Xiao Dingquan

Measurement applications based on pyroelectric properties of ferroelectric polymers

Ferroelectric polymers such as polyvinylidene fluoride and vinylidene fluoride-based copolymers can be used in place of single crystals and ceramics in many devices. In addition, their availability as large-surface-area, low-cost, thin, flexible sheets creates many new possibilities. A review is presented of some of the applications of pyroelectric polymers in measurement devices. >

The preparation of PLT thin films by multi-ion-beam reactive co-sputtering (MIBRECS) technique

Abstract Lanthanium-modified lead-titanate (PLT) thin films have been prepared for the first time by recently developed multi-ion-beam reactive co-sputtering (MIBRECS) technique. The preliminary results of the thin film deposition and analyses studied by X-ray diffraction (XRD) and X-ray photoelectronic spectroscopy (XPS) are presented.

Environmentally conscious ferroelectrics research—present and prospect

Abstract In this paper, the concept of Environmentally Conscious Ferroelectrics (abbr. as Ecoferroe-lectrics) is emphasized, the evaluation methodology of the preparation, processing, and applications of ferroelectrics on environmental load is proposed, the present researches on Ecoferroelectrics are outlined, and some aspects of future researches for Ecoferoelectrics are suggested.

Multi-ion-beam reactive co-sputtering (MIBRECS) system and technique for preparing complex oxide thin films

Abstract Co-deposition techniques which allow to control independently the deposition rates of different components during film growth are promising methods for fabricating complex oxide thin films with good quality and ideal stoichiometry. The present work describes a novel multi-ion-beam reactive co-sputtering (MIBRECS) system and related technique, which allows fine control of film stoichiometry and structure. Initial results in preparing lanthanium modified lead titanate (PLT) ferroelectric thin films by using the system are given in a companion paper.

New progresses in deposition processes of metal oxide thin films

Abstract Metal oxide thin films, in particular the multicomponent ones, are being widely used in optoelectronics and other high technological applications. In recent years, several progresses in fabrication of oxide thin films have been made. In this paper, we survey a variety of deposition processes of oxide thin films with emphasis on some new techniques for successful preparation of multi-component ones, illustrate the general trend of the development, and also outline the development of ferroelectric thin films depostion in China.

RESEARCHES ON THE GROWTH BEHAVIOR OF PbTiO3 THIN FILMS AT THEIR INITIAL STAGES

ABSTRACT PbTiO3 thin films were prepared by RF magnetron sputtering with Ar gas, and the average growth rate was measured as 0.185 nm per minute by Scanning Electron Microscopy (SEM) measurement. PbTiO3 extra thin films at their early stages were deposited under same conditions with different deposition time as 1 min, 3 min and 6 min respectively; and the obtained extra thin films were observed by Atom Force Microscopy (AFM). The experimental results show that at their initial stages, PbTiO3 extra thin films grow through the formation and the diffusion of unit cells on the surface and the films grow with island mode. With the deposition time increasing, the size and the height of the islands increase and the number of islands decreases. The analysis of cross-view of the films sputtered for 1 min with AFM indicates that the height of islands is nearly 0.4 nm, and with increasing of the deposition time to 3 min and 6 min, the height of the islands increases with the integral time of the length of the PbTiO3 crystal unit cell. These results confirm further that the films grow through the diffusion of unit cells on the surface with island mode.

THE GROWTH SIMULATION OF ABO3 TYPE EPITAXIAL THIN FILMS

ABSTRACT A modified solid on solid (SOS) model for the simulation of epitaxial growth of ABO3 type thin films through cell-diffusion on the surface developed by using Monte Carlo (MC) method is presented in this paper. Two diffusion active energy parameters were assumed to be 0.6 eV, which is the diffusion potential barrier on the surface, and 0.8 eV, which is the diffusion potential barrier when a basic unit separates from other units. The results show that the ABO3 expitaxial thin films grow with layer by layer mode at the conditions of higher temperature and lower deposition rate. And with the conditions of lower temperature and higher deposition rate, it is the island mode; and even with same growth mode, the morphology pictures of thin films show that the growth process is different. The shape, size and number of islands are not only related to the growth temperature, but also related to the deposition rate. And the compact initial islands are more likely to develop into smooth thin films with layer-by-layer mode.

Synthesis and Piezoelectric Properties of Lead-free （ Bi0.5 Na0.5 ）1-x（BaaSrb）xTiO3 Ceramics

A new group of lead-free piezoelectric ceramics, (Bi0.5Na0.5)1−x(BaaSrb)xTiO3 (abbreviated as BNBST[100x−100a/100b], 0<x<1, a+b=1), was synthesized. The ceramics were prepared by conventional ceramic sintering technique, and the ceramics with density of 95% of the theoretical one can be sintered without the atmosphere control during the sintering process. The results of the X-ray diffraction (XRD) data show that the ceramics possess a single perovskite phase. The measurements of dielectric and piezoelectric properties reveal that the ceramics provide relatively high piezoelectric charge constant d33 and high planar electromechanical coupling factor kp. For the BNBST6-95/5 ceramics, d33 is equal to 170pC/N, and kp is equal to 32.0%. The fabrication technique for these ceramics is conventional and stable.

Photostriction effect of doped LiNbO3 single crystals

Abstract Photostriction effect and its dependence on light intensity were investigated for lithium niobate (LiNbO3) single crystals doped with Fe2O3, MgO and MgO plus TiO2 respectively. The photoinduced strains of the order of 10−4 were measured by using a micro-displacement detector. The results show that the lower the optical damage threshold of the crystal measured, the larger the magnitudes of the photostrains, and that the dynamic properties of the photostrain change rates are analogous to those of the photocurrent generated when the crystals were illuminated. These results indicate that the photostrain of the crystals is due to both the coupling effect of anomalous photovoltaic and piezoelectric effects and rearrangement of the ions following the excitation of photocarriers in crystals.

Synthesis and Characterization of Nano-Calcium Tungstate Thin Film Via Chemical Solution Processing

CaWO 4 thin films were successfully prepared on glass and Si(100) substrates by chemical solution processing (CSP). The thin films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM), respectively. The results indicate that the CaWO 4 thin film crystallize from an inorganic amorphous phase directly at 350°C. The grain size and the surface roughness of the CaWO 4 thin film can be modulated by annealing processing. Microwave radiation method is helpful to improve the microstructure quality and the chemical homogeneity of the as-prepared thin films. The photoluminescence (PL) spectra of the thin film was positioned in a blue shifted region about 414 nm compared with emission at 440 nm of CaWO 4 crystals, which indicated the optical band gap widening phenomena induced by the quantum size effect.