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Raman spectroscopy is utilized to study the evaluation of vacancies in PbTiO3 thin films subjected to hydrogen atmosphere heat treatment. The B1 mode consisted of only oxygen ion vibration was shifted to lower frequency with increasing heat treatment temperature. It was considered that the oxygen ions were lacking from PbTiO3, and that oxygen vacancies were generated. It was found that the frequency of the B1 mode is proportional to oxygen ion content. Pb ions were also lacking in the PbTiO3 thin films with oxygen ions and the number of oxygen vacancies was larger than that of Pb ions. We suggest that the Raman spectroscopy is a suitable tool for the evaluation of oxygen vacancies in PbTiO3 thin films.

We propose a read-channel system with quasi-synchronous sampling and an adaptive partial-response maximum-likelihood (PRML) method to achieve accurate timing recovery and correct data extraction under high-density recording with a high transfer rate. The proposed system can extract data correctly in the state of either oversampling or undersampling using first-in-first-out flip-flops (FIFOs) and an asynchronously sampled data processable maximum-likelihood detector (ASML). In other words, it allows a sampling clock to be incompletely synchronized with a channel bit. Furthermore, the ASML adaptively learns the references required for calculating branch metrics even though the input data are not synchronized with the channel bit. This system achieves stable data extraction under quasi-synchronous sampling, improves the bit-error-rate performance, and can be applied to next-generation, high-density, and high-transfer-rate storage systems.

The peeling of an impurity-doped NiSi film was investigated. We studied silicidation in detail and showed that its procedure varies depending on the doping site and dopant species used. The uneven crystal growth of NiSi causes the local consumption of polycrystalline silicon; thus voids form at the film interface NiSi/SiO2. These voids lead to film peeling. We also determined why the local consumption of polycrystalline silicon occurs. From the data we obtained, impurity may play a role in the local consumption of polycrystalline silicon.

The molecular orientations of n-alkane (n-C23H48, n-C24H50, n-C25H52, n-C26H54, and n-C27H56) evaporated films prepared by considering various deposition conditions, including the type of substrate, substrate temperature, and evaporation rate, have been systematically investigated by X-ray diffraction analysis and scanning probe microscopy. Two typical molecular orientation states, namely, the "perpendicular orientation state", in which the molecular chain axes are perpendicular to the substrate surface, and the "parallel orientation state", in which the molecular chain axes are parallel to the substrate surface, are observed. At a high substrate temperature and a low evaporation rate, a "perpendicular (P) film", which consists of only the perpendicular orientation state, is obtained. At a low substrate temperature and a high evaporation rate, a "coexistent (C) film", which consists of both the perpendicular and parallel orientation states, is obtained. It is concluded, from the experimental results, that the most thermodynamically stable is the perpendicular orientation state. Furthermore, it is found that the molecular orientation behavior depends on the type of substrate and deposition time. These molecular orientation dependences are considered to be mainly due to a kinetic mechanism rather than the thermodynamic stability in the case of the evaporated film in this study.

In recent years, because of the rapid progress in wireless technology, microwave absorbers or noise suppressors have become necessary for a safe-electromagnetic-wave-level environment. To design microwave absorbers or noise suppressors, it is necessary to have knowledge of complex permittivity and permeability. To this end, we used the coaxial waveguide method between 500 MHz–18 GHz and the free space method with a dielectric lens in the K-band (18–26.5 GHz). In this report, we show the complex permittivity, er* and permeability, µr* of lossy dielectric composite materials such as barium titanate oxide (BaTiO3)/rubber and titanium oxide (TiO2)/rubber. The real part of the complex permittivity, e'r is available for changing the trimming weight ratio of rubber and replacing TiO2 or BaTiO3.

Structural changes of Y2O3 films and La2O3 films deposited on some oxidized silicon substrates were studied using X-ray photoelectron spectroscopy (XPS), Secondary ion mass spectrometry (SIMS), and Fourier transform infrared spectroscopy attenuated total reflection method (FT-IR ATR). Y2O3 and La2O3 films on chemical oxide and NH3 annealed oxy-nitride were prepared by the Low-pressure chemical vapor deposition (LPCVD) method using an lanthanide–dipivaloyl-methanate (Ln–DPM) complex. The Y2O3 film and the La2O3 film on the both kinds of substrate already contained a partly silicate structure at the interface side as a result of an interface reaction during the deposition process. During post deposition annealing, the whole film structure of the Y2O3 and the La2O3 on the chemical oxide changed to a silicate structure due to silicon diffusion with interface reaction. In the case of the Y2O3 film, this interface reaction can be suppressed using thermal oxy-nitride as the interfacial layer. In the case of the La2O3 film, the suppression effect using oxy-nitride was smaller than the case with the Y2O3 film. Also, it was found that there was a strong correlation between the structural change of the films and the change of flat-band-voltage of both Y2O3 and La2O3 MIS diodes during post-deposition-annealing.

In this study, we describe a robust read channel employing a novel timing recovery system and a unique Viterbi detector which extracts channel timing and channel data directly from asynchronous sampling data. The timing recovery system in the proposed read channel has feed-forward architecture and consists entirely of digital circuits. Thus, it enables robust timing recovery at high-speed and has no performance deterioration caused by variations in analog circuits. The Viterbi detector not only detects maximum-likelihood data using a reference level generator, but also transforms asynchronous data into pseudosynchronous data using two clocks, such as an asynchronous clock generated by a frequency synthesizer and a pseudosynchronous clock generated by a timing detector. The proposed read channel has achieved a constant and fast frequency acquisition time against initial frequency error and has improved its bit error rate performance. This robust read channel system can be used for high-speed signal processing and LSIs using nanometer-scale semiconductor processes.

The thermophysical properties of ferroelectric Ba(Ti1-x, Zrx)O3 ceramics were obtained in the temperature range from 310 to 440 K. A radiation calorimeter was used to obtain specific heat capacity, thermal conductivity, and thermal diffusivity simultaneously and independently. A self-check of the data reliability was performed for the obtained results. The anomalies associated with the ferroelectric phase transition were observed for specific heat capacity and thermal diffusivity. The temperature dependence of these properties becomes more diffusive with an increase in Zr content similar to the results of Ba(Ti1-x, Snx)O3 ceramics with Sn content. However, the Zr content did not cause a large change in thermal conductivity and thermal diffusivity unlike the Sn content in the present temperature range. The Curie temperatures obtained from the present experiment changed with Zr content, which are quite consistent with the results obtained from a dielectric measurement by previous authors.

The domain-structure images of (001) plates of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) single crystals were successfully obtained in a vacuum using a contact-resonance piezoresponse force microscope (CR-PFM). During conventional PFM observations at sufficiently high temperature, the modulation voltages applied between the tip and the counter electrode induced polarization reversals and destroyed local domain structures under the tip. With the help of the contact-resonance mode, piezoresponse images could be obtained with a reduced amplitude of the modulation signal, that addressed the issue of the polarization reversals at high temperature. Using this CR-PFM, circular domains 30–100 nm in diameter were observed at temperatures above 175°C.

Simultaneous measurements of specific heat capacity, thermal conductivity and thermal diffusivity have been performed for ferroelectric Ba(Ti1-x,Snx)O3 ceramics. An apparatus based on thermal radiation calorimetry was used in the present measurement. The measurement is performed in a vacuum chamber kept at room temperature in which a disk-shaped sample is heated and cooled slowly on one face by thermal radiation from a flat heater. The values of three thermophysical properties were obtained from the temperatures and the ramp rates of both sample surfaces, the surface emissivity of the sample and the temperature of the heater surface. In this calorimetry, these thermophysical properties were independently obtained, a self-check of the reliability of the results was performed. The measurements were performed in the temperature range from 310 to 440 K. Anomalies in the thermophysical properties were observed near the ferroelectric phase transition temperature. The Curie temperatures of Ba(Ti1-x,Snx)O3 ceramics determined from the experimental results are almost consistent with those obtained by previous authors.

Micro-Raman spectroscopy was employed to investigate the residual strain and oxygen vacancies of BaTiO3-based multilayer ceramic capacitors (MLCCs) with a Ni internal electrode. Strain was found to accumulate around the internal Ni electrodes layers than at other parts of the MLCCs. In addition, the number of oxygen vacancies near the internal Ni electrode was larger than that at any other parts of the MLCCs. These observations clearly show that Raman spectroscopy is extremely useful for evaluating the residual strain and oxygen vacancies in MLCC devices.

Epitaxial BaTiO3 (BTO) thin films of less than 100 nm thickness were grown on Pt(001)/MgO(001) substrates at growth temperatures of 500?700 ?C with a low deposition rate of about 25 nm/h by metal?organic chemical vapor deposition (MOCVD). The BaTiO3 thin films were epitaxialy grown with (001) orientation. These films show quadrangular grains and a dense cross-sectional structure. The relative permittivities of these films grown at 500, 600, and 700 ?C with thicknesses of 62, 65, and 82 nm were 338, 455, and 566 at 1 kHz, respectively. These relative permittivities were higher than those of BTO films prepared by other methods and BTO ceramics with thicknesses less than 100 nm.

Ba(ZrxTi1−x)O3 (BZT) thin films were deposited on a (100)MgO substrate by RF-magnetron reactive sputtering using metal targets. In this paper, a model of the reactive sputtering process using a metal composite target at different reactive gas flow rates is presented. 500-nm-thick BZT thin (x = 0.26) films for high frequency performance showed a single perovskite phase and a high crystallinity on the MgO substrate with only a (001)/(100) orientation at an optimum reactive gas flow rate in Ar + O2. The BZT films had a stoichiometric Ba/Ti ratio and epitaxially grew on the MgO substrate. They showed a dense microstructure without cracks or voids. Their low capacitance and loss tangent showed little dispersion at 1–18 GHz. These results indicated that we succeeded in depositing high-quality and potentially tunable ferroelectric BZT films for high-frequency applications by RF-magnetron reactive sputtering using metal targets.

Sputtering damage of SrRuO3 (SRO) films prepared by RF magnetron sputtering under various growth pressures was investigated by Raman spectroscopy and X-ray photoemission spectroscopy (XPS). Phonon modes that were related to Ru and Sr ions changed and XPS spectra shifted with decreasing growth pressure. These results indicate that Sr ions switched place with Ru ions in SRO films when the SRO films had sputtering damage under low-growth-pressure sputtering condition as determined from Raman spectroscopy and XPS measurement. The antisite ion content increased with decreasing growth pressure. The resistivity of the SRO films also increased with increasing antisite ion content. The dynamics of sputtering damage revealed that the antisite Sr and Ru ions were formed in SRO films.

Ba(Zr x Ti1-x )O3 (BZT) thin films with different Zr contents were deposited on (100) MgO and (100) Pt/(100) MgO substrates by RF-magnetron reactive sputtering using metal targets. The BZT (0 < x < 0.89) thin films had a single perovskite phase with only (001)/(100) orientation. In all cases, the ratio of Ba/Ti was stoichiometric according to X-ray fluorescence spectrometry (WDX) measurement. Atomic force microscopy (AFM) study proved that BZT films possess a dense microstructure without cracks or voids. The grain size was found to decrease with increasing of Zr content. The effect of Zr content on the dielectric constant and leakage current was studied. BZT thin films showed ferroelectric-to-paraelectric properties with increasing Zr content and excellent leakage properties according to measurements of electrical properties. These results indicated that we succeeded in depositing high-quality and low-sputter-damage BZT thin films by reactive sputtering using metal targets.

Microwave absorbability of electromagnetic waves in the frequency range of 1–15 GHz, which is often used in recent wireless applications, for stacks of various numbers of conductive nonwoven fabric sheets with different resistivity was evaluated to clarify their possibility as the broadband microwave absorber in the frequency range of 1–15 GHz. The conductive nonwoven fabric sheets coated with polypyrrole nanoparticles, which had resistivities from 4.6 ×103 to 1.2×102 Ω cm, were prepared by immersing nonwoven fabric sheets in solutions containing various concentrations of an oxidizing agent and a dopant and then exposing the sheets to pyrrole vapor. The real part (ε') and the imaginary part (ε'') of complex permittivity for each conductive nonwoven fabric sheet increased with decreasing frequency, indicating the dispersion of permittivity. In addition, the reflection loss decreased when ammonium persulfate concentration increased and/or the stack size increased. However, the stack of two conductive nonwoven fabric sheets (thickness: 6.6 mm) with a resistivity of less than 120 Ω cm had average reflection losses of less than -10 dB in the frequency range of 1–15 GHz. From this way, it can be considered that the stacked conductive nonwoven fabric sheets prepared in this study can be a new material that effectively absorbs electromagnetic waves in the wide frequency range.

We measured the X-ray photoelectron spectroscopy spectra of the La-incorporated Hf oxide and observed the apparent Hf 4f peak shift toward a lower energy as La concentration increased. To investigate the origin of these peak shifts, we performed first-principles calculations, in which the degree and direction of the obtained peak shifts agreed well with the above-mentioned experimentally observed spectra. Also, we found that the main reason for these peak shifts was the charge-transfer effect. Estimation of the degree of the interface dipole was made possible by a comparison between the experimental values and the theoretical values of the peak shifts.

Thermally induced structural changes in TiN/Hf(La)SiO gate stacks were investigated by back-side X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS). A distinct correlation between bottom oxide growth and an increase in equivalent oxide thickness (EOT) was confirmed under high-temperature annealing at over 850 °C regardless of La content. Back-side XPS also revealed that oxygen and nitrogen diffusion occurs, forming partially oxidized TiON layers at a metal/high-k interface under moderate annealing temperatures of approximately 600 °C, and that annealing at over 750 °C leads to the reduction of the oxide phase and produces a thinner inter-layer with a clear Ti–N bond feature. Moreover, with an increase in annealing temperature, a change in the local atomic configuration in the HfLaSiO dielectric layer was identified from oxygen K-edge spectra. This structural change induced by thermal reaction can be considered as a possible cause of the V th instability of La-incorporated high-k gate stacks. On the basis of these findings on structural changes, the physical origins of the effective work function modulation of the gate stacks are discussed in detail.

We have fabricated a polycrystalline BiFeO3 (BFO) film with a thickness of 650 nm on a Pt/Ti/SiO2/Si substrate by a chemical solution deposition method, and its optical and thermooptic properties were evaluated by spectroscopic ellipsometry. The optical band gap energy of the BFO film was 2.95 eV at 50 °C and monotonically decreased with increasing temperature to 2.79 eV at 530 °C. The extinction coefficient was significantly low at a wavelength longer than 600 nm in the temperature range from 50 to 530 °C. The refractive index of the BFO film was estimated to be 2.96 at 600 nm and 2.68 at 1550 nm at 50 °C using a single Gaussian oscillator, and a thermooptic coefficient of 0.8×10-4 K-1 was obtained at a wavelength of 1550 nm. Although the refractive index decreased with increasing temperature at all wavelengths, the variation was larger at shorter wavelengths. This seems to be caused by the combination of broadening in the Gaussian oscillator vibration and thermal expansion.

A new microwave absorber was formed using stacked polypryrrole nanoparticle-coated nonwoven textiles with surface resistivities from 8.5 ×107 to 3.0 Ω·cm. This microwave absorber showed typical frequency dispersion in both εr' and εr'' in a wide frequency range (1 to 75 GHz). A large reflection loss \dotΓ21 with a wide bandwidth was achieved with εr'' dispersion characteristics.

The electric-field-induced displacements of a Pb(Zr,Ti)O3 (PZT) film plate with Pt/PZT/Pt/Si(100) structure were calculated by the finite element method with various parameters of sample geometry. The sample geometric parameters were the length of the top-electrode L (ranging from 0.1 to 10,000 µm), the PZT film thickness tPZT (ranging from 0.5 to 10 µm), the substrate thickness tsub (ranging from 100 to 1000 µm), and the film type (whether the PZT film was continuous or side-etched). The surface transverse displacements of the PZT film were computed, which corresponded to strains measured using twisted-mode atomic force microscopy (AFM in twisted mode). Five effects that prevent the measurement of intrinsic transverse piezoelectric constant d31 using AFM were clarified. The ideal conditions indicated that the length of the top-electrode, L, is less than or equal to the PZT film thickness tPZT. The continuous PZT was etched to isolate the PZT film plate from the continuous piezoelectric film layer; however, this condition was found to be difficult to satisfy experimentally. Thus, the second-best condition was proposed.

The relationship between the dielectric constant and domain structure was investigated on PMN-xPT (x: 0.27, 0.32 and 0.34) single crystals. As Yan et al. already reported, the cooling rate across the freezing temperature (the relaxor-ferroelectric phase transition temperature) affected the dielectric constant in the ferroelectric phase. In this study, it was found that the lead titanate compositions x affected the cooling-rate dependences of the dielectric constant. The dependences of domain structures on cooling-rate and on the composition x corresponded with the dielectric constant behavior. That is, the average domain size decreased as the dielectric constant was reduced. The relationship between the dielectric constant and domain structure is discussed from the viewpoint of the evolution of polar nanosized regions during the relaxor to ferroelectric phase transition.

The domain structures of (001) plates of (1–x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) single crystals were observed at room temperature after 240°C thermal treatment at various cooling rates. The starting composition of the PMN-PT single crystals was x=0.32; the dielectric constant of the single crystals exhibited a maximum at 153°C. Contact resonance piezoresponse force microscopy (CR-PFM) was utilized for domain imaging, because microdomain images could be obtained without domain structure degeneration. The average size of domains strongly depended on the cooling rate. The obtained domain images were approximately fingerprint patterned on a micron scale, but were fragmented by circular domains on a submicron scale. These finer circular domain structures were probably microdomains that existed in the relaxor phase and were subsequently quenched during the relaxor-to-ferroelectric phase transition.

The piezoelectric response of 1.2-µm-thick Bi4-x Pr x Ti3O12 (BPT, x=0.3, 0.5, 0.7) ferroelectric films with polar-axis orientation is reported. Utilizing a long-range lattice-matching character, BPT films were grown by chemical solution deposition (CSD) on (101)-oriented IrO2 layers which were formed by the oxidation of Ir bottom layers during solution depositions. An effective piezoelectric coefficient d 33=36 pm/V comparable to that of Bi4Ti3O12 (BIT) single crystal was measured in BPT thick films with x=0.3. Related to the decrease in P s, the total strain ε total decreased with increasing x. Stripe-shaped domain structures of ∼20 nm in width were observed in some grains in BPT thick films by piezoresponse force microscopy (PFM) and transmission electron microscopy (TEM). These structures could be attributed to 90° domain walls. The reconfiguration of these domains by the elecric field may occur to contribute to the ferroelectric polarizations resulting in a large value of P sat=50 µC/cm2 in BPT thick films with x=0.3.

A microwave absorber for use in an electronic toll collection (ETC) device, having a central frequency of 5.8 GHz, is fabricated using a composite of dielectric (titanium oxide, TiO2) and magnetic (carbonyl iron, Fe(CO)5) materials. The reflection loss in free space, using a circularly polarized wave, was -20 dB or more around a central frequency of 5.8 GHz at incident angles of up to 60°, which satisfy the necessary conditions for ETC use.

The kinetics in the solid-solid phase transition of an n-alkane crystal, which is the so-called `rotator phase transition', is investigated by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD) and optical microscopy. Primary nucleation rate in the transition on cooling is measured by using droplet crystals, while growth rate is measured by using a single crystal, independently. The growth rate increases rapidly with the increase in the degree of supercooling compared with that on heating. A significant asymmetric behavior of the temperature dependence of the growth rate is observed between temperatures above and below the transition point. The kinetic parameters, i.e., the surface free energies between two solid phases, are estimated from a combination of the primary nucleation rate and the growth rate. It is found that the primary nucleation in the rotator phase transition of n-alkane droplet on cooling is a homogeneous one. Furthermore, the surface free energies on cooling are slightly smaller than those on heating, and this seems to induce the asymmetric behavior of the growth rate.

Four kinds of domain structures (180° c-c, 180° a-a, 90° a-a and 90° a-c domains) on grown surfaces of PbTiO3 single crystals were imaged successfully using vertical and lateral piezoresponse force microscopy (PFM). Domain orientations (i.e., polarization vector distributions) at the surface of each domain structure are presented. These domain images are compared with simultaneously observed surface topographic images decorated by an acid etching treatment.

The particle size dependence of BaTiO3 powder was investigated from the viewpoint of the crystal phase. The crystal phase of BaTiO3 powder was transformed from tetragonal to cubic at a critical particle size of 0.1 µm at room temperature. With decreasing particle size, the Ba ions in the BaTiO3 structure were absent at the surface, and these disordered surface areas increased in small-particle-size BaTiO3 powders and exhibited particle-size dependence.

Both surface electrical potential and surface structure of spontaneously poled Pb0.85La0.15Ti0.963O3 (PLT) c-axis-oriented film on (100)Pt-coated (100)MgO single-crystal substrate were simultaneously measured by Kelvin force microscope in air. The surface electrical potential clearly revealed the polarity of the polarization on the film surface, i.e., the film surface had either positive or negative electrical potential. However, the surface electrical potential was strongly affected by floating charged particles.

Yb L3-edge XAFS spectroscopy was applied to study on the local structures around Yb atoms in ytterbium(III) trifluoromethanesulfonates (Yb(OTf)3) catalysts dissolved in various solution and those in Yb(OTf)3 chiral catalysts prepared by a choice of two types of achiral ligands. XAFS analyses showed the difference in the coordination number of oxygen atoms between Yb(OTf)3 catalysts dissolved in aqueous and nonaqueous solutions, suggesting the activation of the Yb(OTf)3 catalyst by the hydration. For the two Yb(OTf)3 chiral catalysts, both the catalysts were found to be present as trivalent ytterbium oligomer. Curve-fitting analysis of EXAFS showed that the Yb-Yb distance of two catalyst complexes is fairly different from each other, i.e., one is 3.68 Å and the other 4.04 Å, which is expected to explain the difference of the catalytic performance of the two chiral catalysts.

XANES spectroscopy is applied to the characterization of surface species of supported catalysts. In case of vanadium oxide supported on silica (V2O5/SiO2) at low loadings, comparison of the vanadium K-edge XANES spectrum with the spectra of the authentic samples allowed the determination that the surface species is a VO4 tetrahedron where three oxygen atoms of the four are linked to silica support. The coordination environment changed easily by adsorption of water molecules, indicating the direct attachment of water molecules to vanadium atoms. A platinum particle of Pt-sulfated ZrO2, known as a catalyst promoting super acidic reactions, consists of a core of platinum metal particle and surface layers of platinum oxide. The analysis of XANES spectrum of the catalyst sample by using those of Pt metal and α-PtO2 goves the fraction of α-PtO2. Fe ions in Fe, Mn-sulfated ZrO2 catalyst, knowing as a catalyst promoting super acidic reactions, were found to be present inside the ZrO2 as a solid solution and the ions does not directly participate in the super acidic reaction. Mn ions are the site of adsorption of reactant gas molecules. The in situ XANES spectra at Fe K-edge did not change throughout the reaction and those at Mn K-edge were affected by introduction of reaction gas. Europium amide complex in zeolite is a mixture of trivalent and divalent Eu species. Eu divalent species is an active species for abase-catalyzed reaction. The fraction of Eu divalent species could be determined by danalysis of XANES spectra of Eu L3-edge. The analysis applied to Pt XANES spectra can be applied to the XANES spectra of Rh/TiO2 at Rh K-edge. In the case of a Rh/TiO2 photocatalyst, the reactivity of the catalyst varies with the loading amount of Rh. XANES analysis of the Rh/TiO2 catalysts showed that surface rhodium species are a mixture of Rh metal and highly dispersed Rh2O3 and the fraction of Rh2O3 varies with the loading amount. We found that Rh atoms are present as an oxide form at low loadings even after heating the catalyst in the presence of hydrogen at 673 K.

Spontaneous polarization, P s, dielectric constant, ε s, and piezoelectric constant, d i j , at a given composition and temperature were calculated for all compositions of the Pb(Zr1-x Ti x )O3 system using phenomenological thermodynamics and compared with experimental data by considering the domain effect. In the calculated phase diagram, the first-order phase transition in compositions close to PbZrO3 and PbTiO3, the second-order phase transition in all compositions except those close to PbZrO3 and PbTiO3, and the morphotropic phase boundary between rhombohedral and tetragonal phases could be distinctly observed. The calculated phase diagram was in good agreement with the available experimental data.

Nanometer scale surface morphologies in pure PbTiO3, Mn-doped PbTiO3 and Pb(Zn1/2Nb1/2)0.91Ti0.09O3 single crystals prepared by the flux method have been investigated by atomic force microscopy and discussed in connection with 90° and 180° domains. Regular gradiants with angles of 3.4° to 3.6° at the domain boundary were measured on the (001) surface in as-grown crystals with so-called typical 90° a-c domains. The angle of the gradiant is controlled by the crystal tetragonality ( c/a) in the crystal and is 3.4° to 3.6° in pure PbTiO3 and Mn-doped PbTiO3 with c/a=1.063, and 0.5° to 0.8° in Pb(Zn1/2Nb1/2)0.91Ti0.09O3 with c/a=1.004. In pure PbTiO3 and Mn-doped PbTiO3, the 180° c-c domains are constructed from the trapezoidal form with a step of 80 to 100 nm and confirmed by electric potential measurements using Kelvin force microscopy.

The temperature dependences of Raman scattering spectra were investigated through the ferroelectric phase transition in Ti-rich Pb(Zr x Ti1-x )O3 (x=0.25–0.40). Low frequency spectra show marked dependences on both composition and temperature. Another lower frequency mode appears below the E symmetry soft mode of PbTiO3 as the x increases. The frequencies of the lowest two modes soften slightly, whereas the damping factor of the two modes increases markedly near T c. These phenomena suggest that the displacive type at x=0 gradually changes to the order-disorder type as x increases. The internal bands higher than 100 cm-1 are insensitive to both composition and temperature. The intensity of these modes gradually decreases with increasing temperature. Although all optical modes should be Raman inactive above T c, a quasielastic scattering and a few internal modes are still observed in the spectra. Since the intensities of these modes decrease on further heating, the origin of this intensity cannot be the second order Raman scattering but must be the first order one due to local breakdown of cubic symmetry by some kind of disorder.

The electrical properties of Ba1- x K x BiO3/Nb-doped SrTiO3 all-oxide-type Schottky junctions have been investigated by measuring their current-voltage and capacitance-voltage ( C-V ) characteristics at room temperature. The relative permittivity ε r of Nb-doped SrTiO3 could be approximated as ε r(E)=b/√ a+E 2, where E is the electric field, a and b are constants. Taking into account the field dependent permittivity and interfacial layer, we carried out a quantitative analysis of the potential barrier and 1/C 2-V characteristics. The non-linear 1/C 2-V characteristics could be quantitatively explained by considering the field dependent permittivity and the bias dependence of the barrier height due to the presence of the interfacial layer.

The rotator phase transitions in odd n-alkanes, n-C21H44 and n-C25H52, were investigated by optical microscopy. On cooling an n-C25H52 single crystal, a new transient intermediate state was observed within 1/30 s between the rotator phase (RV) and the low-temperature phase (IV). The rotator phase transition in n-C25H52 proceeds through two successive structural changes: uprighting of molecules and ordering of side packing. The two-stage changes on cooling were found to be peculiar to the transition accompanied by the molecular tilting motion, such as the RV→IV transition in n-C25H52. In contrast, in n-C21H44, the intermediate state was not observed.

Q-switched operation of an erbium-doped fiber laser with fiber grating mirrors is demonstrated for the first time. The resonator was formed by splicing two fiber gratings to erbium-doped fiber ends. One of the fiber gratings was periodically stretched by a piezoelectric transducer for the Q-switching operation. An output pulse with a pulse width of 2.46 µ s and a peak power of 2.1 mW was obtained for a 1.48 µ m pump power of 26 mW. The oscillation wavelength was 1.552 µ m and the repetition rate was 1 kHz. The laser oscillation wavelength was tuned from 1.552 µ m to 1.556 µ m by applying lateral stress to one of the fiber grating mirrors.

Pressure dependence of ferroelectric properties in PbZrO3-PbTiO3 solid state system (PZT) were calculated under hydrostatic stress and compared with experimental results. When the ratio of electrostrictive coefficients in PZT, Q 11/Q 12 was exactly equal to -2.000, the ferroelectric properties were not affected by the application of hydrostatic pressure; i.e. isotropic compressive stress. At ratios other than Q 11/Q 12=-2.000, the Curie points were decreased with increasing hydrostatic pressure, in particular near the morphotropic phase boundary (MPB). The piezoelectric charge and voltage coefficients, d ij and g ij, increased and decreased, respectively, near the MPB with increasing hydrostatic pressure, due to the pressure dependence of the dielectric constant and spontaneous polarization.

Solid solutions of (1- x)Pb(Yb1/2Nb1/2)O3-( x)PbTiO3 x=0 to 0.8 were investigated from the viewpoint of dielectric and piezoelectric properties. With increasing PbTiO3 content (x), phases at room temperature continuously changed from antiferroelectric (x=0), ferroelectric (x=0.1 to 0.15), relaxor (x=0.2 to 0.49), and again to ferroelectric (x>0.49), where crystal structures of all these phases were perovskite. Sintering temperature was lowered to around 950° C in the relaxor phase (x=0.2 to 0.49). Piezoelectric constants exhibited a maximum at x=0.49 to 0.50 near the morphotropic phase boundary (x=0.49). In the sample with x=0.50, Curie point was 349° C, and remanent polarization and coercive field were 32.8 µ C/cm2 and 2.75 kV/mm, respectively. Also, electromechanical coupling factors for planar (k p) and thickness (k t) modes were 0.527 and 0.436, respectively.

A new technique is presented for measuring the group velocity dispersion (GVD) of optical fibers. It makes it possible to measure the GVD of an already installed ultralong dispersion-shifted fiber. The method is based on phase rotation measurement, but it includes erbium amplifiers and an optical circulator or a 100% reflector. This allows round-trip propagation of the modulated signal and the GVD was successfully measured at one terminal. The maximum measurable length is as long as 125 km.