Showing papers in "Japanese Journal of Applied Physics in 1974"
TL;DR: In this article, the authors studied the piezoelectric properties of ferroelectric ceramics comprising bismuth compounds with layer structure, such as PbBi2Nb2O9 and Na0.5Bi4.5Ti4O15.
Abstract: Piezoelectric properties have been studied on ferroelectric ceramics comprising bismuth compounds with layer structure, PbBi2Nb2O9, PbBi4Ti4O15, SrBi4Ti4O15 and Na0.5Bi4.5Ti4O15. These ceramics have the high mechanical quality factor Q(2000~7200), low aging rate of frequency constant Nt(30~60 ppm/time decade), low temperature coefficients both of Nt(-50 ppm/°C) and of coupling factor kt(70 ppm/°C), low Poisson's ratio σ(0.23~0.27), and large anisotropy in coupling factor. A small value of kt in these ceramics probably relates to two-dimensional restriction on permissible rotation of the spontaneous polarization. The poling characteristics in the ceramics can be improved by some additives. Grain boundaries in these ceramics are of nearly rectangular shape, and an etch pattern of fine stripes appears always in parallel to the length of the boundary.
162 citations
TL;DR: In this article, the absorption and reflection spectra of β-Ga2O3 were measured with polarized light in the wavelength region near its absorption edge, and the plate-like crystals of a Ga/HCl/O2/Ar vapor reaction system were obtained.
Abstract: Absorption and reflection spectra of β-Ga2O3 are measured with polarized light in the wavelength region near its absorption edge. The crystals of β-Ga2O3 are grown by using a Ga/HCl/O2/Ar vapor reaction system. The platelike crystals of β-Ga2O3 have (100), (010), and (001) surfaces, and the major surface is (100). The energies of the absorption edge are observed to be 4.90 eV for E//b, 4.54 eV for E//c, and 4.56 eV for E⊥b&c at room temperature. The energies for E//b and for E//c at 77 K are larger than those at room temperature by 40 meV and 220 meV, respectively. Reflection minima are observed at 5.06 eV and 5.30 eV for E//b, and at 4.63 eV and 5.30 eV for E//c at room temperature.
146 citations
122 citations
TL;DR: In this article, the nonlinear optical properties of KNbO3 single crystals were investigated in detail in the orthorhombic phase by using YAG/Nd laser.
Abstract: Nonlinear optical properties of KNbO3 single crystals were investigated in detail in the orthorhombic phase by using YAG/Nd laser. The refractive indices for some laser wavelengths were measured. The nonlinear optical coefficients of this crystal at room temperature were obtained by means of the Maker fringes technique. Results were as follows: d31=35, d32=-40 and d33=-61 relative to d11 of quartz. These values are comparable with those of Ba2NaNb5O15. The temperature dependences of dij coefficients were measured. Critical and noncritical phase-matching conditions were determined. At room temperature, critical phase-matching was possible for d31 and d32 coefficients. The observed phasematching angles were found to be in good agreement with the values calculated from the refractive index data.
119 citations
112 citations
TL;DR: In this article, the in-line holograms of a line-like object of a chemical fiber and a red blood cell were made using AlKα radiation (8.34A) from a two-stage fine focus X-ray generator.
Abstract: X-ray holograms of two- or three-dimensionally distributed objects are recorded and reconstructed. The in-line holograms of a line-like object of a chemical fiber and a point-like object of red blood cell are made using AlKα radiation (8.34A) from a two-stage fine focus X-ray generator. A magnified real image is reconstructed from the negative hologram using a He–Ne laser (6328A). A lateral resolution of about 4 µm and a longitudinal resolution of about 4 mm are obtained in the two-step imaging process.
102 citations
TL;DR: In this paper, the formation of nickel silicides on Si has been studied by the use of glancing angle X-ray diffraction, MeV4He+ backscattering, reflection electron diffraction and replica electron microscopy.
Abstract: The formation of structures of nickel silicides on Si have been studied by the use of glancing angle X-ray diffraction, MeV4He+ backscattering, reflection electron diffraction and replica electron microscopy. By reacting evaporated Ni films with Si wafers in the temperature range of 200 to 800°C, we have found three Ni silicides. The phase Ni2Si starts to form at 200°C at the Si-Ni interface. Around 350°C, the phase NiSi grows from the Si-Ni2Si interface. The NiSi is stable in the temperature range of 350 to 750°C and above that it transforms abruptly to NiSi2. The disilicide grows epitaxially on (111), (110) and (100) surfaces of Si.
88 citations
TL;DR: The perovskite-type compounds Ln1-xSrxCoO3 (Ln=lanthanoid element) were synthesized, and their crystallographic, electric and thermochemical properties were investigated as mentioned in this paper.
Abstract: The perovskite-type compounds Ln1-xSrxCoO3 (Ln=lanthanoid element) were synthesized, and their crystallographic, electric and thermochemical properties were investigated. The region of the perovskite formation was determined. At the lower Sr content, lanthanoid ions, La to Sm except Ce, form the perovskite-type cobalt oxides. From Eu to Er, the lower boundary of the perovskite formation increases as the atomic number increases. The relaxation of a rhombohedral distortion of La1-xSrxCoO3, as Sr content is changed, is quantitatively described. At certain levels of Sr content, the compound shows that its temperature coefficient of resistivity is small in a wide temperature range. The resistivity and the non-stoichiometry of the compounds have a close relation in that the resistivity increases as the oxygen-deficiency is increased.
82 citations
TL;DR: In this paper, the effect of oxygen on the etching rate was also investigated, and it was found that the Si did not decrease up to 12.5% in content of oxygen.
Abstract: In order to enhance an etching rate using a conventional rf sputtering system, sputtering gases of fluoro-chloro-hydro-carbon were examined, the compositions of which were CF4, CCl2F2, CCl3F, CHCl2F, CHClF2, (CCl2F)2, CCl2FCClF2, and (CBrF2)2. Etching specimens were Si, quartz, glass, Al, Mo, stainless steel and photo resist. With the rf power density of 1.3 W/cm2 at the etching table, the etching rate of Si was ranged from 1000 to 2000 A/min, which were ten to twenty times higher than that by argon. High etching rate is considered to be due the formation of volatile compounds on the surface of specimens. However, etching mechanism is not clarified in detail now. The effect of oxygen on the etching rate was also investigated, and it was found that the etching rate of Si did not decrease up to 12.5% in content of oxygen.
82 citations
TL;DR: In this paper, the electron mobility in Si inversion layers in the range of surface electron density Ns=(0.5~5)×1012 cm-2 and temperature T=200~300 K was calculated to account for the scattering due to the surfon deformation potential.
Abstract: Surfons are acoustic phonons in a body with surfaces, having both bulk and surface modes. To account for the electron mobility µ in Si inversion layers in the range of surface electron density Ns=(0.5~5)×1012 cm-2 and temperature T=200~300 K, scattering due to the surfon deformation potential is calculated. Qualitative features of the calculated mobility µcalc such as its dependence upon Ns and T, its variation with the surface orientation and its anisotropy agree with experiments. Quantitatively, however, µcalc is about three times as large as the values measured so far, when the estimated scattering by optical phonons is taken into account. The effect of the phonon reflection on the surface is about 15%. The theory uses the deformation potential constants and all the other parameters from bulk measurements. Some of these values could perhaps be different in the surface region, or the value of the mobility may become bigger as sample preparation techniques improve further so that the discrepancy may be less pronounced.
81 citations
TL;DR: In this article, the adsorption of CO on Ru(001) has been studied using a combination of techniques: LEED/Auger, Kelvin probe contact potential changes, and flash desorption mass spectrometry.
Abstract: The adsorption of CO on Ru(001) has been studied using a combination of techniques: LEED/Auger, Kelvin probe contact potential changes, and flash desorption mass spectrometry. Adsorption of CO is reversible at temperatures and pressures as high as 700 K and 10-4 Torr, respectively. Two binding states of CO are identified, and isosteric heats determined both from work function changes and from LEED intensity measurements agree well with flash desorption energies. A disordering of the CO layer due to repulsive interactions between neighbors at high coverages is postulated. Electron beam-induced LEED pattern changes are characterized and found to have a high cross section (~7×10-17 cm2) at ~110 eV.
TL;DR: In this article, the acceptor density formed by heat treatment shows minimum at a certain arsenic vapor pressure (PAs, min), and the relation between the annealing temperature (TH) and this PAs is given as PAs,min\fallingdotseq2.
Abstract: Te-doped GaAs crystals were heat-treated under various arsenic vapor pressures, and the defects related to nonstoichiometry were studied. The acceptor density formed by heat treatment shows minimum at a certain arsenic vapor pressure (PAs, min), and the relation between the annealing temperature (TH) and this arsenic vapor pressure PAs, min is given as PAs, min\fallingdotseq2.6?106exp {-1.05 eV/(kTH)} Torr. The density of acceptors related with defects, probably two sorts of acceptors generated at lower pressures and at higher pressures respectively, is at the same time in proportion to the concentration of the initial donor impurity (Te). Therefore complexes associated both with the donor impurity (Te) and with the defects due to the deviation from the stoichiometric composition are formed. These complexes are responsible for both the 0.18 eV acceptor level and the 1.30 eV emission band at 77 K. Furthermore defects with acceptor levels of 0.12 eV and 0.15 eV, are investigated. These defects are unstable and disappear by reannealing at comparatively low temperatures (300?400?C) leaving acceptor levels at 0.18 eV.
TL;DR: In this article, the authors describe adsorption studies of serveral inorganic and organic species on single crystal Ni(111) using ultraviolet photoemission spectroscopy (hv=21.2 eV).
Abstract: We describe adsorption studies of serveral inorganic and organic species on single crystal Ni(111) using ultraviolet photoemission spectroscopy (hv=21.2 eV). Adsorbate orbital ionization energies and line shapes have been measured and surface reactions have been studied. Ionization energies for chemisorbed unsaturated hydrocarbons (C2H2, C2H4, and C6H6) exhibit large surface-induced relaxation shifts (~1–3 eV) relative to their gas phase counterparts as well as π-orbital bonding shifts (~0.9–1.5 eV). We estimate these π-d bonding interaction strengths and chemisorption energies using Mulliken's donor-acceptor theory as described by Grimley for weak chemical bonds and show that an observed surface reaction, i.e. the dehydrogenation of chemisorbed ethylene (C2H4) to chemisorbed acetylene (C2H2) for T\gtrsim230 K, becomes exothermic only for the chemisorbed species due to the π-d electron interaction.
TL;DR: In this paper, the Hartree-Fock approximation for the upward shift in the alkali valence level due to the image force was shown to be overestimated by up to a factor of two from the result that the self-image energy of an electron at a distance d from a metal surface is given by v=e2/4d.
Abstract: An important contribution towards the well-known ionization of alkali atoms chemisorbed at low coverages on transition metal surfaces comes from the upward shift in the alkali valence level due to the image force. The Hartree-Fock approximation for this upward shift, in which the image of the adatom electron cloud is assumed static, may differ by up to a factor of two from that using the result that the self-image energy of an electron at a distance d from a metal surface is given by v=e2/4d. The resolution of this problem depends on the lifetime of an electron in the adatom orbital and the dielectric response of the metal surface. A simple model Hamiltonian is put forward which includes these effects, and which is solved in limiting cases. In particular it is found that the HF approximation should overestimate the upward shift in the case of a substrate such as tungsten. Possible implications for the screening of the Coulomb interaction between electrons in an adatom orbital are discussed.
TL;DR: In this article, the size and shape of the particles varied with the collection positions as well as with the evaporation conditions such as the gas pressure and evapse temperature, and the results showed a general trend that the crystallites with larger surface area formed in the outer zone while those with smaller surface area forming in the inner zone.
Abstract: Particle samples collected at various positions in metal smokes were studied by electron microscopy. The size and shape of the particles varied with the collection positions as well as with the evaporation conditions such as the gas pressure and evaporation temperature. The results showed a general trend that the crystallites with larger surface area formed in the outer zone while those with smaller surface area formed in the inner zone, provided that their volume was the same: hexagonal plates (Mg & Be) and rods (Mn & Te) formed in the outer zone while hexagonal polyhedra (Mg), rhombic dodecahedra (Be & Mn) and pear-shapes (Te) formed in the inner zone.
TL;DR: In this paper, a new derivation of the LEED pattern of a stepped surface was proposed to predict and evaluate also the pattern of the surface on a non-primitive lattice.
Abstract: Clean surfaces produced by cleavage or ion bombardment and annealing mostly show atomic steps. With a new derivation of the LEED pattern of a stepped surface it is now possible to predict and evaluate also the pattern of a surface on a non-primitive lattice. With the use of high precision LEED data depression of the edge atoms of about 0.25 A is supported by several independent observations. On cleaved silicon and germanium surfaces the step density is determined for each spot of the surface. At clean cleaved silicon surfaces the photo surface voltage has been measured by scanning the surfaces with an electron beam. A correlation between the photo surface voltage and the angle of inclination of the respective spot of the surface towards the (111) face reveals the existence of one-dimensional surface states ("edge states"). It is therefore important to know the existence and properties of atomic steps on clean surfaces in both structural and electronic respects.
TL;DR: In this paper, the nature of the neutral species rf sputtered from several oxide targets has been studied using a technique in which the sputtered particles are ionized in the glow discharge and are then detected with a quadrupole mass filter.
Abstract: The nature of the neutral species rf sputtered from several oxide targets has been studied using a technique in which the sputtered particles are ionized in the glow discharge and are then detected with a quadrupole mass filter. The extent to which the species MO+ are observed relative to the species M+ during the rf sputtering of an oxide target MxOy is studied as a function of M-O bond energy, rf power and discharge gas pressure. The results suggest that in certain cases the intensity of sputtered neutral molecules may exceed that of sputtered neutral atoms.
TL;DR: In this article, the authors studied the incorporation of Mn2+ and Eu2+ ions in β-Al2O3-like host crystals and compared the emission and excitation spectra of the phosphors with those of Kβ-Al 2O3.
Abstract: Incorporation of Mn2+ and Eu2+ ions in β-Al2O3-like host crystals has been studied. Under ultraviolet excitation, both BaO6Al2O3: Eu, Mn and La2O311Al2O3: Eu, Mn show intense green fluorescence caused by the energy transfer from Eu2+ to Mn2+. The efficiency of the luminescence is comparable to that of Zn2SiO4: Mn when excited by 254 nm light. Emission and excitation spectra of the phosphors were compared with those of K β-Al2O3. The difference in the atomic packing in the mirror plane of these aluminates appears to be reflected in the emission spectra of Mn2+. The quenching temperature for the sensitized fluorescence of Mn2+ is governed by the Eu2+ ions, replacing mono-, di-, or tri-valent large cations in these compounds.
TL;DR: Graphite fibers with a high degree of crystallinity have been prepared by heat treatment of carbon fibers at temperatures above 2800°C as mentioned in this paper, and they have lengths ranging up to 25 cm, and diameters from 10 to several hundred microns.
Abstract: Graphite fibers with a high degree of crystallinity have been prepared by heat treatment of carbon fibers at temperatures above 2800°C. The original carbon fibers were produced through a deposition technique by cracking vaporized benzene in carrier gas of hydrogen at about 1100°C. They have lengths ranging up to 25 cm, and diameters from 10 to several hundred microns. The graphite fibers consist of concentric tubes of graphite layers having a three-dimensional crystallinity, and the c-axes of the crystallite are nearly perpendiclar to the fiber axis. The electrical resistivity is 60–100 µΩcm along the fiber axis at room temperature, the temperature dependence being similar to that of the graphite whiskers in the range from room temperature down to liquid helium temperature. They also show a high degree of strength and flexibility. A fiber with a diameter of about 10 µm exhibits tensile strength of 50 t/cm2 and Young's modulus of 2000–3000 t/cm2.
TL;DR: The photoluminescence studies of the carbon doped epitaxial gallium arsenide revealed that a pair of emission bands at 1.493 eV and 1.490 eV (D-A) were attributed to the carbon acceptor on arsenic site as discussed by the authors.
Abstract: The photoluminescence studies of the carbon doped epitaxial gallium arsenide revealed that a pair of emission bands at 1.493 eV (B-A) and 1.490 eV (D-A) were attributed to the carbon acceptor on arsenic site. The sharp doublet emission lines at 1.5127 eV and 1.4937 eV were identified with the exciton recombination bound to a neutral carbon acceptor and the two-hole transition in which the neutral carbon acceptor is left in an excited state, respectively. From the observation of these emissions, the 1S3/2 ground and 2S3/2 excited state energies of carbon acceptor were found to be 26.5 meV and 7.5 meV above the valence band edge, respectively. The results were supported by the effective mass arguments and by the dependence of the binding energy on the atomic number of impurities.
TL;DR: In this paper, the ordered structure of adatoms is discussed in the light of a theory which determines rigorously the ground state of the extended range lattice gas model, and several examples are discussed to show that an appearance or absence of an ordered structure at a particular density yields informations about the adatom interaction.
Abstract: The ordered structure of adatoms is discussed in the light of a theory which determines rigorously the ground state of the extended range lattice gas model. Several examples are discussed to show that an appearance or absence of an ordered structure at a particular density yields informations about the adatom interaction. The intermediate phase which may appear at finite temperatures is discussed briefly.
TL;DR: The phase diagram of the system Ga-Se has been determined by the differential thermal analysis (DTA) as mentioned in this paper, and the main features of the diagram are as follows: (1) the melting point of GaSe is 938± 3°C and Ga2Se3 is 1005±3°C, and the monotectic transition occurs at 915°C in the lower composition region than 50 at.%Se.
Abstract: The phase diagram of the system Ga-Se has been determined by the differential thermal analysis (DTA). The main features of the diagram are as follows: (1) the melting point of GaSe is 938±3°C and Ga2Se3 is 1005±3°C. (2) the monotectic transition occurs at 915°C in the lower composition region than 50 at.%Se. (3) the eutectic is formed at 884°C in the composition region between GaSe and Ga2Se3. (4) the solidified samples in the region between Ga2Se3 and Se consist of mixtures of Ga2Se3 and Se. At higher selenium composition, the DTA peaks observed at about 140°C and 45°C probably correspond to the crystallization and the glass transition of selenium respectively. In the composition region less than 50 at.%Se, the sublimation products consist of gallium and GaSe. The phases of Ga2Se and Ga3Se2 reported by other authors are not observed.
TL;DR: In this paper, two scattering mechanisms are discussed theoretically for the interpretation of observed low temperature mobility in n-channel inversion layers of Si MOS, one is the scattering due to interface roughness and a simplified model is investigated.
Abstract: For the interpretation of observed low temperature mobility in n-channel inversion layers of Si MOS, two scattering mechanisms are discussed theoretically. The one is the scattering due to interface roughness and a simplified model is investigated. The other is the scattering by the charged centers. The former can explain the carrier concentration dependence of the mobility in high carrier concentration region. The latter is introduced for the interpretation of the mobility at low carrier concentration with some considerations of the charge distribution.
TL;DR: In this paper, an automated evaluation of dc and pulsed dc electroluminescent (EL) properties in the system ZnS: Mnx: Cuy has been made on films deposited by rf co-sputtering from three targets of znS, Mn and Cu by an automated method.
Abstract: Evaluation of dc and pulsed dc electroluminescent (EL) properties in the system ZnS: Mnx: Cuy has been made on films deposited by rf co-sputtering from three targets of ZnS, Mn and Cu by an automated method. Enhancement of the performance of the EL films was achieved by coating them with current-limiting rf-sputtered cermet films. The optimum composition of the EL films was found to be 0.6 and 0.3 mole% Mn and Cu, respectively. Mean brightnesses of up to 770 fL and 20 fL have been measured with pulsed dc excitation at 12.5% and 0.1% duty cycle, respectively, at power efficiencies in the range of 10-4 to 10-3, (0.04 to 0.4 lumens/watt). Thus far, cell half-life of 400 hr (at 15 fL constant brightness) has been achieved. This work was sponsored by the U.S. Army Electronics Command, Ft. Monmouth, NJ, under Contract No. DAABO7–69–C–0290.
TL;DR: In this article, single domain particles of Fe alloys (Fe versus Ni, Cu, Si, Cr, Gd and Ho) were prepared by the evaporation method and the saturation magnetization, remanent magnetization and coercive force of these particles were measured by an automatic magnetic balance.
Abstract: Single domain particles of Fe alloys (Fe versus Ni, Cu, Si, Cr, Gd and Ho) were prepared by the evaporation method. The saturation magnetization, remanent magnetization and coercive force of these particles were measured by an automatic magnetic balance. The dispersion of the anisotropy of Fe, Co and Ni particles were determined by a torque meter. The characteristics of these alloy particles were discussed in terms of their applicability to industrial use. The stability for oxydation and the magnetic orientation of particles have already been reported in the previous paper of this series. By choosing a suitable composition of alloys, the coercivity of the prepared particles can be controlled in the range of 200 to 1800 Oe. It was found that the anisotropy dispersion of Fe-Ni alloy was smaller than that of a commercial CrO2 tape.
TL;DR: The saturation magnetostriction constants of YIG and Fe(1-x)Alx (x=0.25) single crystals were measured by a capacitance method at room temperature as mentioned in this paper.
Abstract: The saturation magnetostriction constants λ100 and λ111 of YIG and Fe(1-x)Alx (x=0.17, 0.20, 0.23, 0.25) single crystals were measured by a capacitance method at room temperature. The capacitance cell used in this experiment was designed to be convenient for measuring the constants of spherical samples from 0.5 mm to 10 mm in diameter with sufficient sensitivity to measure elongations of 0.1A. The magnetostriction constants λ100 and λ111 of YIG were -1.43×10-6 and -2.88×10-6 respectively and were in very good agreement with the values observed by Callen, Clark, DeSavage, Coleman and Callen.