Twinning structure of LaGaO3 grown by the Czochralski method

Fink‐Finowicki, J.; Berkowski, M.; Pajączkowska, A.

doi:10.1007/bf02403651

Cited by 20 publications

(18 citation statements)

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“…For this material the lowest density of twins is observed in single crystals grown on (101) and (100) oriented seeds [5,6]. In each of the crystal growth processes, regardless of the crystal orientation, the very important factors deciding on the low twins density are: (i) good quality of the seed, (ii) low temperature gradients above the melt surface and (iii) the good beginning of crystal growth [5], in which the growth process starts only at the original seed material (after melting of the outer parts of the seed, occurring just below the melt surface, and without crystallization on rapidly growing region at the seed center).…”

Section: Experiments and Resultsmentioning

confidence: 90%

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Defects in Detwinned LaGaO₃Substrates

et al. 1997

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Single crystals of lanthanum gallate would be the suitable substrate for YBaCuO films except for the phase transition and the tendency to twinning existing in this material. However, by appropriate choice of growth conditions in the Czochralski method, it is possible to grow single crystal of LaGaO3 with low density of twin boundaries. Special stress and temperature treatment can then be applied to such materials to remove majority of existing twins. The substrates were examined by X-ray topography before and after detwinning and the surface was scanned with a profilometer.

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Section: Experiments and Resultsmentioning

confidence: 90%

“…It is well known that, under a stress applied along specific crystallographic directions, at temperatures near the phase transition, the twin boundaries can be moved leading to a single-domain crystal. We tested this procedure for LaGaO3 [5].…”

Section: Experiments and Resultsmentioning

confidence: 99%

Defects in Detwinned LaGaO₃Substrates

et al. 1997

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“…Ferroic domain structures have been investigated in a large number of chemical compositions with the structure of the GdFeO 3 type: natural and synthetic CaTiO 3 crystals [12,[25][26][27][28], (Mg,Fe)SiO 3 [14,26], CaGeO 3 , MnGeO 3 , SmAlO 3 [14], LaGaO 3 [29][30][31][32][33][34], NdGaO 3 [8,35].…”

Section: Introductionmentioning

confidence: 99%

“…Experimental techniques were optical microscopy [8,25,31,33,35], X-ray diffraction [8,25,30,33,35], high-resolution electron microscopy and selected--area electron diffraction [14,[26][27][28]. X-ray topography [29,32,34] allowed to find the orientation of domain states or the composition planes between domains.…”

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confidence: 99%

Symmetry Pattern and Domain Wall Structure in GdFeO₃Perovskite Type

2010

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Symmetry relations between the domain states in GdFeO 3 type crystals have been obtained using group--theoretical analysis for prototype and ferroelastic space groups. Models for possible domain pairs are developed. The ion locations on the domain boundary were estimated as intermediate positions between the sites in crystal structure of neighboring domain states. It is shown that the crystalline structure of the boundary approaches to the prototype phase structure -the ideal ABO 3 perovskite-type structure, however certain deformations remain. In addition to the shifts of the all ions the tilts of oxygen octahedra of the some type and related displacements of A ions should take place during the switching of orientation states. The tilts of octahedra and displacements of A ions are sufficient to form translation states (antiphase domains). Antiphase domains can have boundaries between themselves basically along the three faces of the orthorhombic cell.

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“…Usually one notes a negative influence of this fact on critical parameters of synthesized HTSC films [1]. Majority of works [2][3][4][5][6][7] dealing with twinning problem in these substrate materials is focused on experimental determination of the twin states' orientation only. This work is devoted to theoretical investigation of twinning in NdGaO 3 that has a rhombic structure and is one of the most perspective substrate materials.…”

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Orientation States in Rhombic NdGaO₃

Savytskii¹,

Ubizskii²,

Vasylechko³

et al. 1997

Acta Phys. Pol. A

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The ferroelastic domain structure of NdGaO 3 is analyzed by three theories: group symmetry, tensor method and twinning by pseudosymmetry. The theories provide a coherent description of domain pairs and a determination of the position of W and S walls.PACS numbers: 62.20. Dc, 61.72.Mm Wide use of the rare-earth orthogallate and orthoaluminate single crystals as the substrate materials for HTSC fllms attracts considerable interest to the study of their crystal and twinning structure. Ability to twinning is due to result of small lattice deviation of ideal cubic structure. Usually one notes a negative influence of this fact on critical parameters of synthesized HTSC films [1]. Majority of works [2][3][4][5][6][7] dealing with twinning problem in these substrate materials is focused on experimental determination of the twin states' orientation only. This work is devoted to theoretical investigation of twinning in NdGaO 3 that has a rhombic structure and is one of the most perspective substrate materials.Neodymium gallate has a rhombic cell (space group Pbnm) with parameters a = 0.54276 nm, b = 0.54979 nm, c = 0.77078 nm [6] at the room temperature. Its crystal structure as that of most stoichiometric compounds of the ΑΒΧ3 composition can be also considered as a small deformation of an ideal cubic (prototypic) perovskite cell (point group G = m3m) which transforms into monoclinic one with parameters a = b = 0.3863 nm, c = 0.3854 nm and a = 89.26°. This pseudoperovskite monoclinic cell with a = b has a symmetry of point group F = mmm. Relation between parameters of rhombic and pseudoperovskite monoclinic cells (see Fig. 1) can be written in the form According to the paper [8] the symmetry reducing of point group from G = m3m (order n = 48) to F = mmi m (order n = 8) can cause the appearing of a low-symmetric (ferroelastic) phase of the n G /nF = 6 different twin orientation states (ferroelastic domains) with the same crystal structures but of another lattice space orientation.Let us assume that the axes orientation of ferroelastic domain D1 is the same as shown in Fig. 1. Further calculations will be carried out in chosen geometry.The point group of the NdGaO3 rhombic phase for monodomain D1 is F = mmm (231)

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Twinning structure of LaGaO3 grown by the Czochralski method

Cited by 20 publications

References 11 publications

Defects in Detwinned LaGaO₃Substrates

Defects in Detwinned LaGaO₃Substrates

Symmetry Pattern and Domain Wall Structure in GdFeO₃Perovskite Type

Orientation States in Rhombic NdGaO₃

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Twinning structure of LaGaO3 grown by the Czochralski method

Cited by 20 publications

References 11 publications

Defects in Detwinned LaGaO3Substrates

Defects in Detwinned LaGaO3Substrates

Symmetry Pattern and Domain Wall Structure in GdFeO3Perovskite Type

Orientation States in Rhombic NdGaO3

Contact Info

Product

Resources

About

Defects in Detwinned LaGaO₃Substrates

Defects in Detwinned LaGaO₃Substrates

Symmetry Pattern and Domain Wall Structure in GdFeO₃Perovskite Type

Orientation States in Rhombic NdGaO₃