First-principles Investigation of Thermodynamic Properties of CrNbO4 and CrTaO4

In the present study, the DFT+U method was employed to predict the thermodynamic properties of Cr2O3, Nb2O5, and Ta2O5. Results were benchmarked with experimental data showing high accuracy, except for the negative thermal expansion (NTE) of Nb2O5, which is attributed to its polymorphic complexity. Additionally, we extended our analysis to rutile-type oxides CrNbO4 and CrTaO4, examining their entropy and heat capacity at finite temperatures. CrNbO4 displayed slightly higher entropy and heat capacity at high temperatures. The mean linear thermal expansion coefficients for CrNbO4 and CrTaO4 from 500 K to 2000 K were predicted to be 6.00*10-6/K and 13.49*10-6/K, respectively, corroborating with DFT predictions and experimental evidence. Our research highlights the precision of the DFT+U and phonon methods in predicting the thermodynamic properties of oxide materials, offering insights into the design of corrosion-resistant materials.