Abstract
The effects of Zn2+ incorporation on the phase formation, thermal expansion, phase transition, and vibrational properties of HfMg1−xZnxMo3O12 are investigated by XRD, dilatometry, and Raman spectroscopy. The results show that (i) single phase formation is only possible for x ≤ 0.5, otherwise, additional phases of HfMo2O8 and ZnMoO4 appear; (ii) The phase transition temperature from monoclinic to orthorhombic structure of the single phase HfMg1−xZnxMo3O12 can be well-tailored, which increases with the content of Zn2+; (iii) The incorporation of Zn2+ leads to an pronounced reduction in the positive expansion of the b-axis and an enhanced negative thermal expansion (NTE) in the c-axes, leading to a near-zero thermal expansion (ZTE) property with lower anisotropy over a wide temperature range; (iv) Replacement of Mg2+ by Zn2+ weakens the Mo–O bonds as revealed by obvious red shifts of all the Mo–O stretching modes with increasing the content of Zn2+ and improves the sintering performance of the samples which is observed by SEM. The mechanisms of the negative and near-ZTE are discussed.
Highlights
Large difference in coefficients of thermal expansion (CTE) of materials could lead to performance deterioration and even failure of devices due to thermal stress when temperature changes abruptly or frequently
We investigate the effects of Zn2+ incorporation on the structure, phase transition, thermal expansion, and vibrational properties of HfMgMo3O12
When x = 0.0, the diffraction peaks are corresponding to HfMgMo3O12, which adopts an orthorhombic structure with space group Pnma or Pna21 (Marinkovic et al, 2008)
Summary
Large difference in coefficients of thermal expansion (CTE) of materials could lead to performance deterioration and even failure of devices due to thermal stress when temperature changes abruptly or frequently.
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