Abstract. Lead-free (K 0.38 Na 0.58 Li 0.04 )(Nb 0.86 Ta 0.10 Sb 0.04 )O 3 (KNLNTS) + x mol% Fe 2 O 3 (x = 0 ~ 1) ceramics were prepared by conventional solid state reaction technique. The effect of Fe 2 O 3 doping on the phase structure, microstructure and electrical properties of KNLNTS ceramics were studied. The addition of Fe 2 O 3 was found to be effective in enhancing densification of KNLNTS ceramics. When x = 0.3, the piezoelectric constant d 33 and planar piezoelectric coupling coefficient k p reached highest while maintaining a relatively high Curie point of 318 o C; d 33 =257 pC/N and k p =52 %, which suggests that the ceramics are promising for electromechanical transducer and actuator applications.
The effects of CaZrO3 substitution on the crystal structure, electric field–induced strain, and piezoelectric properties of Bi0.5(Na0.78K0.22)0.5TiO3 ceramics have been investigated. The CaZrO3 substitution resulted in a transition from ferroelectric tetragonal to pseudocubic symmetry with relaxor characteristics, leading to degradations in the piezoelectric coupling coefficient, electromechanical quality factor, and piezoelectric coefficient d33. However, the electric field–induced strain was significantly enhanced by the CaZrO3-induced phase transition and reached a highest value of Smax/Emax = 617 pm/V when CaZrO3 content reached 3 mol%. The result supports a prediction that a large strain at the ferroelectric–relaxor transition region can be observed when the tolerance factor of the Bi-perovskite is decreased by the substitution of ABO3-type modifiers.
We synthesized a novel photoresponsive monomer, silicon-containing azo monomer with paired mesogens in the side chain, by reacting 3-methacryloxypropylmethyldichlorosilane with 2-[2-(4-cyano-azobenzene-4 0 -oxy)ethylene-oxy]ethyl alcohol, a mesogenic group. Corresponding homopolymer and copolymers with methyl methacrylate were generated via radical polymerization with AIBN as a radical initiator. Investigations of their thermal properties and optical textures confirmed the monomer and the homopolymer have smectic structures. Homo-and copolymer films showed high potential as reversible data recording media via photoinduced alignment of azobenzene groups with irradiation of a linearly or circularly polarized light. Out of all the samples, the copolymer films with high azo dye contents showed the best resolution in the recorded data as well as the fastest response to a pump beam due to large optical birefringence induced in a write-in process. Strong dependence of the stability of the data stored in the films on the glass transition temperature of the polymers was also observed. In addition, high-quality holographic grating patterns were inscribed even on the copolymer film with azo molar content of only 7.0% using a modified two-wave mixing technique. V V C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: [6734][6735][6736][6737][6738][6739][6740][6741][6742][6743][6744][6745] 2008
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