Solid state synthesis and structural refinement of polycrystalline La𝑥Ca1-𝑥TiO3 ceramic powder

[摘要] Perovskite structure based ceramic precursors have a characteristic property of substitution in the ``A" site of the ABO₃ structure. This makes them a potential material for nuclear waste management in synthetic rock (SYNROC) technology. In order to simulate the mechanism of rare earth fixation in perovskite, La_ð‘�? Ca_{1-ð‘�?}TiO₃ (where ð‘�? = 0.05) has been synthesized through ceramic route by taking calculated quantities of oxides of Ca, Ti and La as starting materials. Solid state synthesis has been carried out by repeated pelletizing and sintering the finely powdered oxide mixture in a muffle furnace at 1050°C. The ceramic phase has been characterized by its powder diffraction pattern. Step analysis data has been used to determine the structure of solid solution of lanthanum substituted calcium titanate. The SEM and EDAX analyses also confirm that the CaTiO₃ can act as a host for lanthanum. X-ray data has been interpreted using CRYSFIRE and POWDERCELL softwares. The â„�?, ð‘�?, 𝑙values for different lattice planes have been generated from the experimental data. The lanthanum substituted perovskite crystallizes in orthorhombic symmetry with space group ð‘�? ð‘�?? ð‘�? ð‘�? (#62). Following unit cell parameters have been calculated: ð‘�? = 5.410, ð‘�? = 7.631, ð‘�? = 5.382. The calculated and observed values of corresponding intensities, 2𝜃, and density show good agreement. GSAS based calculation for bond distances Tiâ€�?�O, Caâ€�?�O, Laâ€�?�O and bond angles Tiâ€�?�Oâ€�?�Ca, Caâ€�?�Oâ€�?�Ca, Laâ€�?�Oâ€�?�Ti have been reported.

[学科分类] 材料工程

[关键词] Ceramic;La;Ca;titanate;GSAS;rietveld analysis;XRD;EDAX;SEM.