The first bulk synthesis of ReO3-type tungsten trioxide, WO3, from nanometric precursors

A perovskite form of WO3 has been synthesized in bulk for the first time at 0.66 GPa and 973 K with a=3.7823(4) Å [a0=3.7719(4) Å, at ambient conditions] from nanometric powder of WO3 with an average crystallite size of 35 nm. Data collected during tests to determine both the likelihood of retaining the structure at room temperature and the effect of high pressure on distortion have afforded analysis of thermal expansivity and compressibility of this phase. These result in VT=53.407(5)exp(−3.9(12)×10−6(T−298)+1.91(9)×10−8(T2−2982)) Å3 and equation of state parameters of V0=53.67(4) Å3, K0=41.8(19) GPa with ∂K/∂P=K′=5.6(12).