 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

68. Crystal Structure Body centered cubic (bcc): primitive (rombohedron)  conventional cell Face centered cubic (fcc): conventional  primitive cell Fractional coordinates : 000,100, 010, 001, 110,101, 011,111, ½ ½ 0, ½ 0 ½, 0 ½ ½ ,½1 ½ , 1 ½ ½ , ½ ½ 1 Primitive and conventional cells 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Fractional coordinates : 000, 100, 101, 110, 110,101, 011, 211, 200

69. Crystal Structure Hexagonal close packed cell (hcp): conventional  primitive cell Fractional coordinates : 100, 010, 110, 101,011, 111,000, 001 Primitive and conventional cells -hcp 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara points of primitive cell 120 o

74. Crystal Structure Wigner-Seitz Cell - 3D 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

75. Crystal Structure Lattice Sites in Cubic Unit Cell 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

77. Crystal Structure X = ½ , Y = ½ , Z = 1 [½ ½ 1] [1 1 2] Examples 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara 210 X = 1 , Y = ½ , Z = 0 [1 ½ 0] [2 1 0]

79. Crystal Structure X = -1 , Y = -1 , Z = 0 [110] Examples of crystal directions X = 1 , Y = 0 , Z = 0 [1 0 0] 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

80. Crystal Structure Examples X =-1 , Y = 1 , Z = -1/6 [-1 1 -1/6] [6 6 1] We can move vector to the origin. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

82. Crystal Structure Miller Indices Miller Indices are a symbolic vector representation for the orientation of an atomic plane in a crystal lattice and are defined as the reciprocals of the fractional intercepts which the plane makes with the crystallographic axes. To determine Miller indices of a plane, take the following steps; 1) Determine the intercepts of the plane along each of the three crystallographic directions 2) Take the reciprocals of the intercepts 3) If fractions result, multiply each by the denominator of the smallest fraction 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

83. Crystal Structure Example-1 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Axis X Y Z Intercept points 1 ∞ ∞ Reciprocals 1/1 1/ ∞ 1/ ∞ Smallest Ratio 1 0 0 Miller İndices (100) (1,0,0)

84. Crystal Structure Example-2 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Axis X Y Z Intercept points 1 1 ∞ Reciprocals 1/1 1/ 1 1/ ∞ Smallest Ratio 1 1 0 Miller İndices (110) (1,0,0) (0,1,0)

85. Crystal Structure Example-3 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Axis X Y Z Intercept points 1 1 1 Reciprocals 1/1 1/ 1 1/ 1 Smallest Ratio 1 1 1 Miller İndices (111) (1,0,0) (0,1,0) (0,0,1)

86. Crystal Structure Example-4 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Axis X Y Z Intercept points 1/2 1 ∞ Reciprocals 1/( ½ ) 1/ 1 1/ ∞ Smallest Ratio 2 1 0 Miller İndices (210) (1/2, 0, 0) (0,1,0)

87. Crystal Structure Example-5 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Axis a b c Intercept points 1 ∞ ½ Reciprocals 1/1 1/ ∞ 1/( ½ ) Smallest Ratio 1 0 2 Miller İndices (102)

88. Crystal Structure Example-6 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

89. Crystal Structure Miller Indices Indices of the plane (Miller): (2,3,3) Indices of the direction: [2,3,3] 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Reciprocal numbers are: Plane intercepts axes at (100) (200) (110) (111) (100) 3 2 2 [2,3,3]

90. Crystal Structure 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

91. Crystal Structure Example-7 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

93. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

94. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

95. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Find out which one is wrong?

97. Crystal Structure 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

101. Crystal Structure a- Simple Cubic (SC) 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

102. Crystal Structure Atomic Packing Factor of SC 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

104. Crystal Structure Atomic Packing Factor of BCC 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara 2 (0 . 433a)

106. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

107. Crystal Structure 4 (0 . 353a) Atomic Packing Factor of FCC 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara FCC 0 . 74

108. Crystal Structure Atoms Shared Between: Each atom counts: corner 8 cells 1/8 face centre 2 cells 1/2 body centre 1 cell 1 edge centre 2 cells 1/ 2 lattice type cell contents P 1 [=8 x 1/8] I 2 [=(8 x 1/8) + (1 x 1)] F 4 [=(8 x 1/8) + (6 x 1/2)] C 2 [=(8 x 1/8) + (2 x 1/2)] Unit cell contents Counting the number of atoms within the unit cell 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

109. Crystal Structure Example; Atomic Packing Factor 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

111. Crystal Structure 2 - HEXAGONAL SYSTEM Atoms are all same. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

112. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

113. Crystal Structure 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

115. Crystal Structure 5 - ORTHORHOMBIC SYSTEM Orthorhombic ( Simple )  = ß =  = 90 o a  b  c Orthorhombic (B ase-centred)  = ß =  = 90 o a  b  c Orthorhombic (BC)  = ß =  = 90 o a  b  c Orthorhombic (FC)  = ß =  = 90 o a  b  c 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

116. Crystal Structure 6 – TETRAGONAL SYSTEM Tetragonal (P)  = ß =  = 90 o a = b  c Tetragonal (BC)  = ß =  = 90 o a = b  c 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

117. Crystal Structure 7 - Rhombohedral (R) o r Trigonal Rhombohedral (R) o r Trigonal (S) a = b = c,  = ß =  90 o 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

120. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

125. 8 ce l l Cesium Chloride Cs + Cl - 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

127. Crystal Structure Bravais Lattice : Hexagonal Lattice He, Be, Mg, Hf, Re (Group II elements) ABABAB Type of Stacking Hexagonal Close-packed Structure a=b a=120, c=1.633a, basis : (0,0,0) (2/3a ,1/3a,1/2c) 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

132. 5- Zinc Blende 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

133. Crystal Structure 5- Zinc Blende Zinc Blende is the name given to the mineral ZnS. It has a cubic close packed (face centred) array of S and the Zn(II) sit in tetrahedral (1/2 occupied) sites in the lattice . 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

135. Crystal Structure Lattice goes into itself through Symmetry without translation 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Operation Element Inversion Point Reflection Plane Rotation Axis Rotoinversion Axes

141. Crystal Structure Axis of Rotation 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

142. Crystal Structure Axis of Rotation 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

143. Crystal Structure Can not be combined with translational periodicity! 5-fold symmetry 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

144. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Symmetry Elements for Cubic System Axis of Symmetry present in cubic system 3-Tetrads 4-triads 6-diads Total-13 axes of symmetry Total =13+9+1 = 23 elements of symmetry Centre of symmetry

145. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

146. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara The characteristic symmetry elements in each of the seven groups are listed below The characteristic symmetry elements in each of the seven groups are listed below Cubic Three triads Hexagonal One hexad (// z) Tetragonal One tetrad (// z) Trigonal One triad (// [111]) Orthorhombic Three perpendicular diads (// x, y and z) Monoclinic One diad (// y) Triclinic -

147. 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara Concept Map

150. Crystal Structure 03/11/2011 Intro to Solid State by Dr Dattu Joshi, MSU, Vadodara

151. IMPERFECTIONS IN CRYSTALS

155. CLASSIFICATION OF IMPERFECTIONS There are three types of imperfections exist in general. (A) Crystal Imperfections or atomic imperfections) (B) Electronic Imperfections (C) Transient Imperfections

160. Different types of point defects in crystals

161. Vacancy

163. Point defects in ionic crystals

171. Point defects in elemental solids

172. Frenkel defects in ionic crystals

173. Cation and Anion vacancy

194. We take the blue atoms as the base plane for what we are going to built on it, we will call it the "A - plane". The next layer will have the center of the atoms right over the depressions of the A - plane; it could be either the B - or C - configuration. Here the pink layer is in the "B" position

195. If you pick the B - configuration (and whatever you pick at this stage, we can always call it the B - configuration), the third layer can either be directly over the A - plane and then is also an A - plane (shown for one atom), or in the C - configuration. If you chose "C", you get the face centered cubic lattice (fcc) If you chose "A"; you obtain the hexagonal close packed lattice ( hcp ), The stacking sequences of the two close-packed lattices therefore are fcc: ABCABCABCA... hcp: ABABABA...

196. Trends of Research In Crystal Growth

198. Properties exploited Device Crystal 1 Uniformity alone X-ray prisms Neutron collimators Lithium fluoride 2 Uniformity giving reproducible mechanical properties and abrasion resistance Turbine blades Gramophone styli Bearings Tape-recorder heads Wire drawing dies Metals Sapphire Ruby Ferrites Diamond 3 Uniformity eliminating scattering of electromagnetic waves Lenses, prisms and optical windows Lasers* Microwave filters Alkali and alkaline earth halides Yttrium aluminum garnet Yttrium iron garnet 4 Uniformity reducing charged carrier scattering Transistors*, Diodes* Thyristors * Photocells Silicon, germanium and gallium arsenide Cadmium suiphide 5 Uniformity reducing scattering of sound waves Resonant filters Delay lines Quartz Lithium niobate Zinc oxide 6 Uniformity allowing exploitation of tensor properties Nicol prism Ultrasonic transducers Gramophone pick-ups Fluorite Rochelle salt Lithium sulphate

204. Survey of the methods of crystal growth In some cases huge quantities of crystals are grown annually e.g. silicon, quartz, germanium, Rubby, and di-hydrogen phosphates of potassium and ammonium Growth from Approximate % growth Melt 80 Vapour 7 Low Temperature solution 5 High Temperature Solution 5 Solid 3 Hydrothermal 2

205. Classification of Growth Techniques

206. Growth from the pure melt

207. Growth from the pure melt

208. Growth from Solution

209. Growth from Solution

210. Single Crystals for Research Purposes Crystal Doping Agent Uses  -Al 2 O 3, TiO 2 , CaF 2 Transition elements Paramagnetic studies CaWO 4 , etc. Rare Earths and Actinides Masers; Lasers ZnS, CdS, Organic Crystals Cr, Mn, Cu, Ag, Tl, etc. Fluorescence Photoconductivity Photoelectricity Ge, Si, InSb, GaAs, SiC, PbTe, Bi 2 Te 3 Donor or acceptor impurities Semiconductivity, Thermoelectric, Galvanomagnetic effects Fe 3 O 4 , MFe 2 O 4 , BaFe 12 O 19 , Y 3 Fe 5 O 12 Paramagnetic substituents Magnetic studies BeO, MgO,  -Al 2 O 3, UO 2 Pure Reactor material Al 2 SiO 5 , aluminosilicates, ZrSiO 4 , C, BN, WC, ThO 2 ZrO 2 , Si 3 N 4 , etc. Pure Refractories, abrasives, Structural materials Alkali halides,  -SiO 2 , CaF 2 , SrTiO 3 Pure Optical materials

211. Methods of Crystal Assessments Method Destructive or Non-destructive Information given 1 Chemical analysis Spectrographic analysis D Composition 2 X-ray analysis N Structure (Some information on composition) 3 X-ray fluorescence spectroscopy N Composition 4 Electron diffraction N Structure, surface detail 5 Electron microscopy N Surface detail 6 Electron beam X-ray spectroscopy N Composition 7 Optical spectroscopy, IR  UV N Structure and composition 8 Electron spin resonance N Purity (structure) 9 Optical examination N Imperfections, Surface detail 10 Etching, decorating N/D Perfection 11 Measurement of specialized physical properties (electrical or magnetic) N Perfection, purity

212. Requirements for growth control

217. Verneuil 1902, Auguste Verneuil characteristics : no crucible contamination highly pure starting material (>99.9995%) strict control of flame temperature precise positioning of melted region vibration growth

219. temperature T melt Bridgman-Stockbarger characteristics : charge and seed are placed into the crucible no material is added or removed (conservative process) axial temperature gradient along the crucible

224. Czochralski-Kyropoulos A seed crystal mounted on a rod is dipped into the molten material. The seed crystal's rod is pulled upwards and rotated at the same time. By precisely controlling the temperature gradients, rate of pulling and speed of rotation, a single-crystal cylindrical ingot is extracted from the melt. The process may be peformed in controlled atmosphere and in inert chamber. Jan Czochralski (1885 - 1953) characteristics : charge and seed are separated at start no material is added or removed (conservative process) charge is held at temperature slightly above melting point crystal grows as atoms from the melt adhere to the seed seed grown crystal molten raw material heating elements seed grown crystal molten raw material Kyropoulos Czochralski 1918 1926

225. Pulling direction of seed on rod Heater Crucible Inert atmosphere under pressure prevents material loss and unwanted reactions Layer of molten oxide like B 2 O 3 prevents preferential volatilization of one component - precise stoichiometry control Melt just above mp Growing crystal Crystal seed Counterclockwise rotation of melt and crystal being pulled from melt, helps unifomity of temperature and homogeneity of crystal growth CZOCHRALSKI

229. zone melting ultra-pure silicon characteristics : only a small part of the charge is molten material is added to molten region (nonconservative process) molten zone is advanced by moving the charge or the gradient axial temperature gradient is imposed along the crucible

231. other methods (1) melt non congruently decompose before melting have very high melting point undergo solid state phase transformation between melting point and room temperature growth from solutions key requirement high purity solvent insoluble in the crystal oxides with very high melting points PbO, PbF 2 , B 2 O 3 , KF very slow, borderline purity, platinum crucibles, stoichiometry hard to control carried on at much lower temperature than melting point typical solvents: main advantage: limitations: molten salt (flux) growth a liquid reaction medium that dissolves the reactants and products, but do not participate in the reaction flux:

232. other methods (2) high quality layers of III-V compounds (Ga 1-x ln x As, GaAs x P 1-x ) GaAs and GaSb from Ga solution liquid phase epitaxy advantage lower temperatures than melt growth limitation very slow, small crystals or thin layers aqueous solution at high temperature and pressure typical example: quartz industry SiO 2 is grown by hydrothermal growth at 2000 bars and 400 °C because of α-β quartz transition at 583°C hydrothermal growth

233. crystal purity (1) Solubility of possible impurity is different in crystal than melt, the ratio between respective concentrations is defined as segregation coefficient (k 0 ) impurity equilibrium concentration in crystal impurity equilibrium concentration in melt As the crystal is pulled impurity concentration will change in the melt (becomes larger if segregation coefficient is <1). Impurity concentration in crystal after solidifying a weight fraction M/M 0 is:

238. crystal purity (2) As a consequence, floating zone method will give crystals with lower concentration of impurities having k<1 than Czochralski growth The effective segregation coefficient (k e ): multiple pass may be run in order to achieve the required impurity concentration there is no contamination from crucible

239. crystals for DBD DBD application constraints ββ emitters of experimental interest impurity allowed (g/g): T = 10 18 – 10 24 yr usual T i < 10 12 yr close to detection limit of the most sensitive techniques used for quantitative elemental analysis (NAA, ICP-MS)

240. TeO 2 crystal (1) relatively low melting point distorted rutile (TiO 2 ) structure anisotropy of expansion coefficient TeO 2 (paratellurite) a = 4.8088 Å c = 7.6038 Å short:: 1.88 Å long:: 2.12 Å

241. TeO 2 crystal (2) raw material preparation Te TeO 2 99.999% TeO 2 +HCl->TeCl 4 +H 2 O TeO 2 2Te+9HNO 3 -> Te 2 O 3 (OH)NO 3 +8NO 2 +4H 2 O Te 2 O 3 (OH)NO 3 ->2 TeO 2 +HNO 3 TeCl 4 +4NH 4 OH->Te(OH) 4 +4NH 4 Cl Te(OH) 4 ->TeO 2 +H 2 O HNO 3 TeO 2 HCl TeCl 4 TeCl 4 NH 4 OH TeO 2 TeO 2 washing filtering washing drying

242. TeO 2 crystal (3) TeO 2 crystal is particularly repellent to impurities most of radioactive isotopes have ionic characteristics incompatible with substitutional incorporation in TeO 2 crystal growth seed grown Xtal molten TeO 2 heating Czochralski molten TeO 2 Bridgman seed grown Xtal Bridgman grown crystals are more stressed than Czochralski ones annealing at about 550°C helps in removing the residual stresses

243. TeO 2 crystal (4) Te possible substitutional ions in TeO 2 238 U (T=4.5·10 9 yr) 184 W (T=3·10 17 yr)

244. TeO 2 crystal (5) radiopurity main radioactive series crucible material activation products natural radioactivity

245. conclusion shares of 20 000 tons, world crystals production in 1999 ECAL-CMS: (  80 tons PWO)/2000-2006 CUORE: (  1 ton TeO 2 )/?