Robust high pressure stability and negative thermal expansion in sodium-rich antiperovskites Na3OBr and Na4OI2

Authors

Yongrong Wang, University of Nevada, Las Vegas
Ting Wen, Huanghe Science and Technology CollegeFollow
Changyong Park, Carnegie Institution of WashingtonFollow
Curtis Kenny-Benson, Carnegie Institution of Washington
Michael G. Pravica, University of Nevada, Las Vegas
Wenge Yang, Carnegie Institution of WashingtonFollow
Yusheng Ziao, University of Nevada, Las Vegas

Document Type

Article

Publication Date

1-1-2016

Publication Title

Journal of Applied Physics

Volume

119

Issue

2

First page number:

1

Last page number:

6

Abstract

The structure stability under high pressure and thermal expansion behavior of Na3OBr and Na4OI2, two prototypes of alkali-metal-rich antiperovskites, were investigated by in situ synchrotron X-ray diffraction techniques under high-pressure and low temperature. Both are soft materials with bulk modulus of 58.6 GPa and 52.0 GPa for Na3OBr and Na4OI2, respectively. The cubic Na3OBr structure and tetragonal Na4OI2 with intergrowth K2NiF4 structure are stable under high pressure up to 23 GPa. Although being a characteristic layered structure, Na4OI2 exhibits nearly isotropic compressibility. Negative thermal expansion was observed at low temperature range (20–80 K) in both transition-metal-free antiperovskites for the first time. The robust high pressure structure stability was examined and confirmed by first-principles calculations among various possible polymorphisms qualitatively. The results provide in-depth understanding of the negative thermal expansion and robust crystal structure stability of these antiperovskite systems and their potential applications.

Repository Citation

Wang, Y., Wen, T., Park, C., Kenny-Benson, C., Pravica, M. G., Yang, W., Ziao, Y. (2016). Robust high pressure stability and negative thermal expansion in sodium-rich antiperovskites Na3OBr and Na4OI2. Journal of Applied Physics, 119(2), 1-6.
http://dx.doi.org/10.1063/1.4940020