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

摘要

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 orthorhom-bic, 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.