Crystal structure ofLaTiO3.41under pressure

Abstract

The crystal structure of the layered, perovskite-related LaTiO3.41 (La5Ti5O 17+δ ) has been studied by synchrotron powder x-ray diffraction under hydrostatic pressure up to 27 GPa (T = 295 K). The ambient-pressure phase was found to remain stable up to 18 GPa. A sluggish, but reversible phase transition occurs in the range 18-24 GPa. The structural changes of the low-pressure phase are characterized by a pronounced anisotropy in the axis compressibilities, which are at a ratio of approximately 1 : 2 : 3 for the a, b, and c axes. Possible effects of pressure on the electronic properties of LaTiO3.41 are discussed.

Bulk modulus and thermodynamic properties of electron-doped calcium manganate—Ca1−xRExMnO3

“…We report the bulk modulus of LaMnO 3 as 212 GPa in its paramagnetic insulating phase and similar high value of bulk modulus were reported for manganites by several researchers in the past. The value of bulk modulus of LaMnO 3 is close to reported value of 182 GPa of Youn et al [41] and 190 GPa for LaTiO 3 [50]. The calculated value of bulk modulus of CaMnO 3 is 255 GPa and it is close to 211 GPa reported by Youn et al [41].…”

High-pressure infrared spectroscopy on quasi-one-dimensional metals

“…Based on the low-frequency reflectivity we could monitor a pressure-induced dimensional crossover of the electronic properties. It evolves continuously in bNa 0.33 V 2 O 5 starting from the lowest applied pressure; for LaTiO 3.41 indications for the crossover are found only above 14 GPa, possibly related to a structural phase transition, the onset of which was observed at 18 GPa under nearly hydrostatic conditions [11]. The pressure dependence of the pronounced MIR band observed for both compounds along the conducting axis is consistent with an explanation in terms of polaronic excitations.…”

“…Furthermore, an increase of the background dielectric constant (by 15% at maximum) according to the Clausius-Mossotti relation [15] was assumed to account for the pressure-induced reduction of the unit cell volume [16,11].…”

“…The metallic behavior of the material along the a axis might be related to the chains of octahedra, connected via their apical oxygen atoms. The application of external pressure up to P = 18 GPa leads to continuous changes of the crystal structure [11]: The axis compressibilities are anisotropic with a ratio of approximately 1:2:3 for the a, b, and c axes. The large compressibility along c results from the highly compressible oxygen-rich layers separating the LaTiO 3 -type slabs.…”

Structural change of layered perovskite La2Ti2O7 at high pressures

“…External pressure can be used to ''tune'' the structure and properties of materials. Pressure effects on LaTiO 3.41 , which belongs to the n ¼ 5 of the homologous series, have been recently studied [13] and unusually anisotropic compressibilities and a pressure-induced phase transition were reported. In this paper, we report the structural behavior of the monoclinic La 2 Ti 2 O 7 at pressures up to 30 GPa.…”