Guo-Ju Chen

Effects of lanthanum doping on the dielectric properties of Ba(Fe0.5Nb0.5)O3 ceramic

The relaxor type of ferroelectric material Ba(FeNb)1∕2O3, which has a partially disordered perovskite structure, has been characterized and shown a maximum plateau of the dielectric permittivity depending upon the temperature. The dielectric constant at a low frequency is up to 30 000 at room temperature. While the single-phase La-doped Ba(FeNb)1∕2O3, Ba1−xLax(Fe1∕2Nb1∕2)1−x∕4O3(0⩽x⩽0.2) has a monoclinic structure solid solutions up to x⩽0.2, the lattice parameters decrease with an increasing La concentration. The temperature dependence of the dielectric constant of the La-doped Ba(FeNb)1∕2O3 was measured with different La contents, showing that the dielectric permittivity is higher than 105 at an 8mol% La concentration. The present dielectric dispersion was interpreted on the basis of the interfacial polarization at the grain-boundary region.

Synthesis and characterization of zinc titanate doped with magnesium

Zinc titanate crystals doped with magnesium have been grown by conventional solid state reaction technique using metal oxides. It is shown that they are semiconductors. The characteristics of zinc titanate samples were found to depend on the heating conditions and the amounts of additions. Our studies revealed that magnesium can replace the zinc ion and forms a solid solution in the ZnTiO3 phase. The electrical resistivity of (Zn,Mg)TiO3 varied with sintering temperature, and has a minimum when sintered at 900 8C. Increasing amounts of magnesium will also decrease the resistivity. A V-shaped temperature dependence of resistivity was observed. Furthermore, the dielectric constant increased with sintering temperature and decreased with increasing amounts of magnesium. It also shows a maximum Q factor at a frequency of 8 GHz for the sample of (Zn0.9, Mg0.1)TiO3 sintered at 900 8C. q 2003 Elsevier Ltd. All rights reserved.

The structure and properties of zinc titanate doped with strontium

Abstract Doped and undoped zinc titanate powders were prepared by a conventional solid state reaction technique using metal oxides. The characteristics of zinc titanate samples were found to depend on the heating conditions and the amounts of additions. It is shown that they are semiconductors, and the formation of SrTiO3, α-Zn2TiO4, rutile phase, morphology roughness and open porosity increase with increasing the amounts of doped Sr. The electrical resistivities of doped and undoped zinc titanate reveal a transition from semiconductor behavior to metal-like behavior as the temperature increased. All samples represent the V-type resistivity–temperature characteristic and possess the typical PTCR characteristics above room temperature.

Inductive magnetization of low-temperature ordered L10-FePt with CoAg underlayer

The feasibility of controlling film microstructure and nanocomposition of FePt film with various compositions of the CoAg underlayer by ion beam sputtering accompanied by an external magnetic field was performed. The characteristic of phase separation of the CoAg underlayer was employed to induce an inductive magnetism region which reduced the annealing temperature acquired for L10-FePt. The segregation of Co atoms could influence the corresponding magnetic properties of FePt. After annealing at 400°C, the FePt∕CoAg films deposited under the magnetic field showed a larger coercivity (Hc=5kOe) than that of the film deposited without a magnetic field (Hc=0.4kOe).

EPITAXIAL GROWTH OF NON-POLAR A-PLANE ZNO ON R-PLANE SAPPHIRE SUBSTRATES BY MOCVD AND RF-SPUTTERING

Epitaxial growth of non-polar

Residual stress and thermal stability of the Fe-Ni-Cr/Invar bimetal membrane used for microactuation

(11\bar 20)\;{\rm{Zno}}

The structural characterization and dielectric properties of the La1-xKxCo1-xNbxO3 (x=0-1) system

thin films (a-plane ZnO) on

Two-Step Annealing for Nickel-Induced Crystallization of Amorphous Silicon Films

{\rm{(1\bar 102)}}

Investigation of the Defect Structure of Congruent and Fe-Doped LiNbO3 Powders Synthesized by the Combustion Method

sapphire (r-plane sapphire) were successfully implemented through metal organic chemical vapor deposition (MOCVD) and radio-frequency sputtering, respectively. For ZnO film deposited by sputtering, the growth temperature and the flow ratios of argon to oxygen were shown to significantly influence the crystalline quality and surface morphology of ZnO films. Flat surface ZnO epitaxial film can be grown by MOCVD. The epitaxial relationship between ZnO and sapphire substrate is

Crystal structure and electronic structure of the La1-xKxCo1-xNbxO3 oxides

{\rm{(11\bar 20)}}_{{\rm{Zno}}}_\parallel\;(1\bar 102)\;_{{\rm{Sapphire}}}