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Solid state chemistry ppt
- 1. Chapter: solid state presented by: Dr. Akhtar S. Shah H. J. Thim College of Arts & Science, Jalgaon 425001, India
- 2. INTRODUCTION: 1. Crystalline solid: The solids having atoms arranged in regular and repeating manner. Ex: NaCl, ice etc. 2. Amorphous solid: The substance which are hard and rigid having definite shape but no definite arrangement of constituents. Ex: Rubber, plastic, glass etc.
- 3. Properties of crystals 1. Polymorphism: The phenomenon of existence of same subtance in two or more crystalline forms. Eg: AgI(hexagonal) AgI(cubic) 2. Allotrophism/ Allotropy: The phenomenon of existence of same element in two or more crystalline forms. Eg: C(cubic) C(tetragonal)
- 4. 3. Isotrophic substances/ Isotropy: The substances having properties such as Coefficient of thermal expansion, Electrical conductivity, Thermal conductivity, Refractive index and Solubility are same in all directions. Eg: Rubber, plastic, glass. 4. Anisotropic substances: The substances having properties such as Coefficient of thermal expansion, Electrical conductivity, Thermal conductivity, Refractive index and Solubility are different in different directions. Eg: AgI, K2Cr2O7, ice etc.
- 5. Etch figures: The characteristics pattern formed on the surface of anistropic crytal due to directional differences in solubility. Eg: Ice, K2Cr2O7 Unit cell: The fundamental building block of a crystal lattice having shape related to that of crystal lattice. Eg: 2D unit cell, 3D unit cell. Crystal lattice/ Space lattice/ Point lattice: The array of points in space is called.
- 6. Weiss indices: The intercept made on 3- coordinate axes in terms of unit distances. Miller indices: The reciprocal value of intercept in terms of unit distances. X-ray diffraction: The x rays and interatomic distance in solids are near about same, 2 x 10-8 to 5 x 10-8 cm. Hence x rays are scattered from solid surface which give constructive interference knwon as diffraction.
- 7. Braggs Equation Condition of maximum intensity Path difference= n了 Equation: 2dsin = n了 Where, d = interplanar distance, = glancing angle n = order of reflection (1, 2, 3 ..) 了 = wavelength of x- rays
- 8. Application of Braggs equation To determine interplanar distance. d= n了/ 2sin To determine wavelength of x ray. 了 = 2dsin/n Braggs x ray spectrometer Instrumentation: X ray tube Slits Rotating table with scale Solid crystal Ionisation chamber Electometer Application: To determine interplanar distance. Disadvantage: it require big size undistorted crystal which difficult to obtained.
- 9. Distance between planes in simple cubic lattice: d= . a . (h2+k2+l2) Where, a= interplanar spacing hkl= Miller indices Number of atoms (n): n = .N.a3 M Where, = density of substance, N = Avogadro number a = Edge length/ Side length M= mol.wt. of substance
- 10. Unit cell of nacl The NaCl is fcc lattice. Each Na+ surrounded by 6Cl-. Each Cl- surrounded by 6 Na+. Total no. of Cl- =(8x1/8) + (6x1/2) = 4 Cl- Total no. of Na+ =(12x1/4) + 1 = 4 Na+ Hence unit cell contain 4 NaCl molecules.
- 11. Method of indexing Defn: trial and error method for determination of values of hkl for each observed values of dhkl. h2+k2+l2 = (a/dhkl) 2 Sr. no. h2+k2+l2 hkl 1 1 100 2 2 110 3 3 111 4 4 200 5 5 210
- 12. Powder method of crystal analysis Powder of crystalline substance filled in capillary. X-ray is incident on it , forming diffraction pattern on photographic plates. Intensity of x-ray on photographic plate give information about quantitative analysis. Spacing between two neighbouring line of diffraction pattern give information about quantitative analysis.
- 13. Semiconductor Defn: The material which is non conductor at room temperature but conductor at higher temp, and in impure state. Ex: Si, Ge etc. Types: 1. p-type semiconductor: Si + B p-type semiconductor 2. n-type semiconductor: Si + As n-type semiconductor Applications: Used in TV, calculator, rectifier, solar cells etc.
- 14. Solar cell p-type semiconductor and n- type semiconductor are joined together to form p-n junction. This p-n junction is connected to circuit is become semiconductor. When light incident on it photo electron flow from p-type to n-type.