Polymorphism of InS at high pressures

In situ X-ray diffraction has been used to study high-pressure polymorphism of InS up to ～ 13 Gpa in the 293–573 K temperature range. The phase transition InS I?arr2;InS II is found under isothermal compression at p_t = 7.5 ± 0.5 GPa and T = 293 K; at p_t = 6.0 ± 0.5 GPa and T = 573 K. InS II crystallizes in the structural type of Hg₂Cl₂: $\text{a = 3.823 ± 0.008}\text{A}\text{?}$; $\text{c = 10.868 ± 0.030}\text{A}\text{?}$; c/a = 2.843; Z = 4; D_4h¹⁷(I4/mmm); V_p/V₀ = 0.85; p = 10 GPa, T = 293 K. X-ray powder data indicate a continuous change of the orthorhombic structure of InS I with increasing pressure associated with the transition to the tetragonal phase InS II.