• S Ramanathan

      Articles written in Pramana – Journal of Physics

    • SANS investigation on evolution of pore morphology for varying sintering time in porous ceria

      A K Patra S Ramanathan D Sen S Mazumder

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      Precipitates of ceria were synthesized by homogeneous precipitation method using cerium nitrate and hexamethylenetetramine at 80°C. The precipitates were ground to fine particles of average size ∼0.7 μm. Circular disks with 10 mm diameter, 2 and 3 mm thickness were prepared from the green compacts by sintering at 1300° C for three different sintering times. Evolution of the pore structures in these specimens with sintering time was investigated by small-angle neutron scattering (SANS). The results show that the peak of the pore size distribution shifts towards the larger size with increasing sintering time although the extent of porosity decreases. This indicates that finer pores are eliminated from the system at a faster rate than the coarser ones as sintering proceeds and some of the finer pores coalesce to form bigger ones.

    • Effect of heat treatment on pore structure in nanocrystalline NiO: A small angle neutron scattering study

      J Bahadur D Sen S Mazumder S Ramanathan

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      Nanocrystalline nickel oxide powders were calcined at 300, 600 and 900°C and pore structure evolution was followed by small angle neutron scattering (SANS). Pore size distributions at two widely separated size ranges have been revealed. Shrinkage of larger-sized pore with reduction in polydispersity has been observed with increasing heat treatment temperature. The pore structures at various heat treatment temperatures do not scale. This has been attributed to the grain boundary diffusion leading to an asymmetric shrinkage of the pores.

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