Fedo4 Tetrahedral Structure

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This essay will evaluate the Haines et al. Also, the essay will discuss about how the structure of FePO4 will change at various temperature ranging from 294K to 1073K. FePO4's A cation is a transition metal, thus it is not the same as other α-quartz isotopes. FePO4' has α-quartz structure which is tetrahedral when it is at a very low temperature. Under huge pressure, FePO4's structure goes through a phenomena called β-phase which it became a more condensed octahedral structure. Incoherence will be seen during the first order transition. The cell parameters and volume inflates greatly as temperature surges. The increase is not linearly related. The thermal expansion coefficient is calculated as α (K-1)= 2.924 x 10-5 + 2.920 x
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In the structure, it comprises of PO4 tetrahedrons. It serves a significant role in shaping the structural integrity and properties. The tetrahedral distortion comprises of tetrahedral tilt angle δ and inter-tetrahedral bridging angle θ. Both the bond length and the O-PO angle play a part in the tetrahedral distortion when the temperature increases. At the moment, it is more appropriate to identify tetrahedrons as a structured body because the tetrahedral tilt is more essential in contributing to the tetrahedral distortion. In essence, tetrahedral tilt caused tetrahedral distortion. It is measured by tilt angle δ and is dependent on temperature considerably. In the case of quartz-type FePO4, the cell parameters and the volume of the α phase surges significantly and non-linearly when temperature increases. The main cause to the thermal expansion is resulted from angular variations. This is established by the variation in the correlated tilt angles and two symmetrically independent inter-tetrahedral Fe-O-P bridging angles. Hence, the dependence on temperature of thermal expansion is dependent on the angular variations of inter-tetrahedral brdging angles and tetrahedral tilt angles. Using Landau-type model, the temperature dependence of this angle is defined as: δ2 = 2/3 δ02 [1 + (1 – ¾ (T – Tc/T0 – Tc))^1/2]. δ0 is the decline in tilt angle at the transition temperature (980K) and Tc is the temperature for the second-order transition. Using the equation, we can calculate δ4 for FePO4. When the phase changed from α to β, the cell parameters and fractional atomic coordinates in the α phase incline towards the values in β phase. It will display irregular changes at the first order transition at 980K. There are substantial variation in bond distances and angles. It is known that α-β transition in quartz can be demonstrated using a single order parameter, the tilt angle δ. FePO4 uses the

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