lab_report_4 - Crystallography and X-Ray Diffraction...

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Crystallography and X-Ray Diffraction Objective : The aim of this experiment is to determine the crystal structure of an unknown pure element by using X-ray diffraction method. Specimens : Unknown specimen. Apparatus : 1. X-Ray Diffractometer. 2. Calculator. Theory : Crystal structures of elements can be classified as crystal systems. There are seven crystal systems which are made up of different lattice parameters (Unit cell edge lengths and interaxial angles). We can determine these crystal systems by using X-ray diffraction. Diffraction occurs when a wave encouters a series of regularly spaced obstacles, that are capable of scattering the wave, and have distance between themselves comparable in magnitude to the wavelengths. In addition, waves should have a certain phase relation between themselves. A diffracted beam may be defined as a beam composed of a large number of scattered rays mutually reinforcing one another. In diffraction, the reflection angle ( θ29 , interplanar spacing in cubic system (d hkl ) or wave length ( λ29 can be found by using Bragg’s law. n λ=2 d hkl sin θ ( 1 29 In order to find the lattice length we can use a equation for crystal structures having cubic symetry which is d hkl = a (2)
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√h²+k²+l² Results and Discussion : In this experiment, we have used the equation which is found by combining the Bragg’s law equation with the equation for the lattice length. sin² θ = sin² θ = λ ² (3) ( h²+k²+l² ) s 4a² We have obtained six 2 θ value from the computer for an unknown element. (X-ray diffractometer has transfered the datas into the computer before.) We have used 2 θ in above equation as sin²
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lab_report_4 - Crystallography and X-Ray Diffraction...

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