K C Patil
Articles written in Bulletin of Materials Science
Volume 13 Issue 3 June 1990 pp 179-189
Fine particle fluorescent aluminous oxide materials like Cr3+-doped α-Al2O3 (ruby), MgAl2O4, LaAlO3, Y3Al5O12 and Ce3+-doped Y3Al5O12, LaMgAl11O19, CaAl12O19 and CeMgAl11O19 have been prepared by the combustion of the corresponding metal nitrate-aluminium nitrate-urea/carbohydrazide mixtures at 500°C in less than 5 min. Formation of these Cr3+- and Ce3+-doped aluminous oxides has been confirmed by their characteristic XRD, colour, UV-visible and fluorescence spectra as well as decay time measurements. Ruby (Cr3+/α-Al2O3) powder showed characteristic excitation bands at 406 and 548 nm and emission band at 695 nm with the decay time of 3·6 ms.
Volume 16 Issue 6 December 1993 pp 533-541
Fine-particle ceramic powders such as chromites, manganites, ferrites, cobaltites, aluminas (α-Al2O3, Cr3+/Al2O3, zirconia-toughened alumina, mullite and cordierite), ceria, titania, zirconia (
Volume 17 Issue 6 November 1994 pp 977-987
Oxide materials like perovskite, zirconolite, hollandite, pyrochlore, NASICON and sphene which are used for nuclear waste immobilization have been prepared by a solution combustion process. The process involves the combustion of stoichiometric amount of corresponding metal nitrates and carbohydrazide/tetraformyl trisazine/diformyl hydrazide at 450°C. The combustion products have been characterized using powder X-ray diffraction, infrared spectroscopy, and29Si MAS-NMR. The fine particle nature of the combustion derived powders has been studied using density, particle size, BET surface area measurements and scanning electron microscopy. Sintering of combustion derived powder yields 85–95% dense ceramics in the temperature range 1000°–1300°C.
Volume 17 Issue 6 November 1994 pp 1131-1141
Single crystals of calcium hydrazine carboxylate, monohydrate have been studied by ESR of Mn2+ doped in the calcium sites. X-band ESR indicated a large crystal field splitting necessitating experiments at Q band. The analysis shows two magnetically inequivalent (but chemically equivalent) sites with
One of the principal components of the crystal field, (
Volume 18 Issue 7 November 1995 pp 921-930
Red, blue and green emitting lamp phosphors such as Eu3+ doped Y2O3 (red phosphor), Eu2+ doped Ba0·64Al12O18·64, BaMgAl10O17 and BaMg2Al16O27 (blue phosphors) and Ce0·67Tb0·33MgAl11O19 and Eu2+, Mn2+ doped BaMgAl10O17 (green phosphors) have been prepared by the combustion of the corresponding metal nitrates (oxidizer) and oxalyl dihydrazide/urea/carbohydrazide (fuel) mixtures at 400°–500°C within 5 min. The formation of these phosphors has been confirmed by their characteristic powder X-ray diffraction patterns and fluorescence spectra. The phosphors showed characteristic emission bands at 611 nm (red emission), 430–450 nm (blue emission) and 515–540 nm (green emission). The fine-particle nature of the combustion derived phosphors has been investigated using powder density, particle size and BET surface area measurements.
Volume 42 | Issue 6
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