High temperature transmission electron microscopy and X-ray diffraction studies of twinning and the phase transition at 145°C in LaGaO3

Wang, Yanbin; Liu, X.; Yao, G.-D.; Liebermann, Robert C.; Dudley, Michael

doi:10.1016/0921-5093(91)90356-r

Cited by 48 publications

(39 citation statements)

References 11 publications

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“…Geller and Wood 1956;Wang et al 1990Wang et al , 1991Wang et al , 1992. Thus an examination of variation of twin-domain morphology with temperature may provide important information on the high-temperature phases of CaTiO3.…”

Section: Introductionmentioning

confidence: 98%

Electron microscopy study of domain structure due to phase transitions in natural perovskite

Wang

Liebermann

1993

Phys Chem Minerals

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Abstract. Transmission electron microscopy on natural calcium metatitanate perovskite (dysanalyte) reveals the following twin laws in the orthorhombic (space group Pbnm) phase: reflection twins on the {110} and {112} planes, and 90 ~ rotation twins about the [001] axis (referred to as [001190o twin). Single crystals that were heattreated and quenched from above 1585 K exhibit a dramatic change in domain structure compared with the starting material and specimens quenched from T <1470 K. Mutually perpendicular {110} and [001190o twins are observed throughout the crystal, forming a cross-hatched domain texture. 1/21001] antiphase domains, which are very rarely observed in the starting material, also become dominant in the crystal. This change in domain structure is interpreted as due to a structural phase transition in perovskite at a temperature below 1585 K. From the point symmetry elements that describe the twin laws and the translational elements that relate the antiphase domains, the most likely phase near 1585 K is tetragonal with space group P4/mbm. These results are consistent with high-temperature powder X-ray diffraction study. On the other hand, density of the {112} twins is increased significantly in the crystal quenched from 1673 K. Twin domains are either bound by mutually perpendicular {110} and (001) walls, or by {112} walls with {110} twin domains within the polygonal {112} domains. Both twin density variation and domain morphology suggest that the crystal may be cubic at this temperature. Microstructure of a single crystal deformed at 1273 K and 3.5 GPa (within the orthorhombic stability field) is morphologically quite distinct from that of the heat-treated specimens. Dislocations dominate the microstructure and often interact with twin domain boundaries.

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Section: Introductionmentioning

confidence: 98%

Electron microscopy study of domain structure due to phase transitions in natural perovskite

Wang

Liebermann

1993

Phys Chem Minerals

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“…The reference data for lanthanum gallate (LaGaO 3 ) of SSM are also listed. The crystal structure of lanthanum gallate-based perovskite oxide is known to be orthorhombic (Pb nm) at room temperature [19]. However, perovskite oxide with cubic structure seems to be stabilized by doping Fe for Ga site.…”

Section: Tablementioning

confidence: 99%

Combustion synthesis of doped LaGaO3 perovskite oxide with Fe

Hsieh

Okinaka

Akiyama

2009

Journal of Alloys and Compounds

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La 0.7 Sr 0.3 Ga 0.7 Mg 0.1 Fe 0.2 O 3−δ (LSGMF73712) has been proposed as a new substitute for solid electrolyte in SOFC (solid oxide fuel cells). It has several merits, such as lower operating temperature of SOFC, high transport number of oxide ion and higher electronic conductivity. In this study, the doped-lanthanum gallium with Fe was produced by combustion synthesis, and the effect of particle sizes on sintering behaviors of La(Sr)Ga(Mg)FeO 3−δ samples by spark plasma sintering (SPS) was analyzed by comparing with the traditional solid-state reaction method.In the experiments of the combustion synthesis, lanthanum oxide, strontium carbonate, metallic gallium, pure iron, metallic magnesium and sodium perchlorate were mixed uniformly and were ignited at one end of the sample under the argon atmosphere to complete the combustion process without any additional energy. Not only could this method shorten the processing time, but also it could minimize the sintering temperature in the production. As a result, the product showed definite peaks of lanthanum gallium in X-ray diffraction (XRD) patterns and the product could be sintered at a lower temperature 1473 K by SPS method, in comparison to a conventional solid-state reaction method. Moreover, the sintering temperature of the products could further decrease in a lower temperature 1273 K after ball-mill treatment.

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“…Further, the details of structural parameters were accurately determined from the powder neutron diffraction of single crystal sample of LaGaO 3 and an orthorhombic to rhombohedral structural transition at 425 K was reported [3]. Later, the crystal structure and phase transition of LaGaO 3 were reported in a large number of articles in the literature [4][5][6][7][8][9][10][11][12]. It has been established that LaGaO 3 has an orthorhombically distorted (Pnma) perovskite structure at ambient conditions and undergoes a first order phase transition to a rhombohedrally distorted (R3c) structure around 150 8C.…”

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confidence: 98%

Structural phase transition in lanthanum gallate as studied by Raman and X‐ray diffraction measurements

Dhak

Pramanik

Bhattacharya

et al. 2011

Physica Status Solidi (b)

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Lanthanum gallate (LaGaO 3 ) is known to undergo orthorhombic to rhombohedral first order phase transition at 150 8C. In this article we have shown that by introducing 2% La deficiency in the system, coexistence of above two phases can be obtained at lower temperature and a complete phase transition occurs at 200 8C. The evolution of structural parameters of the system with temperature is reported from X-ray diffraction measurements and Rietveld analysis of the diffraction patterns. The change in local octahedral distortion due to 2% La deficiency is revealed through the shift in the phonon modes of GaO 6 octahedra, in both orthorhombic and rhombohedral phase.

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High temperature transmission electron microscopy and X-ray diffraction studies of twinning and the phase transition at 145°C in LaGaO3

Cited by 48 publications

References 11 publications

Electron microscopy study of domain structure due to phase transitions in natural perovskite

Electron microscopy study of domain structure due to phase transitions in natural perovskite

Combustion synthesis of doped LaGaO3 perovskite oxide with Fe

Structural phase transition in lanthanum gallate as studied by Raman and X‐ray diffraction measurements

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