Thermal expansion behavior of empressite, AgTe: A structural study by means of in situ high-temperature single-crystal X-ray diffraction

The crystal structure of empressite, AgTe, a rare silver telluride, has been investigated by in situ X-ray single-crystal diffraction methods within the temperature range 298-463 K. AgTe remains orthorhombic, space group Pmnb (Pnma as standard), and shows only normal thermal expansion over the entire temperature range. The unit-cell parameters show a gradual increase with the increase of temperature. Slight adjustments in the geometry of Ag-tetrahedra and in the crystal-chemical environment of tellurium atoms occur in a continuous way without abrupt structural changes. The coefficients of thermal expansion along various axes are: alpha(a) = 1.5 x 10(-5) K(-1), alpha(b) = 3.0 x 10(-5) K(-1), alpha(c) = 2.2 x 10(-5) K(-1), and the bulk thermal expansion coefficient alpha(v) is 5.4 x 10(-5) K(-1) for the temperature range 298-463 K. (C) 2008 Elsevier B.V. All rights reserved.