Pressure-induced amorphization of La1/3NbO3

Noked, Ori; Yakovlev, Sergey; Greenberg, Yakov; Garbarino, Gastón; Shuker, R.; Avdeev, Maxim; Sterer, Eran

doi:10.1016/j.jnoncrysol.2011.05.030

Cited by 12 publications

(3 citation statements)

References 27 publications

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“…This indicates that contributions from the atoms at further distances (those above the NbO 6 octahedra) get increasingly masked due to changing local geometry. The changes in the EXAFS spectra suggest that there is a significant increase in the disorder above 7 GPa which is consistent with the previously described change in the x-ray diffraction profiles [3].…”

Section: Resultssupporting

confidence: 91%

“…Perovskites' crystal chemistry is very rich, particularly under non-ambient conditions [2]. Recently, a subgroup of perovskite oxides, namely the A-site deficient Ln 1/3 MO 3 (Ln = La, Pr, Nd, M = Nb, Ta) oxides, was found to undergo irreversible pressure induced amorphization (PIA) at modest pressures around 14.5 GPa [3,4] for niobates (La 1/3 NbO 3 ) and around 18.5 GPa for tantalates Ln 1/3 TaO 3 [4,5]. PIA is subject of intensive research, since the observation of this phenomena in a number of simple materials including ice [6] and α-quartz [7] and in materials with special interest to geophysics such as Fe 2 SiO 4 [9] and Mg 2 SiO 4 [8].…”

Section: Introductionmentioning

confidence: 99%

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Nb K-edge x-ray absorption investigation of the pressure induced amorphization in A-site deficient double perovskite La_1/3NbO₃

Marini

Noked

Kantor

et al. 2016

J. Phys.: Condens. Matter

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Nb K-edge x-ray absorption spectroscopy is utilized to investigate the changes in the local structure of the A-site deficient double perovskite La1/3NbO3 which undergoes a pressure induced irreversible amorphization. EXAFS results show that with increasing pressure up to 7.5 GPa, the average Nb-O bond distance decreases in agreement with the expected compression and tilting of the NbO6 octahedra. On the contrary, above 7.5 GPa, the average Nb-O bond distance show a tendency to increase. Significant changes in the Nb K-edge XANES spectrum with evident low energy shift of the pre-peak and the absorption edge is found to happen in La1/3NbO3 above 6.3 GPa. These changes evidence a gradual reduction of the Nb cations from Nb(5+) towards Nb(4+) above 6.3 GPa. Such a valence change accompanied by the elongation of the average Nb-O bond distances in the octahedra, introduces repulsion forces between non-bonding adjacent oxygen anions in the unoccupied A-sites. Above a critical pressure, the Nb reduction mechanism can no longer be sustained by the changing local structure and amorphization occurs, apparently due to the build-up of local strain. EXAFS and XANES results indicate two distinct pressure regimes having different local and electronic response in the La1/3NbO3 system before the occurence of the pressure induced amorphization at ∼14.5 GPa.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Nb K-edge x-ray absorption investigation of the pressure induced amorphization in A-site deficient double perovskite La_1/3NbO₃

Marini

Noked

Kantor

et al. 2016

J. Phys.: Condens. Matter

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“…An amorphous solid crystallizes under high pressure because its excess free volume is distributed throughout the substance and is consequently released during crystallization. PIA is a prevalent phenomenon in numerous compounds, − and bondings in PIA systems vary widely in accordance with the material system. For example, bonds in SiO 2 are covalent, whereas those in Ca(OH) 2 systems are ionic .…”

Section: Introductionmentioning

confidence: 99%

Pressure-Induced Reversible Amorphization in Hydrogen-Bonded Crystalline Phenyl Carbamate Form-I

Yan

et al. 2017

J. Phys. Chem. C

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We characterized the high-pressure response of hydrogen-bonded crystalline phenyl carbamate (C7H7NO2, PC) form-I through in situ synchrotron X-ray diffraction (XRD) and Raman spectroscopy in a diamond anvil cell (DAC) under pressures of up to ∼13 GPa at room temperature. No evidence for the polymorphic transformation of crystalline PC form-I crystal to form-II was observed under high pressure. The evolution of the XRD patterns and Raman spectra indicated that crystalline PC form-I underwent reversible pressure-induced amorphization (PIA) at 12.7 GPa. Ab initio calculations were performed to account for the changes in molecular arrangements and hydrogen-bonded networks in PC form-I under pressure. Hirshfeld surfaces and fingerprint plots were utilized to directly compare the variations in packing patterns and intermolecular interactions. On the basis of the experimental and calculated results, we proposed that PIA in crystalline PC form-I is driven by the competition between close packing and long-range order. This competition is accompanied by hydrogen-bond collapse.

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NaEu₃(GeO₄)₂(OH)₂: A High‐Pressure‐Stable Photoluminescent Lanthanide Germanate

et al. 2012

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The europium germanate NaEu3(GeO4)2(OH)2 was prepared under mild hydrothermal conditions. In situ synchrotron X‐ray diffraction analysis and photoluminescence spectroscopic measurement in a diamond anvil cell (DAC) under high pressure were performed to study its structural stability as well as the luminescent properties of the Eu3+ ions. The synchrotron X‐ray diffraction analysis revealed that the structure of NaEu3(GeO4)2(OH)2 was stable under pressure that ranged from 1 atm to 20 GPa with only a little distortion, and the unit‐cell compression occurred more readily along the a axis than along the c axis. When the pressure was reduced to ambient pressure, the distortion and the unit cell recovered to the original state. Photoluminescence spectroscopic studies under high pressure showed that the redshift of the 5D0 → 7FJ (J = 0, 1, 2) transitions and the pressure imposed on the sample had a good linear relationship. Also, the intensity of the red emission lines was independent of the pressure in the range from 9 to about 20 GPa.

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Pressure-induced amorphization of La1/3NbO3

Cited by 12 publications

References 27 publications

Nb K-edge x-ray absorption investigation of the pressure induced amorphization in A-site deficient double perovskite La_1/3NbO₃

Nb K-edge x-ray absorption investigation of the pressure induced amorphization in A-site deficient double perovskite La_1/3NbO₃

Pressure-Induced Reversible Amorphization in Hydrogen-Bonded Crystalline Phenyl Carbamate Form-I

NaEu₃(GeO₄)₂(OH)₂: A High‐Pressure‐Stable Photoluminescent Lanthanide Germanate

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Pressure-induced amorphization of La1/3NbO3

Cited by 12 publications

References 27 publications

Nb K-edge x-ray absorption investigation of the pressure induced amorphization in A-site deficient double perovskite La1/3NbO3

Nb K-edge x-ray absorption investigation of the pressure induced amorphization in A-site deficient double perovskite La1/3NbO3

Pressure-Induced Reversible Amorphization in Hydrogen-Bonded Crystalline Phenyl Carbamate Form-I

NaEu3(GeO4)2(OH)2: A High‐Pressure‐Stable Photoluminescent Lanthanide Germanate

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Product

Resources

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Nb K-edge x-ray absorption investigation of the pressure induced amorphization in A-site deficient double perovskite La_1/3NbO₃

Nb K-edge x-ray absorption investigation of the pressure induced amorphization in A-site deficient double perovskite La_1/3NbO₃

NaEu₃(GeO₄)₂(OH)₂: A High‐Pressure‐Stable Photoluminescent Lanthanide Germanate