• Kandalam V Ramanujachary

      Articles written in Bulletin of Materials Science

    • (La2/5Ba2/5Ca1/5)(Mn(2/5)–𝑥Ni𝑥Ti3/5)O3: Rietveld studies, dielectric and magnetic properties of new perovskite-related oxides

      Pika Jha Saroj L Samal Kandalam V Ramanujachary Samuel E Lofland Ashok K Ganguli

      More Details Abstract Fulltext PDF

      Oxides of the type (La2/5Ba2/5Ca1/5)(Mn(2/5)–𝑥Ni𝑥Ti3/5)O3 (0 ≤ 𝑥 ≤ 0.4) have been synthesized by the ceramic route. All the above oxides have been found to crystallize in the cubic perovskite structure. Rietveld refinement of the Ni-based oxide, (La2/5Ba2/5Ca1/5)(Ni2/5Ti3/5)O3 gave rise to a composition (La0.44Ba0.38Ca0.18) (Ni0.42Ti0.58)O2.85(6) and the refined lattice parameter obtained was 3.9411(2) Å (space group 𝑃𝑚$\bar{3}$𝑚; 𝑅(𝐹2) = 0.026, 𝑅p = 0.074, 𝑤𝑅p = 0.087). A shift from antiferromagnetic to paramagnetic behaviour is observed with increase in nickel concentration, the Mn-rich phases showing antiferromagnetism around 5 K. There is a systematic decrease in the dielectric constant, 𝜀 and loss tangent with increase in Ni concentration (from 𝜀 = 592 for 𝑥 = 0 to 𝜀 = 78 for 𝑥 = 0.4).

    • Magnetic and photocatalytic properties of nanocrystalline ZnMn2O4

      Menaka Mohammed Qamar Samuel E Lofland Kandalam V Ramanujachary Ashok K Ganguli

      More Details Abstract Fulltext PDF

      The present study describes the synthesis of ZnMn2O4 nanoparticles with the spinel structure. These oxide nanoparticles are obtained from the decomposition of metal oxalate precursors synthesized by

      the reverse micellar and

      the coprecipitation methods.

      Our studies reveal that the shape, size and morphology of precursors and oxides vary significantly with the method of synthesis. The oxalate precursors prepared from the reverse micellar synthesis method were in the form of rods (micron size), whereas the coprecipitation method led to spherical nanoparticles of size, 40–50 nm. Decomposition of oxalate precursors at low temperature (∼ 450°C) yielded phase pure ZnMn2O4 nanoparticles. The size of the nanoparticles of ZnMn2O4 obtained from reverse micellar method is relatively much smaller (20–30 nm) as compared to those made by the co-precipitation (40–50 nm) method. Magnetic studies of nanocrystalline ZnMn2O4 confirm antiferromagnetic ordering in the broad range of ∼ 150 K. The photocatalytic activity of ZnMn2O4 nanoparticles was evaluated using photo-oxidation of methyl orange dye under UV illumination and compared with nanocrystalline TiO2.

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      Chemical Sciences 2020

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