Although Gd_xY_<1-x>Ca_4O(BO_3)_3 (GdYCOB) crystal is possible to generate noncritically phase-matched third harmonic of 1064-nm light, photo-induced damage limits the UV output power during high-power operation. In this paper we investigate effect of quality of starting materials on photo-induced damage and reduction of the scattering centers by the compositional adjustment of starting materials.
We have grown high-quality nonlinear optical crystal CsB_3O_5 (CBO) by the improvement of starting materials. The crystal enables to generate the third harmonic of 1064-nm light with high conversion efficiency.
We succeeded in obtaining high-quality single-phase sintered powder by mixing the stating materials in aqueous solution. The crystal grown from this material had about 2-fold higher bulk laser-induced damage threshold than that of conventional crystals.
Single crystals of BaMgF_4 (BMF) were grown by the Czochralski technique. Effect of growth conditions on the crystal quality was investigated. Transmission spectrum of grown BMF single crystal exhibited that the absorption edge is about 126 nm and it is transparent at 157 nm and 193 nm.
<111> oriented BaF_2 single crystals, as the optical material for F_2 laser, are grown by the vertical Bridgman-Stockbarger method. After UV laser or ν-ray irradiation, absorption spectra of these crystals are measured. The origin of absorptions are discussed.
Colquiriite-type fluoride single crystals such as LiCaAlF_6 (LiCAF) were grown by the Czochralski method. Grown single crystals of Ce,Na:LiCAF and Eu:LiCAF were free of cracks, colorless and transparent. Thermostimulated luminescence (TSL) peaks were shown in 283℃ and 206℃, and these TSL intensity were about 100 times and 3 times higher than that of Mg,Ti:LiF, respectively In addition, good linearity was obtained with the X-ray irradiation dose.
CeF_3, PrF_3 and NdF_3 single crystals were grown by the C zochralski method. Grown crystals were free of cracks and inclusions, however. PrF_3 single crystal has shown strong tendency of spiral growth. Radioluminescence intensity of PrF_3 was nearly equal to that of BGO, and decay time was 510ns.
Single crystals of BaF_2 and Yb-containing fluorides, such as Yb:BaY_2F_8, BaYb_2F_8 and Yb:LiYF_4, were grown by the Czochralski technique. BaYb_2F_8, with a density of 7 g/cm^3, exhibited a small light yield, however the decay time was very short (0.35 ns), in contrast to that of BaF_2 (0.64 ns).
Yb:GdVO_4 single crystals were grown by the floating zone method and their optical properties were investigated. The grown crystals contained no macroscopic defects such as inclusions and low-angle grain boundaries and had uniform distribution of Yb-concentration. The absorption spectra exhibited strong dependence on polarization of incident beams and the absorption coefficient was about six times as large as that of Yb:YAG with the same Yb-concentration.
Bi_2Sr_2Ca_2CuO_x(Bi-2212) thin film was prepared on MgO(001) single crystal substrates by metal organic decomposition method. XRD measurement showed that the film has c-axis orientation and FWHM of (0010) is 0.016°. The critical temperature (Tc) of the film was 77K.
Bi,Ga-substituted Yttrium Iron Garnet(YIG) films were prepared by metal organic decomposition (MOD) method. The magnetic easy axis perpendicular to the plane was observed in Ga-substituted YIG film. (111) oriented Bi,Ga-substituted YIG films were obtained on GGG(111) substrate.
Niobium-doped lead zirconate stannate titanate (PNZST) AFE films have been prepared on Nb-doped SrTiO_3(100) substrates by an annealing method via a pulsed laser deposition (PLD) technique. For the characterization of the PNZST AFE films, X-ray diffraction (XRD) and atomic force microscopy (AFM) were used. For the first time, epitaxial growth orientation of the PNZST was found to be <001>.
In order to clarify the entire chemical process in silicon-chlorine-hydrogen system on silicon surface, this study evaluates the chemical reaction rate of hydrogen chloride to etch silicon surface, especially at very high concentration of hydrogen chloride gas.
Ge layer was grown on mesa pattern substrate by LPE . By supercooled growth with low supersaturation, the nucleation density was drastically reduced and flat face with few steps was obtained on the upper surface of some mesas.
The growth kinetics of hydrogenated amorphous silicon carbide films was investigated using the RF plasma CVD system with parallel electrodes. Monometylsilane were used with a hydrogen carrier gas. FTIR of the films revealed quantitatively the hydrogen content. It is conclusive that atomic hydrogen and SiH_2 Serve multiply incorporation of hydrogen to the films.
Generally, several metals, such as Ni, Fe, Co and Mo, were doped as the catalysis on the production of diamond, fullerene and carbon nanotube. In the present method, heat treated carbon films containing such metale were analyzed based on transmission electron microscope technique. The difference of crystallization by doped metal has been elucidated. Present result will give the development to a wide range of new opportunities for research and applications in the field of nanotechnology.
Metalorganic chemical vapor deposition of zinc oxide film was performed in a high magnetic field with diethyl zinc and water vapor as starting materials. Magnetic field may become a new control mean for the growth rate, surface morphlogy and crystalline structure.
Phase-change optical disk which can be recorded and erased with high linear speed is studied to realize data transfer rate of 100Mbit/s. The crystallization speed of phase-change material must be raised for high-data-transfer rate. However, the re-crystallization of the phase-change material occurs if crystallization speed is too high. In this report, the re-crystallization is confirmed by the mark profile simulation and the solution is discussed.
The controlling factor and mechanism of polymorphic crystallization were investigated. In the crystallization of amino acids polymorphs the effect of supersaturation and temperature was separately examined, The controlling factor for polymorphic crystallization in anti-solvent crystallization of pharmaceutical and reactive crystallization of calcium carbonate are shown.
In the pharmaceutical drug development, the following are carried out : Polymorphic search and physical properties evaluation for choosing the polymorphism it chooses optimum crystal form of the drug substance. In next stage, the research of the scale-up for manufacturing process and formulation of the drug substance is carried out. In this paper, the case of the research on polymorphism and evaluation in pharmaceutical drug development is introduced.
The crystallization behaviour of fats without and with application of ultrasonic power is investigated in-situ using a synchrotron radiation time resolved small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS). Without ultrasound application, both polymorhic forms β' and β crystallized in the melt of each substance. With ultrasound treatment of the melt the following effects were observed: (i) a marked decrease of induction times for crystallization with respect to those obtained without application of ultrasound, (ii) an increased nucleation rate compared to that without ultrasound treatment, and (iii) a crystallization of only β forms under conditions of initial crystallization temperature of 50℃ and 30℃, respectively, and applied ultrasound of 2 sec. The last finding demonstrates that ultrasound irradiation can be used as an efficient tool for controlling polymorphic crystallization of fats.
It has been clarified that oleamide exhibits four crystalline phase A,B,C and D. A melt crystallized sample showed a reversible solid-state phase transition from A to B at 0℃ and that from D to C at 10℃ on heating. Vibrational spectral data suggested a selective conformational disordering took place in the methyl-sided chain on the latter phase transition. The B and C forms transform gradually to the D form, which is stable below about 45℃.
We made in-situ observation on the overgrowth of n-C_<36>H_<74> at a constant supersaturation by oblique transmission IR method. The polytypic structures of an overgrown crystal show the strong dependence on the supersaturation and the polytypic structure of the substrate crystal. From the analysis of the solubility of each polytypo, it is clarified that the entropy has a profound effect on the relative stabilities of polytypes.
In order to investigate the influence of the lateral packing modes of hydrocarbon chains on the dynamical properties of lipid compounds, we have studied the dynamics of three polymorphic phases of tristearin by using the quasielastic neutron scattering and the solid state ^<13>C NMR. It is clarified that the mobility of the acyl chains depends significantly on the lateral packing. In the a phase with loose lateral packing, large fluctuations of hydrocarbon chain about their chain axes are activated.
We observed simultaneous dissolution and growth of anthracene crystals in saturated solution by pulsed laser irrradiation. The new crystals, which grew by laser irradiation, show different melting point and solubility from the original crystals. The new crystals are concluded to be polymorph of anthracene.
Benzophenone is well known to produce benzopinacol upon light irradiation. We demonstrated that benzopinacol crystal was precipitated and grown from benzophenone in saturated EtOH / Water (1:1) solution by laser irradiation. The morphology of benzopinacol crystal was able to vary from polyhedral, skeletal, needle, to dendrite depending on the laser power. These phenomena were interpreted in terms of supersaturation of beazopinacol, and the processes of nucleation and growth were observed by measuring the dynamic light scattering.
The crystal forms of benzene were observed in a diamond anvil cell under high pressure. The equilibrium form was thin-disk like. The growth form in dilute toluene solutions was octahedron. The stabilities of the forms are interpreted by those of virtual crystals in computer simulation.
Thermal behavior and crystallization structure of trilauroylglycerol (LLL) dispersed in o/w nano-size emulsion with polyglycerine fatty acid esters (PGE) as additives were investigation. The rate and extent of effects on crystallization had a difference by polymerization and esterifications of additives.
In order to find the forsterite formation condition of crystalline grain, we achieved the coalescence experiment between MgO and SiO_2 smokes. It was found that foresterite spherical particles with the size of a few hundred nm in diameter were produced by the coalescence between cubic-shaped MgO particles and spherical SiO_2 particles.
In order to clarify the characteristic of nanoparticle, temperature dependence of SiO_2 particle deposited Al clusters have been analyzed by transmission electron microscope. We produced Al clusters deposited SiO_2 nanoparticles. We found that a part of Al clusters changed to ν-Al_2O_3 crystalline phase at 600℃ and SiO_2 nanoparticles started to sublimate as SiO gas at 800℃.
Our developed method to separate oxide ultrafine particles in smoke has been used on the formation of copper oxide particles produced by the evaporation of metallic copper in a mixture gas. Yellow and white spherical particles were gathered on the negative and positive electrode . The yellow particles were crystalline particle of cuprite and paramelaconite. The white particles were amorphous, Since the white particles were gathered on the positive electrode, the oxide is excess oxygen particles. The detail analysis on these white cupper oxide particles is under way.
A new type of C_<60> needle-like crystal, or C_<60> 'nano' whiskers were grown by a liquid-liquid interfacial precipitation method. It was found that the growth of the nanowhiskers was promoted under illumination. From Raman soattering measurements, it is shown C_<60> moleoules in the pristine nanowhiskers are bonded by weak van der Waals forces. The rate of the photo-polymerization in C_<60> nanowhiskers is much faster than that in C_<60> bulk crystals.
We have found that nano-needle silicon crystals are fabricated on silicon wafer by being exposed to microwave plasma of methane/hydrogen gas mixture with negative biasing after deposition of iron ultra-fine particles by DC sputtering. The size of the nano-needle is 1μm in height 100-200 nm in diameter, and a few nm in top radius, typically. The nano-needle silicon crystals are made of crystalline silicon coated with carbon thin films of a few nm thick.
The phase transition temperature from quasicrystalline to stable crystalline phase was determined direct-observation on a nano-particle prepared by Advanced Gas Evaporation Method (AGEM). We found that Al-Cr quasicrystal nano-particle transforms to hexagonal-Al_8Cr crystalline at 700℃, which is about 200℃ higher than the reported temperature, accompanying with decomposition of Al from Al-Cr alloy.
NiTi shape memory alloy nanoparticles were produced by the flash gas evaporation from the 50 at.% Ni-Ti mixture powder. The superlattice image of B2-phase that is called as the characteristic structure of R-phase has been captured by the high resolution electron microscopic image. The core of particle was R-phase and the mantle layer was B2-phase. These particles were heated directly in the electron microscope. It became evidently that R-phase has never changed to B2-phase, although the temperature has been much higher than the bulk's transition temperature. Therefore the R-phase is one of the stable phase at high temperature.
Present TiC crystallites with the size of less than 3 nm were shown at 14 μm absorption feature. This 14 μm absorption was hardly seen from the bulk to 50 nm size. The absorption feature at 14 μm was weakening due to the growth of TiC crystallites by the heat treatment. Moreover the absorption intensity was depended on the grain surface, i.e., if the carbide grains were covered with carbon layer as is observed in the meteorite, the absorption peaks were remarkably weakening.
Magnetoresistance was measured for both the as-grown carbon micro-coil and the one heat-treated at 3000℃. Magnetic field was applied both perpendicular and parallel to the axis of the carbon micro-coil. No field direction dependence was observed for the as-grown carbon coil measured at 5 K. The magnetoresistance for the coil heat-treated at 3000℃ is 40 % under parallel magnetic field of 12 T measured at 300 K, and 14 % at 12 T under transverse field.
Spectral properties of colloidal crystals tailored by generating a flow of a suspension in a flat capillary cell were examined. Increasing the flow rate, transmittance and uniformity of the crystal texture increased and then saturated. The saturated flow-aligned texture shows excellent optical quality and the crystal will be useful for practical application of colloidal photonic crystal.
We found formation of conical calcite crystals on a glass surface in supersaturated solutions containing two kinds of poly (acrylic acid). The unique morphology of calcite was achieved by the combination of a templating effect of a high-weight PAA at the surface of a substrate and moderate suppression of crystal growth with adsorption of a low-weight PAA.
Helical morphologies were found on inorganic crystals having a triclinic system through a diffusion-limited growth in various gel matrices. The backbone structure of the unique architecture was composed of the twin-like deviational connections of platy crystals. These results suggest that the helical morphologies originated from twisted assembly of tilted subunits.
Amphibole whisker bundles showing unusual topological morphology like helical, ribbon, curl, coil and rope forms and quartz fibrous seam resembling frost column were found for the first time in the mineral kingdom, on short prismatic hedenbergite single crystals in a druse of a skarn sample. Both amphibole whiskers and quartz frost column were formed by VLS mechanism, through reaction between hedenbergite and newly introduced vapor phase containing S and H_2O.