Polymorphism of Ag3VO4

The polymorphism of Ag3VO4 was investigated with temperature dependent synchrotron powder diffraction, and differential scanning calorimetry in the temperature range 295 K <= T <= 893 K. Three crystal structures of Ag3VO4 were identified and determined from powder diffraction data: alpha-Ag3VO4 (T = 295 K, C2/c, a = 10.2672(2) angstrom, b = 4.9814(1) angstrom, c = 10.2240(2) angstrom, beta =116.0(1)degrees, V = 470.0(2)angstrom(3)), beta-Ag3VO4 (T = 423 K, I (4) over bar 2m, a = 4.9968(1) angstrom, c = 9.6911(3) angstrom, V= 241.97(1) angstrom(3)), and gamma-Ag3VO4 (T = 703 K, Fm (3) over barm, a = 7.8386(1) angstrom, V = 481.62(1) angstrom(3)). The crystal structures of all three phases of Ag3VO4 can be described as cubic closed packed arrangements of [VO4](3-) anions with the silver cations occupying all octahedral and tetrahedral voids.