Stability of the tetragonal phase of 
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 under high pressure

Toulouse, Constance; Amoroso, Danila; Oliva, Robert; Cong, Xin; Bouvier, Pierre; Fertey, Pierre; Veber, Philippe; Maglione, Mario; Ghosez, Philippe; Kreisel, J.; Guennou, Maël

doi:10.1103/physrevb.106.064105

Cited by 5 publications

(7 citation statements)

References 65 publications

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“…Here, the region below 100 K is shown with increasing transparency to reflect the uncertainty due to the classical sampling in MD. Experimental Raman spectroscopy data from refs , , and and X-ray diffraction (XRD) data from refs and .…”

Section: Resultsmentioning

confidence: 99%

“…The phase transition to the tetragonal phase as a function of pressure has been investigated experimentally by Raman spectroscopy ,, and XRD measurements. , The experimental results are rather scattered. In Raman studies the phase transition to the tetragonal structure was observed at 11 GPa, 10 GPa, and 19.2 GPa at room temperature and in XRD measurements at 17.2 GPa and 12 GPa . Our observed phase transition, from the cubic to the tetragonal phase at 16.2 GPa falls approximately in the middle of the experimentally observed range.…”

Section: Resultsmentioning

confidence: 99%

“…The pressure-induced transition at room temperature occurs at 9.6 GPa for STO . The same type of transition also occurs in BZO but at a somewhat higher pressure. , On the other hand, the temperature-induced transition at ambient pressure only occurs in STO, not in BZO. In STO the R-tilt mode softens; at about 105 K , it approaches zero, and the material undergoes a phase transition to the tetragonal structure.…”

Section: Discussionmentioning

confidence: 99%

“…The pressure dependence of BaZrO 3 at room temperature has been investigated by several authors. ,− In a recent combined X-ray diffraction and Raman spectroscopy study, it was found that BaZrO 3 undergoes a single phase transition around 10 GPa from the cubic ( Pm 3̅ m ) to the tetragonal ( I 4/ mcm ) phase and retains that structure up to 45.1 GPa. No second phase transition to an orthorhombic or any other tilted phase was observed.…”

Section: Introductionmentioning

confidence: 99%

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Understanding Correlations in BaZrO₃: Structure and Dynamics on the Nanoscale

Fransson,

Rosander,

Erhart

et al. 2023

Chem. Mater.

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Barium zirconate (BaZrO 3 ) is one of few perovskites that is claimed to retain an average cubic structure down to 0 K at ambient pressure while being energetically very close to a tetragonal phase obtained by condensation of a soft phonon mode at the R-point. Previous studies suggest, however, that the local structure of BaZrO 3 may change at low temperature, forming nanodomains or a glass-like phase. Here, we investigate the global and local structure of BaZrO 3 as a function of temperature and pressure via molecular dynamics simulations using machine-learned potential with near density functional theory (DFT) accuracy. We show that the softening of the octahedral tilt mode at the R-point gives rise to weak diffuse superlattice reflections at low temperatures and ambient pressure, which are also observed experimentally. However, we do not observe any static nanodomains but rather soft dynamic fluctuations of the ZrO 6 octahedra with a correlation length of 2−3 nm over time scales of about 1 ps. This soft dynamic behavior is the precursor of a phase transition and explains the emergence of weak superlattice peaks in measurements. On the other hand, when increasing the pressure at 300 K, we find a phase transition from the cubic to the tetragonal phase at around 16 GPa, also in agreement with experimental studies.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Understanding Correlations in BaZrO₃: Structure and Dynamics on the Nanoscale

Fransson,

Rosander,

Erhart

et al. 2023

Chem. Mater.

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“…In the hexagonal phase, only one Raman mode is expected to occur, E ′ (R, IR), which results from the symmetrization of the unit-cell and from the collapse of A 1 (R, IR) and B 1 (R, IR) vibrations. This collapse typically results in frozen vibrational modes due to symmetry restrictions and is associated with a displacive mechanism [56], leading to the emergence of a high-symmetry phase after the transition completion, as, for example, in ReO 3 [61] or BaZrO 3 [62]. In this scenario, we can argue that the tetragonal-to-hexagonal transition has a strong displacive character, as mediated by phonons, evident through the softening in Figure 6b,d.…”

Section: Pressure Evolution Of the Short-range Structurementioning

confidence: 93%

Exploring the Interplay between Structure and Electronic Behavior across Pressure-Induced Isostructural and Structural Transitions in Weyl-Type Semimetal NbAs

Rodrigues,

Mijit,

Rosa

et al. 2024

Crystals

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NbAs is a Weyl semimetal and belongs to the group of topological phases that exhibit distinct quantum and topological attributes. Topological phases have a fundamentally different response to external perturbations, such as magnetic fields. To obtain insights into the response of such phases to pressure, we conducted a comprehensive study on the pressure-induced electronic and structural transitions in NbAs. We used micro-X-ray diffraction (XRD) and micro-X-ray spectroscopy (XAS) techniques to elucidate the changes at different atomic and electronic length scales (local, medium, and bulk) as combined with theoretical calculations. High-pressure XRD measurements revealed a rather common compression behavior up to ~12 GPa that could be fitted to an equation of state formalism with a bulk modulus of K0= 179.6 GPa. Complementary Nb K-edge XAS data unveiled anomalies at pressure intervals of ~12–15 and ~25–26 GPa in agreement with previous literature data from XRD studies. We attribute these anomalies to a previously reported topological Lifshitz transition and the tetragonal-to-hexagonal phase transition, respectively. Analysis of EXAFS results revealed slight changes in the mean next-nearest neighbor distance Nb–As(1) (~2.6 Å) at ~15 GPa, while the second nearest neighboring bond Nb–Nb(1) (~3.4 Å) shows a pronounced anomaly. This indicates that the electronic changes across the Lifshitz transition are accommodated first in the medium-range atomic structure and then at the local range and bulk. The variances of these bonds show anomalous but progressive evolutions close to the tetragonal-to-hexagonal transition at ~25 GPa, which allowed us to derive the evolution of vibration properties in this material. We suggest a prominent displacive character of the I41md→P6¯m2 transition facilitated by phonon modes.

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CO₂ Pressure‐Induced Self‐Trapped Excitons in SrTiO₃

Li,

Chen,

Gao

et al. 2024

Advanced Photonics Research

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With strong electron–phonon coupling, self‐trapped excitons (STEs) are typically formed in perovskite materials, and radiative recombination of STEs can produce broadband emission with large Stokes shifts. STEs are essential to further improve the optoelectronic properties of materials. Surprisingly, 2D system is the edge case, with low even no self‐trapping barriers, leading to effortless formation of STEs. In this work, 2D strontium titanate (SrTiO3) with defects is prepared using supercritical carbon dioxide (SC CO2) and its carrier transport and transition are studied. The appearance of wide photoinduced positive absorption signals in the femtosecond transient absorption spectra is direct evidence for the formation of STEs. The presence of STEs is further supported by the increased Stokes shift and full width at half maximum in the steady‐state photoluminescence spectra.

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Stability of the tetragonal phase of BaZrO3 under high pressure

Cited by 5 publications

References 65 publications

Understanding Correlations in BaZrO₃: Structure and Dynamics on the Nanoscale

Understanding Correlations in BaZrO₃: Structure and Dynamics on the Nanoscale

Exploring the Interplay between Structure and Electronic Behavior across Pressure-Induced Isostructural and Structural Transitions in Weyl-Type Semimetal NbAs

CO₂ Pressure‐Induced Self‐Trapped Excitons in SrTiO₃

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Stability of the tetragonal phase of BaZrO3 under high pressure

Cited by 5 publications

References 65 publications

Understanding Correlations in BaZrO3: Structure and Dynamics on the Nanoscale

Understanding Correlations in BaZrO3: Structure and Dynamics on the Nanoscale

Exploring the Interplay between Structure and Electronic Behavior across Pressure-Induced Isostructural and Structural Transitions in Weyl-Type Semimetal NbAs

CO2 Pressure‐Induced Self‐Trapped Excitons in SrTiO3

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Product

Resources

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Understanding Correlations in BaZrO₃: Structure and Dynamics on the Nanoscale

Understanding Correlations in BaZrO₃: Structure and Dynamics on the Nanoscale

CO₂ Pressure‐Induced Self‐Trapped Excitons in SrTiO₃