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Polycrystalline powder samples of the zinc-substituted strontium cobalt Z-type hexaferrite: Sr3Co2-xZnxFe24O41 (x = 0, 0.5, 1.0, 1.5 and 2.0) were prepared by the polymerizable complex method. Their Mossbauer spectra were measured at room temperature with conventional constant-acceleration spectrometer. Obtained Mossbauer spectra were numerically separated into six discrete components. The relationship between Mossbauer parameters and magnetic properties has been discussed. From the values of the isomer shift, it was found that the iron ion in Sr3Co2-xZnxFe24O41 is trivalent with high spin. The value of the quadrupole splitting increased and changed the sign from negative to positive for the sample with x = 1.5. From the results mentioned above and the analysis of the complex permeability spectra, the magnetocrystalline anisotropy of Sr3Co2-xZnxFe24O41 is changed from c-plane to c-axis at Zn content between x = 1.0 and 1.5. The compositional dependence of the areas of each subspectra showed that Zn2+ ions occupy the sites with down spin at the compositional range of x = 0.0–1.0.

Microrod-type CoFe2O4(CFO)/Bi3.25Nd0.65Eu0.10Ti3O12(00l) (BNEuT) composite thin films were fabricated by a combination of high-temperature sputtering, reactive ion etching, and metal organic chemical vapor deposition (MOCVD) on Pt(100)/MgO(100) substrates. The substrate temperature for MOCVD was varied from 450 °C to 600 °C to examine its effect on the structural, magnetic, and ferroelectric properties. The substrate temperature affects the compressive stress at the interface between the CFO and BNEuT. The surface morphology changed drastically above 550 °C. The room temperature magnetization–magnetic field hysteresis loops for the films showed clear ferromagnetic hysteresis loop and magnetic shape anisotropy. The room temperature polarization–electric field (P−E) hysteresis loops for the films showed a clear ferroelectric hysteresis loop, and slightly leaky P−E hysteresis loop. The coercive field increased slightly with increasing substrate temperature. Judging from the structural, ferromagnetic, and ferroelectric properties, the film deposited at 550 °C has potential as an excellent multiferroic material.

By depositing a high-density ferromagnetic cobalt ferrite (CFO) layer in the rod gaps in c-axis-oriented epitaxial Bi3.9Nd0.3Eu0.1Ti3O12.5 (BNEuT) films with a microrod morphology by metal organic decomposition (MOD), microrod-type multiferroic CFO/BNEuT composite thin films were fabricated. The effects of the soaking time during the annealing treatment on the structural, magnetic, and ferroelectric characteristics of the resulting composite films were investigated. The MOD-deposited and annealed films contained single-phase CFO with a cubic inverse-spinel structure. The Fe/Co ratio for the annealed samples gradually increased with increasing soaking time from 3 to 10 h, because of the transfer of Co atoms from the bottom layer during high-temperature aging. The CFO/BNEuT composite films annealed at 700 °C for 1–10 h exhibited magnetic shape anisotropy, and annealing under a nitrogen atmosphere was effective for improving the magnetic properties. Little soaking time dependence was found for the remanent polarization, which was almost constant at 1.0–1.5 μC cm−2.

The piezoelectric properties of high-temperature-poled high-density solid solutions with compositions of xPb(Mn1/3Nb2/3)O3-yPbZrO3-zPbTiO3 (xPMnN-yPZ-zPT; PMnNZT) with x = 0.020–0.180, y = 0.420–0.580, and z = 0.400–0.560 were investigated by using the resonant-antiresonant frequency method. The two optimal compositions that exhibited large values of d 33 · Q m (p), where d 33 is the piezoelectric coefficient (longitudinal length mode) and Q m (p) is the mechanical quality factor (radial mode) for high-power piezoelectric applications were x = 0.040, y = 0.540, and z = 0.420 in the rhombohedral and the morphotropic phase boundary (MPB) regions and x = 0.095, y = 0.435, and z = 0.470 in the MPB and the tetragonal regions. By comparing the maxima in d 33 · Q m (p) for high-temperature (HT)-poled PMnNZT samples with the maxima in d 33 · Q m (p) for room-temperature (RT)-poled PMnNZT samples that had been previously reported, the ratio of d 33 · Q m (p) HT /d 33 · Q m (p) RT was approximately 1.8, exhibiting a significant improvement due to HT-poling treatments.

High-density solid solutions with compositions of (1−x)(Bi1/2Na1/2)TiO3−xBa(Mn1/3Nb2/3)O3 (BNT-BMN), with x = 0 − 0.06, were prepared by using the conventional ceramic fabrication process. The optimal composition that yielded the best piezoelectric properties for high-power piezoelectric applications was investigated. X-ray diffraction (XRD) analyses of BNT-BMN with x = 0 − 0.06 suggested that the rhombohedral-pseudocubic morphotropic phase boundary (MPB) for this material system is in the compositional region 0.035 ≤ x ≤ 0.04 at room temperature. A hard-mode BNT-BMN with x = 0.03, which lay on the rhombohedral side near the MPB region, exhibited excellent piezo- and ferroelectric properties.

Using a a-axis-oriented epitaxial (Bi3.25Nd0.65Eu0.10)Ti3O12 (BNEuT) thin films with a microplate-like shape as a ferroelectric pillar material, micropillar-type CoFe2O4 (CFO)/ BNEuT(h00)/Nb:TiO2(101) composite multiferroic films were fabricated by metal organic chemical vapor deposition. The deposition time was varied from 90–150 min to examine its effect on the structural, ferroelectric, and ferromagnetic characteristics of the films. All the films exhibit single-phase cobalt ferrite with a cubic inverse spinel structure. The deposited CFO films have a similar columnar structure with a comparatively good step coverage of 37–66%. The room-temperature magnetizationmagnetic field hysteresis loop of the films showed a clear ferromagnetic hysteresis loop, and coercivity decreased from 1.1 to 0.9 kOe with increasing the deposition time. The room-temperature polarization electric field hysteresis loop of the films showed a ferroelectric hysteresis loop, and the effect of the leakage current was the smallest for a deposition time of 120 min.

CoFe2O4 (CFO) thin films were deposited on (Bi3.25Nd0.65Eu0.10)Ti3O12 (BNEuT) micropillar films by a non-aqueous sol-gel method. The pitch size of 2–5 μm in the micropillar films used as ferroelectric pillars, and 5 and 15 CFO deposition cycles were examined for high density of CFO nanoparticles. All the CFO films formed by five deposition cycles on BNEuT micropillar films with a pitch size of 2–5 μm were composed of mostly single-phase CFO with a cubic inverse-spinel structure. All the CFO films deposited on the four BNEuT micropillar films were highly dense and had excellent surface flatness, based on surface field-emission scanning electron microscope observations. Based on the structural, magnetic and ferroelectric characteristics, the optimal pitch size for achieving a high density of CFO nanoparticles was 5 μm, and the optimal number of CFO deposition cycles was five.

a- and b-axis-oriented Bi3.25Nd0.75Ti3O12 (BNT) nanoplates, 3.0-µm thick, were fabricated on conductive Nb:TiO2(101) substrates with 0.79 mass% Nb at 650 °C by high-temperature sputtering. Successively, the fabrication of inorganic-organic composites was carried out by introducing an epoxy resin to the spaces between the BNT nanoplates. The fourier transform infrared spectroscopy (FTIR) and the energy dispersive X-ray (EDX) elemental mapping results confirmed that the fabricated composites were inorganic-organic hybridized materials with cured epoxy resin introduced into the spaces between the BNT nanoplates. Piezoelectric response measurements of the fabricated BNT-epoxy resin composites by using piezoresponse force microscopy (PFM) showed that the composites have potential as piezoelectric microelement materials.

Electrochemical oxygen reduction behavior for a half cell composed of a mixed ionic and electronic conducting (MIEC) oxide and an oxygen excess-type solid electrolyte was investigated. A perovskite-type MIEC oxide, (La 0.6 Sr 0.4 )(Co 1− y Fe y )O 3− δ (LSCF), was employed as a base material for an electrode catalyst of oxygen reduction reaction. As an electrolyte, Al-doped lanthanum silicate [La 10 (Si 5.8 Al 0.2 )O 26.9 (ALSO)] was used, which is a new class of oxide ion conductors with apatite-type structure. The evaluated polarization resistance, R pol , for the reaction largely depended on y , and the minimum resistance was obtained for y = 0.2. The R pol value was 0.3 Ω cm 2 at 1073 K in ambient air [ P (O 2 ) = 2.1 × 10 4 Pa] for y = 0.2. To improve the performance, introduction of silver nano-particles onto the LSCF particles was studied. With the Ag-modification, R pol at 1073 K could be minimized toward 0.08 Ω cm 2 . The cathodic overpotential of the electrode evaluated from DC polarization at 1073 K was 18 mV at 0.1 A cm −2 .

Electronic as well as ionic conducting properties for oxyapatite-type solid electrolytes based on lanthanum silicate, La9.333 + xSi6O26 + 1.5x (LSO) were investigated in the oxygen-excess region (x > ca. 0.3). We have found that the oxygen excess-type LSO (OE-LSO), namely La10Si6O27 on weighted basis, exhibited high conductivity, and substitution of the Si-site of LSO with some dopants (Mn+) had a positive effect toward the conducting property. Furthermore, it was also found that addition of a very small amount of iron ions into the M-doped OE-LSO, La10(Si6-yMn+y)O27-(2–0.5n)y, improved its conductivity. On the other hand, replacement of the La-site with various ions for La10(Si6-yMn+y)O27-(2–0.5n)y did little to improve conductivity. The electronic transport numbers for Al-doped OE-LSO with Fe-addition, (1-α){La10(Si5.8Al0.2)O26.9}-α(FeOγ), evaluated with the Hebb–Wagner polarization method were very low: i.e., 1.1 × 10− 3 and 2.9 × 10− 3 under P(O2) = 1.1 × 104 Pa at 1073 K for α = 0.00 and 0.005, respectively. Conductivity for each sample was unchanged under humidified atmosphere at 1073 K sustained for over 50 h, revealing that both compositions were chemically stable. It was concluded that 0.995{La10(Si5.8Al0.2)O26.9}–0.005(FeOγ) is suitable for the fuel cell electrolytes because of its high and almost pure ionic conductivity, and its good chemical stability under humidified as well as reducing conditions.

Influences on electrical property and phase relationship of oxyapatite-type solid electrolytes based on lanthanum silicate (LSO) were investigated by addition of a small amount of transition metal elements. It was revealed that a very small amount of 3d-transition metal additives into the La-excess-type, i.e., oxygen-excess-type Al-doped LSO, La10(Si5.8Al0.2)O26.9, changed its electrical conductivity. Some metals such as iron and chromium showed a positive effect for an increase in conductivity. The specimen with a nominal composition of 0.995{La10(Si5.8Al0.2)O26.9}–0.005(FeOγ), showed the maximum electrical conductivity among the specimens measured in this study. Formed phases of oxygen-excess-type Al-doped LSO based materials were found to be altered even by addition of a small amount of transition metal oxides. La-rich impurity phases such as La(OH)3 and La2SiO5 are usually detected in the oxygen-excess-type LSO, whereas no formation of La-rich impurity phases was confirmed in the case of iron addition. These results suggest that the enhancement of electrical conductivity by iron addition is due to a disappearance of the La-rich impurity phases as insulators and/or an increase in the concentration of oxygen interstitial carriers within the LSO phase.

Phenyltriethoxysilane (PhTES) and tetraethoxysilane (TEOS) coatings [xPhTES·(100 − x)TEOS (mol%)] (x = 0 − 80) were prepared on polycarbonate (PC) substrate, and adhesion, surface hardness and distribution of phenyl groups were studied. The coatings with more than 60 mol% of PhTES showed good adhesion (≈ 100%), and the pencil hardness of PC substrate (4B) improved to 2B or B after the coatings. Bulk gels with the same compositions were also prepared, and distribution of phenyl groups were estimated using fourier transform infrared (FT-IR) spectroscopy (KBr method for bulk gels and attenuated total reflection (ATR) method for coatings). A significant difference for the distribution of phenyl groups was clearly observed between bulk gels and coatings, suggesting PC substrate affects the distribution of phenyl groups in coatings. The adhesion and FTIR results revealed that there is an interaction caused by π-electrons between benzene rings on PC substrate and phenyl groups of PhTES-TEOS coatings. It was found that the adhesion was strongly correlated with the phenylsilsesquioxane networks formed around PC substrate side.

c-axis-oriented epitaxial 1.2-μm PbMg0.047Nb0.095Zr0.416Ti0.442O3 (PMNZT) films with a comparatively large piezoelectric coefficient d 33 (=90 pC/N) fabricated on Pt(100)/MgO(100) substrates by metalorganic decomposition were treated by hot isostatic pressing (HIP). The HIP-pressure dependence on d 33 of the 1.2-μm PMNZT samples treated at 850°C for 1 h under Ar/O2 mixed gas pressures of 49–196 MPa was investigated. The d 33 value of the HIP-treated samples was almost constant (=60 pC/N), independently of the amplitude in pressure. Although the HIP treatment hardly contributes to an improvement on d 33, it can be expected to minimize the deviation of d 33 and provide highly-reliable piezoelectric elements.

The 3.0-μm (Bi3.25Nd0.75)Ti3O12 (BNT-0.75) films were fabricated on IrO2(101)/ Al2O3(012) substrates by high-temperature sputtering. The XRD pole figure demonstrated that a 3.0-μm BNT-0.75 film deposited on the IrO2 electrode is grown with a strong 10° off-(100)/(010) and a weak (101)/(011) orientations of threefold symmetry. The BNT films represented random orientation near the bottom IrO2 electrode and the intermediate part of the film. In the upper part of the BNT layer, the existence of a- and b-axis-oriented rod-shaped crystals with approximately 0.25 μm width were confirmed. In contrast, the BNT film deposited directly on the Al2O3(012) substrate represented almost completely a- and b-axis orientations in a whole BNT layer.

A crystalline rutile titanium oxide (TiO2)-dispersed porous glass–ceramic was successfully prepared by the phase separation of aluminosilicate-based glass. A rutile TiO2 crystal was clearly observed after the heat treatment of 20TiO2·29SiO2·13Al2O3·28CaO·5MgO·2P2O5·2B2O3·1ZrO2 (mol%) glass at 900°C for 15 h. The glass–ceramic obtained was then treated with an acid solution (3 mol/dm3 nitric acid) to leach its soluble phases. The acid-treated sample became porous, and the glass–ceramic obtained had a large surface area of 74 m2/g. The porous glass–ceramic adsorbed methylene blue (MB) rapidly, and the adsorbed MB was photodecomposed by ultraviolet irradiation.

Porous glasses (PGs) with 4 nm in diameter pores were prepared utilizing a spinodal-type phase separation of Na2O–B2O3–SiO2 glass, and their surface was modified using titanium tetraisopropoxide. Fourier transform infrared measurements revealed that the absorbance for strong hydrogen-bonding OH groups increased after the modification. Bond overlap population (BOP), which is directly related to the strength of the covalent bond, between O and H of OH groups were calculated using density functional theory and first-principles calculations. BOPs decreased by the introduction of Ti atoms on pores. The proton conductivity at 80°C and 90% relative humidity of the titania-modified PG was about five times higher than that of unmodified PG.

Highly dense pellets of an oxygen excess-type lanthanum silicate (La 9.333+x Si 6 O 26+1.5x , x > ca. 0.3, OE-LSO) were successfully fabricated, and their electrical conducting properties were studied. The replacement of Si by Al enhanced its conductivity, and the slightly Al-doped OE-LSO specimen [La 9.62 (Si 5.79 Al 0.21 )O 26.33 ] had excellent features as a solid electrolyte; that is, it had high ionic conductivity and was highly stable under reducing as well as oxidizing conditions at 873-1073 K. In addition, the ionic transference number was higher than 0.99. In the fuel cell utilizing this electrolyte (0.72 mm thick), (La 0.6 Sr 0.4 )(Co 0.2 Fe 0.8 )O 3―δ cathode, and Ni―Ce 0.9 Gd 0.1 O 1.95―δ anode, good performance with the maximum power density of ca. 0.25 W cm ―2 was obtained at 1073 K. In addition, this electrolyte also had high compatibility with these conventional mixed conducting electrodes, according to an analysis near the electrode/electrolyte interfaces after the fuel cell test.

Porous glasses with the surface area of ≈300 m2/g were prepared utilizing the spinodal-type phase separation of Al2O3-doped Na2O–B2O3–SiO2 glasses. The proton conductivity under humidified conditions and their relations to the amount of doped Al2O3 were investigated. The proton conductivity of the glass doped with 2 mol % of Al2O3 was about 6 times higher than that of the undoped glass. Fourier transform infrared (FT–IR) measurements revealed that the absorption by the strongly hydrogen-bonded OH groups increased with increasing the amount of Al2O3. Bond overlap populations (BOPs), which are directly related to the strength of the covalent bond, between the surface OH groups and an absorbed water molecule were calculated based on a first-principles theory (DVXα). The BOP values between O and H of the surface OH groups decreased by the Al2O3 doping. Substitution of Si atoms of the Si–O–Si silica networks with Al atoms, and formation of the Al–OH–Si bonds effectively improved the proton conductivity under humidified conditions.

On the basis of experimental data on the piezoelectric pinpoint composition of ceramics of the ternary system Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 (PMNZT), which we investigated in our previous report, epitaxial PbMg0.047Nb0.095Zr0.416Ti0.442O3 thick films with thicknesses ranging from 0.4 to 1.9 m were fabricated on Pt(100)/MgO(100) substrates by metalorganic decomposition. The film- thickness dependence on the structural and electrical properties (dielectric, piezoelectric and ferroelectric properties) was investigated. All PMNZT films exhibited a highly uniform (001) orientation, regardless of the film thickness. The cross-sectional transmission electron microscope micrographs and all the physical data suggest that high-density PMNZT thick films with a thickness  1.0 m can be expected to function as highly electrically insulating capacitors with high potential for piezo- and ferroelectric applications.

After depositing amorphous (Bi0.5La0.5)(Ni0.5Ti0.5)O3 (BLNT) films on BLNT seed layer/Pt(100)/ MgO(100) substrates by room-temperature sputtering, the crystallization of the perovskite-struc- tured films has been tried by hot isostatic pressing (HIP). The samples with a single-phase perovskite structure HIP-treated at 800°C for 1 h under gas pressures of 0.51.0 MPa showed good crystallinity of  = 0.960.98 without accompanying the precipitation of the secondary phase. It was confirmed that a large root mean square roughness value of 44.2 nm for the sample HIP-treated at 800°C for 1 h under gas pressure of 0.1 MPa is due to innumerable Bi4Ti3O12-like rod-shaped grains precipitated in the film surface, based on atomic force microscopy. It is shown that the BLNT sample HIP-treated at 800°C for 1 h under gas pressure of 1.0 MPa exhibits the best hysteresis loop shape with a remanent polarization of Pr = 5 C/cm2 and a coercive field of Ec = 150 kV/cm of the six.

Porous glasses with 4 nm diameter pores were prepared utilizing a spinodal-type phase separation of Na2O−B2O3−SiO2 glass, and the surface was modified by using mercaptoalkyltrimethoxysilane with different alkyl chain length ((CH3O)3Si(CH2)n-SH, n = 1, 3, 6, 10). The thiol groups (−SH) were oxidized with H2O2 to obtain −SO3H groups. The amount of the introduced silane coupling agents and the reactivity with H2O2 inside the nanopores drastically changed by changing the alkyl chain length (n). The molecular structures, charge distributions, bond overlap populations (BOP) between Si and alkyl chains, as well as net charges of thiol groups were calculated based on a density functional theory and a first-principle theory (DVXα). The charge distribution calculations suggest that oxygen atoms on pores affect significantly for both the net charge of S and BOP, and the BOP values were directly related with the in situ oxidation reactivity of silane coupling agents. The porous glasses modified with the silane coupli...

Electrical properties of an apatite-type oxide ionic conductor, lanthanide silicates (Ln9.33+xSi6O26+1.5x, LnSO; Ln = La or Nd) which are expected as novel solid electrolytes for the intermediate-temperature solid oxide fuel cell (IT-SOFC) have been investigated in detail. Its total electrical conductivity was almost P(O2)-independent, while a slight dependence of the conductivity on P(O2) was observed under high P(O2) conditions at high temperatures. The conductivity for La10Si6O27 was much higher than that for Nd10Si6O27. This was probably due to a difference in an accepting capacity of excess oxide ions. The excess oxide ions, formed by introducing the excess Ln elements (x), play an important part in oxide ion conduction. In the case of Ln = Nd system, formation of the excess oxide ions was blocked probably due to its smaller lattice volume than that of Ln = La system.

The Bi(Zn0.5Ti0.5)O3–PbTiO3 solid solution was modified by the replacement of A- and B-site cations in the perovskite crystal with lanthanum and magnesium so as to realize ferroelectric and piezoelectric functionalities. This substitution reduces the covalency and increases the ionic bonding in the crystal. The tetragonal perovskite solid solution with composition 0.33(Bi0.7La0.3)(Zn0.15Mg0.35Ti0.5)O30.67PbTiO3 was demonstrated to exhibit ferroelectric and piezoelectric functionalities with high Curie temperature (Tc = 300 °C) and parameters of relative permittivity (e33T/e0 = 410), remanent polarization (Pr = 30 µC/cm2), coercive field (Ec = 47 kV/cm), piezoelectric coefficient (d33 = 94 pC/N), and tolerance factor (t = 0.993). This material is thus suitable for use as a high-temperature piezoelectric with performance comparable to that of Pb(Zr,Ti)O3 (PZT).

Dense solid electrolytes based on lanthanum silicate, La 10 Si 6 O 27 (LSO) were fabricated and their electrical conducting properties were studied in detail under various atmospheres, including H 2 O- or D 2 O-humidified argon. The family showed almost P (O 2 )-independent conductivity, while a slight increase in conductivity with increasing P (O 2 ) was observed in the high temperature region. The ionic transport number evaluated from the O 2 /Ar oxygen concentration cell was higher than 0.964 at 1073–1273 K. The current–voltage characteristic of the fuel cell employing the dense LSO electrolyte was also investigated.

A proton-conducting solid electrolyte membrane based on polyvinyl phosphonic acid (PVPA) and 3-glycidoxypropyltrimethoxysilane was developed via the sol–gel process. The electrical conductivity of the organically modified membrane obtained with optimum composition was 3.7 × 10−2 S/cm at 80°C under 90% relative humidity (RH), which was sufficient for its practical use as a solid electrolyte for fuel cells. In addition, a membrane based on polyphosphoric acid (PPA) and alkoxysilane was fabricated for comparison, by employing polyethylene glycol dimethacrylate (PDM) as an additive. Although the PPA system (with PDM) exhibited similar electrical conductivity to the PVPA system, the latter had superior mechanical strength and flexibility. Furthermore, the PVPA-based membrane with optimum composition was thermally stable up to ca. 200°C. The membrane exhibited electrical conductivity of 1.3 × 10−2 S/cm at 125°C even under 30% RH, which was similar to that of Nafion® at the same temperature under 100% RH.

A proton-conducting solid electrolyte membrane based on polyvinyl phosphonic acid (PVPA) and 3-glycidoxypropyltrimethoxysilane was developed via the sol–gel process. The electrical conductivity of the organically-modified membrane obtained with optimum composition was 3.7 × 10 − 2 S·cm − 1 at 353 K under 90% of relative humidity (RH), which was sufficient for its practical use as a solid electrolyte for fuel cells. In addition, a membrane based on polyphosphoric acid (PPA) and alkoxysilane was fabricated for comparison by employing polyethylene glycol dimethacrylate (PDM) as an additive. Though the PPA system (with PDM) exhibited similar electrical conductivity to the PVPA system, the latter had a superior mechanical strength and flexibility. Furthermore, the PVPA-based membrane with optimum composition was thermally stable up to ca. 473 K. The membrane exhibited electrical conductivity of 1.3 × 10 − 2 S·cm − 1 at 398 K even under 30% of RH, which was similar to that of Nafion® at the same temperature under 100% of RH.

The epitaxial growth and formation mechanism of the partially La- and Nd-substituted perovskite structures, and the ferroelectric properties of bismuth lanthanoid nickel titanate [(Bi1-xLax)(Ni0.5Ti0.5)O3; BLNT and (Bi1-xNdx)(Ni0.5Ti0.5)O3; BNNT] based solid solution films deposited on Pt(100)/MgO(100) substrates by rf sputtering have been investigated using X-ray diffraction, transmission electron microscope, and polarization–electric field hysteresis loop measurements. BLNT samples at x≥0.3 and BNNT samples at x≥0.4 were confirmed to have a single-phase perovskite structure. This small difference is speculated that it is related to metal–oxygen bond dissociation energy. The sample substituted with La exhibited the best hysteresis loop at x = 0.5 with a remanent polarization of Pr = 12 µC/cm2 and the sample substituted by Nd exhibited the best hysteresis loop at x = 0.4 with a remanent polarization of Pr = 2 µC/cm2.

Epitaxial Pb(Zr 0.3 Ti 0.7 )O 3 films with different thicknesses and a preferential c-axis orientation were successfully fabricated on PbTiO 3 /Pt(100)/MgO(100) substrates from an amorphous state by hot isostatic pressing (HIP). Based on the results of X-ray pole figures, all the PZT films with ferroelectric layer thicknesses of 100–300 nm after HIP were almost completely epitaxial. Since the 200-nm-thick PZT film has the largest initial pulse-derived switchable polarization and an intermediate reduction rate of the three samples, its polarization fatigue characteristics are relatively superior to these of the others. From the measurements of static imprint characteristics, the observed shifts of the PZT samples apparently decreasing with decreasing film thickness.

Improvement of the dielectric properties of inorganic-organic composites with 0–3 connectivity is attempted by silanol treatment of the inorganic filler surface. The inorganic filler has high relative permittivity and low dielectric loss, and is coupled with epoxy resin in the composites. Silanol treatment of the filler is performed by adding a small amount of water to a silane coupling agent, and the dielectric properties of the resultant composite are found to be comparable over a filler content range of 50–80 vol% to the properties of composites fabricated using filler treated by toluene reflux. On the basis of the relationship between relative permittivity and inorganic filler content, it is shown that the experimentally determined properties of the composites are in good agreement with theoretical values calculated using Nielsen's complex rule.

A mixed ionic and electronic conducting hydrogen separation membrane, which consisted of proton-conductive oxide and metallic palladium, was fabricated. A porous alumina tube was employed as a support, and proton-conductive oxide particles were introduced into a microporous top layer of the support by an impregnation method. Palladium particles were deposited into the same porous layer by chemical vapor deposition. Hydrogen permeated preferentially via the membrane thus obtained with a hydrogen permeance ( P H 2 ) of 1.2 × 10 − 9 mol·m − 2 ·s − 1 ·Pa − 1 at 873 K. Selectivity for hydrogen ( P H 2 / P N 2 ) increased with the operating temperature due to an increase in proton conductivity of the membrane, and P H 2 / P N 2 = 5.7 was attained at 873 K.

Global warming is becoming an urgent environmental problem. Among CO2 separation processes such as cooling and condensation, solvent scrubbing, adsorption and membrane, membrane separation process is utilized for the flue gas emitting from electric power generation plant; iron works plant and cement plant etc. Another important field is removal of CO2 of natural gas and coal gas [1, 2]. CO2 storage needs to have low environmental impact, low cost and conform to national and international laws. The main optioned for storing CO2 underground which have been examined by the IEA Greenhouse Gas R&D Programme are storage in depleted oil and gas reservoirs, deep saline reservoirs and unminable coal seams [3]. A key technology to attain the membrane separation process is the development of a highly CO2-selective separation membrane with chemical and thermal stability [4]. Recently, active research has been carried out on inorganic-organic nanohybrids prepared by the sol-gel method, which gives products with good thermal and chemical stability and allows formation of high quality membranes [5–8]. Here, nanohybrid means an organic polymer is dispersed at the molecular level in a SiO2 matrix composed of siloxane networks. The most common method to obtain the nanohybrid utilizes hydrogen-bonding interactions between polar functional groups of organic polymers and silanol groups of the silica matrix. Chujo et al. reported that the polymers could be successfully produced without formation of hydrogen bonds between the polymer molecules. For example, poly(2-methyl-2-oxazoline), poly(N-vinylpyrrolidone) etc. could be dispersed in a silica matrix at the molecular level [9]. In the case of the branched polyether, the polymer may be dispersed at the molecular level through hydrogen bonding between the silanol groups of the silica matrix and the polyether oxygens as indicated in Fig. 1. The membrane formed with the branched polyether shows high CO2 selectivity at room temperature (selectivity of CO2 against N2 is 50 at 308 K). However, the selectivity readily decreases at above room temperature [10]. In this paper, we report a CO2-selective inorganic-organic nanohybrid membrane with high chemical and thermal stability prepared from the branched polyether. The typical preparation process of the sol was as follows. To prepare a 5 wt% branched polyether membrane, the sol composition was branched polyether/tetraethoxysilane (TEOS)/acetonitrile = 1:69:465 (weight ratio). The branched polyether was sourced from Daiso Co. Ltd. The molecular weight of the polymer is 520,000 and its molecular structure is shown in Fig. 1. Here, wt% of branched polyether indicates the weight percent of branched polyether relative to the amount of branched polyether and silica hydrolyzed TEOS. Acetonitrile was employed as solvent. In order to perform the hydrolysis, HNO3 and H2O were also added in the following mol ratios: TEOS/HNO3/ H2O = 1:0.01:2. In a typical synthesis, the homogeneous sol was prepared by stirring a mixture of TEOS, T. Yazawa (&) M. Kishimoto T. Inoue A. Mineshige M. Kobune Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji-City, Hyogo 671-2201, Japan e-mail: yazawa@eng.u-hyogo.ac.jp

Crystalline Pb(Zr0.3Ti0.7)O3 films with (001), (101) and (111) orientations were successfully fabricated on PbTiO3(PT)/Pt(111)/SiO2/Si(100) substrates, crystallized from an amorphous state by hot isostatic pressing (HIP). The crystallized PZT films had a preferential (001) orientation, with the degree of c-axis orientation α in the range of 0.49 to 0.61. From measurements of fatigue and imprint characteristics, PZT films HIP-treated at 1.5 MPa using a three-step (500-600-700°C) annealing program were shown to have the ability to be used as high-endurance and high-density element materials for ferroelectric random access memory (FeRAM) applications.

(Bi0.5Na0.5TiO3)0.94(BaTiO3)0.06 (BNBT-6) ceramics without additives and BNBT-6 ceramics with 0–0.8 mass% MnO2 were produced by a conventional ceramic fabrication technique. The effect of MnO2 addition on the pyroelectric coefficient, P, is investigated in detail. The figure of merit, F D, for specific detectivity of pyroelectric infrared sensors is calculated using the specific heat obtained and other pyroelectric parameters, and the optimal MnO2 content is discussed. The measurement revealed the detailed temperature dependence of the volume specific heat, and the room-temperature volume specific heat of BNBT-6 ceramics (2.8 JK−1 cm−3) is lower than that of PZT (3.1 JK−1 cm−3). The maximum P value, obtained at 0.2 mass% MnO2, was 3.5 × 10−8 C/cm2 K. The present BNBT-6 ceramics with 0.2 mass% MnO2 exhibited an excellent F D that was 4.7 × 10−9 Ccm/J. The BNBT-6 ceramics with 0.2 mass% MnO2 are highly promising as lead-free pyroelectric materials for pyroelectric infrared sensors.

Defect chemistry for a mixed conductor, La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ was studied. Samples were treated under controlled oxygen partial pressure, P (O 2 ), conditions at 1273 K [10 − 11.1 ≤ P (O 2 )/atm ≤ 1], and cooled to room temperature. Oxygen nonstoichiometry and valences of transition metal ions for the treated samples were evaluated by iodometry and X-ray absorption spectroscopy, respectively. With decreasing P (O 2 ), preferential reduction of Co 3+ to Co 2+ was observed, while iron preserved its higher valence above 3 under conditions studied. A dependency of its electrical conductivity on P (O 2 ) was discussed along with a change in concentration of oxygen vacancies and mixed valences.

Inorganic–organic composites with a 0–3 connectivity are fabricated from inorganic particles with a high relative permittivity (er) and a low dielectric loss (tan δ), and epoxy resin. The compacted powder obtained by pulverizing BaZrO3–BaTiO3–Ba(Fe1/2Ta1/2)O3 (BZTFT) ceramics has 1/12th the er and 72 times the tan δ of the ceramics. On the basis of the relationship between er and BZTFT filler content, the experimental values of the composites are determined to be in good agreement with theoretical values calculated by following Nielsen's complex rule in the filler content range of 50–80 vol %. The temperature dependence of the dielectric properties of BZTFT powder/epoxy resin (90/10, v/v) composites measured at different frequencies suggests that the temperature characteristics of the present materials correspond to the Z8T characteristics [Z8T; Electronic Industries Association (EIA) standard: ΔC/C25 °C is expressed as a rate of change within +22 and -33% in the temperature range from 10 to 150 °C] when represented by the temperature characteristics of surface-mounted capacitors. It is shown that the effect of the vacuum drying of the filler on the dielectric properties of the composites is larger than that of the silane coupling treatment and that the dielectric properties can be improved synergistically by performing both treatments.

The morphotropic phase boundary (MPB) for the PMNZT series of high-density ceramics (xPb(Mg1/3Nb2/3)O3-yPbZrO3-zPbTiO3; x=0.1-0.2, y=0.400-0.486, z=0.395-0.477) is relocated based on analyses of the dielectric, piezoelectric and ferroelectric properties of incremental compositions. The PMNZT ceramics, fabricated by the columbite route, exhibit a single-phase perovskite structure. The refined MPB line is shifted toward the PbTiO3 (PT) side in the ternary field by approximately 2.4 mol% from the position reported in the literature and the pinpoint composition for piezoelectric applications is further shifted toward the PT side by approximately 1.2 mol% from the obtained MPB line. The PMNZT 14.2/41.6/44.2 (100x/100y/100z) composition near the MPB line is shown to have properties suitable for practical applications.