Pure and La^3+/Nd³⁺ Doped SrTiO₃ Powders Obtained by Solid State Reaction and Microwave Assisted Hydrothermal Synthesis

Abstract:

Strontium titanate ceramic powders (SrTiO₃), pure and doped with lanthanum (La³⁺) and neodymium (Nd³⁺), were synthesized by solid state reaction (SSR) and microwave assisted hydrothermal technique (MHT). For SSR, a mixture of SrCO₃, TiO₂, La₂O₃ and Nd₂O₃ oxides was performed in stoichiometric ratio, to produce SrTiO₃ (STO), Sr_0.96La_0.04TiO₃ (STO-04La), Sr_0.96Nd_0.04TiO₃ (STO - 04Nd) and Sr_0.96La_0.02Nd_0.02TiO₃ (STO-02La02Nd), in a ball mill, for 3.5 h. This mixture was dried at 70°C for 24h. This powder was calcined at 1150°C for 2h in a conventional oven. For MHT synthesis, Ti (C₄H₉O)₄, SrCO₃, La₂O₃ and Nd₂O₃ precursors were solubilized in nitric acid (10M), in stoichiometric proportions to form STO , STO-04La, STO-04Nd and STO-02La02Nd. This solution was precipitated adding NH₄OH (10M). Quota of 2g of precipitated powder was then dried in an air oven at 70°C for 24 hours, and then added to 40 ml of a KOH solution (10M). These suspensions were subjected to MHT for 1h, at 120°C. The ceramic powders obtained by the two routes were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The crystallite size was calculated by Scherrer method and from SEM image, linear intercept method for both the SSR and MHT powders was used to measure the particles size, which show the increase of particles size related to the cation substitution.

• Periodical: Materials Science Forum (Volume 820)
• Pages: 167-171
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.820.167
• Online since: June 2015
• Authors: André Silva Chaves, Olívia de Andrade Raponi, Maria Virginia Gelfuso, Daniel Thomazini
• Keywords: Hydrothermal, Strontium Titanate, Thermoelectric

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