Hydrothermal magic for the synthesis of new bismuth oxides

The hydrothermal method is an interesting synthesis process for obtaining new phases. Many bismuth oxides with trivalent (Bi 3+ ), pentavalent (Bi 5+ ), and mixed-valence bismuth (Bi 3+ and Bi 5+ ) have been synthesized by hydrothermal reactions using NaBiO 3 · n H 2 O as the starting material. This exciting starting compound has produced a variety of crystal structures via hydrothermal reactions. The hydrothermal products may adopt PbSb 2 O 6 -, ilmenite-, tritutile-, pyrochlore-, fluorite-, and perovskite-type structures, which are never achieved by high-temperature solid-state reactions. Some of them exhibit interesting properties such as photocatalytic activity, superconductivity, and magnetic frustration. It is not too much to say that the hydrothermal route employing NaBiO 3 · n H 2 O opens a new world of crystal chemistry of bismuth oxides. A variety of bismuth oxides have been synthesized by hydrothermal reactions using NaBiO 3 · n H 2 O as a starting material.