Systematic Structural Change in Selected Rare Earth Oxide Pyrochlores as Determined by Wide-Angle CBED and a Comparison with the Results of Atomistic Computer Simulation

Tabira, Yasunori; Withers, Raymond; Minervini, Licia; Grimes, Robin W.

doi:10.1006/jssc.2000.8712

Cited by 77 publications

(54 citation statements)

References 18 publications

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“…In both systems, the linear decrease in lattice parameter for the pyrochlore phase is found to agree with Vegard's law for cubic systems and is directly related to the change in average ionic radius from La 3+ (1.16 Å ) to Y 3+ (1.019 Å ). This agrees with previously published results based on lattice simulations of disordered pyrochlores [30][31][32][33][34]. The change in the value of the x-coordinate of the 48f position as a function of increasing Y content is more complex and is illustrated for both systems in Fig.…”

Section: Neutron Diffractionsupporting

confidence: 91%

Lanthanum pyrochlores and the effect of yttrium addition in the systems La2−xYxZr2O7 and La2−xYxHf2O7

Whittle

Cranswick

Redfern

et al. 2009

Journal of Solid State Chemistry

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The crystal structures of the compounds La 2Àx Y x Zr 2 O 7 and La 2Àx Y x Hf 2 O 7 with x ¼ 0.0, 0.4, 0.8, 1.2, 1.6, and 2.0 have been studied using neutron powder diffraction and electron microscopy to determine the stability fields of the pyrochlore and fluorite solid solutions. The limits of pyrochlore stability in these solid solutions are found to be close to La 0.8 Y 1.2 Zr 2 O 7 and La 0.4 Y 1.6 Hf 2 O 7 , respectively. In both systems the unit cell parameter is found to vary linearly with Y content across those compositions where the pyrochlore phase is stable, as does the x-coordinate of the oxygen atoms on the 48f (x, 3 8 , 3 8 ) sites. In both systems, linear extrapolations of the pyrochlore data suggest that the disordering is accompanied by a small decrease in the lattice parameter of approximately 0.4%. After the pyrochlore solid solution limit is reached, a sharp change is observed from x$0.41 to 0.375 as the disordered defect fluorite structure is favoured. Electron diffraction patterns illustrate that some short-range order remains in the disordered defect fluorite phases.

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Section: Neutron Diffractionsupporting

confidence: 91%

Lanthanum pyrochlores and the effect of yttrium addition in the systems La2−xYxZr2O7 and La2−xYxHf2O7

Whittle

Cranswick

Redfern

et al. 2009

Journal of Solid State Chemistry

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“…The [7] 0.325 longitudinal and transverse acoustic velocities (along the [100] direction) are estimated with v l = c 11 /ρ and v t = c 44 /ρ, where ρ is the mass density of the material. 31 We can then define the mean sound velocity as:…”

Section: B Elastic Constantsmentioning

confidence: 99%

First-principles study of structural, elastic, and bonding properties of pyrochlores

2005

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Density Functional Theory calculations have been performed to obtain lattice parameters, elastic constants, and electronic properties of ideal pyrochlores with the composition A2B2O7 (where A=La,Y and B=Ti,Sn,Hf, Zr). Some thermal properties are also inferred from the elastic properties. A decrease of the sound velocity (and thus, of the Debye temperature) with the atomic mass of the B ion is observed. Static and dynamical atomic charges are obtained to quantify the degree of covalency/ionicity. A large anomalous contribution to the dynamical charge is observed for Hf, Zr, and specially for Ti. It is attributed to the hybridization between occupied 2p states of oxygen and unoccupied d states of the B cation. The analysis based on Mulliken population and deformation charge integrated in the Voronoi polyhedra indicates that the ionicity of these pyrochlores increases in the order Sn-Ti-Hf-Zr. The charge deformation contour plots support this assignment.PACS numbers: 91.60.Ki

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“…2 [18]. The lattice parameter of LZ is 10.8 Å in Shimamura's experiments and 10.802 Å in Tabira's work [21]. …”

Section: Crystal Structurementioning

confidence: 78%

“…The structure type can be considered as an ordered defect fluorite structure with the trivalent rare earth Ln respectively. Tabira et al determined the x value of La2Zr2O7 using systematic row wideangle convergent beam electron diffraction (CBED) techniques [21]. The results showed that the x value varied systematically with the rare earth ion radius, the larger radius corresponding to the larger x value.…”

Section: Crystal Structurementioning

confidence: 99%

See 1 more Smart Citation

Lanthanum zirconate based thermal barrier coatings: A review

Zhang

Guo

Jung

et al. 2017

Surface and Coatings Technology

192

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This review article summarizes the latest information about the manufacturing techniques of lanthanum zirconate (La2Zr2O7, LZ) powder and La2Zr2O7 based thermal barrier coatings (TBCs). Lanthanum zirconate is a promising candidate material for TBC applications, due to its lower thermal conductivity and higher thermal stability compared to other traditional TBC systems. In this work, the physical, thermal, and mechanical properties of the powder and coatings are evaluated. The durability experiments of the TBCs in various thermal, mechanical, and corrosive conditions is also reviewed. In addition, theoretical studies on the powder and coatings properties are presented. Finally, future research directions of lanthanum zirconate as TBC applications are proposed.

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Systematic Structural Change in Selected Rare Earth Oxide Pyrochlores as Determined by Wide-Angle CBED and a Comparison with the Results of Atomistic Computer Simulation

Cited by 77 publications

References 18 publications

Lanthanum pyrochlores and the effect of yttrium addition in the systems La2−xYxZr2O7 and La2−xYxHf2O7

Lanthanum pyrochlores and the effect of yttrium addition in the systems La2−xYxZr2O7 and La2−xYxHf2O7

First-principles study of structural, elastic, and bonding properties of pyrochlores

Lanthanum zirconate based thermal barrier coatings: A review

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