The Preparation And Properties Of High-density Zr₂(WO₄)(PO₄)₂ Negative Thermal Expansion Ceramics

In a large temperature range, the ceramic material of Zr2(WO4)(PO4)2 has obvious negative thermal expansion and has very good chemical stability, thermal stability, high mechanical stability, especially ability against presure. So the ceramic material of Zr2(WO4)(PO4)2 is a very promising negative thermal expansion material. In usual Zr2(WO4)(PO4)2 is synthesized by the traditional solid-phase method which consums too much time and energy and only prepares low-density bulk samples. In this thesis, Zr2(WO4)(PO4)2 ceramic material was successfully synthesized by the high temperature rapid synthesis method, which reduces energy consumption and improves efficiency, ZrO2, WO3, and P2O5 as raw materials. The stability, negative thermal expansion, optical absorption, Raman spectrum of the material were investigated. The overall conclusions are as follows:1. Zr2(WO4)(PO4)2 which was high pure and dense product was synthesized by a high temperature rapid synthesis method. To improve the density of Zr2(WO4)(PO4)2 ceramics, MgO and 2wt% PVA were added respectively, as sintering additive and adhesive. SEM image was used to observe the microstructure of the material.2. Temperature Raman spectroscopy and DSC indicate that there is no phase transition in Zr2(WO4)(PO4)2 ceramics from -160 to 1050℃.3. The linear coefficients of thermal expansion of the samples were measured with a dilatometer.4. UV-Vis-NIR spectrophotometer was used to test the absorption spectrum of Zr2(WO4)(PO4)2 to estimate the band gap.5. The Raman peaks were roughly identified.