DiscussionGallium sulfide, Ga2S3, is a III-VI semiconductor whose monoclinic phase possesses at room-temperature a blue-green luminescence [3][4][5]. Often referred to as a-Ga2S3, the monoclinic Ga2S3 crystallizes in space group Cc and contains ordered vacancies [2]. In addition to its luminescence properties, Ga2S3 also exhibits partial vapor pressures of Ga2S(g) that increase with decreasing temperature and decrease with increasing temperature in the range 1230 Κ < Τ < 1260 Κ, where a phase transformation was postulated [6], Its anomalous vapor-pressure behavior has made Ga2S3 a model system for the study of a class of high-temperature condensed-phase transformations in it and other sulfides and chalcogenides exhibiting anomalous temperature dependence of vapor pressure. Recent data, from the first time-of-flight neutron powder diffraction experiments performed on samples undergoing effusion [1], revealed a disordering, monoclinic-to-hexagonal phase transformation in the same temperature range as the anomalous vapor pressure, 1240 Κ -1260 Κ [7]. For the monoclinic phase of Ga2S3, four single-crystal structures have been published [2,8,9,10]. Work on the high-temperature structures of Ga2S3 determined by neutron scattering has made it desirable to reanalyze its single-crystal structure at a specified temperature. The figure shows the corner-sharing GaS4 tetrahedra of the structure as viewed along the [001 ] direction and the channels created by the ordered vacancies. Table 1. Data collection and handling.
GaAbstract Ga 2 S 3 , monoclinic, Clcl (No. 9), a = 11.107(2) A, b = 6.395(1) A, c = 7.021(1) Α, β = 121.17(3)°, V= 426.7 A 3 , Ζ = 4, R g i(F) = 0.035, wR ni (F 2 ) = 0.084, T= 294 K.
