# On the thermodynamic aspect of zinc oxide polymorphism. Calorimetric study of metastable rock salt ZnO

## TL;DR

This study measures the enthalpy of dissolution of zinc oxide polymorphs to determine the thermodynamic properties of the phase transition between metastable rock salt and stable wurtzite forms.

## Contribution

It provides the first direct calorimetric measurement of the enthalpy change for the rock salt to wurtzite phase transition in ZnO.

## Key findings

- Enthalpy of dissolution for rock salt ZnO measured at 303 K.
- Enthalpy of dissolution for wurtzite ZnO measured at 303 K.
- Standard enthalpy of phase transition determined as -11.7 kJ/mol.

## Abstract

The enthalpies of dissolution of metastable rock salt and thermodynamically stable wurtzite polymorphs of zinc oxide in aqueous H2SO4 have been measured in direct calorimetric experiments at 303 K and 0.1 MPa and the obtained results enabled determination of the standard enthalpy of the rock salt-to-wurtzite phase transition in ZnO, {\Delta}trH = -11.7+/-0.3 kJ/mol.

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Source: https://tomesphere.com/paper/1706.03368