In recent years electronic devices such as multilayer ceramic capacitors (MLCs) are urgently required to be miniaturized to meet the high integration demands of microelectronic devices. High dielectric constant materials with ultra-fine grains are highly needed to achieve a thinner dielectric layer. To manufacture reliable MLCs, agglomerate-free, high crystalline and superfine ceramic particles with high purity are required. Barium titanate (BaTiO3) has good dielectric and ferroelectric properties, and is widely used in MLCs. Although the bulk properties of BaTiO3 ceramics have been widely investigated in the past, more recently, there has been a renewal of interest in nanoscale particles of this material because their electrical properties are strongly dependent upon the grain size and the crystalline structure. Nanocrystalline BaTiO3 particles have been prepared by various wet chemical methods. Among which the hydrothermal method presents some particular advantages such as obtaining high-crystallized powders with narrow grain size distribution and high purity (without heat treatment at high temperature), the yield of a well-defined composition, and a better control of grain size and morphology. In this work, both cubic and tetragonal BaTiO3 nanoparticles (with size of 20 to 100 nm) have been prepared by hydrothermal technique using as-prepared titanium hydroxide and barium hydroxide as starting materials. The microstructure (crystal structure, grain size and distribution, grain morphology, domain structure and microstructural defects) of the tetragonal and cubic phases of nano-sized BaTiO3 particles is examined by XRD, SEM, and (HR)TEM, respectively. The related results will be discussed and presented.
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