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APPLIEDPHYSICS
Text BooksBook 1: Applied Physics by Dr. M.Chandra sekhar & Dr. Appala naidu,V.G.S. Book linksBook 2 Introduction to Solid...
Suggested / Reference Books Book 1 Material science and Engineering by V Raghavan PHI publishers Book 2 Material Science b...
Book 5: Applied Physics byP.K.Palaniswamy,ScitechPublications(India)Pvt.Ltd.Book 6: Material Science by MS Vijaya & GRanga...
UNIT-1Bonding in solidsCrystal structuresX-ray diffractions                     5
APPLIED PHYSICS CODE : 07A1BS05     I B.TECHCSE, IT, ECE & EEE    UNIT-1: CHAPTER1NO. OF SLIDES :31                       6
UNIT INDEX                         UNIT-IS.No.          Module          Lecture   PPT Slide                               ...
Lecture-1            IntroductionIntroduction: Generally matter consists in threestates i.e., depending on their internal ...
Lecture-2            Types of BondingAn atom consists of positively charged nucleussurrounded by negatively charged electr...
Bonds generally classified into five               classes.1. Ionic bonding2. Covalent bonding3. Metallic bonding4. Hydrog...
Ionic Bonding: An ionic bonding is  the attractive force existing between  a positive ion and a negative ion  when they ar...
Properties of ionic solids:1.Ionic solids are crystalline in nature.2.They are hard and brittle.3.They have high melting a...
5.They are soluble in polar solvents and  insoluble in Non-polar solvents.6.In an ionic crystal, a cation is surrounded  b...
Covalent Bonding:  The arrangement of electrons in an outer shell is achieved by a process of valence electron sharing rat...
Properties of Covalent solids:1.Covalent bonds are directional. Change in the   direction of the bond results in the forma...
4.When compared with ionic solids, these solids   have relatively low melting and boiling   points.5.Pure covalent solids ...
17
Metallic Bonding: The valence electrons from all the atoms belonging to the crystal are free to move throughout the crysta...
Properties of Metallic solids:1.Metallic bonds hold the atoms   together in metals.2.Metallic bonds are relatively weak.3....
5.They have high number offree electrons.6.They possess high electricaland thermal conductivity.7.Metals are opaque to lig...
Hydrogen Bonding:Covalently bonded atoms often produce an electric dipole configuration with hydrogen atom as the positive...
Properties of Hydrogen solids:1.The hydrogen bonds are directional.2.The bonding is relatively strong as compared  to othe...
6.They are transparent to light.7.Since elements of low atomic numbers form  such solids, they have low densities.8.When w...
Van der Waals(Molecular) Bonding: Weak and temporary (fluctuating) dipole bonds between hydrogen are known as van der Waal...
Properties of Van der waals bonding:1.Van der waals bonds are nondirectional.2.Van der waals bonding is weaker than the  h...
5.They are soluble in both polar and non polar liquids.6.They are usually transparent to light.Examples of Van der Waals b...
1. The mechanical, thermal,   electrical and other properties of   materials are related to chemical   bonding and structu...
3. The force that holds atoms together is   called bonding force. Under the bonded   condition the potential energy is   m...
Primary Bondings have bondenergies in the range of 0.1-10eV/bond. Ionic, Covalent andmetallic bondings are the examples. S...
Lecture-3Cohesive energy of NaCl molecule:                                      30
Lecture-4The Madelung constant is afunction of crystal structureand can be calculated fromthe geometrical arrangementof io...
UNIT INDEX                         UNIT-IS.No.           Module                Lecture   PPT Slide                        ...
Lecture-5             INTRODUCTION   Matter is classified into three kinds, they aresolids, liquids and gases. In solids, ...
CRYSTALLINE SOLIDS            AMORPHOUS SOLIDS1. In crystalline solids, the 1. In amorphous solids, the    atoms or molecu...
LATTICE POINTS : Lattice points denote the position of atoms or molecules in the crystals.SPACE LATTICE : The angular arra...
2D-SPACE LATTICE :   It is defined as an infinite array of points in 2-  D space in which every point has the same  enviro...
3D- Space LatticeIt is defined as an infinite array of points in 3D-Space in which every point has the same environment w....
BASIS : Certain atoms or molecules are attached to each lattice point in the crystal structure. These atoms or molecules ...
The repeating unit assembly – atom,molecule, ion or radical – that is located ateach lattice point is called the BASIS. Th...
Unit Cell :Unit cell of a crystal is the smallest volume of a crystalline solid or geometric figure from which the entire...
Lecture-6LATTICE PARAMETERS OF AN UNIT CELL The lines drawn parallel to the lines ofintersection of any three faces of the...
The angle between the axes Y and Z = α    The angle between the axes Z and X = β    The angle between the axes X and Y = γ...
BRAVAIS LATTICESA 3dimensional lattice is generated byrepeated translation of three non-coplanarvectors a,b &c.There are o...
SIMPLE CUBIC     44
BODY CENTRED CUBIC        45
FACE CENTRED CUBIC        46
TETRAGONAL    47
BODY CENTRED TETRAGONAL           48
ORTHORHOMBIC     49
BODY CENTREDORTHORHOMBIC     50
BASE CENTREDORTHORHOMBIC      51
FACE CEN TREDORTHORHOMBIC      52
MONOCLINIC    53
BASE CENTRED MONOCLINIC           54
TRICLINIC    55
RHOMBOHEDRAL     56
HEXAGONAL    57
Lecture-7Atomic packing factor is the ratio of volume occupied by the atoms in an unit cell to the total volume of the un...
Metallic crystals have closest packing intwo forms (i) hexagonal close packed and(ii) face- centred cubic with packingfact...
Lecture-8           MILLER INDICESIn a crystal orientation of planes or faces can  be described interms of their intercep...
All equally spaced parallel planes have the  same miller indices.  . If a normal is drawn to a plane (h k l), the  directi...
Important features in miller              indices                               Lecture-91. When a plane is parallel to an...
4. If a plane passes thought origin, it is defined   in terms of a parallel plane having non-zero   intercept.5. If a norm...
UNIT INDEX                        UNIT-IS.No.         Module           Lecture   PPT Slide                               N...
Lecture-10X-Ray Powder Diffraction                           65
Lecture-1066
Lecture-10X-Ray Powder Diffraction (XRPD) isone of the most powerful techniquesfor analyzing the crystalline nature ofsoli...
Lecture-10XRPD is perhaps the most widely used X-raydiffraction technique for characterizing materials.As the name suggest...
Lecture-10The term powder means that the crystallinedomains are randomly oriented in the sample.Therefore, when the 2-D di...
Lecture-10Powder diffraction data can be collectedusing either transmission or reflectiongeometry, as shown below. If the ...
Lecture-10Single crystal diffraction              L                                        e Laue’s method - λ variable, ...
Lecture-11Powder diffractionIn this method the crystal is reduced to afine powder and is placed in a beam ofmonochromatic...
Lecture-11The diagram shows only two scattering planes, butimplicit here is the presence of many parallel, identicalplanes...
Lecture-11• Angles are used to calculate the interplanar  atomic spacings (d-spacings). Because every  crystalline materia...
Lecture-11The position (d) of the diffracted peaks also providesinformation about how the atoms are arranged within thecry...
Lecture-  If the sample consists of tens of randomly 11oriented single crystals, the diffracted beamsare seen to lie on th...
Instrument geometries                       Lecture-11There are several ways of collecting XRPD patterns:Camera methods: G...
The Debye – Scherrer powder camera                          Lecture-1A photographic film is placed around the inner circum...
L Lecture-12                           e         Pinhole source                            c        Film located on came...
View of an instrument   Lecture-12                         80
Lecture-10     Lecture-1081
X-Ray Powder Diffraction Instruments                                Lecture-12                 82
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Unit 1

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Unit 1

  1. 1. APPLIEDPHYSICS
  2. 2. Text BooksBook 1: Applied Physics by Dr. M.Chandra sekhar & Dr. Appala naidu,V.G.S. Book linksBook 2 Introduction to Solid State Physicsby C. Kittel, Wiley Eastern Ltd.Book 3Nanotechnology by Mark Ratnerand Daniel Ratner, Pearson Education 2
  3. 3. Suggested / Reference Books Book 1 Material science and Engineering by V Raghavan PHI publishers Book 2 Material Science by M Arumugam, Anuradha agencies Book 3Solid state physics by Ashcroft, Mermin, Thomson learning Book 4Solid state physics by Gupta & Kumar,K.Nath & Co. 3
  4. 4. Book 5: Applied Physics byP.K.Palaniswamy,ScitechPublications(India)Pvt.Ltd.Book 6: Material Science by MS Vijaya & GRangarajan, Tata Mc Graw HillBook 7: Applied Physics by K. Vijay Kumar &T.Srikanth, S. Chand & Company Ltd.Book 8: Nano materials by A.K. Bandyopadhyay,New Age International Publishers 4
  5. 5. UNIT-1Bonding in solidsCrystal structuresX-ray diffractions 5
  6. 6. APPLIED PHYSICS CODE : 07A1BS05 I B.TECHCSE, IT, ECE & EEE UNIT-1: CHAPTER1NO. OF SLIDES :31 6
  7. 7. UNIT INDEX UNIT-IS.No. Module Lecture PPT Slide No. No. 1 Introduction L1 8 2 Types of bonding L2 9-29 3. Estimation of L3 30 cohesive energy. 4. Made lung constant. L4 31 7
  8. 8. Lecture-1 IntroductionIntroduction: Generally matter consists in threestates i.e., depending on their internal structure.Normally the states are solid state, liquid state,and gaseous state. In solids stated as the closercollection of atoms result in bulk materials calledsolids. Solids are usually strong and exhibitelastic character. Solids can be broadly classifiedas either crystalline or Non-crystalline. Thearrangement of atoms in a solids is determinedby the character, strength and directionality of thebinding forces. The bonds are made of attractiveand repulsive forces. 8
  9. 9. Lecture-2 Types of BondingAn atom consists of positively charged nucleussurrounded by negatively charged electron cloud. Whentwo atoms are brought closer there will be both attractiveand repulsive forces acting upon. The value of the energyneed to move an atom completely away from itsequilibrium position is a measure of “Bonding Energy “between them.This energy varies depending on the type of bonding. The bonds are made up of attractive and repulsiveforces. Different charge distributions in the atoms giverise to different types of bonding. 9
  10. 10. Bonds generally classified into five classes.1. Ionic bonding2. Covalent bonding3. Metallic bonding4. Hydrogen bonding5. Vander walls bonding. 10
  11. 11. Ionic Bonding: An ionic bonding is the attractive force existing between a positive ion and a negative ion when they are brought into close proximity. These ions are formed when the atoms of different elements involved lose or gain electrons in order to stabilize their outer shell electron configurations. 11
  12. 12. Properties of ionic solids:1.Ionic solids are crystalline in nature.2.They are hard and brittle.3.They have high melting and boiling points.4.Since all the electrons are tightly bound with the ions, ionic solids are good insulators of electricity. 12
  13. 13. 5.They are soluble in polar solvents and insoluble in Non-polar solvents.6.In an ionic crystal, a cation is surrounded by as many anions as possible and vice- versa.Examples of ionic solids:NaCl, KCl, KBr, MgO, MgCl2,KOH, andAl2O3 are few examples of ionic solids. 13
  14. 14. Covalent Bonding: The arrangement of electrons in an outer shell is achieved by a process of valence electron sharing rather than electron transfer. 14
  15. 15. Properties of Covalent solids:1.Covalent bonds are directional. Change in the direction of the bond results in the formation of different substance.2.Since different covalent solids have very much different bond strengths, they exhibit varying physical properties. For example, the diamond is the hardest substance with very high melting point. It is a very good insulator of electricity.3.Covalent solids are hard and brittle. They posses crystalline structure. 15
  16. 16. 4.When compared with ionic solids, these solids have relatively low melting and boiling points.5.Pure covalent solids are good insulators of electricity at low temperatures.6.When covalent crystals are doped with certain impurities, they becomes semi-conductors.Examples of Covalent solids:S,I, Ge, Si, diamond and graphite. 16
  17. 17. 17
  18. 18. Metallic Bonding: The valence electrons from all the atoms belonging to the crystal are free to move throughout the crystal. The crystal may be considered as an array of positive metal ions embedded in a “cloud” or “sea” of free electrons. This type of bonding is called metallic bonding. 18
  19. 19. Properties of Metallic solids:1.Metallic bonds hold the atoms together in metals.2.Metallic bonds are relatively weak.3.Metallic solids are malleable and ductile.4.Metallic bond is non directional. 19
  20. 20. 5.They have high number offree electrons.6.They possess high electricaland thermal conductivity.7.Metals are opaque to light.Examples of metallic solids:Sodium, Copper, Gold, Silver,Aluminum. 20
  21. 21. Hydrogen Bonding:Covalently bonded atoms often produce an electric dipole configuration with hydrogen atom as the positive end of the dipole if bonds arise as a result of electrostatic attraction between atoms, it is known as hydrogen bonding. 21
  22. 22. Properties of Hydrogen solids:1.The hydrogen bonds are directional.2.The bonding is relatively strong as compared to other dipole-dipole interactions.3.Hydrogen bonded solids have low melting points.4.Since no valence electrons are available in such solids they are good insulators of electricity.5.They are soluble in both polar and nonpolar solvents. 22
  23. 23. 6.They are transparent to light.7.Since elements of low atomic numbers form such solids, they have low densities.8.When water is in the form of ice, hydrogen bond results in lower density; but when it melts, it becomes more closely packed liquid and hence its density increases.Example of hydrogen bonded solids: Water molecule in the form of ice, ammonia molecules. 23
  24. 24. Van der Waals(Molecular) Bonding: Weak and temporary (fluctuating) dipole bonds between hydrogen are known as van der Waals bonding and they are nondirectoinal. (OR) Secondary bonding arising from the fluctuating dipole nature of an atom with all occupied electron shell filled is called van der waals bonding. 24
  25. 25. Properties of Van der waals bonding:1.Van der waals bonds are nondirectional.2.Van der waals bonding is weaker than the hydrogen bonding.3.Van der waals bonded solids have low melting point.4.Since no valence electrons are available, such solids are good insulators of electricity. 25
  26. 26. 5.They are soluble in both polar and non polar liquids.6.They are usually transparent to light.Examples of Van der Waals bonded solids: Solid neon, Solid argon. 26
  27. 27. 1. The mechanical, thermal, electrical and other properties of materials are related to chemical bonding and structure.2. The atoms/molecules in solids are very strongly held together by interatomic/ intermolecular forces called bonding in solids. 27
  28. 28. 3. The force that holds atoms together is called bonding force. Under the bonded condition the potential energy is minimum.4.The amount of energy required to separate the atoms completely from the structure is called cohesive energy. This energy is also called energy of dissociation. 28
  29. 29. Primary Bondings have bondenergies in the range of 0.1-10eV/bond. Ionic, Covalent andmetallic bondings are the examples. Secondary Bondings have energiesin the range of 0.001-0.5eV/bond.Hydrogen bonding and van der waalsbonding are the examples. 29
  30. 30. Lecture-3Cohesive energy of NaCl molecule: 30
  31. 31. Lecture-4The Madelung constant is afunction of crystal structureand can be calculated fromthe geometrical arrangementof ions in the crystal. 31
  32. 32. UNIT INDEX UNIT-IS.No. Module Lecture PPT Slide No. No. 1 Introduction-space L5 3-10 lattice –unit cell 6 Lattice parameters. L6 11-27 bravais lattices 7 Structure and packing L7 28-30 fractions. 8. Miller indices. L8-9 31-33 32
  33. 33. Lecture-5 INTRODUCTION Matter is classified into three kinds, they aresolids, liquids and gases. In solids, all the atomsor molecules are arranged in a fixed manner.Solids have definite shape and size, where as inliquid and gasses atoms or molecules are notfixed and cannot form any shape and size. On basis of arrangement of atoms or molecules,solids are classified into two categories, they arecrystalline solids and amorphous solids. 33
  34. 34. CRYSTALLINE SOLIDS AMORPHOUS SOLIDS1. In crystalline solids, the 1. In amorphous solids, the atoms or molecules are atoms or molecules are arranged in a regular and arranged in an irregular orderly manner in 3-D manner, otherwise there pattern, called lattice. is no lattice structure.2. These solids passed 2. These solids do not internal spatial symmetry posses any internal of atomic or molecular spatial symmetry. orientation.3. If a crystal breaks, the 3. If an amorphous solid broken pieces also have breaks, the broken pieces regular shape. are irregular in shape. Eg: M.C : Au, Ag,Al, Eg : Glass, Plastic, Rubber. N.M.C: Si, Nacl, Dia. 34
  35. 35. LATTICE POINTS : Lattice points denote the position of atoms or molecules in the crystals.SPACE LATTICE : The angular arrangement of the space positions of the atoms or molecules in a crystals is called space lattice or lattice array. 35
  36. 36. 2D-SPACE LATTICE : It is defined as an infinite array of points in 2- D space in which every point has the same environment w.r.t. all other points. The dots represent the lattice points in which atoms can be accommodated. Taking O as an arbitrary origin in XY – plane constructed. b The two translations vectors ā and ē are taken OP b along X-axis and Y-axis respectively. The resultant vector T can be represented asT=n1ā +n2 Where n1, n2 are arbitrary integers. 36
  37. 37. 3D- Space LatticeIt is defined as an infinite array of points in 3D-Space in which every point has the same environment w.r.t. all other points. In this case the resultant vector can be b expressed as T=n1ā +n2 +n3 . Where n1, n2, n3 c b, c are arbitrary integers and, ā, & are translational vector along X,Y,Z-axis respectively 37
  38. 38. BASIS : Certain atoms or molecules are attached to each lattice point in the crystal structure. These atoms or molecules attached to any lattice point form the basis of a crystal lattice. Hence, crystal structure = Lattice + Basis. In order to convert the geometrical array of points molecules are located on the lattice points. 38
  39. 39. The repeating unit assembly – atom,molecule, ion or radical – that is located ateach lattice point is called the BASIS. The basis is an assembly of atomsidentical in composition, arrangement andorientation. Thus, Again we say that thecrystal structure is formed by logicalrelation Space lattice + Basis = CRYSTALSTRUCTURE. 39
  40. 40. Unit Cell :Unit cell of a crystal is the smallest volume of a crystalline solid or geometric figure from which the entire crystal is built up by translational repetition in three dimensions.Since the unit cell which reflects the structure of the crystal structure of the crystal lattice has all the structural properties of the given crystal lattice, it is enough to study the shape and properties of the unit cell to get the idea about the whole crystal 40
  41. 41. Lecture-6LATTICE PARAMETERS OF AN UNIT CELL The lines drawn parallel to the lines ofintersection of any three faces of the unit cellwhich do not lie in the same plane are calledcrystallographic axes. An arbitrary arrangement ofcrystallographic axes marked X,Y,&Z. Theangles between the three crystallographicaxes are known as interfacial angles orinteraxial angles. 41
  42. 42. The angle between the axes Y and Z = α The angle between the axes Z and X = β The angle between the axes X and Y = γ The intercepts a,b&c define the dimensions of an unit cell and are known as its primitive or characteristic intercepts on the axes. The three quantities a,b&c are also called the fundamental translational vectors. 42
  43. 43. BRAVAIS LATTICESA 3dimensional lattice is generated byrepeated translation of three non-coplanarvectors a,b &c.There are only 14 distinguishable ways ofarranging points in 3d space.These 14 space lattices are known asBravais lattices. 43
  44. 44. SIMPLE CUBIC 44
  45. 45. BODY CENTRED CUBIC 45
  46. 46. FACE CENTRED CUBIC 46
  47. 47. TETRAGONAL 47
  48. 48. BODY CENTRED TETRAGONAL 48
  49. 49. ORTHORHOMBIC 49
  50. 50. BODY CENTREDORTHORHOMBIC 50
  51. 51. BASE CENTREDORTHORHOMBIC 51
  52. 52. FACE CEN TREDORTHORHOMBIC 52
  53. 53. MONOCLINIC 53
  54. 54. BASE CENTRED MONOCLINIC 54
  55. 55. TRICLINIC 55
  56. 56. RHOMBOHEDRAL 56
  57. 57. HEXAGONAL 57
  58. 58. Lecture-7Atomic packing factor is the ratio of volume occupied by the atoms in an unit cell to the total volume of the unit cell. It is also called packing fraction. The arrangement of atoms in different layers and the way of stacking of different layers result in different crystal manner. 58
  59. 59. Metallic crystals have closest packing intwo forms (i) hexagonal close packed and(ii) face- centred cubic with packingfactor 74%. The packing factor of simple cubicstructure is 52%. The packing factor of body centred cubicstructure is 68%. 59
  60. 60. Lecture-8 MILLER INDICESIn a crystal orientation of planes or faces can be described interms of their intercepts on the three crystallographic axes. Miller suggested a method of indicating the orientation of a plane by reducing the reciprocal of the intercepts into smallest whole numbers.o These indices are called Miller indeces generally represented by (h k l). 60
  61. 61. All equally spaced parallel planes have the same miller indices. . If a normal is drawn to a plane (h k l), the direction of the normal is[h k l]. Separation between adjacent lattice planes in a cubic crystal is given by d= u/ ---h 2+k2+l2. where a is the lattice constant and (h k l) are the Miller indices. 61
  62. 62. Important features in miller indices Lecture-91. When a plane is parallel to any axis, the intercept of the plane on that axis is infinity. Hence its Miller index for that axis is zero.2. When the intercept of a plane on any axis is negative a bar is put on the corresponding Miller index.3. All equally spaced parallel planes have the same index number (h k l). 62
  63. 63. 4. If a plane passes thought origin, it is defined in terms of a parallel plane having non-zero intercept.5. If a normal is drawn to plane (h k l), the direction of the normal is (h k l). 63
  64. 64. UNIT INDEX UNIT-IS.No. Module Lecture PPT Slide No. No. 9 Braggs law. L10 3-9 10 Laue method L11 10-15 11. powder method. L12 16-20 64
  65. 65. Lecture-10X-Ray Powder Diffraction 65
  66. 66. Lecture-1066
  67. 67. Lecture-10X-Ray Powder Diffraction (XRPD) isone of the most powerful techniquesfor analyzing the crystalline nature ofsolids. XRPD capabilities includemicro-diffractometry, flat plate orcapillary sample configuration,spinning and rocking methods,variable temperature and humidityconditions, and a unique sampleconveyor system to overcome sampleinhomogeneity effects. 67
  68. 68. Lecture-10XRPD is perhaps the most widely used X-raydiffraction technique for characterizing materials.As the name suggests, the sample is usually in apowdery form, consisting of fine grains of singlecrystalline material to be studied. The techniqueprovides information that cannot be obtained anyother way. The information obtained includestypes and nature of crystalline phases present,structural make-up of phases, degree ofcrystallinity, amount of amorphous content,microstrain & size and preferred orientation ofcrystallites. The technique is also used forstudying particles in liquid suspensions orpolycrystalline solids (bulk or thin film materials). 68
  69. 69. Lecture-10The term powder means that the crystallinedomains are randomly oriented in the sample.Therefore, when the 2-D diffraction pattern isrecorded, it shows concentric rings of scatteringpeaks corresponding to the various d spacingsin the crystal lattice. The positions and theintensities of the peaks are used for identifyingthe underlying structure (or phase) of thematerial. This phase identification is importantbecause the material properties are highlydependent on structure (think, for example, ofgraphite and diamond). 69
  70. 70. Lecture-10Powder diffraction data can be collectedusing either transmission or reflectiongeometry, as shown below. If the particlesin the powder sample are randomlyoriented, both methods will yield the sameresults. 70
  71. 71. Lecture-10Single crystal diffraction L e Laue’s method - λ variable, θ fixed. c t Rotating crystal method - λ fixed, θ variable u r to some extent. e - 1 0 Why not single crystal methods? • It may be difficult to obtain a single crystal. • The usual form of a material may be polycrystalline. • Problems with twinning or phase transitions complicate structural assignments. 71
  72. 72. Lecture-11Powder diffractionIn this method the crystal is reduced to afine powder and is placed in a beam ofmonochromatic X-rays. Each particle is atiny crystal or an assemblage of smallercrystals randomly oriented with respect tothe the incident beam.Powder methods - λ fixed, θ variable. 72
  73. 73. Lecture-11The diagram shows only two scattering planes, butimplicit here is the presence of many parallel, identicalplanes, each of which is separated from its adjacentneighbor by a spacing d.Constructive interference occurs when (A+B)/λ = n,coinciding with Bragg’s law, nλ= 2dsin θ. The integer nrefers to the order of diffraction. For n = 1, (A+B) = λ and 73
  74. 74. Lecture-11• Angles are used to calculate the interplanar atomic spacings (d-spacings). Because every crystalline material will give a characteristic diffraction pattern and can act as a unique ‘fingerprint’, the position (d) and intensity (I) information are used to identify the type of material by comparing them with patterns for over 80,000 data entries in the International Powder Diffraction File (PDF) database, complied by the Joint Committee for Powder Diffraction Standards (JCPDS). By this method, identification of any crystalline compounds can be made even in complex samples. 74
  75. 75. Lecture-11The position (d) of the diffracted peaks also providesinformation about how the atoms are arranged within thecrystalline compound (unit cell size or lattice parameter).The intensity information is used to assess the type andnature of atoms. Determination of lattice parameter helpsunderstand extent of solid solution (complete or partialsubstitution of one element for another, as in somealloys) in a sample.The ‘d’ and ‘I’ from a phase can also be used toquantitatively estimate the amount of that phase in amulti-component mixture.The width of the diffracted peaks is used to determinecrystallite size and micro-strain in the sample. 75
  76. 76. Lecture- If the sample consists of tens of randomly 11oriented single crystals, the diffracted beamsare seen to lie on the surface of several cones . 76
  77. 77. Instrument geometries Lecture-11There are several ways of collecting XRPD patterns:Camera methods: Guinier, Debye-Scherrer, Gandolfi, 77
  78. 78. The Debye – Scherrer powder camera Lecture-1A photographic film is placed around the inner circumference of thecamera body. The incident beam enters through a pinhole and almost thewhole diffraction pattern is recorded simultaneously. At the point ofentrance the angle is 180° and at the exit the angle is 0°. 78
  79. 79. L Lecture-12  e Pinhole source c  Film located on camera t body u r  Rod shaped sample e  Sample rotates to give - better “randomness”1 0  Almost complete angular range covered79
  80. 80. View of an instrument Lecture-12 80
  81. 81. Lecture-10 Lecture-1081
  82. 82. X-Ray Powder Diffraction Instruments Lecture-12 82

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