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Abstract0.94BaTiO3–(0.06–x)Bi0.5Li0.5TiO3–x Bi0.5Na0.5TiO3 (abbreviated as BT–BLT–BNT with x = 0, 0.015, 0.03, 0.045, 0.06) ceramics were prepared by the traditional ceramic processing route. The structure, dielectric and ferroelectric properties of the samples were investigated by X‐ray diffraction, the temperature dependence of dielectric permittivity, and hysteresis loop measurements. These results showed that all compositions have the perovskite tetragonal phase structure, and the phase‐transition temperature Tc is increasing with increasing x, the Tc is 163 °C for x equal 0.06; and the samples have good ferroelectric properties with lower coercive field and higher remanent polarization. BT–BLT–BNT ceramics prove to be a promising candidate for high‐Tc lead‐free ceramics. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Compositionally graded ferroelectric lead zirconate titanate Pb(Zr1-xTix)O3 (PZT) thin films were grown on Pt/Ti/SiO2/Si substrates by using a sol-gel process. The final structure consists of six layers, up-graded graded films starting from PbZrO3 on the Pt electrode to the top PZT(50) layer, it consists of no Ti, 10%Ti, 20%Ti, 30%Ti, 40%Ti, and 50%Ti respectively. Whereas films with opposite gradient are called down-graded graded films. Structure and dielectric properties of the graded films was investigated by X-ray diffraction, Auger electron spectroscopy and by impedance analysis. The up-graded and down-graded PZT films annealed at 600C, exhibited the remanent polarization values of 18.0 and 24.2 C/cm2, respectively. The typical small signal dielectric constants and loss tan at a frequency of 100 Hz were 523 and 0.018, 544, and 0.020, respectively, for up-graded and down-graded PZT thin films. The temperature dependence of pyroelectric coefficients of the graded PZT films was measured by a dynamic technique. From 20C to 82C, the pyroelectric coefficients of the up-graded and down-graded PZT films up to 374 and 407 C/m2K, respectively.

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Lead-free ceramics with the composition of Mn-doped Ba(Zr0.06Ti0.94)O3 – xmol%MnO2 (BZT6-xMn, x=0, 1 and 2) have been synthesized by a mixed oxide process. Structure and micrograph characterization were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM), which revealed that all samples have the orthorhombic phase with dense and the uniform microstructure. The grain size of Mn-doped BZT6 ceramics decreased with increasing MnO2 doping. The effect of MnO2 doping on the dielectric and ferroelectric properties was also investigated. The maximum dielectric permittivity decreased dramatically with increasing MnO2 doping in the BZT6 ceramics. A peculiar double-hysteresis-like loop was observed. Mn ions as acceptor doping occupy the B site of ABO3 in the form of Mn2+ and Mn3+, which brought an increase in the oxygen vacancies concentration. The defect dipole model was explained the pinning mechanism.

Lead strontium zirconate titanate (Pb0.92Sr0.08)(Zr0.65Ti0.35)O3 (PSZT) thin films were grown on Pt (111)/Ti/SiO2/Si(100) substrates using a simple sol-gel method. X-ray diffraction studies confirmed that all the PSZT films undergone various thermal process show highly preferred (001)-orientation. On the surface image of the thin film, many clusters are found, which are composed by grains in size of 0.5-0.8 mm. Between the clusters, the nano-size grain is about 50-80 nm. The root mean square (RMS) roughness of the film surfaces is 5.1 nm. PSZT thin film exhibit excellent ferroelectric behavior, demonstrated by reproducible hystersis loops with high remnant polarization (Pr =49 μC cm-2) and relative low coercive field (Ec=53.5 kV cm-1). The pyroelectric coefficients (p) were measured, at 26 °C, the p=215 mC m-2 K-1 for PSZT films. The dielectric properties as well as phase transition behavior were characterized and a ferroelectric to paraelectric transition were found in the vicinity of 196 °C.