ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Coupled pressure, phonon, electronic, and defect engineering in CaZnX (X = C, Si, Ge, Sn) half-Heusler compounds: a first-principles investigation

Pratish Rawat, Abhay P. Srivastava, and Brijesh K. Pandey

Department of Mechanical Engineering, Poornima University, Jaipur, India

E-mail: abhay.srivastava831@gmail.com

Received: 7 April 2026  Accepted: 28 May 2026

Abstract:

In this paper, we have performed a detailed first-principles study of cubic half-Heusler CaZnX (X = C, Si, Ge, Sn) and identified a unified structure–property-function relationship for a variety of applications. Based on DFT calculations, the thermodynamic, mechanical, and dynamical stability of all compounds in the C1ᵦ structure is verified, and lattice expansion and elastic softening from C to Sn are observed. Pressure-dependent analysis indicates systematic lattice compression, a higher bulk modulus, and continuous band-gap narrowing due to increased Zn–X orbital hybridization. Phonon dispersion confirms the dynamical stability and demonstrates phonon softening, acoustic-optical gap reduction, and anharmonicity towards the heavier X elements. Electronic transport calculations show a significant increase in Seebeck coefficient (180–260 µV/K) and power factor (6.8–10.8 µW/cm·K²), highlighting the thermoelectric potential for CaZnGe and CaZnSn. Defect analysis shows lower formation energies, a transformation from deep donors to shallow donors, and increased conductivity in the series. In addition, the optical properties show tunable absorption in the visible to near infrared range. In general, we have shown that chemical substitution, pressure, and defect engineering are powerful and complementary approaches to structural, electronic, thermal, and transport properties, making CaZnX compounds good candidates for high-temperature electronics, optoelectronics, and thermoelectric energy conversion.

Keywords: Half-Heusler compounds; CaZnX; Density functional theory; Elastic properties; Thermal transport and electronic band structure; Optical properties; Thermoelectric materials

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-05132-6

Chemical Papers 80 (10) 12297–12328 (2026)