PrVO₄ under High Pressure: Effects on Structural, Optical, and Electrical Properties

Abstract

In pursue of a systematic characterization of rare-earth vanadates under compression, in this work we have studied the phase behavior of zircon-type orthovanadate PrVO4 under high pressure conditions, up to 24 GPa, by means of powder x-ray diffraction. We have found that PrVO4 undergoes a zircon to monazite transition around 6 GPa, confirming previous results found on Raman experiments. A second transition takes place above 14 GPa, to a BaWO4-IItype structure. The zircon to monazite structural sequence is an irreversible first-order transition, accompanied by a volume collapse of about 9.6%. Monazite phase is thus a metastable polymorph of PrVO4. The monazite-BaWO4-II transition is found to be reversible instead and occurs with a similar volume change. Here we report on the axial and bulk compressibility of all phases. We also compare our results with those for other rare-earth orthovanadates. Finally, by means of optical-absorption experiments and resistivity measurements we determined by the first time the effect of pressure in the electronic properties of PrVO4. We found that the zirconmonazite transition produces a collapse of the band gap and an abrupt decrease of the resistivity. Reasons for this behavior are going to be discussed.

Lattice dynamics of zircon-type NdVO4 and scheelite-type PrVO4 under high-pressure

“…Beyond 6.0 GPa, the Raman peak assigned to the zircon structure completely disappears. This can be explained as the consequence of the zircon-to-monazite phase transition, as it has been reported in literature [13,14,16]. However, the Raman peaks of the monazite phase are too weak to be distinguished, so they become imperceptible hereon.…”

“…(S. G.: I41/a, Z = 4) [7][8][9][10], while those with larger cations (R = Ce, Pr) transform into a monazite-type phase (S. G.: P21/n, Z = 4) [11][12][13][14]. However, it has been suggested that some factors such as hydrostaticity or kinetic barriers can play a very important role both in the transition pressure and the structural sequence.…”

“…In reference [16] it has been shown that both the monazite and the scheelite phase can be achieved in PrVO 4 . When zircon-type PrVO 4 is compressed at room temperature (RT), the sample transforms into the monazite phase at 5.5 GPa [14,16]. On the contrary, when the compound is compressed at 7 GPa and heated over 600 • C in a large volume press cell, a mixture of zircon-and metastable scheelite-type PrVO 4 is recovered at room conditions [16].…”

Graph-Text Contrastive Learning of Inorganic Crystal Structure toward a Foundation Model of Inorganic Materials

“…Table 2 is the result for PrVO 4 (mp-19169 on the Materials Project [52]), which has a zircon-type structure and has attracted attention due to its redox activity as photocatalyst [64][65][66]. Its space group I4 1 {amd was retrieved as the second scored one.…”

Graph-Text Contrastive Learning of Inorganic Crystal Structure toward a Foundation Model of Inorganic Materials

“…is the result for PrVO 4 (mp-19169 on the Materials Project), which has a zircon-type structure and has attracted attention due to its redox activity as photocatalyst[65][66][67]. Its space group I4 1 {amd was retrieved as the second scored one.…”