Crystal structure of the high-pressure modification of NdTaO4

Titov, Yu. A.; Sych, A. M.; Соколов, А. Н.; Kapshuk, A. A.; Markiv, V.Ya.; Belyavina, N. N.

doi:10.1016/s0925-8388(00)01043-4

Cited by 35 publications

(22 citation statements)

References 4 publications

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“…6(a) as a function of the volume. We only plot results for the most relevant structures, i.e., tetragonal scheelite (I4 1 /a), 4 monoclinic structure related to BaWO 4 -II (P2 1 /n), 16 monoclinic structure related to LaTaO 4 (P2 1 /c), 41 and an orthorhombic structure with space group Cmca. 42 In agreement with experiments, the scheelite structure is found to be the most stable structure at ambient pressure.…”

Section: Calculations: Scheelite Phasementioning

confidence: 99%

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Compression of scheelite-type SrMoO4 under quasi-hydrostatic conditions: Redefining the high-pressure structural sequence

Errandonea

Gracia

Lacomba-Perales

et al. 2013

Journal of Applied Physics

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The high-pressure behavior of tetragonal SrMoO 4 was analyzed by Raman and optical-absorption measurements. Pressures up to 46.1 GPa were generated using diamond-anvil cells and Ne or N 2 as quasi-hydrostatic pressure-transmitting media. A reversible phase transition is observed at 17.7 GPa. A second transition is found at 28.8 GPa and the onset of a third one at 44.2 GPa. The pressure dependence of Raman-active modes is reported for the different phases and the pressure evolution of the fundamental band-gap reported for the low-pressure phase. The observed changes in the Raman spectra contradict the structural sequence determined from previous experiments performed under higher non-hydrostaticity. This fact suggests that deviatoric stresses can influence pressure-driven transitions in scheelite-type oxides. We also report total-energy, lattice-dynamics, and band-structure calculations. They reproduce accurately the behavior of the physical properties of the low-pressure phase and predict the occurrence of phase transitions at pressures similar to experimental transition pressures. According to theory, the high-pressure phases have monoclinic and orthorhombic structures, which are much more compact than tetragonal scheelite. Theoretical results and experiments are compared with previous studies. V C 2013 American Institute of Physics.

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Section: Calculations: Scheelite Phasementioning

confidence: 99%

“…19 These differences between calculations and experiments are typical of DFT calculations. 22,[40][41][42][43][44][45][46] However, they usually describe well the pressure dependence of E g .…”

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confidence: 99%

Compression of scheelite-type SrMoO4 under quasi-hydrostatic conditions: Redefining the high-pressure structural sequence

Errandonea

Gracia

Lacomba-Perales

et al. 2013

Journal of Applied Physics

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“…13, Z =2͒, which was found stable above 17. 18,19 the BaWO 4 -II structure ͑SG P2 1 / n, no. 14, Z =8͒, a high-pressure and -temperature phase observed in BaWO 4 ; 20 and the ambient-pressure structure of SrUO 4 ͑SG Pbcm, no.…”

Section: B High-pressure Phases Second Transitionmentioning

confidence: 99%

Theoretical study of theYLiF4phase transitions under pressure

et al. 2006

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Experimental work has shown that YLiF 4 has a first phase transition from the ambient pressure scheelite to a fergusonite structure at 10 GPa, and a second one at 17 GPa to an unresolved structure. Theoretical work has proposed either M-or MЈ-fergusonite as the second structural phase, and wolframite or a P2 1 / c-symmetry structure as the third. In this ab initio study, we find that the MЈ-fergusonite structure is a better candidate for the second phase of YLiF 4 , and propose a new structure with Cmca symmetry as the third.

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“…The differ- Structure determination and refinement: Program SHELX-97 [40][41][42] [2] (a = 1129.0(4) pm, b = 400.1(1) pm, c = 1806.2(4) pm) are smaller than 0.5 %. For the LnTaO 4 series with Ln = La -Nd and Sm -Lu [3] there is a structural change between Ln = Pr and Ln = Nd, but NdTaO 4 can be obtained via high-pressure synthesis in the LaTaO 4 -type structure [27] as well. Such a structural break very often takes place between praseodymium and neodymium or between neodymium and samarium compounds with the same stoichiometry.…”

Section: Resultsmentioning

confidence: 99%

About Lanthanoid Fluoride Selenide Oxoselenotantalates with the Composition Ln₃F₂Se₂TaO₄ (Ln = La – Nd)

Grossholz

Buyer

Lotter

et al. 2020

Zeitschrift anorg allge chemie

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After solid‐state reactions of the light lanthanoid metals, their oxides and fluorides as well as selenium in sealed tantalum ampoules with sodium chloride as a fluxing agent at 850 °C for 8 days needle‐shaped single crystals of Ln3F2Se2TaO4 (Ln = La – Nd) were obtained. They crystallize in the orthorhombic space group Pnma analogous to La3F2Se2NbO4 with a = 1133–1120 pm, b = 400–393 pm and c = 1812–1778 pm (Ln = La – Nd) for Z = 4 as the first known quinary lanthanoid(III) oxoselenotantalates(V) with fluoride and selenide anions. The three crystallographically different Ln3+ cations are all surrounded by nine anions (O2–, F– and Se2–) each. Tantalum resides in an octahedral chalcogen coordination by forming trans‐vertex oxygen‐connected [TaO5Se]7– polyhedra, which build up chains 1∞{[TaOV2/2Ot3/1Set1/1]5–} along [010]. The sites of the four crystallographically different oxygen atoms and the two distinct fluoride anions were established by bond‐valence calculations. One fluorine and three oxygen atoms are surrounded tetrahedrally by cations, while another fluoride and oxide anion exhibit just triangular non‐planar coordination spheres. The two independent Se2– anions have five or six cationic neighbors.

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Crystal structure of the high-pressure modification of NdTaO4

Cited by 35 publications

References 4 publications

Compression of scheelite-type SrMoO4 under quasi-hydrostatic conditions: Redefining the high-pressure structural sequence

Compression of scheelite-type SrMoO4 under quasi-hydrostatic conditions: Redefining the high-pressure structural sequence

Theoretical study of theYLiF4phase transitions under pressure

About Lanthanoid Fluoride Selenide Oxoselenotantalates with the Composition Ln₃F₂Se₂TaO₄ (Ln = La – Nd)

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Crystal structure of the high-pressure modification of NdTaO4

Cited by 35 publications

References 4 publications

Compression of scheelite-type SrMoO4 under quasi-hydrostatic conditions: Redefining the high-pressure structural sequence

Compression of scheelite-type SrMoO4 under quasi-hydrostatic conditions: Redefining the high-pressure structural sequence

Theoretical study of theYLiF4phase transitions under pressure

About Lanthanoid Fluoride Selenide Oxoselenotantalates with the Composition Ln3F2Se2TaO4 (Ln = La – Nd)

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Resources

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About Lanthanoid Fluoride Selenide Oxoselenotantalates with the Composition Ln₃F₂Se₂TaO₄ (Ln = La – Nd)