Raman study of HoFe₃(BO₃)₄ at simultaneously high pressure and high temperature: p–T phase diagram

Abstract

Raman spectra of a HoFe3(BO3)4 crystal chip has been investigated at simultaneously high temperature and high pressure (up to 7.1 GPa and 560 K). On the basis of Raman analysis, the assignment to one of the two possible crystal phases has been made. The experimental p–T phase diagram of HoFe3(BO3)4 was established. An increase in the pressure leads to an increase in the temperature of transition. The phase boundary equation was obtained. Neither triple points nor a phase with new symmetry was revealed in the phase diagram. A critical point with the temperature T = 560 K and the pressure p = 2.53 GPa was found. The nanocrystals with different shapes began to grow on crystal surface after reaching that point. The composition of new nanocrystals is identical to the composition of initial crystal. Copyright © 2017 John Wiley & Sons, Ltd.

In‐situ Raman study of phengite compressed in water medium under simultaneously high P–T parameters

“…Calibration of temperature (dependence of the sample temperature on the thermocouple temperature; the last is determined with accuracy ±0.5°С) was performed by method. [22,23] The accuracy of this method in the sample temperature (T) determination is estimated as ±5°С. The maximum P-T values reached in our experiments with phengite specimens were 12.52 GPa and 373°С.…”

“…Accuracy of P determination is equal to ±0.05 GPa. Calibration of temperature (dependence of the sample temperature on the thermocouple temperature; the last is determined with accuracy ±0.5 °С) was performed by method . The accuracy of this method in the sample temperature ( T ) determination is estimated as ±5 °С.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part XII

“…Krylov et al presented a Raman study of HoFe 3 (BO 3 ) 4 at simultaneously high pressure and high temperature that yielded a P–T phase diagram. On the basis of their Raman analysis, the assignment to one of the two possible crystal phases was made . Maruyama et al described pressure‐induced phase transitions of vaterite, a metastable phase of CaCO 3 .…”

“…On the basis of their Raman analysis, the assignment to one of the two possible crystal phases was made. [206] Maruyama et al described pressure-induced phase transitions of vaterite, a metastable phase of CaCO 3 . Their results indicate that vaterite undergoes more complex phase transitions at high pressure than other polymorphs of calcium carbonate, calcite, and aragonite.…”

GeoRaman

“…In a study of temperature‐induced transformations in self‐assembled peptide nanotubes, promising for applications in biocompatible systems, biosensors, and biochips, Zelenovskiy et al for the first time showed that such transformations may be considered in the context of evolution of H 2 O molecules subsystem inside the nanotubes. In situ Raman spectroscopy at simultaneous high‐pressure and high‐temperature conditions was used by Krylov et al to establish a phase diagram of multiferroic HoFe3(BO3)4 material up to 7 GPa and 560 K. A fruitful combination of Raman spectroscopy and computational quantum chemistry allowed Yushina et al to reveal a “centrosymmetric to non‐centrosymmetric” phase transition caused by proton ordering in organic polyiodide material, promising as nonlinear response‐based optical switch. A comprehensive study of nonlinear optical material δ‐BiB3O6 by means of polarized Raman spectroscopy supported by simulations based on the interatomic potentials approach is presented in the paper of Strikina et al.…”