J. Mater. Sci. Technol. ›› 2023, Vol. 146: 80-85.DOI: 10.1016/j.jmst.2022.10.054

• Research Article • Previous Articles     Next Articles

The enhanced negative thermal expansion in less-oxygen-vacancies copper pyrophosphate

L. Lu Xiea,b,1, T. Fei Shia,1, J. Chao Lina,*, X. Kai Zhangd, X. Kang Zhonga, K. Ke Liua,b, B. Ke Donga,b, Cheng Yange, X. Lian Wanga,b, T. Jiao Xionga,b, W. Sheng Yanb,f, J. Ping Xud, H. Can Chend, Wen Yind, Ming Lia, Peng Tonga,b,**, W. Hai Songa, Y. Ping Sunc,a   

  1. aKey Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China;
    bUniversity of Science and Technology of China, Hefei 230026, China;
    cAnhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China;
    dSpallation Neutron Source Science Center, Dongguan 523803, China;
    eDepartment of Chemistry, University of Warsaw, 02093 Warsaw, Poland f National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
  • Received:2022-09-22 Revised:2022-09-22 Accepted:2022-09-22 Published:2023-05-20 Online:2023-05-15
  • Contact: * E-mail addresses: jclin@issp.ac.cn (J.C. Lin); ** Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China. E-mail addresses: tongpeng@issp.ac.cn (P. Tong)
  • About author:1 These authors contributed equally to this work.

Abstract: For oxides, controlling the concentration of oxygen vacancy is a useful way to optimize their functional properties. However, when it comes to the field of negative thermal expansion (NTE), much less attention has been paid to the effect of oxygen vacancy on NTE, though oxide-typed NTE materials account for more than 40% of the total NTE materials. Here, we report that the linear coefficient of thermal expansion at 250-350 K of copper pyrophosphate (i.e., Cu2P2O7) can be significantly improved from -13.88 to -36.60 ppm/K when the synthesis temperature is raised from 1073 to 1373 K. The combined study including X-ray absorption near edge structure, neutron powder diffraction, and X-ray diffraction has confirmed the selective vacancies in the O1 site for low-temperature synthesized samples, which suppress both the phase-transition and framework-structure driven NTE simultaneously. Our result proposes a new approach for optimizing the NTE effect of oxides.

Key words: Negative thermal expansion, XANES, Oxygen vacancy, Oxide, Lattice distortion, Phase transition