Order–disorder phase transformations in quaternary pyrochlore oxide system: Investigated by X-ray diffraction, transmission electron microscopy and Raman spectroscopic techniques

Radhakrishnan, A. N.; Rao, P. Prabhakar; Sibi, K.S.; Deepa, M.; Koshy, Peter

doi:10.1016/j.jssc.2009.06.016

Cited by 18 publications

(9 citation statements)

References 33 publications

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“…One of the F 2g modes is caused by the 8a oxygen sublattice vibration, and the other modes are attributed to 48f oxygen sublattice vibrations. 18 As reported before, 16 The full width at half maximum of the Raman active bands of the pyrochlore is significantly decreasing, which indicates coarsening of the structure and growth of the particle size when the powders are annealed at progressively higher temperatures. This corresponds well with the increase in the crystallite size measured by XRD and growth of the particle size observed by TEM.…”

Section: Resultssupporting

confidence: 53%

Glycine–nitrate synthesis of Sr doped La₂Zr₂O₇pyrochlore powder

Orlovskaya

Chen

Miller

et al. 2011

Advances in Applied Ceramics

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Materials with A 2 B 2 O 7 (pyrochlore) structure have received significant attention for their applications as new protonic conductors and materials used in electronic devices. One of the unique synthesis routes for La 2 Zr 2 O 7 (pyrochlore) powders is the glycine-nitrate combustion method, which shows superior properties of the synthesised powder using glycine as a complexing agent. The Sr doped La 2 Zr 2 O 7 powders in pure pyrochlore structure were produced using this approach. Selected characteristics of the synthesised powders, such as crystal structure, lattice parameters, crystallite size, the vibrational properties, the morphology of the particles, along with the specific surface area and particle size, have been investigated. The dependence of some properties on annealing temperatures of the powders has been studied.

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Section: Resultssupporting

confidence: 53%

Glycine–nitrate synthesis of Sr doped La₂Zr₂O₇pyrochlore powder

Orlovskaya

Chen

Miller

et al. 2011

Advances in Applied Ceramics

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“…4). According to the crystal structure of defect uorite and pyrochlore, 27,32 the lattice constant of the defect uorite layer is almost one half that of the pyrochlore unit cell layer as shown by the difference of the (111) spacing. In Fig.…”

Section: Resultsmentioning

confidence: 99%

High conductivity of La₂Zr₂O₇nanofibers by phase control

Liu

Yao

et al. 2014

J. Mater. Chem. A

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“…Recently, we have reported an order-disorder transformation in a quaternary pyrochlore oxide system, Ca 2 Ta 2 O 7 -Y 2 Zr 2 O 7 characterised by powder X-ray diffraction, Raman spectroscopy and TEM studies. 32 In the present study, we have prepared a series of pyrochlore-type solid solutions, (Ca x Gd 1-x ) 2 (Zr 1-x M x ) 2 O 7 (x = 0.1, 0.2, 0.3, 0.4, 0.5 and M = Nb or Ta) and studied their structural as well as electrical properties. In addition to this, lattice thermal expansion studies on this system was performed by high-temperature XRD measurements.…”

Section: Introductionmentioning

confidence: 99%

Influence of disorder-to-order transition on lattice thermal expansion and oxide ion conductivity in (CaxGd1−x)2(Zr1−xMx)2O7 pyrochlore solid solutions

et al. 2011

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The effect of simultaneous substitutions of Ca at A site and Nb or Ta at B site in pyrochlore-type solid solutions: (Ca(x)Gd(1-x))(2)(Zr(1-x)M(x))(2)O(7) (x = 0.1, 0.2, 0.3, 0.4, 0.5 and M = Nb or Ta) were studied by powder X-ray diffraction (XRD), FT NIR Raman spectroscopic techniques and transmission electron microscopy. The solid solutions were prepared by the conventional high-temperature ceramic route. The XRD results and Rietveld analysis revealed that the defect fluorite structure of Gd(2)Zr(2)O(7) progressively changed to a more ordered pyrochlore phase by simultaneous substitutions at A and B sites. Raman spectroscopy reveals the progressive ordering in the anion sublattice with simultaneous doping. High-resolution images and selected-area electron diffraction patterns obtained from TEM confirms the XRD and Raman spectroscopic results. High-temperature XRD studies show that the lattice expansion coefficient in these pyrochlore oxides is of the order of 10(-6) K(-1). Lattice thermal expansion coefficient increases with increase of disorder in pyrochlore oxides, and hence the variation of thermal expansion coefficient with composition is also a good indicator of disordering in pyrochlore-type oxides. The ionic conducting properties of the samples were characterised by impedance spectroscopy, and it was found that Nb-doped compositions show a considerable change in conductivity near the phase boundary of disordered pyrochlore and defect fluorite phases.

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Order–disorder phase transformations in quaternary pyrochlore oxide system: Investigated by X-ray diffraction, transmission electron microscopy and Raman spectroscopic techniques

Cited by 18 publications

References 33 publications

Glycine–nitrate synthesis of Sr doped La₂Zr₂O₇pyrochlore powder

Glycine–nitrate synthesis of Sr doped La₂Zr₂O₇pyrochlore powder

High conductivity of La₂Zr₂O₇nanofibers by phase control

Influence of disorder-to-order transition on lattice thermal expansion and oxide ion conductivity in (CaxGd1−x)2(Zr1−xMx)2O7 pyrochlore solid solutions

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Order–disorder phase transformations in quaternary pyrochlore oxide system: Investigated by X-ray diffraction, transmission electron microscopy and Raman spectroscopic techniques

Cited by 18 publications

References 33 publications

Glycine–nitrate synthesis of Sr doped La2Zr2O7pyrochlore powder

Glycine–nitrate synthesis of Sr doped La2Zr2O7pyrochlore powder

High conductivity of La2Zr2O7nanofibers by phase control

Influence of disorder-to-order transition on lattice thermal expansion and oxide ion conductivity in (CaxGd1−x)2(Zr1−xMx)2O7 pyrochlore solid solutions

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Glycine–nitrate synthesis of Sr doped La₂Zr₂O₇pyrochlore powder

Glycine–nitrate synthesis of Sr doped La₂Zr₂O₇pyrochlore powder

High conductivity of La₂Zr₂O₇nanofibers by phase control