DFT-Based Computational Investigation of Mechanical, Acoustic and Thermal Properties of Cd_1−xZn_xTe Alloys for Radiation Detector Applications

Zinc substitution in Cd_1−xZn_xTe (CZT) alloys emerges as a powerful strategy for engineering their structural, elastic, mechanical, acoustic and thermal properties, thereby enhancing their potential for high-performance optoelectronic and radiation detection applications. In this work, a comprehensive first-principles investigation based on Density Functional Theory, within both the Generalized Gradient Approximation and the Local Density Approximation, is conducted to systematically explore the composition-dependent behavior of CZT across the full concentration range (0 ≤ $\times$ ≤ 1) in the cubic zinc-blende phase. The calculated elastic constants satisfy the Born stability criteria for all compositions, confirming the intrinsic mechanical stability of the alloys upon Zn incorporation. A pronounced and continuous increase in the bulk modulus, shear modulus and Young modulus is observed with increasing Zn content, revealing a significant enhancement in lattice rigidity driven by the formation of shorter, stronger Zn–Te bonds and improved bond covalency. Despite this stiffening, CZT alloys consistently exhibit ductile behavior, as demonstrated by positive Cauchy pressures, Pugh ratios well above the critical value for ductility (B/G > 1.75), and Poisson ratios within the range of 0.29–0.37, indicating a favorable balance between strength and deformability. The Vickers hardness shows a systematic increase from 1.89 to 6.66 GPa with Zn concentration, highlighting improved resistance to plastic deformation while maintaining the moderate hardness typical of II–VI semiconductors. Additionally, the moderate elastic anisotropy indicates controlled directional dependence without compromising structural integrity. Concurrently, the monotonic enhancement of the longitudinal, transverse and average sound velocities reflects increasingly efficient elastic wave propagation and improved lattice cohesion. The Debye temperature rises significantly from approximately 163 to 227 K, providing strong evidence of reinforced interatomic bonding and superior thermal stability. Collectively, these results deliver a coherent and in-depth theoretical framework demonstrating that the physical properties of CZT alloys can be precisely tuned through compositional engineering. This tunability, combined with their inherent stability and balanced mechanical performance, positions CZT as a highly promising and versatile material platform. It is well suited for next-generation radiation detectors and advanced semiconductor devices operating, even under demanding mechanical and thermal conditions.