Sintering and microstructure of BaTiO₃ nano particles synthesized by molten salt method

In order to establish thinner dielectric layers in thick film electronic components such as MLCC (Multilayer ceramic capacitor), BaTiO₃ nanoparticles have been utilized. However, studies on the synthesis of nanoparticles smaller than 20 nm, the characteristics of the BaTiO₃ powder, and the powder's sintering are lacking. Therefore, this paper aims to synthesize BaTiO₃ particles smaller than 20 nm by using the molten salt method and evaluate the microstructure and dielectric properties by varying the sintering temperature from 750°C to 1200°C. Through the molten salt method and by using KOH-KCI mixed salt, 20 nm BaTiO₃ powder was synthesized at a low temperature of 150°C. Sintering the pellets formed from the synthesized 20 nm BaTiO₃ nano powder led to the observation of an unusual phenomenon where the particles grew to approximate sizes below 850°C where densification progressed. At sintering temperatures above 950°C, particles that expanded into rod shapes were observed and these particles were identified to be unreacted TiO₂ based on the results of the EDX (Energy Dispersive X-ray Spectroscopy) analysis and phase analysis results.