The derivative structure of silicate garnets in grandite

Takéuchi, Yoshio; Haga, Nobuhiko; Umizu, Shigetomo; Satô, Gen P.

doi:10.1524/zkri.1982.158.1-2.53

Cited by 56 publications

(28 citation statements)

References 10 publications

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“…To prove the lowering of crystal symmetry it is necessary to investigate a number of indicators: deformation of the unit cell, differences in intensities of re ection that are equivalent in the Laue class m3m, the presence of re ections that are forbidden in the space group Ia3d. These indicators have been found in grandite garnets (Akizuki et al, 1998;Allen and Buseck, 1988;Badar and Akizuki, 1997;Hirai and Nakazawa, 1986;Takéuchi et al, 1982), but not all indicators were revealed in the same crystal.…”

Section: Lowering Of a Crystal Symmetrymentioning

confidence: 80%

“…Ordering was found experimentally by X-ray structural analysis (Takéuchi et al, 1982;Kingma and Downs, 1989;Gali, 1983). However, the origin of this ordering remains to be established.…”

Section: General Remarksmentioning

confidence: 97%

“…Calculating mismatch strains (see below) we took (Allen and Buseck, 1988;Hariya and Kimura, 1978;Murad, 1976;Takéuchi et al, 1982). the differences between values of lattice constants in the neighbouring zones Da/a, as systematic changes of lattice constants; they did not distort the results signi cantly.…”

Section: Calculation Of Lattice Constantsmentioning

confidence: 99%

“…Mechanism 1a has been suggested for grandite garnets many times and there are a lot of experimental data which support this hypothesis (Akizuki, 1984;Akizuki et al, 1998;Allen and Buseck, 1988;Takéuchi et al, 1982). On the other hand, although mechanism 2 has been mentioned in some papers, no systematic studies of grandite garnets are available.…”

Section: Introductionmentioning

confidence: 99%

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On the origin of anomalous birefringence in grandite garnets

et al. 2001

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The origin of anomalous birefringence of grossular-andradite (grandite) garnets from skarns in Mali and Russia was considered. The crystals had complex optical patterns which can be induced by superposition of two phenomena: mismatch compositional strain (stress birefringence) and growth ordering of atoms (growth dissymmetrization). Study of the crystals using several experimental techniques (optical microscopy, microprobe analysis, X-ray diffraction topography and X-ray single crystal diffraction) as well as calculations of anomalous birefringence has confirmed this hypothesis. Depending on the crystal composition and growth conditions, the relative magnitude of each phenomenon controls the various optical effects. As a result one can see two groups of crystals which are found to have fundamentally different anomalous optical properties: crystals with low (<0.001) and high (0.001 0.015) values of birefringence. The spatial distribution of birefringence within each group is different and this fact is related to different mechanisms causing optical anomalies: stress birefringence and growth dissymmetrization for these two groups, respectively.

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Section: Lowering Of a Crystal Symmetrymentioning

confidence: 80%

“…Ordering was found experimentally by X-ray structural analysis (Takéuchi et al, 1982;Kingma and Downs, 1989;Gali, 1983). However, the origin of this ordering remains to be established.…”

Section: General Remarksmentioning

confidence: 97%

Section: Calculation Of Lattice Constantsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the origin of anomalous birefringence in grandite garnets

et al. 2001

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“…Numerous experimental studies of crystals with optical anomalies of this kind revealed complicated optical patterns (sector zoning, sub-sector zoning (Akizuki, 1981;Akizuki et al, 1994)), metastable optical anomalies (Shtukenberg et al, 1998), and distortions of crystal structure resulting in the lowering of its symmetry (Takéuchi et al, 1982). However, the scheme describing the origin of growth dissymmetrization (see above) has not yet been supported quantitatively, and until now could only be considered as a hypothesis.…”

Section: Introductionmentioning

confidence: 99%

Effect of growth conditions on the birefringence of mixed crystals revealed in alum solid solutions

2000

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An experimental study of optical anomalies in solid solutions of alums in relation to their composition, growth temperatures and rates, and hydrodynamic regime was carried out. Theoretical analysis of the data showed that they can be understood in terms of a mechanism of kinetic ordering of the isomorphous atoms (the phenomenon of so-called 'growth dissymmetrization'). A theoretical model is presented which is supported by data for a number of minerals and synthetic compounds, which are known for their optical anomalies due to growth dissymmetrization.

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Optisch anomale Kristalle

Kahr

McBride

1992

Angewandte Chemie

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The derivative structure of silicate garnets in grandite

Cited by 56 publications

References 10 publications

On the origin of anomalous birefringence in grandite garnets

On the origin of anomalous birefringence in grandite garnets

Effect of growth conditions on the birefringence of mixed crystals revealed in alum solid solutions

Optisch anomale Kristalle

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