Fast divalent ion conduction in Ba++, Cd++ and Sr++ beta″ aluminas

Dunn, Bruce; Farrington, G. C.

doi:10.1016/0025-5408(80)90196-8

Cited by 103 publications

(27 citation statements)

References 7 publications

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“…This paper reports one of a series of studies in which divalent cations of different radii and electronic configurations have been introduced into the spinel host lattice of fl"-alumina. The ionic conductivity of Ca 2+ fl"-alumina has been reported by Dunn & Farrington (1980), and found to be quite similar to that of Ba 2÷, Sr 2÷ and Cd 2÷ fl"-alumina. The purpose here is to determine the detailed distribution of Ca 2÷ ions in the conduction plane of Ca 2÷ fl"-alumina.…”

supporting

confidence: 64%

The Ca2+ distribution in Ca2+ β''-alumina

Aldén¹,

Farrington²

1984

Acta Crystallogr C

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supporting

confidence: 64%

The Ca2+ distribution in Ca2+ β''-alumina

Aldén¹,

Farrington²

1984

Acta Crystallogr C

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“…The electronic conductivities of both the NTCDA-bayerite and "pure" bayerite powders were measured to be approximately 10 -6 S.cm -1 showing that the paramagnetic species does not influence the conduction of bayerite and thus the conduction must occur through ion motion 55 . The electronic reflectance UV-VIS spectra of NTCDA and NTCDA-bayerite composite are shown in Figure 6.…”

Section: Ntcda-bayerite Powder Characterizationmentioning

confidence: 99%

Synthesis and properties of new paramagnetic hybrid bayerite from Al(0)/naphthalene dianhydride reaction

et al. 2010

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The reaction of Naphthalene 1,4,5,8-dianhydride (NTCDA) with elemental aluminum(0) powder is studied in an aqueous alcoholic KOH mixture to search for the NTCDA anion and dianion electron-adducts. After analyzing various reaction conditions it was found that the reaction yielded a greenish precipitate in 3:1 (v:v) ethanol:water mixture. This powder is composed mainly of aluminum trihydroxide crystallites of bayerite [a-Al(OH 3 ) (s) ] and the organic content is approximately 6%. This hybrid material proved to be paramagnetic even after exposure to air for one year and at temperatures up to 200 °C. Typical carbonylic bound to metal IR bands and reflectance UV-VIS spectra demonstrate the entrapment of NTCDA radical anion into the aluminum trihydroxide, hence rendering its green color and a paramagnetic behavior. Thus, besides the understanding of an aluminum reaction in suspension, the entrapment of an organic material (NTCDA) that stays stable as the corresponding radical can provide an interesting option for the synthesis of aluminum trihydroxide composites.

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“…In the present study, single crystals of Sr 2+ fl"-alumina have been prepared by ion exchange from Na + ff'-alumina crystals. The ionic conductivity of Sr 2+ ff'-alumina has been reported by Dunn & Farrington (1980). It was found to resemble closely the conductivity behaviour of Ba 2+, Ca 2+ and Cd 2+ ff'-aluminas.…”

mentioning

confidence: 54%

The Sr2+ β''-alumina

Aldén¹,

Thomas²,

Farrington³

1985

Acta Crystallogr C

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pathways with maxima at sites 6(c) and 9(d) (R3m notation). Best least-squares fit for Sr 2+ ions following noncentrosymmetric space group R3m; occupations of successive 6(c), 9(d), 6(c), ... sites in approximate ratios 1"1:0.65, respectively. Sr 2+ distribution at 6(c) sites is fitted to a vibrational model involving third-rank cumulants (~'ijk's). Column oxygen 0(5) occupies a 3(b) site. The refined x value in the structural formula is 0-87 (2), indicating a 37% substitution of Al (2)by Mg. The centrosymmetric spinel-block framework is retained from Na ÷/?"-alumina.Introduction. In the present study, single crystals of Sr 2+ fl"-alumina have been prepared by ion exchange from Na + ff'-alumina crystals. The ionic conductivity of Sr 2+ ff'-alumina has been reported by Dunn & Farrington (1980). It was found to resemble closely the conductivity behaviour of Ba 2+, Ca 2+ and Cd 2+ ff'-aluminas. The mean ionic distributions and shortrange order are found to be significantly different, for example, in Ba z+ /?"-alumina (Thomas, Ald6n, McIntyre & Farrington, 1984) and Ca z+ ff'-alumina (Ald+n, . The purpose here is to determine the detailed distribution of Sr 2+ ions in the conduction plane of Sr 2+ /?"-alumina, as part of a project aimed at understanding the ionic-conductivity mechanism for divalent ions in/?"-alumina. The SrZ+-ion radius (1.18 A) is intermediate between that for Ca 2+ (1.00/k) and Ba 1+ (1.35/k) (Shannon, 1976).Experimental. Single crystals of Sr 2+ fl"-alumina were prepared by ion exchange from Na + fl"-alumina crystals grown at 1963-1998 K. The exchange was performed in a Sr(NOa)2:SrC12 melt (mol ratio 47:53) at 823 K for 24 h. The remaining Na + content was shown to be <0.1%, using a 22Na radioactive isotopic form of Na + fl"-alumina to monitor the exchange (Farrington & Dunn, 1982). Intensity measurements made on a triangular platelet with well defined faces (max./min. dimensions: 0.130/ 0.048 mm respectively). Intensity data recorded using a Nonius CAD-4 automatic diffractometer, controlled by a PDP8/A computer. Integrated intensities of-h+k+l = 3n reflections measured using an 09-20 step-scan technique, 50 steps. Total of 2392 reflections of type +h,k,l measured out to sin0/2 = 0-950/k -~. Instrumental stability and crystal setting checked by monitoring the intensities of three test reflections: no significant variation throughout the data collection. The crystal could be confirmed through its systematic absences (-h+k+l 4: 3n in the hexagonal cell) to retain the R3m space-group symmetry of Na + fl"-alumina. Cell parameters determined from a least-squares fit of 25 0 angles in the range 0-20 ° measured on the diffractometer for the same crystal as was used for the data collection. Intensity data corrected for background, Lp and absorption effects (assuming composition removed, leaving 1874 for the refinements. A crude picture of the Sr 2+ distribution in the conduction plane was obtained following a refinement of the scale factor, using the positions of the Al(Mg) and O atoms taken from the ...

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Fast divalent ion conduction in Ba++, Cd++ and Sr++ beta″ aluminas

Cited by 103 publications

References 7 publications

The Ca2+ distribution in Ca2+ β''-alumina

The Ca2+ distribution in Ca2+ β''-alumina

Synthesis and properties of new paramagnetic hybrid bayerite from Al(0)/naphthalene dianhydride reaction

The Sr2+ β''-alumina

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