Synthesis of a high pressure phase of FePO4

A CrVO₄ type FePO₄ polymorph with a=5.227, b=7.770 and $\text{c}\text{=6.322}\text{A}\text{?}$ has been synthesized at 50 kb and 900° C. The density is 3.90 g/cc, and increase of 22.6% over the quartz modification. The results of magnetic and Mossbauer effect measurements indicate that iron ions are in the high spin trivalent state in both phases. The quadrupole splitting of 1.90 mm/sec for Fe³⁺ of the high pressure phase is much larger than the 0.60 mm/sec for low pressure phase.