小舟 正文

BiFeO3 (BFO) thin films have been prepared on SrTiO3 (001) single crystal substrates by sputtering process which is suitable for mass production. Domain structure can be controlled by off-cut angle and direction of SrTiO3 substrates. A lateral PFM and a XRD reciprocal space mapping results reveal the BFO thin film on SrTiO3 (001) with 4o off-cut along [110] is single domain. The single domain BFO shows well-saturated ferroelectric D-E hysteresis loops at R.T. © 2012 IEEE.

350-nm-thick BiFeO3(BFO) thin films have been deposited by dual ion beam sputtering on SrRuO3-buffered SrTiO3(001) substrates of 0° and 0.5° off-cut along [100] at various Bi2O3-side/Fe2O3-side beam current ratio. The BFO thin film on 0.5° off-cut STO substrate deposited at beam current ratio of 20 mA/30 mA show fully saturated D-E hysteresis loops at room temperature. The remanent polarization (2Pr) was 132 μC/cm2. Stripe domain structure was also observed in IP piezoelectric response image. It is considered that the improvement of leakage of BFO on 0.5° off-cut STO substrate is due to reduction of 109° domain walls. © 2011 IEEE.

Epitaxially a- and b-axis-oriented (Bi 3.25Nd 0.75) Ti 3O 12 (BNT-0.75) films and nanoplates have been fabricated on four Nb:TiO 2(101) substrates with 0-0.79 mass% Nb by high-temperature sputtering. It is shown from piezoresponse scanning force microscopy (PFM) measurements that the effective piezoelectric coefficients (d 33) at room temperature derived from the two linear gradients for the asymmetric displacement-voltage hysteresis loop are 11-13 pm/V. © 2011 IEEE.

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. © 2008 Elsevier Ltd. All rights reserved.

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. © 2008 Elsevier B.V. All rights reserved.

高分子型刺激応答膜は生化学や医療の分野での適用が考えられているが、熱に弱い、水や有機溶媒によって生じる膨潤からの細孔径変化、応答により膜の劣化が激しい等様々な問題が生じている。これらの問題を解決するために本研究では、表面改質した多孔質ガラスの刺激応答膜を創製し、そのpH応答性を検討した。

固体高分子形燃料電池の電解質にはパーフルオロスルホン酸系の電解質膜が使用されている。しかし、低加湿、100℃以上では著しく導電性が低下する問題がある。そのため耐熱性に優れ、無加湿・低加湿条件でプロトン導電性を有する材料が研究されている。そこで本研究では、新規のプロトン導電性材料として、ゾル-ゲル法によって、シリカ骨格中にポリビニルリン酸(PVPA)をドープさせ、有機-無機ナノハイブリッド膜を作製し、導電率を評価した。得られた膜は80℃、相対湿度90%で1×10-3S/cmの導電率を示した。また、ドープさせるPVPAを増やすと導電率も増加した。

Raman spectra of Yb-doped strontium cerate SrCe1-xYbxO3-delta were measured to evaluate their defect structure, which is much expected to influence their physical properties, such as solubility and diffusivity of protons in these oxides. In spectra, a signal showing existence of oxygen vacancies was observed at about 630 cm(-1) for doped samples. The intensity of this band increased with oxygen vacancy formation by Yb-doping and by annealing at high temperatures in dry [low P(H2O)] or reducing [low P(O-2)] conditions. Since a clear relationship between a peak intensity of the oxygen vacancy band and dopant concentration was obtained, it was found oxygen nonstoichiometry in SrCe1-xYbxO3-delta system could be evaluated using this relationship. (C) 2003 Elsevier B.V. All rights reserved.

High-density ceramics with a composition of 0.24Pb(Zn<FONT SIZE="-1">_1/3</FONT>Nb<FONT SIZE="-1">_2/3</FONT>)O<FONT SIZE="-1">₃</FONT>· 0.384PbZrO<FONT SIZE="-1">₃</FONT>· 0.376PbTiO<FONT SIZE="-1">₃</FONT> were fabricated in the sintering temperature range of 1050-1250°C by the hybrid sintering (HS) process using a 28 GHz microwave technique and hot pressing. Their physical properties were compared with those of specimens conventionally sintered (CS) at 1220°C. All the obtained HS specimens were confirmed to have the single-phase perovskite structure in the present sintering temperature range. The average grain size of the HS specimens sintered at 1100-1250°C was estimated to be around 3.1-3.8 μm; that (= 3.1 μm) of HS specimens sintered at 1100°C was larger than that (= 3.0 μm) of CS specimens. The highest electromechanical coupling factor, k<FONT SIZE="-1">_p</FONT>, reached approximately 68% in the sintering temperature range of 1130-1220°C. The remanent polarization, P<FONT SIZE="-1">_r</FONT>, and the coercive field, E<FONT SIZE="-1">_c</FONT>, of the HS specimens which exhibited a slim and rectangular P-E hysteresis loop were 44 μC/cm<FONT SIZE="-1">²</FONT> and 9 kV/cm, respectively. The highest k<FONT SIZE="-1">_p</FONT> of approximately 68% and the optimal sintering temperature of 1130°C were obtained by means of hybrid sintering.

High-density 0.5PbNi_<1/3>Nb_<2/3>O_3・0.345PbTiO_3・0.155PbZrO_3(0.5PNN・0.345PT・0.155PZ)ceramics were prepared by normal sintering with the addition of 0-3.66 mol% MnO_2 and their piezoelectric and ferroelectric properties were investigated. The effect of MnO_2 addition on significantly lowering the value of tan δ in the range of 0.37 to 0.93 mol% was proven. The lowest value (=0.37%) of tan δ was obtained in ceramics with 0.75 mol% MnO_2. Electromechanical coupling factors, k_p and k_<31>, and the piezoelectric constant, d_<31>, decreased with increasing amount of MnO_2 addition. The highest values of k_p, k_<31> and d_<31> were 0.66, 0.38 and -362 pC/N, respectively, and were obtained in the ceramics without MnO_2. The effect of MnO_2 addition on improving the value of the mechanical quality factor, Q_m, was proven in the range of 0.93 to 1.85 mol% and the improvement was around twenty times that of the sample without MnO_2. The distortion in the shape of P-E hysteresis loops for samples with MnO_2 addition suggested that oxygen vacancies formed by substituting Mn^<3+> ions for B-site ions (e.g., Ti^<4+> and Zr^<4+> ions) in the perovskite structure partially inhibited the polarization reversal in the ferroelectrics. 0.5PNN・0.345PT・0.155PZ ceramics with 0.75-0.93 mol% MnO_2 show great promise as practical materials for piezoelectric applications.

Sodium yttrium calcium-oxyhydroxyapatites powders with compositions of {[Ca9.98-0.9xY0.9Na0.02](PO4)(6)[(OH)(1.98-0.9x)O(0.9)square(0.02)],x=0.1.0(here square denotes vacancies at OH lattice sites} were synthesized by the wet process. Porous (Ca, Y, Na)-Ap (here Ap denotes apatite) ceramics having apparent porosities of around 33% were prepared at high temperature under steam flow. On the basis of the results of X-ray diffraction, all the obtained ceramics exhibited almost single-phase (Ca, Y, Na)-Ap with hexagonal structure, The impedance for all samples linearly changed from 106 to 104 Omega at 50degreesC in the humidity range of 40-95%RH. Apatites produced by substituting Y3+ and Na+ for Ca2+ in apatite structure showed an excellent conductivity. This is attributed to both ordinary protonic conduction caused by the self-dissociation of physically adsorbed water and another conduction caused by OH vacancies introduced by substituting Y3+ and Na+ for Ca-sites.

Highly c-axis-oriented PLZT films with compositions of (Pb0.925La0.075)(ZryTi1-y)(0.981)O-3, where y = 0.2-0.4, were deposited on Pt(100)/MgO(100) by the rf-magnetron sputtering, applying an intermittent deposition comprised of the repetition of deposition and nondeposition. It was confirmed that the highest figures of merit, EM. and F.M.D* for the pyroelectric IR sensors were obtained by using powders with excess PbO of 20 mol% added to PLZT, as sputtering targets in the preliminary experiment. The PLZT film with y = 0.2 exhibited the highest EM. for voltage responsivity Rv of approximately 5.3 x 10(-13) C . m/J among the three samples studied, which was around 1.8 times larger than that of PLZT ceramic with y = 0.2. The top-electrode sizes of around 500 and 250 mu m diameters were suitable for the measurement of pyroelectric properties, judging from the characteristics of the materials and the accuracy of the measuring instruments.

In this work, we studied the effect of various elements on the relative dielectric constant, epsilon(r), by adding 1-3 mol% of an element to soda glass, 15Na(2)O . 15CaO . 70SiO(2), the mother glass. The structure of the dielectric coating layer for the glass-lined discharge electrode was investigated in terms of the breakdown voltage and epsilon(r). It was found that most rare-earth elements (Pr, Lu, Eu, Gd, Sm) are more effective in increasing epsilon(r) than other elements. From the viewpoint of the breakdown voltage of the glass-lined layer, it is desirable that a cover coating with a high epsilon(r) is directly coated onto the base metal without using a ground coating with low epsilon(r), to obtain the optimum improvement effects. As the results of experiments, the 3CoO . 3NiO . 3MnO(2) . 3Pr(6)O(11). 30Bi(2)O(3). 20BaO . 50B(2)O(3) (mol%; CNMPBBB) glass was found to have a high epsilon(r), of 16 and good adhesion with steel. CNMPBBB glass is highly promising for use in glass-lined discharge electrodes.

{(1-x)Pb(Sc1/2Ta1/2)O-3-xPb(Sc1/2Nb1/2)O-3+0.5 mass% MnO2} (PST-PSN) solid-solution ceramics, where x=0.1-0.9, were prepared by normal sintering in a PbO atmosphere. The physical, dielectric and pyroelectric properties were evaluated using PST-PSN ceramics with x=0.1-0.9, respectively. All the obtained samples were high density sintered bodies with the low apparent porosities of less than 0.2%, ranging in bulk densities from 7.67 x 10(3) to 8.55 x 10(3) kg/m(3). The temperature dependence of the relative dielectric constant, epsilon(r) for PST-PSN ceramics apparently exhibited the diffuse phase transition in all the compositions. Assuming that the volume specific heat, C-v of the present samples with x 0.4-0.9 are 2.5 x 10(6) J/m(3).K, x=0.4 PST-PSN sample exhibited the highest figures of merit, F.M. for voltage responsivity, R-v of around 8.5 x 10(-14) C.m/J and F.M.D* for specific detectivity, D* of around 5.9 x 10(-11) C.m/J, among the six samples studied here.

High density lanthanum-modified lead zirconate titanate (PLZT) ceramics with compositions of ((Pb0.925La0.075)(ZryTi1-y)(0.981)O-3 0.5 mass% MnO2), where y = 0.1-0.9, were prepared by hot iso-static pressing (HIP). After the relative dielectric constant epsilon(r) at room temperature increased gradually with increasing Zr content in the tetragonal region, exhibiting a maximum in the vicinity of the morphotropic phase boundary (MPB) between tetragonal and rhombohedral structures, it decreased remarkably in the rhombohedral region. For 0.2 less than or equal to y less than or equal to 0.5, the pyroelectric coefficient P at room temperature showed relatively large values (greater than or equal to 3.0 x 10(-4) C/m(2) . K). The PLZT sample for y = 0.2 exhibited the highest figures of merit (F.M.) for voltage responsivity R-v of approximately 3.0 x 10(-13) C . m/J and (F.M.D*) for specific detectivity D* of approximately 10.5 x 10(-11) C . m/J among the seven samples studied.

Zirconium-modified lead lanthanum titanate {(Pb0.925La0.075)(ZryT11-y)0.981O3+0.5 mass% MnO2, y=0-0.10, (PLZT)} ceramics and films were prepared by hot isostatic pressing and rf-magnetron sputtering, respectively. The pyroelectric properties of PLZT ceramics and films were investigated in detail. Assuming that the volume specific heat Cv of present ceramics and films is 3.2 J/cm(3) degrees C, the PLZT films exhibited the highest figures of merit F.M. of 1.4 x 10(-10) Ccm/J for voltage responsivity and F.M.D* of 1.6 x 10(-8) Ccm/J for specific detectivity of pyroelectric infrared sensors, which were around 7.0 times and 2.8 times, respectively, larger than those of present ceramics and PLZT(4/44/56) ceramics previously reported. The present films of y=0.04-0.10 are substantially expected as element materials for pyroelectric infrared sensors.

High density lanthanum-modified lead zirconate titanate (PLZT) ceramics with compositions of {(Pb0.925La0.075)(ZryTi1-y)(0.981)O-3+0.5 mass% MnO2}, where y=0-0.10, were synthesized by hot isostatic pressing (HIP). All the pressed samples had the high relative density of 99.9% of theoretical density. The pyroelectric properties of the poled PLZT ceramics with y=0-0.10 were evaluated. The relative dielectric constant epsilon(r) at room temperature was in the range of 290 to 334 and increased linearly with increasing Zr content, while the Curie temperature T-C decreased slightly. The rates of linear increase m(1) and decrease m(2) calculated from the slope of the linear plot of epsilon(r) and T-C with y were approximately 4.0/mol% Zr and 0.6 degrees C/mol% Zr, respectively. Assuming that the volume specific heat C-v of the present samples with y=0-0.10 are 3.2 x 10(6) J/m3.K, y=0.10 PLZT sample exhibited the highest figures of merit F.M. for voltage responsivity of around 0.20 x 10(-12) C.m/J and F.M.D* for specific detectivity D* of around 0.57 x 10(-10) C.m/J, among the nine samples studied here. The figure of merit F.M.D* of y=0.10 PLZT sample matched epsilon(r) of element materials with those of field-effect transistors (FET) used in the sensor circuit was superior to those of PLZT (4/44/56) ceramic and {(1-x)Pb0.9La0.1Ti0.975O3+xMgO} (PLMT) ceramic with x=0.005 that hare been previously reported.

The translucent and colorless calcium and strontium hydroxyapatite (Ca, Sr)-HAp ceramics with compositions of (Ca10-10xSr10x) (PO4)(6)(OH)(2), where x=0-0.8, were successfully prepared by hot isostatic pressing (HIP). The physical properties of obtained samples with x=0-0.8 were investigated, The lattice constants and hexagonality, cia, of (Ca, Sr)-HAp samples gradually increased with increasing Sr content and were in good agreement with the data listed in JCPDS cards. The relative density for all samples HIP-treated was in the range of 96.4 to 99.7%. The values of Vickers hardness, H-V, for all samples were almost constant in the range 5.5-5.9 GPa regardless of the change in x, exhibiting the good approximation to the Hv values of natural teeth. From the FE-SEM observations, the obtained samples had almost pore free microstructures consisting of about 1.6-1.9 mu m HAp grains. Judging from FT-IR measurements, there is the possibility that the (Ca, Sr)-HAp ceramics HIP-treated are applicable to special uses such as optical matched filters.

PLZT films around 3 mu m thick with compositions of ((Pb0.925La0.075)(ZryTi1-y)(0.981) + 0.5 mass%MnO2) where y = 0-0.10, which have an appropriately small relative dielectric constant (similar to 200) were deposited on Pt(100)/MgO(100) by rf magnetron sputtering. The pyroelectric properties of PLZT films as element materials for pyroelectric IR sensors were investigated in detail. Assuming that the volume specific heat C-v of the present films is 3.2 J/cm(3) . K the PLZT films exhibited the highest F.M. of 1.4 x 10(-10) C . cm/J and F.M.D* of 1.0 x 10(-8) C . cm/J, which were around 1.8 times and 1.5 times larger than those of PLT films, respectively Consequently, the figures of merit for the pyroelectric IR sensors could be improved by adding a small amount of Zr to PLT.

High density tetragonal PZT ceramics with compositions of (Pb(ZrxTi1-x)O-3+0.5 mass% MnO2}, where x=0.10-0.50, were synthesized by hot isostatic pressing (HIP). Pressed samples with x=0.20 had the highest bulk density of 7.82 g/cm(3), which is 98.2% of the theoretical density. The pyroelectric properties of poled PZT ceramics with x=0.10-0.50 were evaluated. The Curie temperature T-C decreased linearly with increasing Zr content. The rate of linear decrease m calculated from the slope of the linear plot of T-C with x was approximately 3.0 degrees C/mol% Zr. The PZT sample with x=0.20 exhibited the highest figure of merit F.M. of around 2.1x10(-11) C . cm/J. Assuming that the volume specific heat C-v of the present sample with x=0.20 and that of {Pb(ZrxTi1-x)O-3+2 mass% ZnBi2/3Mn1/3O3} (PZT-ZBM) ceramic with x=0.30 that has already been reported are the same (3.1 J/cm(3) . K), the F.M. for voltage responsivity of pyroelectric IR sensors fabricated using these ceramics which have the same tetragonal structure should be nearly equal.

Ruthenium-doped PbTiO3 {(1-x)PbTiO3+xRuO(2), x=0-0.018, (PRT)} twin crystals were grown by the flux cooling method. The pyroelectric properties of the poled PRT crystals with x=0.005-0,009 were measured. The addition of RuO2 markedly affected the crystal size and reduced the crystal imperfections of PbTiO3. Based on observations by scanning electron microscopy and the back-reflection Laue method, black platelike crystals with x=0.009 in particular exhibited excellent crystallinity. Based on the results of identification and chemical analysis and measurement of pyroelectric properties, the limit of substitutional solubility of Ru4+ ions for Ti in PbTiO3 was estimated to be in the vicinity of 1.1 mol%. The figures of merit F.M. for voltage responsivity of pyroelectric IR sensors were satisfactory for samples with x=0.005-0.009; in particular, the sample with x=0.009 showed the highest F.M. of around 5.5 x 10(-11) C . cm/J, which is nearly equal to those of {(1-x)PbTiO3+xMgO, x=0.045, (PMT)} single crystals. Judging from the measurement of pyroelectric properties of the PRT crystals, crystals with x=0.009 are suitable as element materials for point-type pyroelectric IR sensors.

Lanthanum- and magnesium-modified PbTiO3 {(1-x). Pb0.9La0.1Ti0.975O3+x . MgO, x=0-0.025, (PLMT)} ceramics and thin films were prepared by normal sintering method and rf-magnetron sputtering method, respectively. The pyroelectric properties of PLMT ceramics and thin films were investigated in detail. The Curie temperature for all samples of both ceramics and films decreased linearly with increasing Mg. The highest figures of merit F.M. for the PLMT ceramics and films were around 0.18 X 10(-10) C . cm/J at x=0.005 and 1.05 X 10(-10) C . cm/J at x=0.010, reaching around 2.8 times and 1.5 times as large as those of PL10(x=0 in PLT) ceramics and films, respectively. The highest F.M. in PLMT films attained to around 5.8 times that in PLMT ceramics. This is principally attributed to substantial differences in pyroelectric properties (epsilon r and P) between ceramics and thin films.