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A series of 0–3 composites of lead zirconate titanate (PZT)/ferroelectric odd–odd nylons was prepared with variations in the size of PZT powder and in the dipole density of ferroelectric odd–odd nylons. The as-formed PZT powder prepared by a spray-drying technique consists of spherical granules composed of large numbers of interconnected fine particles. Electrical properties of the composites as a function of the size of this particular PZT powder and the dipole density of ferroelectric odd–odd nylons were studied. With the PZT powder sintered at 1100°C, the relative permittivity, polarization, and piezoelectric strain coefficient (d33) of the PZT/nylon composites increased with increasing powder size of PZT. The electrical properties of the composites also increased as the dipole density of the polymer increased. The PZT/nylon 57 composite exhibited a high-relative permittivity and piezoelectric strain coefficient d33 due to an increase in its dipole density. The optimum relative permittivity and polarization of this composite were obtained by the PZT with an average granule size of 95 μm. The highest piezoelectric strain coefficient d33 of the 0–3 composite was found at 28 pC/N whereas the relative permittivity was approximately 73.

A series of 0-3 composites of lead zirconate titanate (PZT) and nylon77 was prepared with PZT volume fractions between 0.1 and 0.6 using the combined method of solvent casting and hot pressing. Depending upon the volume fraction of PZT, the relative permittivities of the composites were found to be in the range of 200–2000 when measured at the highest practically possible temperature of 200°C. As PZT volume fraction increases, both the relative permittivity and the piezoelectric constant d33 increase. The best combination of electrical properties and flexibility was obtained in 0.5 PZT volume fraction composites. At this composition, the remanent polarization Pr of composites was up to 1000 mC/m2 at the applied electric field of 40 MV/m and it increased with an increase in temperature. The highest piezoelectric strain coefficient d33 was obtained at 17 pC/N in 0.6 PZT volume fraction composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

The effect of isovalent and aliovalent substitutions in Bi 0.5 Na 0.485 La 0.005 TiO 3 (BNLT) compounds were studied within the additive ranges of 0-2.5 at%. The Zr 4+ , Nb 5+ and Fe 3+ ions were selected as the substituents. The modified BNLT compounds were prepared by conventionally mixed-oxide method. The calcination and sintering were performed at the temperatures of 750-850 °C and 1050-1150 °C, respectively. An increase in the substituents contents affected the physical and piezoelectric properties. The BNLT compositions with the addition of 1 at% Zr 4+ , Nb 5+ and Fe 3+ ions exhibited high relative permittivities (e r ) at 730, 735 and 660, respectively. The modified-BNLT with an addition of 1.0 at% Fe provided a piezoelectric coefficient (d 33 ) of 155 pC/N, Curie temperature (T c ) of 320 °C and electromechanical coupling factors in planar (k p ) and thickness (k t ) modes of 15 and 45%, respectively.

It is known that Curie temperature of barium titanate system can be altered by the substitution of dopants into either A- or B-site. Dopants could pinch transition temperature, lower Curie temperature, and raise the rhombohedral-orthorhombic and orthorhombic-tetragonal phase transition close to room temperature. This isovalent substitution could improve the ferroelectric properties of the BaTiO 3 -based system. In this study, barium zirconate titanate Ba(Zr x Ti 1-x )0 3 (BZT; x = 0, 0.02, 0.05 and 0.08) ceramics were prepared by conventionally mixed-oxide method. The ferroelectric properties of BZT ceramics were investigated. Increasing Zr content in the BaTiO 3 -based compositions caused a decrease in Curie temperature (T c ). At T c , the highest relative permittivity of BZT with an addition of 0.08 mol% of Zr was 12,780. The BZT specimens with the additions of 0.05 mol% and 0.08 mol% of Zr presented the remanent polarization at 25 μC/cm 2 and 30 μC/cm 2 , respectively.

With growing concern on health and safety worldwide, a requirement for environmentally benign piezoelectrics are continually increasing. The Bi0.5Na0.5TiO3 (BNT) ceramic is a promising piezoelectric material without the lethal element, Lead.Conventional mixed oxide method generally yields BNT with grains in the micron range. Nanocrystalline materials could be obtained by chemical route but at high expense.Reaction of Bi2Ti4O11 with excessive Na2CO3, has been found to produce nanocrystalline BNT at low temperature. SEM showed recrystallization of BNT. Crystallize size calculation from X-ray diffraction confirmed that the size of the crystals were in nanometer range.