Negative thermal expansion, optical and electrical properties of HfMnMo2PO12-delta

作者：Zhang Niu; Zhou Wenjin; Chao Mingju; Mao Yanchao; Guo Juan; Li Yuxiang; Feng Dongsheng; Liang Erjun

来源：Ceramics International, 2015, 41(10): 15170-15175.

DOI：10.1016/j.ceramint.2015.08.090

• Negative thermal expansion
• HfMnMo2PO12-delta
• Solid state method
• Impedance spectra
• Photoluminescence

A new type of negative thermal expansion (NTE) material HfMnMo2PO12-delta was synthesized using a solid state method, and its NTE, optical and electrical properties were systematically studied. HfMnMo2PO12-delta exhibited NTE property from room temperature (RT) to 420 K with the coefficient of thermal expansion (CTE) -3.59 x 10(-6) K-1. The coupling rotation of RUMs caused by transverse vibrations of bridge-O atoms and distortion of polyhedral due to Jahn-Teller effect and oxygen vacancies are attributed to the NTE behavior. The electrochemical impedance presents positive thermal coefficient (PTC) effect (RT - 420 K) at extremely low frequency, where the temperature scope coinciding to that of its NTE indicates an interesting internal relation. The electron scattering caused by vacancy defect contribute to the PTC effect. And the oxygen vacancy and Jahn-Teller effect were confirmed by the absorption and photoluminescence spectra.

• 出版日期2015-12
• 单位郑州大学; 中原工学院