Single crystals of undoped Li2WO4 and Li2W1?0.0125Mo0.0125O4: formation enthalpies, heat capacity in the temperature range 320–997 K?

Dalton Transactions Pub Date: 2021-07-30 DOI: 10.1039/D1DT01620B

Abstract

The Li2WO4 single crystal was first grown by applying the Czochralski technique with weight control and low-temperature-gradients. A single crystal of Li2WO4 is one of the perspective materials for researching rare events. The heat capacity for a Li2W1?0.0125Mo0.0125O4 single crystal has been determined by DSC calorimetry in the temperature range 320–997 K for the first time. No anomalies in the heat capacity associated with phase transitions were found. The standard formation enthalpy for the Li2WO4 single crystal was studied using reaction calorimetry. It has been shown that the relation of standard formation enthalpies for Li2W1?xMoxO4 (x = 0.15–0) with function (1?x)W + xMo are close to linear, which allows one to predict the thermodynamic properties for single crystals with isotopes Li2W1861?0.0125Mo1000.0125O4 and Li2W186O4. It was shown that single crystals with isotopes are more thermodynamically stable than without isotopes.

Graphical abstract: Single crystals of undoped Li2WO4 and Li2W1?0.0125Mo0.0125O4: formation enthalpies, heat capacity in the temperature range 320–997 K
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