Comparing The Chemistry Of Fepo4 And Α-Fepo4

1068 Words3 Pages

Paragraph 1: Compare and Contrast the crystal structures and crystal chemistry of Quartz α-FePO4 and β-FePO4.
The research paper discusses the inversion of quartz type FePO4 from α-FePO4 to β-FePO4 along the temperature range 294K to 1073K.
We first take a look at the difference in lattice and space symmetry between the
2 polymorphs, α-FePO4 and β-FePO4. α-FePO4 is of the space group P3121, with a space group number 152. It has a trigonal lattice symmetry. β-FePO4 is of the space group P6422, with a space group number 181. It has a hexagonal lattice symmetry. Next, we analyse the similarities in crystal chemistry between α-FePO4 and β-
FePO4. To do so, we have to first understand how other quartz homeotypes like
SiO2 are able to have the same structure even though their chemical composition
is …show more content…

We look at the cations in SiO2 and FePO4, as anions within these two homeotypes are similar. We find out that SiO2 contains the cation Si4+
(tetravalent), while FePO4 contains the cations Fe3+ (Trivalent) and
P5+(pentavalent). As such, we are able to construct an alter-bound equation of
Fe3+ + P5+ ! 2 Si4+ whereby total charge on either end of the equation is 8+ and total species on both sides of the equation is 2.
Lastly, we focus on the transition from α-FePO4 to β-FePO4 with changes in temperature. At low temperatures from 294K to 969K, FePO4 exists as a α polymorph. At 980K, first order transition occurs, as inter-tetrahedral and tilt angles decreases at an increasing rate as temperature increases from

Open Document