Advanced Materials Research Vols. 11-12

Abstract: Mechanical destruction of acicular asbestos has been carried out as a process for decontamination. The dehydration reaction of asbestos occurred at 600°C and has been completed for 2 h at that temperature. This dehydration reaction of asbestos led to weakening of the mechanical properties of asbestos. After grinding, the microstructure of asbestos appeared no acicular shape. Further, this technique could be applied to asbestos-containing cement board. The spent cement board has about 10-20 mass% of asbestos (chrysotile: Mg3Si2O5(OH)4) and 5 mm thickness was used. After heating at 600°C for 2 h and grinding, the microstructure of the sample also appeared no acicular shape. Thus it was cleared that heating at 600°C and then grinding treatment for asbestos (chrysotile) has a grate important effect of mechanical and chemical destruction of asbestos in both cases of free asbestos and asbestos-containing cement board.

Abstract: Formation of clusters with high corrosion resistance on anodic films of Aluminum by Ni ions implantation was studied. Ni ions were implanted in anodic films of 1070 aluminum at an energy of 40 keV with dose of 5.0×1017 ions/cm2. XPS analysis reveals that Ni is present in the states of metallic Ni and NiO on the surface of the anodic film. Electrochemical results show that anodic films with Ni ions implantation provide relatively higher corrosion resistance in NaCl solution. The anti-corrosion clusters on the surface of anodic films should be the main reason for better corrosion resistance of the implanted samples.

Abstract: This article summarizes the work of the author’s lab based on crystallography. The topics are categorized in the following three fields: The first category is crystallographic analysis of materials, the second one is correlations between crystal structure and their properties, and the third one is crystallography for processing such as epitaxy, topotaxy and templates. The examples for these categories are: (1) multilayer ceramic capacitor (MLCC); (2) microwave dielectrics of tungstenbronze-type like solid solutions, and piezoelectric materials langasite (La3Ga5SiO14); (3) thin film growth of GaN or AlN on sapphire for example of epitaxy, hydroxy-apatite grown on diopside for topotaxy, and template growth of microwave dielectrics for template. Crystallography is useful in all studies, but is not almighty. Interdisciplinary study between crystallography and solid state physics is necessary to make clear the mechanism of the properties.

Abstract: A chemical solution deposition process for preparation of highly (100)-oriented Ba(Zr0.05Ti0.95)O3 films was developed. The orientation degree of Ba(Zr0.05Ti0.95)O3 thin films prepared by this process can reach up to 99.1%. The electrical properties of the (100)-oriented films prepared by this process have been studied. The Ba(Zr0.05Ti0.95)O3 films with a thickness of about 270 nm show a dielectric constant of ∼740 and a loss tangent of ∼3%. The remanent polarization (2Pr) and coercive field (2Ec) are 3.2 μC/cm2 and 34 kV/cm, respectively.

Abstract: KNbO3 thin films were grown on (100) and (110) SrTiO3 substrates by liquid phase epitaxy (LPE) technique. The film orientation and surface morphology were characterized by XRD and AFM, respectively. The limited phase diagram of K2O-Nb2O5-V2O5 system was prepared by DTA measurement to investigate the effect of V2O5 flux on the LPE growth of KNbO3 film. The use of V2O5 flux enhanced a film growth rate at lower growth temperature.

Abstract: Dense KBa2Nb5O15 ceramics have been first prepared from the accurate treatment of powder mixing under ordinary pressure-less sintering. The sample prepared by the calcined powder mixed by a planetary ball-milling showed a relatively high density of 94.7% and a homogeneous microstructure resulting from the inhibition of abnormal grain growth. The electric properties of KBa2Nb5O15 ceramics was controlled by the preferential crystallographic orientation. The remanent polarization (Pr) of the sample cut parallel to the pressing direction demonstrated above two times larger (2.9 μC/cm2) than that of the perpendicular-cut sample (1.3 μC/cm2) at 150°C.

Abstract: A metallodielectric metamaterial have been investigated by using FDTD (Finite Difference Time Domain) method and fabricated with a resin based rapid prototyping machine. It was composed of 7 layers of parallel periodic copper wires embedded in resin. The metallodielectric metamaterial shows a different near field distribution with direction of incident electric field E that causes different electromagnetic (EM) properties. In particular, when incident electric field E is vertical to the wires inside resin, we observe enhacement of electric field in the vicinity of the embedded metal wires according to the incident direction of electirc field E as compared with dielectirc wihout metal wires. The enhanced electric field by the embedded metal wire is responsible for the enhancement of effective dielectric constant.

Abstract: In order to clarify the validity of the model of crystal defects that was proposed by the authors to explain the electrochemical properties of the proton conducting oxide, the total electrical conductivity of the sintered sample of SrCe0.95Yb0.05O3-X was measured under the controlled oxygen and hydrogen potentials. The results show that the dependence of conductivity on the potentials is reasonably explained by the reported defect model.