An Outline Of An Investigation

1283 WordsSep 30, 20156 Pages
Paragraph 1 This research paper aims to describe and explain the observed structural evolution of Iron (III) Phosphate, FePO4, upon subjected to time-­‐of-­‐flight neutron powder diffraction, which causes an increase in temperature from 294 K to 1073 K. FePO4 exists as a tetrahedral lattice structure of the α-­‐quartz at relatively low temperatures, of which its structural parameters tend towards the β-­‐phase at conditions of high temperatures. α-­‐FePO4 has a space group of quartz, P3121 and hence following the table of space groups in 3-­‐dimensions, assumes Bravais lattice of a trigonal lattice system under trapezohedral class. It exhibits primitive centering of motiff, consist of a 31 screw axis at the origin with atoms rotated at 120° and translated 1/3 towards the C-­‐axis. Β-­‐FePO4 has a space group of P6422, and assumes a Bravais lattice of hexagonal lattice system under hexagonal trapezohedral class. It displays a 64 screw axis at the origin, rotated at 60° and translated 2/3 towards the C-­‐axis. It has been observed experimentally that the structural evolution described involves a transition from the α-­‐FePO4 polymorph to β-­‐ FePO4 polymorph as temperature approaches 980 K. This can be supported with observations in the cell parameters and atomic coordinates involving increasing Fe – O – P bridging angles θ and decreasing tetrahedral tilt angles δ in α-­‐phase polymorph, causing the values to tend towards β-­‐phase polymorph, which exhibits a first-­‐order
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