P. S. Qiu

Effect of La content on characterization of PLZT ceramics

Abstract This work has been undertaken with a view to study the effect of lanthanum content on properties of PLZT ceramics. The polycrystalline complex compounds of PLZT with Pb1−xLax(Zr0.40Ti0.60)1−x/4O3, +10% PbO formula were prepared from the nano-size individual oxides powders by hot-pressed process. Transparent PLZT (x/40/60) bulk ceramics with pure tetragonal phase was obtained. The studies of the microstructures, dielectric and ferroelectric properties of the ceramics were carried out. The experiment results showed that when La content increased from 7 to 13 mol.%, the grain size increased from 2 to 7 μm. La content also effects the dielectric property obviously, the dielectric constant increased with La content increasing. Moreover, the ferroelectric properties are sensitive to the variation of La content.

Optical and electrical properties of ZnO nanocrystalline textured films prepared by DC reactive magnetron sputtering

ZnO thin films were deposited by DC reactive magnetron sputtering using a metal zinc target. The crystallinity microstructure and surface morphology of ZnO thin films were investigated by X- ray diffraction (XRD) and scanning electron microscopy (SEM). The composition of ZnO thin film was characterized by XPS. The optical properties of ZnO thin film were obtained by spectroscopy ellipsometry and UV-VIS spectrometry. The optical bandgap was found to be 3.29eV of direct-transition type. The low frequency (1kHz- 100kHz) dielectric properties of ZnO thin film were also discussed. The dielectric constant and dielectric loss at 10kHz are 13.4 and 0.03 respectively.

DIELECTRIC AND PIEZOELECTRIC PROPERTIES OF Mn DOPED (K, Na)0.96Sr0.02NbO3 CERAMICS

ABSTRACT Dense lead free ceramics with composition of (K0.5Na0.5)0.96Sr0.02Nb1-x MnxO3 (x = 0,0.01,0.02,0.03,0.04) were successfully prepared by conventional mixed oxide method, and their dielectric and piezoelectric properties have been investigated. The X-ray diffraction patterns indicated phase transition from peroveskite structure with orthorhombic symmetry to pseudo-tetragonal symmetry with increasing Mn content. Low loss tangent and relative high planar electromechanical coupling factor were obtained at x = 0.02 by the introduction of Sr and Mnion. The main parameters for the composition of x = 0.02 are: ϵ33 T/ϵ0 = 479, d33 = 121 kp = 41%, Qm = 298, tanδ = 1.6%, Tc = 391°C. The rates of resonant frequency variation, αfr, and planar coupling factor variation, αkp, with temperature 80°C are −1.85% and +1.19%, respectively. This material may be suitable for applications in ultrasonic transducers.

EPITAXIAL GROWTH OF PLZT THIN FILM ON SrTiO3 SUBSTRATE BY SPUTTERING METHOD

ABSTRACT PLZT thin films were prepared on SrTiO3 substrate by RF magnetron sputtering method. The electrical measurements were conducted on PLZT films in metal-ferroelectric-semiconductor capacitor configuration (MFS). The PLZT thin films annealed at 650°C showed well-saturated hysteresis loops with remanent polarization and coercive electric field values were 0.3 μ C/cm2 and 36 KV/cm respectively. The relationship between the orientation of thin film and thermal treating condition was discussed. The PLZT thin films with a thickness of 1.5 um were epitaxially grown on SrTiO3 substrate successfully.

Fabrication and characteristics of relaxor ferroelectric PZN-PZT (53/47) thin films by a MOD process

Relaxor ferroelectric (1-x)Pb(Zn1/3Nb2/3)O3 - xPb(Zr0.53Ti0.47)O3 (abbreviated as PZN-PZT (53/47)) (x=0.4-1.0) thin films were prepared by a metallic-organic decomposition (MOD) process on Pt/Ti/SiO2/Si substrates. The influence of PZT (53/47) content on the film phase component has been investigated and analyzed. The ferroelectric and piezoelectric properties of the PZN-PZT(53/47) thin films have been examined and discussed. The lattice spacing d111 of the thin film was found to have a maximum value when the PZT (53/47) content x is about 0.7~0.8; which was attributed to the film lattice distortion. Compared with the pure PZT (53/47) thin film, the 0.2PZN-0.8PZT (53/47) thin film was found to have a much lower coercive electric field (Ec) while the spontaneous and remanent polarization was not decreased obviously. Also a more intensive piezoresponse in micro-area of the 0.2PZN-0.8PZT (53/47)) thin film has been observed by a modified AFM.

Relaxor Ferroelectric 0.2PZN-0.8PZT(53/47) Thick Films Fabricated Using a MOD Process

Crack free peroviskite 0.2PZN-0.8PZT (53/47) thick films up to 6.8 mum were prepared by a metallic-organic decomposition (MOD) process on platinum coated titanium (Pt/Ti) foil substrates by a dipping coating technique. The thick film exhibits a pure perovskite phase structure with dense and uniform microstructure. The dielectric, ferroelectric and piezoelectric properties of the thick film have been examined and discussed. A perfect ferroelectric P-E loop was observed. The efficient piezoelectric coefficient d33,f of the film was estimated by a standard Berlincourt type meter. The measured d33,f value of the 0.2PZN-0.8PZT (53/47) thick film is about 177 pC/N; it is larger than that of the PZT (53/47) thick film examined in the same condition, 98 pC/N. This 0.2PZN-0.8PZT (53/47) thick film promises a good application in the microelectronic devices.

STUDY ON DIELECTRIC AND FERROELECTRIC ANISOTROPY FOR HOT-FORGED PZN-PLZT CERAMICS

ABSTRACT Dielectric and ferroelectric properties of Pb0.88La0.12(Zn1/3Nb2/3)0.3(Zr0.4Ti0.6)0.67O3 ceramics prepared by hot forging method and conventional sintering have been studied. For temperature dependence, the maximum value of dielectric loss measured in the direction perpendicular to the pressing axis was 7 times higher than that measured in the parellel direction and a more broadened dielectric permittivity peak was also observed in the perpendicular direction. Taking into account the fact that no obvious grain orientation was evidenced from the XRD patterns of the compared samples, this anisotropy in dielectric property was attributed to difference in the distribution of stresses and defects in the parallel and perpendicular direction.

Preparation of PZT fine powders for fabricating PZT thick films

Abstract A new process for preparation of PZT fine powder was proposed. By adding acetone and ammonia water to the precursor solution at suitable stages, nanosized powders with minimum agglomeration can be obtained. The effect of these additives on the powder preparation is analyzed according to the principle of the growth dynamics and the agglomeration mechanism of powders. Uniform powders with a perfect perovskite-type PZT phase have been obtained and the size of the powder is in the range of 100–200nm. Pb(Zr.40Ti.60)O3 thick film with 10 μm thickness and excellent properties have been successfully prepared by mixing PZT powders into a PZT sol-gel solution to form a 0/3 ceramic-ceramic composition.