References of "Toulouse, Constance 50034540"
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See detailLattice dynamics and Raman spectrum of BaZrO3 single crystals
Toulouse, Constance UL; Amoroso, Danila; Xin, Cong et al

in PHYSICAL REVIEW B (2019), 100

BaZrO3 is a perovskite that remains in the simple cubic phase at all temperatures, hence with no first-order Raman-active phonon mode allowed by symmetry. Yet, it exhibits an intense Raman spectrum with ... [more ▼]

BaZrO3 is a perovskite that remains in the simple cubic phase at all temperatures, hence with no first-order Raman-active phonon mode allowed by symmetry. Yet, it exhibits an intense Raman spectrum with sharp and well-defined features. Here, we report the evolution of the Raman spectrum of BaZrO3 single crystals in a broad temperature range (4-1200 K) and discuss its origin with the support of detailed first-principle calculations of the lattice dynamics. Phonon calculations are performed not only for the cubic phase of BaZrO3, but also for the low-symmetry phases with octahedra tilts that have been suspected to exist at the nanoscale. We show that the Raman spectrum shows no direct evidence for these nanodomains, but can instead be explained by classical second-order Raman scattering. We provide an assignment of the dominant features to phonon mode combinations. In particular, we show that the high frequency range of the spectrum is dominated by overtones and shows an image of the phonon density of states corresponding to the stretching modes of the oxygen octahedra. [less ▲]

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See detailSingle crystal growth of BaZrO3 from the melt at 2700 degrees C using optical floating zone technique and growth prospects from BaB2O4 flux at 1350 degrees C
Xin, Cong; Veber, Philippe; Guennou, Mael UL et al

in CRYSTENGCOMM (2019), 21(3), 502-512

We report the growth of BaZrO3 single crystals by the optical floating zone technique and the investigation on its flux growth using BaB2O4 as a solvent. 6 mm long colorless and transparent single ... [more ▼]

We report the growth of BaZrO3 single crystals by the optical floating zone technique and the investigation on its flux growth using BaB2O4 as a solvent. 6 mm long colorless and transparent single crystals were obtained with a mirror furnace without the need for post-treatment annealing. Its properties are determined and compared with those of two commercial crystals grown by the tri-arc Czochralski method. The chemical composition was investigated using glow discharge mass spectrometry (GDMS) and secondary ion mass spectrometry (SIMS), which indicate minor impurities of Sr, Hf, Ca and Ti, with maximal concentrations for Sr and Hf in the range of 0.3-0.5 at. The optical band gap determined by UV-visible spectroscopy is found to be similar to 4.8 eV and indicates the high quality of the BaZrO3 crystals grown by the optical floating zone technique. Raman spectroscopy at ambient conditions and at low temperatures down to 4.2 K reveals a relatively sharp second-order spectrum and does not reveal any structural phase transition. Prospective high-temperature solution growth using BaB2O4 self-flux was investigated and led to 150-200 mu m BaZrO3 crystals. This solvent opens the way to grow BaZrO3 at half its melting point by the flux method. [less ▲]

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