Structural Evolution Of Iron Phosphate, Fepo4 And Fepo4

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The research paper first described the structural evolution of Iron Phosphate, FePO4 from temperature 294K to 1073K, in α phase and in its ß-quartz type. There are both similarities and differences in the crystal chemical relationship between quartz (SiO2) and FePO4. The structural parameters of α-FePO4 at low temperature range skews towards the parameter values for ß-quartz type when it is at high temperatures. Angles between elements Fe, O and P increase whilst tilt angles decrease significantly as changes between the two phases near the temperature of 980K. Distance between Fe and O, and between Si and O in FePO4 and quartz (SiO2) is non linear with temperature in both compounds. Angles in the α-phase fluctuate to greater extents as compared …show more content…
Tilt angle, δ, is related to coordinates of the oxygen atoms in the strucure. ß-phase occurs at 980K. In the α-phase, increases in temperature results in a rise in volume. As temperature increases, volume decreases and vice versa. 2 factors which are pertinent to this relationship are the different Fe-O-P angles as well as inter-related wilt angles. Using the thermal expansion coefficient equation (as mentioned in the paragraph above), appropriate values may be obtained. Angles in α-FePO4 undergoes vibrations of larger magnitudes than in the ß-phase, where in fact, angular vibrations do not exist. Regarding symmetrical changes for its polymorphs, the mechanism is composed of FePO4 units. In its quartz form, tetrahedral rings were studied. The degree of distortion of angles in the ß-phase depends on certain conditions. When the angle is in between 22 and 136 …show more content…
As temperature continues rising from 294K up till 969K, the Fe-O bond distance shortens, followed by a decrease in this particular bond angle. These changes eventually lead to modifications to size of the cell and its volume. On the other hand, for the P-O4 bond, higher temperatures lead to compression which results in smaller bond angles. According to a study, the Fe-O4 bond length and bond angles in the compound’s quartz form may be attributed to the workings of temperature. When pressure increases, along with higher temperatures, cell size and cell volume begin to undergo changes, and bond angles become smaller eventually. Various other factors also govern the stability of the entire structural formation. Referring to the table below which is extracted from the report, we are able to tell how α and ß transition is affected by the coordinates of ∂1 and ∂2 where diffraction takes

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