A Vadivel Murugan
Articles written in Bulletin of Materials Science
Volume 29 Issue 1 February 2006 pp 7-9 Nanomaterials
A gel was formed when a aqueous solution of Mg(NO3)2, NbF5 and citric acid in stoichiometric ratio was heated on a water bath. No precipitation was observed at acidic pH and gellation was complete with evaporation of the solvent. This gel on decomposition at 750°C produced nanocrystallites of ternary oxide, Mg4Nb2O9 (M4N2). The phase contents and lattice parameters were studied by powder X-ray diffraction (XRD) at various temperatures. Particle size and morphology were studied by transmission electron spectroscopy (TEM). For comparison, M4N2 powders were also prepared by conventional ceramic route at 900°C.
Volume 29 Issue 3 June 2006 pp 221-223 Ceramics
An aqueous mixture of ammonium oxalate and ammonium hydroxide was used to coprecipitate barium and strontium ions as oxalates and niobium ions as hydroxide under basic conditions. This precursor on calcining at 750°C yielded Sr0.5Ba0.5Nb2O6 phase. This is a much lower temperature than that prepared by traditional solid state method (1000°C) as reported for the formation of Sr0.5Ba0.5Nb2O6 (SBN). Transmission electron microscopic (TEM) investigations revealed that the average particle size was 80 nm for the calcined powders. The room temperature dielectric constant at 1 kHz was found to be 1100. The ferroelectric hysteresis loop parameters of these samples were also studied.
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