Solid‐State Preparation of BaTiO₃‐Based Dielectrics, Using Ultrafine Raw Materials

Abstract

BaTiO 3 and Ba(Ti,Zr)O 3 dielectric powders have been prepared from submicrometer BaCO 3 , TiO 2 , and ZrO 2 . By use of submicrometer BaCO 3 the intermediate formation of Ba 2 TiO 4 second phase can be widely suppressed. Monophase perovskites of BaTiO 3 were already formed at 900°C and Ba-(Ti,Zr)O 3 at 1050°C. Aggregates of very small subgrains could be easily disintegrated to particle sizes <0.5 m.

Preparation and properties of BaTiO3 ceramics from the fine ceramic powder

“…Moreover, such wet chemical routes cost too much and are not suitable for mass production. Recently, the advent of purer and finer starting materials at a reasonable price promote the solid-state route to synthesize fine BaTiO 3 powder in lower temperature by using fine or nanocrystalline raw materials [3,[12][13][14]. However, it could lower the crystallinity with decreasing the firing temperature.…”

“…However, it could lower the crystallinity with decreasing the firing temperature. On the other hand, it is well believed that for the conventional solid state reaction the morphology and size of BaTiO 3 is primarily determined by the size of the raw materials [11][12][13] and the homogeneity of the mixture [14]. The common solution to the homogeneity problem is just to increase the mixing time but take little effect [15][16][17][18].…”

Synthesis of submicron BaTiO3 particles by modified solid-state reaction method

“…When its grain size in bulk body is 0.6-0.8 m, the properties are generally optimal [3]. Accordingly, one should use BaTiO 3 particles of 100-200 nm as the starting material taking into account the grain growth that occurs during the sintering process [4][5][6]. Conventional solid-state reaction is one of the most commonly used synthetic methods for fabricating pure BaTiO 3 particles; however, it often requires a high calcination temperature to obtain pure BaTiO 3 phase and the final product is usually coarse and seriously agglomerated which fails to satisfy industrial needs.…”

Accelerated formation of barium titanate by solid-state reaction in water vapour atmosphere

“…Recent studies have clearly shown that the reduction of the particle size of the raw materials (BaCO 3 and TiO 2 ) to submicrometer or even to nanoscale results in a significant decrease of the calcination temperatures. [1][2][3] By using the submicrometer BaCO 3 (d 50 = 0.17 μm) and fine TiO 2 (d 50 = 0.2 μm), single phase of BaTiO 3 was almost obtained at 900 °C for 6 h. 1 The formation of BaTiO 3 by solid-state reactions of nanocrystalline BaCO 3 and TiO 2 powders was completed at 700-800 °C. [2][3] In addition, mechanochemical effects are known to be quite effective to reduce the calcination temperatures for solid-state reactions.…”