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Home Material Sciences Nanosize barium titanate powder for new generation of passive electronic components

Nanosize barium titanate powder for new generation of passive electronic components

Description

The miniaturization of the electronic components, in par-ticular the passive components like multilayer ceramic ca-pacitors, is a rapidly developing area of R&D worldwide. The multilayer ceramic capacitor (MLCC) with dielectric formulations based on the ferroelectric compound BaTiO3 already compete with conventional high-capacitance Al- or Ta-electrolytic capacitors. Utilization of nanosized particles and nanostructured bulk ceramics is the most promising way to improve volumetric efficiency that leads to higher capacitance in smaller volumes, i.e. an ongoing miniaturiza-tion process of these components. The nanosized barium titanate powder (particle size of 10-25 nm, specific sur-face area less than 40 m2/g) has been obtained from unstable precursors by the original technology of rate-controlled calcination (RCC).

Innovative Aspect and Main Advantages

The innovative aspect of this technology concerns calcination procedure of doped precursor. The precursor is decomposed under rate-controlled conditions to obtain the doped nanosized barium titanate. Normally the RCC proceeds under non-isothermal conditions with variable heating rate, which is a function of chemical transformation rate. The feedback established between transformation degree and instantaneous temperature is the main innovation and feature of this technique (fig.1).


Fig. 1 The scheme of rate-controlled calcinations.

The RCC calcination regime of heating results in smallest particle sizes of 20-25 nm shown here in Figs. 2, 3.

Areas of Application

Nano BaTiO3 powder and nanograins ceramics is of highest interest for such industrial applications as mul-tilayer capacitors. The segment of market of ceramic multilayer capacitors is around $6 billion. The main customer is the electronics industry covering medical, consumer, telecommunication, computing, automobile, and military etc. The miniaturization of electronic de-vices is actual now: the trends are thinner active layers, better dispersion, and finer dielectric particles; present state-of-the-art product has particles ~ 100 nm and layers of a few microns. Today’s industry uses BaTiO3 powders doped with 10-15% CaZrO3, CaTiO3, Dy2O3, MnO to produce the X7R or Y5V series of dielectric layers. Usually, particle size of both admixed dopants and BaTiO3 is the same, around 100-200 nm. Future trends require much smaller particles ~20 nm, much thinner layers 0.2-0.5 micron to increase markedly the specific capacity. The revolutionary solution is 100 nm thick ceramics requires particles of 10-15 nm in size giving after sintering the grains of 40-50 nm in size i.e. on the edge of ferroelectricity.

Nanoscale barium titanate powder is also attractive for manufacturing of nanocomposites with polymer matrix. These nanocomposites are considered prospective for attenuators, sensors, transformers and other applica-tions.


Fig. 2 Barium titanate particle size distribution after RCC: differential curve (a) and tabulated values (b).


Fig. 3 HRTEM image of as-prepared barium
titanate nanopowder


Fig. 4 The pilot rotary tube furnace for RCC technology

Stage of Development

We designed and assembled the pilot rotary-tube furnace, equipped it by the system of gas and temperature control. This furnace allows transferring the RCC from laboratory to pilot installment due to temperature gradient along the furnace. The projected annual yield of Nanosize barium titanate powder from this furnace is 27-30 t (Fig.4).

Contact Details

Contact person: Andrey V. Ragulya
Frantsevich Institute for Problems in Materials Science of NASU
Departament Nanoceramics and Nanocomposites
Address: Kiev-680, 3, Krzhizhanovsky
Tel: (380-44) 424-7435
Fax: (380-44) 424-2131
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

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