A new family of compounds with tetrahedral anions: Pb$_n$BiO$_n$(XO$_4$), X = V, P, As, n = 1, 2, 4. A comparison with lead oxysulfates Pb$_n$PbO$_n$(SO$_4$)
Résumé
The thermal behavior and crystallographic characteristics of nine compounds, Pb$_n$MO$_n$(XO$_4$) with M = Bi, Pb, X = V, P, As, S and n = 1, 2, 4, are reported. A previously reported γ phase for Pb$_2$BiO$_2$(VO$_4$) was shown to consist of a mixture of PbBiO(VO$_4$) and Pb$_4$BiO$_4$(VO$_4$) that resulted from a kinetically controlled decomposition of Pb$_2$BiO$_2$(VO$_4$) at elevated temperatures. The relationship between the α, β and δ transitions for Pb$_2$BiO$_2$(VO$_4$) was clarified. All of these phases contain the tetrahedral anion XO$_4$ that imparts thermal and structural similarities as well as specifications that can be ascribed to anion size differences.