Zr1−xYbxWMoO8−x/2 (x = 0, 0.04) ceramics fabricated by in situ synthesis from trigonal polymorph: preparation, sintering process, and negative thermal expansion properties

• Published in: Journal of materials science Vol. 47; no. 23; pp. 8061 - 8066
• Main Authors: Zhao, Ruiqi, Chen, Xi, Ma, Hui, Wang, Xishu, Zhao, Xinhua
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.12.2012
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; Densification; Diffraction; Materials Science; Phase transformations; Polymer Sciences; Precursors; Sintering (powder metallurgy); Solid Mechanics; Synthesis; Thermal expansion; Sinter Time; MoO3; Sinter Process; Negative Thermal Expansion; Ceramic Surface
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-012-6698-2

In this study, negative thermal expansion (NTE) Zr 1− x Yb x WMoO 8− x /2 ( x  = 0, 0.04) ceramics were fabricated by in situ synthesis from trigonal polymorphous precursors for the first time. Phase transition was studied by means of powder X-ray diffraction. Study on the sintering process of Zr 1− x Yb x WMoO 8− x /2 ( x  = 0, 0.04) ceramics was performed by calcining a series of precursor pellets at 950, 980, and 1000 °C for different times, varying from 1 min to 1 h. The results indicate that the sintering process can be mainly divided into three stages: phase transition from trigonal precursors to cubic Zr 1− x Yb x WMoO 8− x /2 ( c -Zr 1− x Yb x WMoO 8− x /2 , 0–5 min), densification of c -Zr 1− x Yb x WMoO 8− x /2 (6–30 min), and the final sintering stage with little densification (>30 min). Densification reaches almost the maximum in the duration of ~30 min at assigned temperature. Temperature has little influence on densification of ZrWMoO 8 , but improves that of Zr 0.96 Yb 0.04 WMoO 7.98 evidently. In addition, densification of ZrWMoO 8 can be promoted markedly by introduction of Yb 3+ .