Barium titanate powder synthesis

J Synthesis and Modification of Submicron Barium Titanate Powders... 

Blanco-Lopez, M.C., Rand, B., and Riley, RL., J. Ear. Ceram. Soc., 17, 281,1997. Lu, S., Lee, B.I., and Wang, Z., Synthesis of redispersible nano-sized barium titanate powders by hydrothermal method, in Ceramic Transactions, vol. 106, Dielectric Materials Devices, edited by K.M. Narr and A.R. Bhalla, American Ceramic Society, Westerville, OH, 2000. 

Phule, D. P., and Risbud, S. H., Sol-gel synthesis of barium titanate powders using barium acetate and titanium(IV) isopropoxide, Adv. Ceram. Mat., 3, 183 (1988). 

Chien, A.T., Speck, J.S., Lange, F.F., Daykin, A.C., Levi, C.G. Low temperature/low pressure hydrothermal synthesis of barium titanate powder and heteroepitaxial thin films. J. Mater. Res. 10, 1784-1789 (1995)... 

Ragulya, A.V., Vasyl kiv, O.O., Skorokhod, V.V. Synthesis and sintermg of nanociystaUine barium titanate powder under non-isothermtd conditions I. Control of dispersity of barium titanate during its synthesis from btirium tittmyl-oxtdate. Powder Metall. Metal Ceram. 36(3/4), 170-175 (1997)... 

Ragulya, A.V. Rate-controlled synthesis tmd sintering of nanocrystaUme barium titanate powder. Nanostruct. Mater. 10,349-355 (1998)... 

Synthesis of barium titanate powders by aerosol pyrolysis of a Pechini-type precursor solution./. Mater. Chem.,... 

K. Osseo-Asare, F. J. Arriagada, and J. H. Adair, "Solubility Relationships in the Coprecipitation Synthesis of Barium Titanate Heterogeneous Equihbria in the Ba—Ti—C2O4—H2O System," in G. L. Messing, E. R. Fuller, Jr., and Hans Hausin, eds.. Ceramic Powder Science Vol. 2,1987, pp. 47-53. 

The most significant commercial product is barium titanate, BaTiO, used to produce the ceramic capacitors found in almost all electronic products. As electronic circuitry has been rniniaturized, demand has increased for capacitors that can store a high amount of charge in a relatively small volume. This demand led to the development of highly efficient multilayer ceramic capacitors. In these devices, several layers of ceramic, from 25—50 ]lni in thickness, are separated by even thinner layers of electrode metal. Each layer must be dense, free of pin-holes and flaws, and ideally consist of several uniform grains of fired ceramic. Manufacturers are trying to reduce the layer thickness to 10—12 ]lni. Conventionally prepared ceramic powders cannot meet the rigorous demands of these appHcations, therefore an emphasis has been placed on production of advanced powders by hydrothermal synthesis and other methods. 

Barium titanate and BaTi03-based materials are most commonly used for ceramic capacitors with high dielectric permittivity. BaTi03 powder of extremely high quality (in respect of its purity, stoichiometry, particles morphology) is required for most of the modem applications. This characteristic may be considerably improved by the application of alkoxide precursors. Thus, it is of no surprise that synthesis of BaTi03 and BaTi03-based materials from metal alkoxides attracted considerable attention for several decades. The first works on... 

With the exceptions of quartz and emerald, the typical crystals grown hydrothermally are small. There is no inherent reason for this. Hydrothermal synthesis of fine powders of barium titanate and similar dielectric materials is of importance in capacitor manufacture. 

Synthesis and Dispersion of Barium Titanate and Related Ceramic Powders... 

The information about nanocrystalline ferroic powders fabricated by various chemical synthesis technologies is reported in Table 5.2. Their possible applications are also listed. Powders of the same ferroics for two different applications might be obtained by different techniques since the requirements of size distribution, morphology, agglomeration and impurity composition are determined by different technological conditions. For example, barium titanate is a dielectric with high dielectric constant and it is widely used in multilayer ceramic capacitors, whereas semiconducting properties of rare-earth doped BaTiOs are important for thermistors. 

Barium titanate. The continuous miniaturization of integrated electronic devices forces to manufacture active and passive components of smaller size, including multilayer capacitors (MLCCs) [285,286]. This accounts for a significant breakthrough in the synthesis of ultrafine BaTiOs powders in recent years [287]. 

The maximum specific surface of barium titanate corresponds to the heating rates interval 35-60 °C/h. (Table 5.10). Slower or faster heating also yields fine oxide powders, but with coarser particles or stronger agglomerates than those in so called optimal regime. An optimal mode of thermally activated synthesis uses the optimality criterion such as minimum particle size of the final product. 

The hydrolysis of a mixture of metal alkoxides forms a fairly successful route for the synthesis of complex oxide powders (67). However, most metal alkoxides are expensive, and their hydrolysis requires carefully controlled conditions because of their sensitivity to moisture. The controlled hydrolysis of a mixture of salt solutions appears to be more difficult, but its use has been demonstrated by Matijevic (61) for a few systems, including barium titanate and strontium ferrite. 

Frey M.H., Payne D.A. Synthesis and processing of barium titanate ceramics from alkoxide solutions and monolithic gels. Chem. Mater. 1995 7 123-129 Fu X., Qutubuddin S. S)mlhesis of titania-coated sMca nanoparticles using a nonionic water-in-oil microemulsion. Colloids Surf. A 2001 179 65-70 Ganguli D. Sol-emulsion-gel synthesis of ceramic particles. Bull. Mater. Sd. 1999 22 221-226 GanguU D., Chatteijee M. Ceramic Powder Preparation A Handbook. Boston Kluwer Academic Publishers, 1997... 

---