KCaAs and KCaP: promising half-Heusler compounds for UV protection and thermoelectric applications

Abstract This study investigates the structural, electrical, optical, and thermoelectric properties of the half-Heusler compounds KCaAs and KCaP using the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method within the framework of density functional theory. Our analysis reveals that both compounds exhibit favourable characteristics for high-performance applications. Specifically, KCaAs and KCaP show high static refractive indices and significant reflectivity in the ultraviolet (UV) range, making them ideal for UV protection and optical devices. Thermoelectric analysis indicates that both materials are p-type semiconductors with high Seebeck coefficients at low temperatures, high electrical conductivity, and relatively low thermal conductivity. The temperature-dependent figure of merit ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic">ZT</mml:mi> </mml:math> ) reveals robust thermoelectric performance across a wide temperature range, with maximum <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic">ZT</mml:mi> </mml:math> values of approximately 0.77 for both compounds. These results suggest that KCaAs and KCaP are promising candidates for thermoelectric applications, offering significant potential for energy conversion and sustainable energy solutions.