Materials Chemistry and Physics 111 (2008) 559–564 Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys B3–B1 phase transition and pressure dependence of elastic properties of ZnS M. Bilge a , S. ¨ Ozdemir Kart a , H.H. Kart a,∗ , T. C ¸a˘ gın b a Department of Physics, Pamukkale University, Kınıklı Campus, 20017 Denizli, Turkey b Department of Chemical Engineering, Texas A&M University, TX 77845-3122, USA article info Article history: Received 22 February 2008 Accepted 7 May 2008 Keywords: Semiconductor Ab initio calculations Phase transitions Elastic properties abstract We have performed the ab initio calculations based on density functional theory to investigate the B3–B1 phase transition and mechanical properties of ZnS. The elastic stiffness coefficients, C 11 , C 12 , C 44 , bulk modulus, Kleinman parameter, Shear modulus, Reuss modulus, Voigt modulus and anisotropy factor are calculated for two polymorphs of ZnS: zincblende (B3) and rocksalt (B1). Our results for the structural parameters and elastic constants at equilibrium phase are in good agreement with the available theoretical and experimental values. Using the enthalpy–pressure data, we have observed the B3 to B1 structural phase transition at 18.5GPa pressure. In addition to the elastic coefficients under normal conditions, we investigate the pressure dependence of mechanical properties of both phases: up to 65GPa for B1-phase and 20 GPa for B3-phase. © 2008 Elsevier B.V. All rights reserved. 1. Introduction ZnS is a wide band gap semiconductor and an attractive mate- rial due to its use in various advanced technological applications in infrared optics, ultraviolet laser devices and electronic image dis- plays, etc. Nanobelts, nanoclusters and various specimens in thin film form have been prepared for this material but the fabrication of large crystal of ZnS is a big problem in many studies due to criti- cal growth condition. This semiconductor compound crystallizes in the cubic zincblende (B3) and wurtzite (B4) structures at ambient pressure. It is well known that there is a phase transition from B3 structure to B1 structure, when the pressure is applied. The pressure induced polymorphic structural transformation as well as unique electro-optical properties of ZnS and its nanostructures present researchers with several challenging problems to study. Over the past few years, several experimental and theoretical studies have been carried out to understand the mechanical and electronic prop- erties of ZnS [1–13]. The pressure at which the phase transition from the B3 structure to the B1 structure for ZnS occurs was first reported as 24.5 GPa [2]. It was estimated to be at 18.5 GPa based on the shock data of Rice et al. [3]. Zhou et al. [4], using x-ray diffrac- tion data, reported the phase transition pressure value as 15GPa. Recently, Chen et al. [1] computed the transition pressure value as 17.5GPa from total energy–volume data and 15.4GPa from equal enthalpies at the transition pressure between two phases. Qteish et al. [5,6] calculated it as 14.7 and 14.5GPa using a first princi- ∗ Corresponding author. Tel.: +90 2582963588; fax: +90 2582963722. E-mail address: hkart@pau.edu.tr (H.H. Kart). ple pseudopotential method and local density approximation for the exchange-correlation potential, respectively. Other theoretical studies on the pressure induced phase transition in ZnS are given in Ref. [1]. When the phase transition occurs, the mechanical properties of material change. The most common assessment of mechanical properties can be made by the determination of its elastic constants. Especially, the elastic constants of materials at high pressures are essential in order to predict and understand material response, strength, mechanical stability, and phase transition. However, only a few studies have conducted on the mechanical properties of ZnS at elevated pressures, as well as the pressure dependence of its elastic constants, so far. The accurate measurement of these quantities is a difficult task due to difficult experimental conditions at high pres- sure. However, ab initio quantum mechanical methods are quite suitable for a systematic study of the elastic properties at ambient or elevated pressure conditions. With the advances in ab initio methods, it has become possible to compute with a great accuracy the structural, mechanical, elec- tronic and optical properties of materials. Therefore, a large number of ab initio studies on the structural and mechanical properties of ZnS have been carried out. Recently, Wang [7] investigated the elas- tic, dielectric and thermodynamics properties of B3 structure of ZnS using first-principles ground state and response-function cal- culations. Sahraoui et al. [8] studied elastic stiffness coefficients and bulk modulus for ZnS under hydrostatic pressure by utilizing density functional theory within the generalized gradient approx- imation (GGA) for exchange-correlation energy. Khenata et al. [9] have studied the structural, electronic and optical properties of ZnS by using the full-potential linear augmented plane-wave method 0254-0584/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.matchemphys.2008.05.012