Stability of the fergusonite phase in GdNbO 4 by high pressure XRD and Raman experiments

Pellicer‐Porres, J.; Garg, Alka B.; Vázquez-Socorro, D.; Martínez‐García, D.; Popescu, Cătălin; Errandonea, Daniel

doi:10.1016/j.jssc.2017.03.019

Cited by 22 publications

(26 citation statements)

References 21 publications

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“…All even ( g ) modes are Raman active, while every optic odd ( u ) mode is infrared active. A ( B ) modes are symmetric (antisymmetric) concerning the two‐order axis [29] . The observed vibrational modes present good agreement with other studies reported in the literature [24,27,30] .…”

Section: Resultssupporting

confidence: 89%

Vibrational Properties of LaNb_0.8M_0.2O_4‐δ (M=As, Sb, V, and Ta)

et al. 2022

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LaNb0.8M0.2O4‐δ (where M=As, Sb, V, and Ta) oxides with pentavalent elements of different ionic sizes were synthesized by a solid‐state reaction method. The vibrational properties of these oxides have been investigated. These studies revealed that the substituent element influences both Debye temperature value as well as the Raman active vibrational modes. Additionally, the low‐temperature vibrational properties of LaNb0.8Sb0.2O4‐δ have been determined to show the phase transition occurrence at 260 K which is lower than previously reported.

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Section: Resultssupporting

confidence: 89%

Vibrational Properties of LaNb_0.8M_0.2O_4‐δ (M=As, Sb, V, and Ta)

et al. 2022

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“…This structure is very similar to the one obtained from XRD experiments and the theoretical transition pressure agrees with the experimental one. Thus, we can conclude that rare-earth niobates with a late lanthanide (like HoNbO4) follow a different structural sequence than other niobates of the same family [14], in analogy to the behavior of RVO4 vanadates [9].…”

Section: Resultsmentioning

confidence: 88%

High-pressure monoclinic–monoclinic transition in fergusonite-type HoNbO₄

Garg¹,

Errandonea²,

Rodríguez‐Hernández³

et al. 2021

J. Phys.: Condens. Matter

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In this paper we perform a high-pressure (HP) study of fergusonite-type HoNbO4. Powder x-ray diffraction experiments and ab initio density-functional theory (DFT) simulations provide evidence of a phase transition at 18.9(1.1) GPa from the monoclinic fergusonite-type structure (space group I2/a) to another monoclinic polymorph described by space group P21/c. The phase transition is reversible and the HP structural behavior is different than the one previously observed in related niobates. The HP phase remains stable up to 29 GPa. The observed transition involves a change in the Nb coordination number from 4 to 6, and it is driven by mechanical instabilities. We have determined the pressure dependence of unit-cell parameters of both phases and calculated their room-temperature equation of state. For the fergusonite-phase we have also obtained the isothermal compressibility tensor. In addition to the HP studies, we report ambient-pressure Raman and infrared (IR) spectroscopy measurements. We have been able to identify all the active modes of fergusonite-type HoNbO4, which have been assigned based upon DFT calculations. These simulations also provide the elastic constants of the different structures and the pressure dependence of the Raman and IR modes of the two phases of HoNbO4. According to ab initio calculations, the reported phase transition is related to a mechanical instability and a phonon softening.

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“…The Raman band near 780-840 cm −1 appears in all the samples, whereas the band near 500-600 cm −1 only existed in sample A. The Raman band around 780-830 cm −1 is corresponding to the vibrational modes of a regular NbO 4 tetrahedron, and the band near 500-700 cm −1 is assigned as the symmetric stretching mode of the NbO 6 octahedra [1,18,19]. The correlation between the Raman wavenumbers for the stretching bands in niobate compounds and the Nb-O bond length has previously been established.…”

Section: Resultsmentioning

confidence: 91%

“…Cs 2 Nb 4 O 11 is the one that coexisted with NbO 6 octahedra and NbO 4 tetrahedra in the structure [12,18]. The tetrahedral NbO 4 structure is rarely found in niobium oxide compounds because the Nb 5+ atom is usually too large to fit into an oxygen-anion tetrahedron and exists in the rare earth ANbO 4 (A = Y, Sm, and La) compounds [1,2,19]. To investigate the effect of MO x shape on photocatalytic activity, the challenge is preparing the sample containing NbO 4 tetrahedra.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Physical and Photocatalytic Activity of a New Niobate Oxide Material Containing NbO₄ Tetrahedra

Pan

Wang

Zhang

et al. 2018

International Journal of Photoenergy

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The shape and connection type of MOx are critical to the physical and chemical properties. A series of new material Sr2-xNaxNbO4 containing NbO4 tetrahedra was prepared by controlling the ratio of SrCO3 to sodium niobate under ambient air. With increasing the content of Sr in the sample, the MOx shape will change from NbO6 octahedra to NbO4 tetrahedra, which is confirmed by the Raman scattering spectra. With increasing the content of NbO4 in the sample, the lattice parameter increases, optical band gap becomes larger, and the surface changes to be more active for oxygen adsorption, resulting in a higher photocatalytic activity.

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Stability of the fergusonite phase in GdNbO 4 by high pressure XRD and Raman experiments

Cited by 22 publications

References 21 publications

Vibrational Properties of LaNb_0.8M_0.2O_4‐δ (M=As, Sb, V, and Ta)

Vibrational Properties of LaNb_0.8M_0.2O_4‐δ (M=As, Sb, V, and Ta)

High-pressure monoclinic–monoclinic transition in fergusonite-type HoNbO₄

Preparation and Physical and Photocatalytic Activity of a New Niobate Oxide Material Containing NbO₄ Tetrahedra

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Stability of the fergusonite phase in GdNbO 4 by high pressure XRD and Raman experiments

Cited by 22 publications

References 21 publications

Vibrational Properties of LaNb0.8M0.2O4‐δ (M=As, Sb, V, and Ta)

Vibrational Properties of LaNb0.8M0.2O4‐δ (M=As, Sb, V, and Ta)

High-pressure monoclinic–monoclinic transition in fergusonite-type HoNbO4

Preparation and Physical and Photocatalytic Activity of a New Niobate Oxide Material Containing NbO4 Tetrahedra

Contact Info

Product

Resources

About

Vibrational Properties of LaNb_0.8M_0.2O_4‐δ (M=As, Sb, V, and Ta)

Vibrational Properties of LaNb_0.8M_0.2O_4‐δ (M=As, Sb, V, and Ta)

High-pressure monoclinic–monoclinic transition in fergusonite-type HoNbO₄

Preparation and Physical and Photocatalytic Activity of a New Niobate Oxide Material Containing NbO₄ Tetrahedra