First-principles calculations of electronic, vibrational, and structural properties of scheelite EuWO4 under pressure

In this paper we report a density functional study of the structural, electronic, and vibrational properties of the EuWO4 compound in the scheelite structure. We use Raman spectroscopy to complement the study for this phase at ambient pressure. The first part of the paper is devoted to analyzing the results obtained with the Perdew-Burke-Ernzerhof for solids exchange-correlation functional within the GGA+U approximation and compare those with our experimental results and reported available data. We also present the evolution of these properties, for the same crystal structure, up to 8 GPa. The second part of the paper is devoted to discussing our study on the high-pressure phase transitions of EuWO4, for which we follow the evolution of the structural properties as a function of pressure. The results show that the high-pressure behavior of EuWO4 is very similar to that of CaWO4, SrWO4, BaWO4, and PbWO4, for which the scheelite structure undergoes a phase transition to the fergusonite structure, an observation also supported by our experimental data. Additionally, we can also conclude that at higher pressures, EuWO4 evolves to the BaWO4-II and Cmca crystal phases.