Structure of the liquid semiconductor GeSe

Abstract

The partial structure factors and pair distribution functions for liquid GeSe at 727(2) °C were measured by using the method of isotopic substitution in neutron diffraction. The results show that the liquid retains little memory of the high-temperature crystalline phase of GeSe. On melting, there is a reduction in the Ge-Se coordination number from 6 to 3.2(2) and both Ge-Ge and Se-Se homopolar bonds become features of the molten state with contact distances of 2.36(2) and 2.34(2) Å and coordination numbers of 0.8(1) and 0.22(3) respectively. The results are discussed by reference to the structures of molten CuSe and CuBr, which contain electronegative species of the same or similar size. The structure is also compared with that of the glass-forming network melt GeSe2 and it is found that, unlike the latter, there is no strong indication of intermediate-range atomic ordering as manifest by a prominent first sharp diffraction peak in one of the measured partial structure factors.