Study of Mercuric Iodide Near Melting Using Differential Scanning Calorimetry Raman Spectroscopy, and X-Ray Diffraction.

摘要

High-temperature studies of mercuric iodide (HgI sub 2 ) involving differential scanning calorimetry (DSC), Raman spectroscopy, and x- ray powder diffraction have failed to confirm the existence of a red-colored tetragonal high-temperature phase called alpha '-HgI sub 2 reported by S.N. Toubektsis et al., (S.N. Toubektsis, E.K. Polychroniadis, and N.A. Economou, J. Appl. Phys., 58(5) (1985) 2070), using DSC measurements. The multiple DSC peaks near melting reported by Toubektsis are found by the present authors only if the sample is heated in a stainless-steel container. Using a Pyrex container or inserting a platinum foil between the HgI sub 2 and the stainless-steel container yields only one sharp, single DSC peak at the melting point. The nonexistence of the alpha ' phase is confirmed by high- temperature x-ray diffraction and Raman spectroscopy performed in the vicinity of the melting point which clearly indicate the existence of the yellow orthorhombic beta -HgI sub 2 phase only. The experimental high-temperature DSC, Raman, and x-ray diffraction data are presented and discussed. 14 refs., 8 figs., 2 tabs. (ERA citation 13:049193)