Compressibility and thermoelasticity of CrN

ABSTRACT

We report experimental determination of compressibility and thermoelasticity for CrN based on in situ high pressure/high temperature synchrotron x-ray diffraction measurements. The pressure-induced cubic-to-orthorhombic phase transition is observed at ∼ 5 GPa in high-quality CrN samples synthesized using a high pressure reaction route. Equation of state, bulk modulus and axial compressibility of this material are obtained by analysis of high pressure x-ray diffraction data collected at room temperature. Both cubic and orthorhombic phases have a similar bulk modulus value of 257 (5) and 262 (6) GPa, respectively. For orthorhombic CrN, the b-axis has the most axial incompressibility, which should be associated with magnetic properties. In addition, the isothermal equation of states is also determined at different temperatures of 300, 400, 600, 800, 1000, and 1200 K, respectively. Some of the important thermoelastic properties of cubic CrN are thus derived, including temperature derivative of bulk modulus $\mathrm{\partial }{K}_T/\mathrm{\partial }T=-2.95\left(5\right)\times {10}^{-2}\mathrm{G}\mathrm{P}\mathrm{a}\cdot {\mathrm{K}}^{-1}$ and volumetric thermal expansivity $a_T\approx a_0+a_1\cdot T$ where a₀= 1.95 (16)×10⁻⁵ K⁻¹ and a₁= 4.39 (3)×10⁻⁹ K⁻¹.

KEYWORDS:

• Chromium nitride
• CrN
• high pressure
• thermal equation of state
• phase transition

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Key Research Platforms and Research Projects of Universities in Guangdong Province (grant number 2018KZDXM062), the Guangdong Innovative & Entrepreneurial Research Team Program (grant number 2016ZT06C279), the Shenzhen Peacock Plan (grant number KQTD2016053019134356), the Shenzhen Development & Reform Commission Foundation for Novel Nano-Material Sciences, and the Research Platform for Crystal Growth & Thin-Film Preparation at SUSTech. The work was also partially supported by the Shenzhen Development and Reform Commission Foundation for Shenzhen Engineering Research Center for Frontier Materials Synthesis at High Pressure. The use of 16BM-D beamline of HPCAT (at APS/ANL and the at X17B2 beamline at NSLS-I/BNL supported by the U. S. Department of Energy, Office of Science, and Office of Basic Energy Sciences.