A theoretical study on the structural and physical properties of the ground-state CaC. (February 2015)

• Record Type: Journal Article
• Authors: Qian, Yan; Wu, Haiping; Kan, Erjun; Lu, Ruifeng; Tan, Weishi; Deng, Kaiming
• Is Part Of: Solid state communications. Volume 203(2015)
• Page Start: 10
• Page End: 15
• Publication Date: 2015-02
• Subjects: A. CaC -- C. Structural property -- D. Electronic structure; Solid state chemistry -- Periodicals; Solid state physics -- Periodicals; Chimie de l'état solide -- Périodiques; Physique de l'état solide -- Périodiques; 530.41
• DOI: 10.1016/j.ssc.2014.11.011
• Languages: English
• ISSNs: 0038-1098

Abstract

Abstract: Because of no experimental report on the half-metallic CaC theoretically found by Gao et al. in 2007, it is necessary to explore the nature of this fact, and the reason is revealed via density-functional theory study in this work. By a particle swarm structural search firstly, several CaC allotropes are found, including the half-metallic one with F- 43 m space group. Among the found compounds, six allotropes have the negative formation energies with Ccma, P 4/ mmm, Immm, Cm (8), Pmm 2, and Cmmm space groups while the half-metallic one has positive formation energy of 2.67 eV. Furthermore, through the study on the dynamical properties of these six thermally stable CaC allotropes, only the one with P 4/ mmm symmetry exhibits dynamical stability. Based on the above fact, CaC with P 4/ mmm symmetry, instead of the F- 43 m one, perhaps can be experimentally synthesized due to both the thermodynamic and dynamically stabilities. Highlights: Several CaC structures were found by CALYPSO code. The stable CaC with both thermodynamically and dynamically stabilities shows P4/mmm space group. The stable CaC exhibits metallic nature, instead of half-metallic character.