Control of Reaction Pathways for Rapid Synthesis of Negative Thermal Expansion Ceramic Zr2P2WO12 with Uniform Microstructure

The reaction pathways to synthesize Zr2P2WO12 (ZPW) from ZrO2, WO3, and P2O5 are studied. It is found that there exist two different reaction pathways: One is direct reaction, while another is through an intermediate phase ZrP2O7. The reaction pathways are determined by drying and sintering temperatures. By controlling the reaction pathways, namely avoiding the intermediate phase, negative thermal expansion ceramic ZPW can be synthesized within several minutes. Besides, as-synthesized specimens possess much smaller and uniform grain size distribution than those synthesized by conventional methods. The investigation paves a way toward rapid and environmental friendly synthesis of ZPW and related compounds.