Substitution of aluminium by gallium in β-alumina

Brinkhoff, H. C.

doi:10.1016/s0022-3697(74)80145-9

Cited by 13 publications

(4 citation statements)

References 14 publications

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“….Earlier studies performed on the substitution of aluminium by gallium in polycrystalline /3-alumina (Brinkhoff, 1974) show that the unit-cell parameters increase linearly with gallium content, but this increase did not change the Na ÷ ion conductivity. K ÷ ion conductivity, on the other hand, decreased with increasing gallium content.…”

Section: Commentmentioning

confidence: 82%

Potassium β''-aluminogallate

Edström¹

1999

Acta Crystallogr C

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Section: Commentmentioning

confidence: 82%

Potassium β''-aluminogallate

Edström¹

1999

Acta Crystallogr C

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“…In [3-alumina, the unit cell is made of two such blocks and the conduction plane is a symmetry plane for the structure, whereas [Y'-alumina has three blocks, linked by conduction layers which are not mirror planes for the lattice. The unit cell parameters are a regular function of the gallium to aluminium ratio [8,11,12]. As shown in Fig.…”

Section: Structure Descriptionmentioning

confidence: 99%

71Ga,27Al and23Na solid state MAS NMR of β- and β″-aluminogallates

et al. 1993

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Two series of compounds with sodium 13-and [Y'-alumina structure have been studied in which the aluminium is partly replaced by gallium. The level of substitution has been varied from x(Ga/Ga + Al)~ 0.3 to 0.8. The approximately quantitative analysis of aluminium and gallium NMR of these aluminogallates has allowed us to determine a gallium site occupancy for the different values of x. For sodium, several sites have been shown anda correlation between gallium substitution and sodium positioning has been proposed. The structures are affected by the changes in cation size from aluminium to gaUium. The sites occupancy has been determined and allows one to understand the distortions, due to gallium insertion, in the structures.

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“…In 1951, Foster and Stumpf (8) described the extensive isomorphism between the alumina and gallia systems and, in particular, prepared the gallium analogs of sodium and potassium beta-alumina. 1 Fast ion conduction has recently been demonstrated in this material (9)(10)(11), and it is apparent that it has the same highly defective structure as ~-A1208.…”

mentioning

confidence: 96%

“…The importance of the alkali aluminate, fl-A12Os, as a solid electrolyte in secondary batteries and other electrochemical applications is well known (10). The gross features of the ~-A1203 structure that allow the high mobility of the alkali ions are clearly recognized, and detailed mechanisms of the conduction process have been proposed (2)(3)(4)(5)(6)(7).…”

mentioning

confidence: 99%

Flux Growth of the Gallium Analog of Beta ‐ Al2 O 3

Foster

Scardefield

1976

J. Electrochem. Soc.

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The importance of the alkali aluminate, fl-A12Os, as a solid electrolyte in secondary batteries and other electrochemical applications is well known (10). The gross features of the ~-A1203 structure that allow the high mobility of the alkali ions are clearly recognized, and detailed mechanisms of the conduction process have been proposed (2-7). It is recognized that neither Na +, A1 + + +, nor perhaps even oxygen itself is specifically required for the high conduction in this structure, but rather an open, highly defective layer in the lattice is necessary through which an ion species can move with a low activation energy via a vacancy mechanism. In beta-alumina the requisite structure must result in part from charge compensation by Na + and vacancies when the Mg + + of spinel (MgAleO4) is replaced by A1 + + +, but the process is complex and not completely understood.There is a very large number of other crystals with the spinel structure, and the process of fast ion conduction should be common to many of them if the same charge compensating substitutions can be made. In 1951, Foster and Stumpf (8) described the extensive isomorphism between the alumina and gallia systems and, in particular, prepared the gallium analogs of sodium and potassium beta-alumina. 1 Fast ion conduction has recently been demonstrated in this material (9-11), and it is apparent that it has the same highly defective structure as ~-A1208.In spite of the similarities between ~-A12Q and its gallium analog, subtle differences are expected which can be exploited to increase our understanding of this interesting class of materials. For example, because Ga + + + is slightly larger than A1 + + +, the slot width--the distance across the conducting plane--is slightly greater in the gallium analog. This should result in higher conductivity for the gallium compound, especially for the larger alkali ions. The uptake of water in the conduction plane, which has a profound effect on the stability and conductivity of the beta-aluminas (12), is also likely to be quantitatively and perhaps qualitatively different in the gallium analogs. Finally, subtle differences between the A120~-Na20 and Ga203-Na20 systems should make it possible to elucidate features of these complex phase diagrams by providing an alternative system to study.It is desirable to employ high quality monocrystals in a study of the properties of a new material. The present paper describes progress toward producing such crystals of the gallium analog of ~-A1208 by a flux growth method. With growth parameters thus determined, it should also be possible to prepare monocrystalline layers by a liquid-phase epitaxial technique if a suitable substrate can be found. * Electrochemical Society Active Member.

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Substitution of aluminium by gallium in β-alumina

Cited by 13 publications

References 14 publications

Potassium β''-aluminogallate

Potassium β''-aluminogallate

71Ga,27Al and23Na solid state MAS NMR of β- and β″-aluminogallates

Flux Growth of the Gallium Analog of Beta ‐ Al2 O 3

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