High-pressure investigations of CaTiO3 up to 60 GPa using X-ray diffraction and Raman spectroscopy

Abstract

In this work, we investigate calcium titanate (CaTiO3 - CTO) using X-ray diffraction and Raman spectroscopy up to 60 and 55 GPa respectively. Both experiments show that the orthorhombic Pnma structure remains stable up to the highest pressures measured, in contradiction to ab-initio predictions. A fit of the compression data with a second-order Birch-Murnaghan equation of state yields a bulk modulus K0 of 181.0(6) GPa. The orthorhombic distortion is found to increase slightly with pressure, in agreement with previous experiments at lower pressures and the general rules for the evolution of perovskites under pressure. High-pressure polarized Raman spectra also enable us to clarify the Raman mode assignment of CTO and identify the modes corresponding to rigid rotation of the octahedra, A-cation shifts and Ti-O bond stretching. The Raman signature is then discussed in terms of compression mechanisms.

arXiv comment11 pages, 6 figures, 4 tables

References in corpus (4)

• Ab initio calculations of phonon spectra in ATiO3 perovskite crystals (A = Ca, Sr, Ba, Ra, Cd, Zn, Mg, Ge, Sn, Pb)
• Pressure-temperature phase diagram of SrTiO3 up to 53 GPa
• Phase transitions and ferroelectrics: revival and the future in the field
• Infrared study of the phonon modes in PrMnO${}_3$ and CaMnO${}_3$

Cited by in corpus (7)

• Multiple high-pressure phase transitions in BiFeO3
• Rules and mechanisms governing octahedral tilts in perovskites under pressure
• Lattice dynamics and Raman spectrum of BaZrO3 single crystals
• Jahn-Teller, polarity and insulator-to-metal transition in BiMnO3 at high pressure
• Soft antiphase tilt of oxygen octahedra in the hybrid improper multiferroic Ca3Mn1.9Ti0.1O7
• High-pressure phase transitions in BiFeO3: hydrostatic vs. non-hydrostatic conditions
• Bismuth-based perovskites as multiferroics