论文标题

prvo $ _4 $在高压下:对结构,光学和电气特性的影响

PrVO$_4$ under High Pressure: Effects on Structural, Optical and Electrical Properties

论文作者

Bandiello, Enrico, Popescu, Catalin, da Silva, Estelina Lora, Sans, Juan Ángel, Errandonea, Daniel, Bettinelli, Marco

论文摘要

为了追求在压缩下的稀有地球物质的系统表征,在这项工作中,我们介绍了在高压条件下锆石型正叉型prvo $ _4 $ _4 $的多方面研究,直到24 GPA。我们发现,Prvo $ _4 $在6 GPA左右经历了一个锆石向独居石过渡,这证实了Raman实验发现的先前结果。第二次过渡发生在14 GPA以上,向Bawo $ _4 $ -I-型结构进行。锆石到独居石的结构序列是不可逆的一阶转变,伴随着大约9.6%的体积崩溃。因此,独居阶段是prvo $ _4 $的亚稳态二元组。发现单唑 - bawo $ _4 $ -II过渡是可逆的,并且发生了类似的体积更改。在这里,我们报告并讨论了所有阶段的轴向和大量可压缩性。我们还将我们的结果与其他稀土矫形器的结果进行了比较。最后,通过光吸收实验和电阻率测量,我们确定了压力对PRVO $ _4 $的电子性质的影响。我们发现,锆石 - 摩纳唑转变会产生带隙的崩溃,电阻率突然降低。讨论了这种行为的物理原因。密度功能理论模拟支持我们的结论。

In pursue of a systematic characterization of rare-earth vanadates under compression, in this work we present a multifaceted study of the phase behavior of zircon-type orthovanadate PrVO$_4$ under high pressure conditions, up until 24 GPa. We have found that PrVO$_4$ undergoes a zircon to monazite transition at around 6 GPa, confirming previous results found by Raman experiments. A second transition takes place above 14 GPa, to a BaWO$_4$-I--type 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 PrVO$_4$. The monazite-BaWO$_4$-II transition is found to be reversible instead and occurs with a similar volume change. Here we report and discuss 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 the effect of pressure on the electronic properties of PrVO$_4$. We found that the zircon-monazite transition produces a collapse of the band gap and an abrupt decrease of the resistivity. The physical reasons for this behavior are discussed. Density-functional-theory simulations support our conclusions.

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