Thick film patterns were prepared by an inkjet method with water-based ink containing BaTiO 3 powder. An ethyl cellulose layer was made over Pt electrodes, and oxygen plasma modification was performed. After this modification, patterns on substrates were printed in shape. The measurement of the contact angle of ink on the ethyl cellulose layer and the X-ray photoelectron spectroscopy of the ethyl cellulose layer were carried out. From the obtained results, wettability was determined to be improved by increasing the number of hydrophilic functional groups on the surface of ethyl cellulose layer. Surface observation using a scanning electron microscope was carried out on a modified ethyl cellulose layer. Surface roughness due to the etching effect of oxygen plasma was observed to increase with modification time. After firing at 1340 C for 1 h, the BaTiO 3 film thickness was approximately 30 mm. The electric properties of BaTiO 3 films were examined. The dielectric constant and tan were 2200 and 0.05 at 1 kHz, respectively. The remanent polarization and coercive field measured from a P-E hysteresis curve were 3.1 mC/cm 2 and 1.1 kV/cm, respectively. These results indicate that an inkjet printing method using a modified EC layer is applicable to the fabrication of thick films on substrates.
The electronic structures and structural properties of body-centered cubic Ti-Mo alloys were studied by first-principles calculations. The special quasirandom structures (SQS) model was adopted to emulate the solid solution state of the alloys. The valence band electronic structures of Ti-Mo and Ti-Mo-Fe alloys were measured by hard x-ray photoelectron spectroscopy. The structural parameters and valence band photoelectron spectra were calculated using firstprinciples calculations. The results obtained with the SQS models showed better agreement with the experimental results than those obtained using the conventional ordered structure models. This indicates that the SQS model is effective for predicting the various properties of solid solution alloys by means of first-principles calculations.
The effects of CuO or NiO addition on the sintering temperature and electrical properties of 0.92(K 0.47 Na 0.47 Li 0.06 )NbO 3 -0.07BaZrO 3 -0.01 (Bi 0.5 Na 0.5 )TiO 3 ceramics with a temperature-stable morphotropic phase boundary were investigated. The ceramics without any additives and those with NiO exhibited a tetragonal phase. The ceramics with CuO exhibited the coexisting orthorhombic and tetragonal phases. The sintering temperature was reduced by the addition of NiO or CuO. NiO addition was also effective for broadening the range of the sintering temperature window. The d 33 , radial-mode electromechanical coupling factor, and remanent polarization of the ceramics with NiO were 238 pC/N, 0.39, and 14 µC/cm 2 , respectively; moreover, the measured values of the ceramics with CuO were all lower than those of the ceramics with NiO. The results suggest that NiO acted as a sintering aid among grains, and the sintering temperature window was consequently broadened. In the case of CuO addition, Cu ions replaced the A-and B-sites of the ceramics, and such replacement reduced the tetragonality. As a result, the electrical properties of the ceramics with CuO were lower than those of the ceramics with NiO.
The effects of doping MgO into (Ba0.6Sr0.4)TiO3 (BST) fired under a reducing atmosphere were investigated in order to prepare BST thick films with Ni electrodes by the screen-printing method. MgO-doped BST thick films fired under a reducing atmosphere showed insulation resistance. Grain growth in the thick films was advanced by MgO doping. The dielectric constant near T
C of the bulk ceramics and thick films increased with increasing MgO concentration up to 2 and 10 mol %, respectively. Mg ion substitution to the B-site was also observed up to these concentrations. The tunability and tan
δ of thick films with MgO concentrations of 2 and 4 mol % at an electric field of 10 V/µm were approximately 77 and 0.3%, respectively. It is expected that thick films prepared by screen printing will be applicable to tunable devices with Ni electrodes.
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