High‐Temperature Zirconium Phosphates

Abstract

The existence of two zirconium phosphate compounds has been established. The “normal” phosphate, ZrP2O7, has a reversible inversion at 300 °C. and dissociates to the zirconyl compound, (ZrO)2P2O7, at 1550°C., with the simultaneous loss of P2O5 as vapor. The room‐temperature form of ZrP2O7 is cubic with refractive index 1.657 ± 0.003. The zirconyl compound has a stable existence to temperatures around 1600°C. and is characterized by a very low linear thermal‐expansion coefficient.

Structure of ZrV2O7from −263 to 470°C

“…For TiP O with a room-temperature subcell of 7.9 A s , normal positive thermal expansion is observed (15). For ZrP O with a room-temperature subcell of 8.2 A s , thermal expansion above its phase transition is unusually low but positive (16). For UP O with a at room temperature about 8.6 A s , thermal expansion is slightly negative (17,18).…”

Pyrophosphates of Tetravalent Elements and a Mössbauer Study of SnP2O7

“…their abnormally high amplitudes of thermal motion result in dynamic (time-averaging) simulation of linear P-0-P groupings. The transformation 11 + 111 is reversible and is confirmed by independent dilatometric evidence (28); the enthalpy change associated with the process between 530 and 575 "K has been estimated as 130 callmol (3).…”

Chemistry of tetravalent actinide phosphates—Part II

“…39-0207), zirconium [19,20,27,31,32], and hafnium [19,29] oxide phosphates were also presented in the literature in three forms. Gebert and Tillmanns [27] wrote for the first time the formula Zr 2 O(PO 4 ) 2 .…”