Large Range of Nonstoichiometry in Barium Ortho Aluminate Prepared Through Gel-to-Crystallite Conversion

Nayak, M and Kutty, TRN (1996) Large Range of Nonstoichiometry in Barium Ortho Aluminate Prepared Through Gel-to-Crystallite Conversion. In: Materials Research Bulletin, 31 (2). pp. 227-234.

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Abstract

Nonstoichiometric barium ortho aluminate with the general formula $Ba_{1-x}Al_2O_{4-x}$ (0 < x < 0.56) was synthesized by the thermal decomposition of barium aluminium oxyhydroxide prepared through gel-to-crystallite conversion method. Phase singularity was confirmed by x-ray powder diffraction. The large range of nonstoichiometry is explained in terms of $Ba^{2+}$ vacancies within the corner sharing $AlO_4$ network, whereby the nepheline structure extends into the stuffed tridymite lattice. HREM studies indicated the ordering of point defects leading to the formation of extended defects and stacking faults. The coordination of aluminium remained tetrahedral as revealed by 27 Al MAS NMR. On doping with Eu(II), $Ba_{1-x-y}Eu_yAl_2O_{4-x+y}$ (0.005 < y < 0.05) shows the emission maximum around 500nm, the intensity of which increases with the x-value

Item Type:	Journal Article
Publication:	Materials Research Bulletin
Publisher:	Elsevier
Additional Information:	Copyright of this article belongs to Elsevier.
Keywords:	A. oxides;C. electron microscopy;C.nuclear magnetic resonance (NMR) D. defects;D. luminescence
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	25 Aug 2008
Last Modified:	19 Sep 2010 04:31
URI:	http://eprints.iisc.ac.in/id/eprint/8680

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