Negative thermal expansion (NTE) is an abnormal thermophysical phenomenon. Although NTE has been discovered in a growing number of materials, it is difficult to achieve both strong NTE and a wide operating temperature range in one material. In this work, the strong NTE of the oxide Cu2PVO7 is reported in a wide temperature range (αv ∼-26.01 × 10-6 K-1, 100-648 K), where the thermal expansion is highly anisotropic. The NTE capacity of Cu2PVO7 is outstanding among the NTE framework structure oxides. Joint methods of high-resolution synchrotron X-ray diffraction, extended X-ray absorption fine structure, pair distribution function of synchrotron X-ray total scattering, density functional theory calculations, and maximum entropy model calculations were carried out to reveal the NTE mechanism of Cu2PVO7. Transverse vibrations of O atoms together with deformations of CuO5 and P/VO4 polyhedral units account for the rotation and twist among the polyhedra, leading to the NTE. The present work pushes forward progress in research regarding strong NTE oxides.

Strong Negative Thermal Expansion of Cu2PVO7 in a Wide Temperature Range

Sanson A.;Venier A.;
2021

Abstract

Negative thermal expansion (NTE) is an abnormal thermophysical phenomenon. Although NTE has been discovered in a growing number of materials, it is difficult to achieve both strong NTE and a wide operating temperature range in one material. In this work, the strong NTE of the oxide Cu2PVO7 is reported in a wide temperature range (αv ∼-26.01 × 10-6 K-1, 100-648 K), where the thermal expansion is highly anisotropic. The NTE capacity of Cu2PVO7 is outstanding among the NTE framework structure oxides. Joint methods of high-resolution synchrotron X-ray diffraction, extended X-ray absorption fine structure, pair distribution function of synchrotron X-ray total scattering, density functional theory calculations, and maximum entropy model calculations were carried out to reveal the NTE mechanism of Cu2PVO7. Transverse vibrations of O atoms together with deformations of CuO5 and P/VO4 polyhedral units account for the rotation and twist among the polyhedra, leading to the NTE. The present work pushes forward progress in research regarding strong NTE oxides.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3403185
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