Liancheng Zhao

Structure and Photo-Damage Resistance of Li-Rich LiNbO3 Crystals Co-Doped with Zn2+/Er3+

The pure congruent LiNbO 3 , Er:LiNbO 3 and Zn,Er co-doped Li-rich LiNbO 3 crystals were grown by Czochralski method. The X-ray diffraction method and ultraviolet-visible absorption spectra of the crystals were used to analyze the structure of the crystals. The photo-damage ability resistance of the crystals was measured. The Zn,Er co-doped Li-rich LiNbO 3 crystals show a decrease in lattice constant values, a shift in absorption edge of ultraviolet-visible absorption spectra towards shorter wavelength, and three orders of magnitude increase in photo-damage resistance compared to congruent LiNbO 3 crystal. The intrinsic and extrinsic defects are discussed to explain the enhance of the photo-damage ability resistance.

Preparation, morphology, and mechanical properties of modified-PU/UPR graft-IPN nanocomposites with BaTiO3 fiber

Abstract Acrylate-modified polyurethane (PU) resin was used and then interpenetrated with unsaturated polyester resin (UPR), to form interpenetrating polymer networks (IPNs) and gradient IPNs cured at room temperature. The polymerization processes were traced through IR techniques, through which the phase separation in systems could be controlled effectively. Results of the morphology and miscibility of the multi-phase materials, obtained by TEM, indicate that the domains in these systems were constricted to the nanometer range. Thermomechanical analyzer (TMA) detection results showed that through interpenetration between networks; the glass transitional temperature ranges of systems can be linked up apparently. Mechanical characteristics showed that the IPNs obtained exhibit different types of characteristics varying from elastomer to brittle plastics. The systems were composited with BaTiO3 fibers and the composite techniques were determined. Also, the morphology and mechanical properties were discussed in detail.

Materials science communication synthesis of pzt nanocrystalline powder by a modified sol-gel process using zirconium oxynitrate as zirconium source

Abstract Lead zirconate titanate (PZT) nanocrystalline powder with a composition near the morphotropic phase boundary (Zr/Ti = 52/48) was prepared by a modified sol-gel method. Zirconium oxynitrate, tetrabutyl titanate, and lead acetate trihydrate were used as raw materials and ethylene glycol as solvent. The solubility of zirconium oxynitrate in ethylene glycol was improved greatly when tetrabutyl titanate was added stoichiometrically. This route simplified the chemical processing of PZT-based solutions. The formation mechanisms of the sol and the gel were discussed. The mixed precursor was dried at 120 °C and annealed at 450 °C for 2 h. Well-crystallized nanometer size PZT powder was obtained and characterized by differential thermal analysis, thermogravimetric analysis, X-ray diffraction, and transmission electron microscopy.

Effects of rare earth Eu doping on ferroelectric properties of PbZr 0.52 Ti 0.48 O 3 thin films by sol-gel methods

Samples of (100)-oriented PZT thin films with 0-2 at% rare earth Eu dopant (PEZT) were fabricated on (111)Pt/Ti/SiO2/Si substrate by a sol-gel method. Ferroelectric properties such as P-V loop, C-V and I-V characteristics were investigated with RT-66A tester and HP4194 impendence analyzer, respectively. Improved polarization (Pr = 37.5 µC/cm2), the low leakage current (J = 1 × 10-9 A/cm2 at the electric field of 400 mV/m) were obtained in the PZT thin films with 1 at% Eu dopant (denoted as PEZT1), comparing to the pure PZT thin films (Pr=30.4 µC/cm2, J=5×10-9 A/cm2 at me electric field of 400 mV/m). The Rayleigh constant was introduced to clarify the nature of Eu doping effects on the ferroelectric properties of PZT thin films. Up to 1 at% Eu dopant, the Rayleigh constant reaches its highest value, which indicates the minimal intrinsic defects in the PEZT1 lattice. According to the plot of ionic radii vs. % B site occupancy of the added dopants, calculated by Roy et al. [Interg. Ferroelectrics 43 (2002) 373], Eu additive mainly occupied the A site and served as donor dopant. Therefore, it was speculated that the improvement of ferroelectric properties shown in the PEZT1 thin films is due to the minimal intrinsic defects present in the crystal lattice. The deteriorate effects exhibited in the PZT thin films with more than 2% Eu dopant (denoted as PEZT2) was caused by the increased intrinsic defects or the increased concentration of the B site substitution or acceptor dopants. As a demonstration, sharp and symmetric switching peaks were observed in PEZT1 film capacitors, while broadened and asymmetric switching peaks were shown in PEZT2 ones in the C-V curves, compared with pure PZT film capacitors.

Synthesis of Pb1−xEux(Zr0.52Ti0.48)O3 nanopowders by a modified sol–gel process using zirconium oxynitrate source

Abstract Rare earth Eu-doped lead zirconium titanate (PEZT) nanocrystalline powders with a composition near the morphotropic phase boundary (Zr/Ti=52/48) were prepared by a modified sol–gel method. DTA/TG, IR and XRD were used to determine the thermal and phase changes in the formation of PEZT crystalline powders. The maximal doping content of Eu and the effect of Eu3+ cation substitution for Pb2+ cation on the microstructure of PZT were developed with XRD. The grain size of PEZT nanopowders is about 20xa0nm determined by TEM.

Preparation of platinum silicide films by pulsed laser deposition and pulsed laser annealing

The formation of PtSi ultra-thin films prepared by pulsed laser deposition during pulsed laser annealing has been studied. The growth sequence of the Pt2Si and the PtSi phases that evolved as the result of the diffusion reaction in the bilayers was examined by X-ray photoelectron spectroscopy (XPS) and the structure characteristics of PtSi were investigated by XPS. X-ray diffraction (XRD) and atomic force microscopy (AFM). Superb uniformity of PtSi films and smooth PtSi/Si interfaces were obtained by pulsed laser annealing.

Optical damage resistance in Zn:Nd:LiNbO3 laser crystals

Abstract A series of Zn, Nd co-doped LiNbO 3 crystals were grown by Czochralski technique with 0.5xa0mol% of Nd 2 O 3 and with 0, 4.0, and 7.0xa0mol% of ZnO, respectively. Their optical damage resistance was characterized by measurement of the photo-induced birefringence change. The optical damage resistance of Zn (7.0xa0mol%):Nd:LiNbO 3 was much higher than that of Nd:LiNbO 3 . The ultraviolet-visible (UV-Vis) absorption spectra and the infrared (IR) transmission spectra of Nd:Zn:LiNbO 3 crystals were measured and investigated. The defects were discussed in this paper to explain the optical damage resistance in the Zn:Nd:LiNbO 3 crystals.