Thermal stability of the layered modification of Cu0.5ZrTe2 in the temperature range 25–900 °C

The thermal stability of the layered modification of the Cu0.5ZrTe2 polycrystalline inter­calation compound, synthesized at room temperature, has been studied in the temperature range 25–900 °C. A change in the occupation of the octa­hedral and tetra­hedral coordinated sites in the inter­layer space of the zirconium ditelluride was observed using in-situ time-resolved synchrotron X-ray powder diffraction experiments. The formation of the rhombohedral CuZr2Te4 phase, which is stable in the temperature range 300–700 °C, has been observed. The copper inter­calation at room temperature leads to the formation of a phase in which the Cu atoms occupy only octa­hedral sites in the inter­layer space. At temperatures above the decay temperature of the rhombohedral CuZr2Te4, a layered phase with Cu atoms uniformly distributed between octa­hedral and tetra­hedral sites in the inter­layer space is stable. The changes in the crystal structure independent of temperature are in agreement with the previously proposed model, according to which the stability of the layered or the rhombohedral phase is determined by the entropy factor associated with the distribution of the inter­calated atoms between the octa­hedral and tetra­hedral sites in the inter­layer space.