Characteristics and Formation Mechanism of BaTiO3 Powders Prepared by Twin-Fluid and Ultrasonic Spray-Pyrolysis Methods

Authors


  • P. K. Gallagher–contributing editor

  • Supported by the Ministry of Science and Technology of Serbia through the project “Synthesis, Designing of Structures and Properties of Monolith and Composite Materials” and Yugoslavia-United States scientific and technological cooperation (NIST, Grant No. JF 928-71).

Abstract

Spherical fine (micrometer and submicrometer in size) homogeneous BaTiO3 powders were synthesized from ethanol: water solutions of BaCl2 and TiCl4 using the spray-pyrolysis technique. Two different atomizers—twin-fluid and ultrasonic, with a resonant frequency of 2.5 × 106 Hz—were used for mist generation. Hollow spherical particles containing a certain amount of unreacted BaCl2 phase and having a mean particle diameter of 2.5 μm were obtained at 1173 K using a twin-fluid atomizing system. Decomposition of precursors and their transition to the cubic BaTiO3 phase occurred, even at 973 K in the case of the ultrasonic atomizing system. For the initial droplet size of 2.2 μm and residence time of ∼60 s, spherical BaTiO3 particles with the mean particle diameter of 0.53 μm were obtained. A BaTiO3 formation mechanism has been proposed as a reaction between TiO2 and BaCl2 rather than a reaction of oxides.

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