arXiv subjects
Publications and source records attributed to Andrey N. Baranov.
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, ΔtrH = -11.7+/-0.3 kJ/mol.
Very recently Leitner et al. [Thermochimica Acta 572 (2013) 1-5] have tried to extract the thermodynamic data of rock-salt ZnO from ab initio and experimental data available in the literature. In this Comment we show that neglecting (i) the strongly pronounced kinetic features of the pressure-induced phase transition in ZnO at room temperature and (ii) results of calorimetric measurements available in the literature [Russ. Chem. Bull. 59 (2010) 325-328] makes the proposed set of thermodynamic functions completely incorrect.
Lattice parameter of metastable high-pressure phase of zinc oxide, rock-salt ZnO was measured in the 10-300 K temperature range using synchrotron X-ray powder diffraction. No phase transition was observed down to 10 K. The lattice parameter of rock-salt ZnO was found to increase from 4.266 Å in the 10-80 K range up to 4.2752(3) Å at 298 K, while the volume thermal expansion coefficient increases from slight negative values below 40 K up to 4.77\times10^-5 K^-1 at 298 K.