The crystal growth of calcite at a low temperature range was carried out by the hydrothermal method usingamorphous calcium carbonate which has excellent solubility in water. Amorphous calcium carbonate was prepared by thewet chemical reaction of a stoichiometric mixture of CaCl2 and Na2CO3. An important factor was the reaction temperaturemethod, NH4NO3 solutions were found to be the most promising solvents to grow calcite single crystals. The hydrothermalconditions for high growth rates of calcite single crystals were as folows: starting material: amorphous calcium carbonate,solvent: 0.01 m NH4NO3, temperature: 180oC, duration: 30 days. And properties of calcite single crystals were folows:dislocation density: 106~107 cm2, UV-visible transmittance: about 80 % from 190 to 400 nm and birefringence: 0.17~0.18.Also, it can be known from the FT-IR results that the absorption peak by injection of HCO3 and OH ions was not shown.Key words Amorphous calcium carbonate, Hydrothermal method, Calcite single crystal, Polarization device
Lead scandium tantalate powders were prepared by a molten salt synthesis method using NaCl-KCl as a flux.Variations in phase formation and particle morphology were investigated for the temperature range from 700oC to 800oC.Pb(Sc1/2Ta1/2)O3 with pure perovskite phase was formed at 750omorphology and the average particle size below 0.5m. The results were discused with respect to DTA, X-ray diffraction,and microstructural characterization data.
TiNx powder have been fabrication by making of reaction between titanium powder and Si3N4 bowl during a planetary milling. Milling times were maintained for 1hour, 5hours, and 10hours, respectively. The XRD result showed existence of non-stoichiometric compound of TiN0.26 after 5hours milling and coexistence of TiN with TiN0.26 after 10hours milling. Particle size distribution was investigated by particle size analyzer and microstructure was analyzed by FE-SEM. The size of titanium was decreased with increasing the milling time and the mean size of TiNx after 10hours milling was increased by 200nm.
Biomimetic actuators that can produce soft-actuation but large force capability are of interest. Nafion, an effective ionomeric material from DuPont, has been shown to produce large deformation under low electric fields (<10V/ mm). Carbon nanotube/polymer nanocomposites were cast to enhance the electromechanical properties of the composites. Multiwalled carbon nanotube (M-CNT)/Nafion nanocomposites were prepared by a solution casting to investigate the effect of M-CNT loading in the range of 0 to 7wt% on electromechanical properties of the M-CNT/Nafion nanocomposites. The measured elastic modulus and actuation force of the M-CNT/Nafion nanocomposites are drastically different, showing larger elastic modulus and improved electromechanical coupling, from the one without M-CNT.
The 5 mol% ZnO doped LiNbO3 film and the 2 mol% MgO doped LiNbO3 film were grown on the LiNbO3 (001) substrate by liquid phase epitaxy (LPE) method with Li2CO3-V2O5 flux system. The crytsallinity and the lattice mismatch between Zn : LiNbO3 film and Mg : LiNbO3 film were analyzed by x-ray rocking curve (XRC). In addition, the
ZnO and MgO distribution in the cross-section of the multilayer thin films was observed using electron probe micro
It is demonstrated that the annealing process for Ti in-diffusion to z-cut LiNbO3 at temperature lower than the curie temperature in a platinum (Pt) box can cause a ferroelectric micro-domain inversion at the +z surface and Li out-diffusion, therefore which should be avoided or suppressed for waveguide type periodically poled lithium niobate (PPLN) devices. The depth of the inversion layer depends on the Ti-diffusion conditions such as temperature, atmosphere, the sealing method of LiNbO3 in the Pt box and crystal orientation is experimentally examined. The result shows that the polarization-inverted domain boundary appears at the only +z surface and its thickness is about 1.6mm. Also, for the etched LiNbO3 surface the domain shape was observed by the optical microscope and atomic force microscopy (AFM), and distribution of the cation concentrations in the LiNbO3 crystal by the secondary ion mass spectrometry (SIMS).