Anomalous thermal expansion of silver gallium telluride

A precise X-ray determination of the lattice parameters of silver gallium telluride, AgGaTe₂, has been made in the temperature range 301 to 667 K with a Unicam 190 mm high-temperature powder camera. The data have been used to evaluate the coefficients of thermal expansion, α⊥ and α, at various temperatures. It has been observed that the `c' parameter decreases while the `a' parameter increases with increasing temperature as in the case of AgGaSe₂ and AgGaS₂, which also have a chalcopyrite-type structure. The magnitudes of both α_⊥ and α increase non-linearly with increasing temperature.