Several experiments were conducted to examine the effects of the molecular weight of polyesters formed by polymerization of citric acid and ethylene glycol on the development of phase formation and agglomerate of Zr-riched lead zirconate titanate Pb (Zr0.95Ti0.05) O3 powders prepared by the Pechini method. Evolvement of the chelation of citric acid and metallic ions was detected by FTIR spectroscopy. Phase behavior and morphology of powders calcined at temperature range of 400 to 800℃ for 2h were studied by powder X-ray diffraction and scanning electron microscopy. The molar ratio of citric acid and ethylene glycol could affect the chelation between carboxylate groups and metallic ions but had no effect on the formation of Pb (Zr0.95Ti0.05) O3. Higher molecule weight of polyester formed from citric acid and ethylene glycol could help the formation of the final crystalline phase and gave soft agglomerate particles of Pb (Zr0.95Ti0.05) O3 powders.

The internal rotation, geometry, energy, vibrational spectra, dipole moments and molecular polarizabilities of poly (vinylidene fluoride) (PVDF) of a- and b-chain models were studied by density functional theory at B3PW91/6-31G (d) level. The effects of chain lengths and monomer inversion defects on the electric properties and vibrational spectra were examined. The results show that the tgtgo conformation angle between g and go is about 55 and the ttt conformation is a slightly distorted all-trans alternating planar zigzag with 175 repeating motif. The average distance between adjacent monomer units in the b-PVDF is 2.567

The hydrogen-free diamond-like carbon (DLC) films are potential materials to be used as infrared anti-reflection protective coatings if their optical absorption can be reduced to get relatively thick films needed. In this study, hydrogen-free DLC films were deposited by the physical vapor deposition (PVD) method in an unbalanced magnetron sputtering (UBMS) system with a rectangle graphite target of 440

Relaxor-based 0.7Pb (Mg1/3Nb2/3) O3-0.3PbTiO3 (PMN-PT) thin films were grown epitaxially on silicon substrates by sol-gel method and PbO cover coat technique, and investigated by x-ray diffraction, auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The phase development and microstrure evolution of the PMN-PT film were significantly affected by the final annealing temperature and time. A perovskite PMN-PT film was obtained after annealing at 850℃ for 1min. Then, highly <100>-oriented and textured PMN-PT films could be achieved by using a LaNiO3 perovskite template.

The complex dielectric response of tungsten bronze Sr1-xBaxNb2O6 (SBN (1-χ)/χ,χ"0.40, 0.50, and 0.60) relaxor ferroelectric ceramics has been carefully studied as a function of temperature between-180 and 450℃. Three distinct relaxation features were observed in all the compositions. The thermal hysteresis of dielectric maximum was considered to be associated with "lock in" of the incommensurate phase. It was confirmed by investigation of the Curie-Weiss behaviour in the higher temperature range. In addition, it was found that the weakness of the dielectric dispersion below the ferroelectric-paraelectric phase transition temperature can be induced by ageing and poling. These results are discussed in terms of the polarization fluctuation and metastability of polar microregions.

Using tetrabutyl titanate, calcium nitrate and copper nitrate, a gel of these compounds was obtained at room temperature which on subsequent heat treatments led to CaCu3Ti4O12 (CCTO) powder at 900 C for 1h. On sintering further at 1060 C for 48 h, the dielectric constant of CCTO ceramics is above 35000 at 1kHz, and it displays a good tune behavior. Impedance spectroscopy on CCTO ceramics demonstrates that they are electrically heterogeneous and consist of semiconducting grains with insulating grain boundaries. The dc bias experiment demonstrates clearly that the grain boundary response is consistent with a Schottky barrier response. Therefore, CCTO ceramics display an internal barrier layer capacitor (IBLC) behavior.

We show clear experimental evidence for two phase transitions in titanium doped lead magnesium niobate compositional disordered ferroelectrics. One is the diffuse phase transition near the temperature of the dielectric permittivity maximum, which is often called the characteristic of relaxor ferroelectrics (relaxors). Another is a first-order transformation from relaxor ferroelectric to normal ferroelectric, corresponding to a zero-field spontaneous polar micro-macrodomain switching. According to X-ray diffraction (XRD) measurements, thermal analysis and transmission electron microscope (TEM) results, a dynamic behavior of polar microregions is necessary to explain the phenomena, which is more similar to a stress induced martensitic transformations form cubically stabilized perovskite parent-phase. It is also observed that the dynamic behavior of polar regions was influenced by the titanium doping.

The dielectric properties of compositional disordered perovskite ferroelectrics (1-χ) Pb(Mg1/3Nb2/3) O3-χPbTiO3 (x=0:00, 0.10, 0.20, 0.40) were investigated as a function of temperature and frequency. The non-Debye relaxation of Pb (Mg1/3Nb2/3) O3 was observed clearly around the temperature of the dielectric permittivity maximum (Tm). The frequency dependence of Tm was analyzed using a generalized Arrhenius relationship ω =ω0 exp [2 (T0/Tm) p]. For relaxors with different compositions, a clear change in dynamic behavior can be indicated by the power parameter p, which is related to the growth of interactions between polar microregions. The degree of dielectric relaxation and degeneration of the compositions from relaxor ferroelectrics to normal ferroelectrics can be explained by the interaction of polar microregions.

The perovskite structure of Pb (Zn1/3Nb2/3)O3 (PZN) ceramics was stabilized by adding a Ti-rich side tetragonal Pb (Zr0.47Ti0.53) O3 (PZT) across the morphotropic phase boundary (MPB). The 0.5 PZN-0.5 PZT specimen was found to have a two-phase zone, having a high piezoelectric coefficient, d33 (430 pC/N), an electromechanical coupling factor, kp (0.67), a field-induced strain, S (0.24% at 2 kV/mm), and a remnant polarization, Pr (27μC/cm2). A phase transition from a rhombohedral to tetragonal phase occurred when a relatively low electrical field was applied to the specimen. This transformation occurred only when the rhombohedral phase coexisted with an equal amount of the tetragonal phase of the perovskite structure. Small rhombohedral domains, which were present around the relatively large tetragonal domains, transformed as a result of the applied field. The excellent electromechanical properties at the MPB composition are attributed to this phase transition in the PZN based ceramics.