Thermochromic behavior (400 < T °C < 1200 °C) of barium carbonate/binary metal oxide mixtures

Irreversible thermochromism over a wide temperature range has been observed from the decomposition of a mixture of a barium carbonate and a metal oxide. The control of the reaction temperature can be predicted from the calculation of the Madelung energy of the barium/transition metal mixed oxide formed consecutively with the decarbonatation. Moreover, the Madelung energy of this formed mixed oxide may be predicted from bond valence considerations. This study offers a simple predictive approach to propose temperature indicators with significant optical contrast and a thermochromic temperature varying between 400 and 1200 °C.

► Thermochromic mixtures of carbonates/oxides are obtained.
► The mixtures allow marking the T° range 400 °C–1200 °C.
► The thermochromic T° is predicted from mixture composition/bond valence theory.