A domain structure in periodically poled stoichiometric LiNbO₃ was observed by confocal micro-Raman scanning spectroscopy. The 180°-domain, which is nominally invisible by Raman scattering due to equivalency of Raman selection rule for adjacent domains, was clearly visualized with a spatial resolution of 460 nm. At domain walls, an enhancement of Raman intensity was observed in optical modes that are closely related to the Nb–O bond, while there was no significant change in Li-ion related modes. Nb–O covalent bonds would be deformed by opposite ferroelectric displacements of ions across domain walls, to modify an electric polarizability of the Nb-ion related modes.

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BaTiO₃ crystals synthesized through the crystallization of 40BaO–40TiO₂–15SiO₂–5Al₂O₃ glass were characterized from Raman scattering spectrum, second harmonic generation (SHG), and polarization measurements. The structure of BaTiO₃ nanocrystals (~70 nm) formed initially was suggested to be pseudo-cubic (small tetragonality), and perovskite-type ferroelectric BaTiO₃ crystals were formed in the heat-treatments at high temperatures of ~930°C. The lines consisting of BaTiO₃ crystals were patterned at the surface of CuO-doped glass by irradiations of continuous-wave Yb:YVO₄ lasers with a wavelength of 1080 nm. It was confirmed that BaTiO₃ being present in the laser-irradiated parts exhibits SHGs and, in particular, BaTiO₃ formed in the laser ablation region has a tetragonal structure and a Curie temperature of ~135°C.

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0.3BaTiO₃–0.1Bi(Mg_1/2Ti_1/2)O₃–0.6BiFeO₃ ceramics were either doped with vanadium or sintered in calcined powder with the same composition. Compared to an undoped ceramic sintered without the calcined powder, both ceramics showed reduced leakage current densities (lower than 1 × 10⁻⁷ A/cm²) and absence of dielectric relaxation behaviors observed in frequency- and temperature-dependent dielectric measurements. The Curie temperatures of both samples were higher than 460°C. The maximum field-induced strain over the applied field, S_max/E_max, of 366 pm/V for the undoped ceramic sintered without the calcined powder increased to 455 and 799 pm/V for the V-doped sample and the sample sintered with the calcined powder, respectively. The increase was discussed with reduced concentrations of bismuth vacancy–oxygen vacancy defect dipoles.

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High-quality rutile TiO₂ nanocrystals have been synthesized by a simple hydrothermal treatment of a watersoluble titanium–glycolate complex at 200°C. The obtained samples were composed of rod- or whisker-like nanocrystals. The aspect ratios of these nanocrystals could be controlled by adding glycolic acid. Combined characterizations with X-ray diffraction, Raman scattering and high-resolution transmission electron microscopy revealed the formation of highly phase-pure and well-crystallized rutile nanorods/nanowhiskers with the c-axis orientation. Room-temperature dielectric measurements indicated that the permittivity for the rutile nanowhiskers is ~150 at 100 kHz, which is higher than that for the bulk rutile powder. These observations pave a way for morphological controlled rutile nanocrytals to find a broad class of technological uses.

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Resonant Raman spectroscopy was applied to evaluate oxygen vacancies in PbTiO_3–x thin films that were heat treated in a hydrogen atmosphere at various temperatures. Additional mode related to oxygen vacancies occurred in the resonant Raman measurement condition, and its intensity was in proportion to the oxygen vacancy concentration. This correlation offers a simple and useful probe for oxygen vacancies in oxide-based devices.

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KNbO₃ (KN)/BaTiO₃ (BT) nanocomposite ceramics, in which a BT nanoparticle is thinly coated with KN crystals through the heteroepitaxial interface, are heat-treated at 1000°C for 10 h, and the crystal structures are investigated by synchrotron radiation powder diffraction. The Rietveld analysis based on the multicomponent models reveals that the volumes of gradually distorted tetragonal components of BT are significantly decreased and the BT-KN solid solutions emerge in the nanocomposites by the heat-treatment. The suppression of the piezoelectric response in the heat-treated nanocomposites compared with the as-synthesized ones is attributed to these changes in the crystal structure. The core/multishell structure model for the ceramic grain is proposed, and the changes in the crystal structure are revealed to be caused at the heteroepitaxial interface regain between BT and KN.

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The dielectric and thermal properties of isotactic polypropylene/magnesium oxide (0–30 vol %) composites were investigated. The dielectric constant of the composite material increased from 2.3 to 3.2 on increasing the MgO content and the observed variation of the dielectric constant with the MgO fraction was in good agreement with the Bruggeman mixing model. Low dielectric losses at microwave frequencies, on the order of 10⁻⁴, were obtained using highly crystalline MgO as the filler, and it was also found that the use of larger MgO particle sizes led to further reductions in the dielectric loss. The absolute value of temperature coefficient of the dielectric constant as well as the coefficient of thermal expansion decreased with increasing MgO content, while thermal conductivity increased with increasing MgO content in a manner which could be predicted using the Maxwell-Garnett mixing model.

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First-priciples density functional theory (DFT) techniques are used to provide atomic-scale insight into the surface structures and crystal morphologies of cubic barium titanate, BaTiO₃. Relaxed surface structures and energies are calculated for 3 low index planes and resulting equilibrium morphology based on Wulff’s theorem with {001} and {011} faces were constructed. The calculated surface energies are strongly dependent on the coordination loss of TiO₆ octahedra at the surface. The optimized structure at the low-energy surfaces shows that only atoms at 1st perovskite layer are displaced from ideal position, while no significant displacements are indicated. On the other hand, the Bader charge analysis shows that the ionicity of whole the cations in the slab (7 perovskite layers) is larger than that in the bulk. Therefore, change of electric property is expected at the surface region, which is not due to the surface reconstruction, but to the change of electronic structure.

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Multiferroic Pb(Zr,Ti)O₃/CoFe₂O₄/Pb(Zr,Ti)O₃ layered thin films were synthesized on Pt/TiO_x/SiO₂/Si substrates by chemical solution deposition using metal–organic precursor solutions. Layered composite films composed of polycrystalline perovskite Pb(Zr_0.52Ti_0.48)O₃ and spinel CoFe₂O₄ phases with no secondary phases were successfully synthesized by controlling conditions such as the coating process. The layered structure of the Pb(Zr_0.52Ti_0.48)O₃/CoFe₂O₄/Pb(Zr_0.52Ti_0.48)O₃ was confirmed by scanning electron microscope observations. These layered films exhibited sufficiently high insulating properties, as well as ferroelectric polarization (P)-electric field (E) and ferromagnetic magnetization (M)-magnetic field (H) hysteresis loops at room temperature. Typical ferroelectric oxide strain behavior was observed under a driving AC (alternate current) field. Furthermore, due to magnetoelectric interaction between the ferroelectric and ferromagnetic (magnetostrictive) layers, the ferroelectric properties of the films altered under an applied magnetic field (approximately 0.5 T).

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LaNiO₃ (LNO) is one of an excellent candidate for oxide electrodes especially for perovskite ferroelectric films since it is perovskite type crystal structure, and therefore it is suitable for lattice matching with conventional perovskite ferroelectrics, Pb(Zr,Ti)O₃ (PZT), BaTiO₃ (BTO), etc. We have been investigating an effect of thermal expansion of the LNO film as PZT/LNO/Si and BTO/LNO/Si structures, where ferroelectric and piezoelectric properties can be improved by a compressive thermals stress implied from the LNO layer to the ferroelectric films. The ferroelectric films also shows high [001] orientation owing to [100] orientation of the LNO film. In the present study, microstructures and crystal structures of the LNO films fabricated on Si substrates by CSD method is investigated by X-ray Diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) in order to understand self-orientation along [100] perpendicular to the film plane. The results obviously indicate that the 1 layer deposited LNO film has almost no orientation, whereas it shows tendency of orientation of [100] perpendicular to the film plane when the layer number increased (upto 4 layers). TEM analysis also shows in-plane tensile stress applied to the LNO film is effectively decreased by porous LNO structure, which leads in-plane compressive stress to the ferroelectric films prepared on the LNO films.

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Bismuth potassium titanate, (Bi_1/2K_1/2)TiO₃ (BKT), ceramics were fabricated using KHCO₃ as a starting material to control K amount precisely. Then, we fabricated (Bi_1/2K_(1+x)/2)TiO₃ [BKT-10000x] ceramics to clarify an effect of poor or excess K ions in BKT ceramics for physical and electrical properties. The BKT-10000x ceramics were prepared by a conventional ceramic fabrication process, and then high density ratios of about 97% were obtained in all BKT-10000x ceramics (10000x = −10–100). The precise control of K amount did not strongly affect the sinterability for BKT ceramics. On the other hand, electrical properties such as ferroelectric, strain and piezoelectric behaviors of BKT ceramics are very sensitivity to the amount of K ions. Therefore, it is very important to control the amount of K in BKT ceramics.

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Epitaxial (K_xNa_1−x)NbO₃ films with 3 µm in thickness were deposited at 240°C on (100)_cSrRuO₃//(100)SrTiO₃ substrates by hydrothermal method. XRD patterns and Raman spectra were systematically changed with increasing x values. XRD patterns and Raman spectra was not dramatically changed by the annealing treatment at 600°C for 10 min under O₂ atmosphere. On the other hand, the electrical and piezoelectric properties were improved by this annealing treatment; leakage current density was diminished and longitudinal piezoelectric response was increased to 69 pm/V at x = 0.51.

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The behaviors of intrinsic unit-cell strains under applied electric fields (E) along the ⟨100⟩ direction were investigated for rhombohedral Pb(Zn_1/3Nb_2/3)O₃–(6–7%)PbTiO₃ (PZN–PT) single crystals by in-situ high-energy synchrotron radiation X-ray diffraction study. The E-induced unit-cell strains accompanied with a reversible phase transition from rhombohedral to tetragonal via two monoclinic phases agree well with the macroscopic strain properties observed for the crystals. The structural analyses using the single-crystal X-ray diffraction and domain observations with piezoresponse force microscopy lead to a conclusion that the E-induced unit-cell strains are mainly responsible for the high piezoelectric performance of the PZN–(6–7%)PT single crystals.

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This study investigated the effect of excess PbO and post-annealing on the crystallinity and the microstructure of Pb(Mg_1/3Nb_2/3)O₃ (PMN) epitaxial thin films. PMN thin films were deposited on SrTiO₃ (STO) (001) substrates using a chemical solution deposition (CSD) process with rapid thermal annealing (RTA) of spin-coated metallo-organic decomposition (MOD) solutions. The nominal film composition was Pbx(Mg_1/3Nb_2/3)O₃ (x = 1.0 or 1.1). All films showed the (001)_PMN//(001)_STO, [001]_PMN//[001]_STO epitaxial relationship and were single phase perovskite PMN without any pyrochlore phases. The Pb_1.1(Mg_1/3Nb_2/3)O₃/SrTiO₃ thin film post-annealed at 973 K with facing treatment showed the highest crystallinity of 0.8° in full width at half maximum (FWHM) of the 002_PMN rocking curve. Transmission electron microscopy (TEM) revealed PbO nanoparticles on the surface of the PMN thin films. The film composition was almost stoichiometric. On the other hand, the Pb_1.1(Mg_1/3Nb_2/3)O₃/SrTiO₃ thin film post-annealed at 973 K without facing treatment showed crystallinity of 1.0° and no PbO nanoparticles. The film composition was almost stoichiometric. These results indicate that the excess PbO is not incorporated into the PMN films. Instead, it volatizes from the film surface, which improves the crystallinity and inhibits the PMN decomposition.

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The crystal structure, piezoelectric and ferroelectric properties of the Bi_0.5−0.5xNa_0.5−0.5xSr_xTi_1−xZr_xO₃ (BNSTZ) ceramics were characterized in this study. From the variations in the lattice parameters, the solubility limit of the BNSTZ ceramics was determined to be x = 0.075. The crystal structure refinement revealed that the distortion of (Bi, Na and Sr)O₁₂ polyhedron decrease with increasing x and such the variation in the distortion exerts an influence on the decrease in remnant polarization from 35 to 28 µC/cm². Although the slight shifts of the depolarization temperature (T_d) and rhombohedral-tetragonal phase transition temperature (T_R-T) to lower temperature were recognized, it suggested that the shift of T_d is predominant for the increase in dielectric constant at room temperature which leads to the enhancement of the d₃₃ value. As a result, the d₃₃ and k_p values were 85 pC/N and 18.7%, respectively at x = 0. 075.

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Cordierite (Mg₂Al₄Si₅O₁₈) is a candidate for millimeter-wave dielectrics, and has two polymorphs due to ordering of Si and Al ions on Si/AlO₄ tetrahedra: disordered high symmetry form called as indialite and ordered low symmetry form cordierite. Indialite/cordierite glass ceramics exhibited much higher Qf value of 200,000 GHz than conventional solid state reaction ceramics of 40,000 GHz, which were fabricated by crystallization of glass pellet. The glass ceramics having indialite as a dominant phase showed high Qf. The crystal phases are analyzed by Rietveld method. In this paper, the ordering ratios of indialite and cordierite are estimated by the volumes and covalencies of Si/AlO₄ tetrahedra.

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Barium titanate (BaTiO₃, BT) ceramics with various grain sizes were prepared by hot isostatic pressing (HIP) and post-annealing. The dielectric and piezoelectric properties were evaluated. Grain growth was suppressed in the ceramics prepared by HIP. The average grain sizes of the ceramics were controlled by changing the post-annealing temperature. Dense BT ceramics with submicron grain sizes were obtained by annealing below 1000°C. The highest piezoelectric d₃₃ coefficient, 172 pC/N, measured by a d₃₃ meter was obtained in the BT ceramics prepared by HIP at 900°C under the pressure of 200 MPa and annealed at 1100°C in air for 48 h. The dynamic electric field-induced strain increased with the annealing temperature, and 700 pm/V of Strain/Field was obtained in the BT ceramics prepared by HIP under the same conditions and annealed at 1300°C in air for 48 h.

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We designed advanced transparent-comb-electrode photonic crystals (TCE PCs) to use the longitudinal electro-optic (LEO) effect, so they are composed of Al-doped ZnO (AZO) layers, which serve as internal/external electrodes, and centered (Pb,La)(Zr,Ti)O₃ (PLZT) layers, which serve as EO material. The simulated transmittance spectra of a multilayer interference (MLI) model revealed the conditions in the AZO and PLZT film thicknesses and the AZO/PLZT period number for a narrow photonic band gap (PBG). The TCE PCs consisted of four periods of AZO/PLZT, and it was fabricated by RF magnetron sputtering through metal mask patterning. Finally, a refractive index change induced by the LEO effect of the PLZT layers was accomplished by applying the voltage dependence of transmittance spectra that were well fitted with a revised (MLI) model considering light absorption and scattering. The PCs exhibit large refractive index changes of 1.3 × 10⁻² and 2.9 × 10⁻² at DC voltages of 4 and 8 V, respectively. The corresponding PBG shifts were 3.9 and 8.5 nm, implying high a PBG tunability of ~1 nm/V.

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Self-supported (Bi_0.5Na_0.5)TiO₃ (BNT) dense ceramic films with a thickness of approximately 20 µm have been fabricated by use of an aerosol deposition method with heat treatment and sapphire single crystal substrates. Investigations of their constitution phase and crystal structure, observation of their microstructure, and measurement of polarization properties and leakage current density (J) were performed. Wlile the films heat-treated at 800 and 900°C in air indicated the low J ≈ 10⁻⁷ A/cm² at 150 kV/cm, the sintered bulks and the films annealed at 900°C in the BNT starting raw powder showed the relatively high J of approximately 10⁻⁶ A/cm² at 150 kV/cm. These films heat-treated at 800 and 1000°C in air and sintered bulks showed the almost the same coercive field (E_c) of approximately 57 kV/cm (in the 56 to 58 kV/cm range), and the films heat-treated at 1000°C in air exhibited good polarization properties and remanent polarization (P_r) of 25 µC/cm². The AD method is proposed to be effective for obtaining self-supported BNT thick films with good saturated hysteresis loops and low J.

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Micromachined ultrasonic transducers (MUTs) are attractive devices for medical imaging systems. In order to observe biological tissue images clearly, ultrasonic waves above 100 MHz in a thickness oscillation mode are required. Therefore, the film thickness of the piezoelectric materials like lead zirconate titanate (PZT) is required less than 10 µm. In this study, to adapt the demand of high frequency ultrasonic, thickness mode transducers using the PZT thick film were prepared with a CSD process, a FEM simulation, and a micro fabrication process. The effects of the side length of PZT thick film structure and the Si substrate thickness on the electrical impedance properties were investigated, because the mechanical oscillation was equivalent to the electrical impedance oscillation. To reduce a series of resonance frequency like a composite resonator, a back side of the Si substrate was removed with deep Si etching process. The PZT thick film with Si substrate cavity structure showed sharp fundamental thickness mode resonance peak at around 168 MHz. Therefore, the fabricated device structure is applicable to the high frequency ultrasonic medical imaging system in the future.

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We investigated the thermoelectric properties of doped multiferroic material: Co-doped BiFeO₃ (BFO) and related materials: Bi₂₄CoO₃₇ and Bi₂₄CoO₃₇–BFO composite systems. Because of their insulating nature, the BFO-based samples showed high Seebeck coefficients compared with other oxides being explored as candidates for new thermoelectric materials such as NaCo₂O₄, and La_0.9Sr_0.99Ca_0.11CoO₄. On the other hand, the Bi₂₄CoO₃₇ sample showed high conductivity. The Bi₂₄CoO₃₇ (20%)–BFO composite sample showed a high power factor, because of its high conductivity and high Seebeck coefficient. These results indicated that the BFO matrix plays an important role in maintaining a high Seebeck coefficient, and that Bi₂₄CoO₃₇ works as a conductive pass on this system.

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In this study, Bi_0.5+0.5xNa_0.5−0.5xTi_1−xMn_0.75xMo_0.25xO₃ (BNTMM) ceramics were synthesized and the influence on their crystal structure and ferroelectric properties of the Bi, Mn and Mo substitutions for Na and Ti was investigated. Based on variations in the lattice parameters, the solubility limit was determined to be x = 0.0075. From crystal structural refinement in the single phase region, it was found that the Bi, Mn and Mo substitutions for Na and Ti may exert an influence on the covalency of B–O (B = Ti, Mn, and Mo) and (Bi,Na)–O bonds, leading to a structural distortion of BO₆ octahedra and (Bi,Na)O₁₂ polyhedra, which may affect the remnant polarization (P_r). The highest P_r value of 40.3 µC/cm² was obtained for x = 0.0075 and the corresponding coercive field E_c was 70.3 kV/cm.

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The effects of Mn₂O₃ addition on the ferroelectric and piezoelectric properties of (K_0.474Na_0.474Li_0.052)(Nb_0.948Sb_0.052)O₃ (KNLNS) defined as KNLNS(Sb₂O₃) and KNLNS(Sb₂O₅) which was synthesized using Sb₂O₃ or Sb₂O₅ powders have been investigated. From X-ray powder diffraction profiles, the coexistence of orthorhombic–tetragonal phases, which have a morphotropic phase boundary (MPB), is shown in the KNLNS–xmol %Mn₂O₃ ceramics. The addition of Mn₂O₃ to the KNLNS(Sb₂O₅) ceramic led to significant improvements in ferroelectric properties, piezoelectric property, and bulk density; moreover, the orthorhombic–tetragonal phase transition temperature was shifted to room temperature. As a result, the d₃₃ values of the KNLNS(Sb₂O₅)–xmol %Mn₂O₃ ceramics increased, ranging from 187 to 264 pC/N, whereas the d₃₃ values of KNLNS(Sb₂O₃)–xmol %Mn₂O₃ were decreased by the Mn₂O₃ addition. These results indicate that the KNLNS(Sb₂O₅)–xmol %Mn₂O₃ ceramics may be a promising candidate material for lead-free piezoelectric ceramics.

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The in-plane compressed (001)-epitaxial (Ba,Sr)TiO₃ [BST] films with different Ba/Sr ratio were fabricated on (001)_cSrRuO₃/(001)SrTiO₃ and (001)_cSrRuO₃/(001)(La,Sr)(Al,Ta)O₃ by RF magnetron sputtering. Regardless of the Ba/Sr ratio, the in-plane compressive strain shifts the ferroelectric phase transition to higher temperatures; however, the magnitude of its impact varies by the Ba/Sr ratio. With increasing the Ba/Sr ratio, the sensitivity to the strain becomes larger, which can be associated with the compositional dependence of Curie–Weiss constant, electrostrictive constant and elastic constant of BST.

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Potassium niobate (KNbO₃) was prepared using a solvothermal method. The synthesis was conducted using niobium oxide (Nb₂O₅) and potassium hydroxide (KOH) as starting materials and ethanol as the reaction medium. X-ray diffraction (XRD) confirmed the presence of perovskite KNbO₃ particles and indicated that the lattice of the KNbO₃ was orthorhombic. The morphology of the KNbO₃ was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM). Energy-dispersive X-ray (EDX) spectrometry was conducted with TEM/STEM, which clearly revealed that the KNbO₃ particles were nanosized and possessed a cubic shape with sharp-edged corners. The STEM-EDX observations indicated that all three elements of potassium (K), niobium (Nb), and oxygen (O) were distributed homogeneously across the nanocubes. Only K, Nb, and O were detected in the EDX spectrum of the KNbO₃ powders obtained. Thus, KNbO₃ nanocubes were successfully prepared using a solvothermal method at low temperature.

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Porous barium titanate (BaTiO₃, BT) ceramics were prepared by a conventional sintering method using two kinds of BT particles. The relationship between pore structure (porosity and pore size) of BT ceramics and their sensor properties was investigated. Since a piezoelectric constant d₃₃ of BT depends largely on the pore structures, the microstructure control of porous BT ceramics is important to improve the figure-of-merit of piezoelectric stress sensor application (g₃₃/ρ). In this study, the maximal piezoelectric g₃₃ constant value of 14.8 × 10⁻³ V·m·N⁻¹ and the maximal g₃₃/ρ value of 3.14 × 10³ V·m⁴·N⁻¹·g⁻¹ were obtained at a porosity of approximately 23%.

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A thin silicon dioxide (SiO₂) layer coating on the surfaces of 150 and 300-nm BaTiO₃ particles was applied by a hydrothermal hydrolysis method. Sodium silicate (Na₂SiO₃) was used as a raw material, and the concentration, temperature, and pH were controlled. The surface-treated BaTiO₃ particles were dried at 120°C and fired at 650°C for 30 min. The thickness of the coated layer was about 4.52 nm, and the layers were homogenously coated onto the BaTiO₃ particles. The structure and morphology of the coated layers were analyzed by XRD, FE-SEM, TEM, and EDX.

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High-temperature thermoelectric properties of BaFe_xTi_1−xO_3−δ (BFT100x) ceramics in air were investigated. Crystal structures of BFT100x ceramics were found to be a mixture of tetragonal or cubic provskite and hexagonal BaTiO₃ phases for x = 0.05–0.20, and a single phase of hexagonal BaTiO₃ for x > 0.30. X-ray diffraction pattern of BFT90 revealed a mixture of hexagonal BaTiO₃ and monoclinic Ba₂Fe₂O₅ phases. Conductivity of BFT100x increased with increase in temperature and Fe concentration. This increase in conductivity originated from the substitution of Ti⁴⁺ with Fe³⁺, which increased the oxygen vacancy of the system. A maximum conductivity of 3.1 × 10² S/m was obtained for BFT90 at 1100 K. Activation energy calculated by resistivity decreased with increase in Fe concentration. Seebeck coefficient of BFT100x increased with increase in temperature and decreased with increase in Fe concentration for x = 0.40–0.80. These results suggested an increase in carrier concentration. Seebeck coefficient of BFT90 was larger than that of BFT80, which is attributable to the mixed structure of BFT90. Power factor of BFT100x increased with increase in temperature and Fe concentration. These results suggested that BaFe_xTi_1−xO_3−δ with mixed structure of hexagonal and monoclinic phases have good potential for enhancing the thermoelectric properties of BaFe_xTi_1−xO_3−δ ceramics.

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We have prepared composites with anisotropic microstructure consisting of silver nanoparticles and zinc oxide pillars using an oblique angle deposition technique, and examined the optical response originating from their anisotropic morphology. The sample was obtained in three steps. First, the assembly of silver nanoparticles was prepared on a silica glass substrate by electron-beam deposition of the silver thin film and subsequent heat treatment. Next, zinc oxide was obliquely grown by using a pulsed laser deposition. Finally the zinc oxide was crystallized by the post annealing to make an array of inclined pillars grown on the top of the silver nanoparticles. The structure and morphology of the composites were elucidated by a combination of X-ray diffraction analysis and transmission electron microscopy. Optical rotation spectroscopy clarifies that the composite shows optical birefringence due to its inclined pillar morphology. The optical rotation spectrum exhibits two peaks, one being associated to the localized surface plasmon resonance of the silver nanoparticles and the other the excitons in the zinc oxide pillars. The present fabrication method is simple and can be applied to obtain anisotropic composites with relatively large dimensions.

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In this study, we investigated the hardening processes and compressive strengths of binary and ternary calcium phosphate cements based on β-tricalcium phosphate [Ca₃(PO₄)₂] (β-TCP) ground by a mortar grinder. The cements were prepared by adding tetracalcium phosphate [Ca₄(PO₄)₂O] (TTCP) and/or calcium hydrogenphosphate dihydrate [CaHPO₄·2H₂O] (DCPD) to the ground β-TCP, which hardened on mixing with disodium hydrogenphosphate [Na₂HPO₄] aqueous solution. The binary cement β-TCP/TTCP with a molar ratio of 2:1 showed a compressive strength of 35 MPa after hardening, which is based on a 1-day acid–base reaction. The ternary cement β-TCP/TTCP/DCPD with molar ratios of β-TCP (50–60%), TTCP (20–30%), and DCPD (14–20%,) showed early hardening and an adequate compressive strength of 30–43 MPa after a 1-day reaction. In particular, the ternary cement with a molar ratio of 3:2:1 (β-TCP:TTCP:DCPD) showed compressive strengths of 17, 43, and 56 MPa after 1 h in air, and 1 and 7 days’ soaking in saline solution, respectively. These ternary cements hardened to give well-connected acicular apatite crystals. The hardening process involved hydrolysis of the ground β-TCP and acid–base reactions of β-TCP/TTCP and DCPD/TTCP.

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Development of all solid-state Li secondary based on the use of dry polymer or inorganic electrolytes is vital as they will be free of solvent leakages and improve inflammability. However, both are still under development for many years due to low ionic conductivity, poor mechanical property and/or large internal impedance associated to poorly defined interfaces. In this paper, we report on a preparation and physicochemical property of mesoporous silica (MPS)/Li conductive polyethylene oxide (Li-PEO)-based polymer hybrid electrolytes (MPS+Li-PEO), and electrochemical performance of the Li/MPS+Li-PEO/LiFePO₄ cell. The hybrid electrolytes showed an improvement of Li⁺ transportation number and a decrease of melting point and glass transition temperature, indicating a positive hybrid effect, or deviation from rule-of-mixtures behavior. The Li/MPS+Li-PEO/LiFePO₄ cell showed a stable charge–discharge capacity of >70 mA h g⁻¹ for 100 cycles at moderate temperature of 60°C and rate of 0.2 C, whereas severe capacity fade began after several of cycles for the cell using conventional Li-PEO electrolyte. AC impedance measurements revealed that the interface Li exchange between electrode and electrolytes related to the stable cyclic performance for the cell using hybrid electrolytes.

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In this study, we have tried to prepare porous Al₂TiO₅ ceramics with potato starch as a pore-forming agent at relatively low sintering temperatures by reactive sintering method using fine-grained starting materials. α-Al₂O₃ powder (0.1 µm) and TiO₂ rutile powder (2 µm) were wet-ball milled in ethanol for 2 h in a planetary ball-mill. The mixed powder was blended with 5–30 wt % of potato starch powder in an agate mortar with ethanol. Green samples with no binder were sintered at 1300–1500°C for 2 h in air. The sample contained finer closed pores (<1 µm) as well as the larger pores (5–80 µm). The finer microstructure formation can be explained by (1) the local heating effect via the combustion of potato starch, and (2) water vapor-assisted effect.

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Planar resistive type SO₂ sensors based on V₂O₅/WO₃/TiO₂ (VWT) have been reported to respond well to SO₂ but with large cross-effects of NO and NH₃. In this study, we added a porous Pt/alumina cover layer on a VWT film in order to decrease the cross sensitivities. The sensor response to SO₂ is hardly affected by the Pt/alumina layer in the case of VWT sensor with 3.0 wt % V₂O₅ with Au electrodes, while the Pt/alumina layer affects the response of other VWT sensors. The VWT sensor (3.0 wt % V₂O₅) with Au electrodes with the porous Pt/alumina cover layer shows much smaller responses to CO, H₂, H₂O, NH₃, and NO compared with the sensor without Pt/alumina cover layer. The porous Pt/alumina cover layer has a potential to improve the selectivity of the VWT sensor.

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ZnO crystals with controllable morphology were synthesized by employing the different source materials. A simple thermal evaporation technique was employed to synthesize ZnO crystals. Morphologies such as tetrapods and inverted cone-shaped rods were realized experimentally through thermal evaporation of Zn and ZnS powder, respectively. The morphology of ZnO crystals could also be controlled by designing the source material. Peculiar ZnO tetrapods with inverted cone-shaped legs were obtained via thermal evaporation of a mixture of Zn and ZnS powder mixed with a certain ratio. The intensity of green emission in the photoluminescence spectrum increased with the increase in the ratio of ZnS to Zn in the source material.

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Cubic silicon nitride (c-Si₃N₄) was prepared at 37–38 GPa and ~1773 K by shock compression of residues of polysilazane, perhydropolysilazane (PHPS), pyrolyzed at 873, 1073 and 1273 K for 2 h. The residues pyrolyzed at 873 and 1073 K were amorphous materials, while the residue pyrolyzed at 1273 K consisted mainly of crystalline α-Si₃N₄. The relative amount of c-Si₃N₄ was the smallest in the shock-compressed product of the residue pyrolyzed at 1273 K, indicating that use of amorphous residues is advantageous for formation of c-Si₃N₄.

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Single-crystal PbMoO₄ nanorods with diameters of 70–80 nm and lengths of about 300–400 nm have been successfully obtained via a surfactant-free sonochemical method. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and electron diffraction (ED). It is found that the precursor played a key role in the preparation of PbMoO₄ nanorods. PbMoO₄ nanorods can be successfully obtained when PbCrO₄ nanorods were used as precursor. Once PbCrO₄ were replaced with Pb(NO₃)₂, PbMoO₄ nanoparticles were formed. The synthesis mechanism was also discussed. It is rational to expect that some other one-dimensional metal molybdates may also be synthesized by this method.

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