Fepo4 Analysis

FePO4 is widely recognized as iron phosphate. It has a great similarity to quartz that has trigonal lattice structure, space group P3121 (group no. 152). When the condition is under 980K, FePO4 becomes α-FePO4 that has trigonal lattice structure too and space group P3121 (group no. 152). In this form, phosphate, iron, and oxygen take up Wyckoff position 3a, 3b, and 6c correspondingly. Every phosphate or iron atom is united to four oxygen atoms, composing corner-connected FePO4 and PO4 tetrahedral subsequently, analogous to how every silicon atom is affiliated to four oxygen atoms to develop a structure of edge-linked tetrahedral in quartz. When the heat is raised and outstrips 980K, it is when the α-FePO4 displays α-β conversion, and the ensuing
In the meantime, the total electrical charge and the topology of the tetrahedral stays unchanged.

The form of α-FePO4 and the form of β-FePO4 are polymorphs. The shift between form α and form β is conditional to temperature. When the heat raises, the atoms in the crystal are going to encounter kinetic energy raise that will result the atoms vibrating more actively and guides to a raise in the volume. So that the raise of the volume can be compensated, the inside of the crystal arrangement has to be changed by tilting of the tetrahedral. A very organized and very symmetrical structure is then formed. In FePO4 case, as the heat changed to 969K from 294K, crystals in α phase displays thermal expansion, where volume and cell frameworks rises as function of heat. Why does this happen? The inter-tetrahedral angular variations of Fe-O-P angles caused this, along with the associated angles. If the heat continues to increase then passed 980K, α-β transition happened and the FePO4 lattice structure converts to hexagonal (from trigonal). As the heat increases, cell volume and parameters still rise and the amount of rise is very little, compared to phase α. Though, when it converts to phase β, we will see substantial decrease of the distance of the bond and the
Nevertheless, a hexagonal cell unit can still be used to either of them. The α-FePO4 is associated with P3121 space group, while β-FePO4 is associated with P6422 space group. The symmetry of these two arrangements is very different. When in a colder condition, 31 axes appear in the cell, especially at the origin. Still, that operator is not available at the point (0,0) of β-FePO4. Also, there are diad rotation spots at the middle of unit cell. These are the operators that are not available in α-FePO4.

The increase of heat make the kinetic energy rises, causing the atomic vibrations to multiply, that apparently make the volume of the unit cell rises. This is concluded by looking at the data, when the heat rises to 969K from 294K, the cell parameter rises to 5.1346 Å from 5.0314 Å, while c rises to 11.3465 Å from 11.2465 Å. At the meantime, the volume of the unit cell also rises to 259.06 Å3 from 246.56 Å3. This kind of expansion is led by the tilting of the tetrahedral and it is very easy to notice by simple