In this study, negative thermal expansion (NTE) Zr1−xYbxWMoO8−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 Zr1−xYbxWMoO8−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 Zr1−xYbxWMoO8−x/2 (c-Zr1−xYbxWMoO8−x/2, 0–5 min), densification of c-Zr1−xYbxWMoO8−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 ZrWMoO8, but improves that of Zr0.96Yb0.04WMoO7.98 evidently. In addition, densification of ZrWMoO8 can be promoted markedly by introduction of Yb3+.
MoO3 Sinter Process Sinter Time Ceramic Surface Negative Thermal Expansion
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The research was supported by the Natural Science Foundation of China (Grants No. 20471010). Ruiqi Zhao also thanks the Doctoral Foundation of Henan Polytechnic University (Grants No. B2009-90) and the Key Technology Foundation of Henan Province (Grants No. 092102210363).