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The effects of weathering on carbon films deposited on Japanese smoked roof tiles were investigated by soft x-ray absorption and emission spectroscopy using synchrotron radiation. X-ray absorption measurements revealed that weathering oxidizes the carbon films and that partial carboxy chemical bonding occurs. Incident angle-dependent x-ray absorption spectra in the C K region confirmed that the degree of the orientation at the surface of the oxidized carbon films decreases with weathering. However, the take-off angle-dependent C K x-ray emission spectra showed that the orientation of the layered carbon structure is maintained in the bulk portion when weathered. Therefore, it is confirmed that oxidation proceeds from the surface of the carbon films. Weathering degrades and oxidizes the surface carbon films, which causes the metallic silver color to change to darker gray.

Surface carbon films on the Japanese smoked roof tile “Ibushi-Kawara” (hereafter “Kawara”) were analyzed by angle-dependent soft X-ray emission spectroscopy using synchrotron radiation. The carbon film microstructure on typical Kawara is 50% carbon-black-like sp2 carbon atoms, which form layer-structured clusters parallel to the basal clay plane, and 50% carbon-black-like atoms, which form random-structured clusters that rigidly connect the layer-structured clusters. Weathered Kawara that has been exposed to sea breezes for numerous years was analyzed to understand the weathering effect from a microstructure point of view. The main weathering effect was the removal of the carbon film. It was also determined that the black stripes, which appear on the degraded “Susumaki” Kawara, are made from random-structured carbon black.

Carbon films on the Japanese smoked roof tile "Ibushi-Kawara" were characterized by high-resolution soft X-ray spectroscopy using synchrotron radiation. By comparing the soft X-ray emission and absorption spectra of Kawara with the reference carbon compounds, it was determined that the carbon films on Kawara consist of mostly carbon-black-like sp2 carbon atoms and that the surface also contains polyethylene-like sp3 carbon atoms. The take-off/incident-angle dependence on the X-ray emission/absorption spectra of Kawara shows that the carbon-black-like sp2 carbon atoms partially form a layer structure oriented parallel to the basal clay plane, and that the degree of orientation of the carbon films is estimated to be 50% that of highly oriented pyrolytic graphite (HOPG). The microstructure of the carbon films on Kawara is one in which half of the carbon-black-like sp2 carbon atoms form layer-structured clusters parallel to the basal clay plane and the rest of the carbon atoms form random-structured clusters which rigidly connect the layer-structured clusters.

Indium-tin-oxide film (ITO) was fabricated on a (100) surface of an yttria-stabilized zirconia (YSZ) single crystal by pulsed laser deposition. The ITO film was characterized by atomic force microscopy and X-ray diffraction measurements. ITO grew heteroepitaxially on the YSZ substrate. The ITO film surface was extremely flat and roughness in height was less than 1 nm. Two organic dyes, copper phthalocyanine and vanadyltetraphenylporphyrin, were vacuum-deposited on the ITO substrate. Their molecular orientations in thin film were investigated by transmission electron microscopy and electron diffraction analysis.

Indium tin oxide (ITO) thin films 60–100 nm thick have been grown on SiO 2 glass by laser irradiation of the substrate during pulsed laser deposition. A laser beam with an energy density of 0.07 J cm −2 (size ∼1 cm 2 ) was directed on to the middle part of the substrates during film growths. Films were deposited from a 95 wt% In 2 O 3 –5 wt% SnO 2 sintered ceramic target at a room temperature and oxygen pressures ( P O 2 ) ranging from 0.13 to 5.99 Pa. The structural, electrical, and optical properties of the laser-irradiated and the nonirradiated parts of the films were studied as a function of P O 2 . Crystalline ITO films with 〈1 1 1〉 preferred orientation were observed at all P O 2 , except 0.13 Pa. Under P O 2 around 1.33 Pa, minimal resistivities of 1.2×10 −4 and 2.3×10 −4 Ω cm were obtained on the laser irradiated and the nonirradiated parts of the deposited films. The observed low resistivity for the laser-irradiated part of the films was a consequence of both the high carrier concentration and Hall mobility of the films. High optical transmittance (>85%) to visible light was obtained.

Electrical properties of crystalline indium–tin-oxide (ITO) films, which were grown on polycarbonate (PC) substrates at room temperature by pulsed laser deposition (PLD) with in situ laser irradiation onto the substrates, were studied. The PC substrates were colored by in situ laser irradiation when the ITO films were prepared on the substrates directly, and the resistivity of the ITO films was extremely high. While the PC substrates were prevented from coloring by pre-deposition of CeO2 film, the resistivity was still high. The introduction of a thin Al2O3 layer between the PC substrate and CeO2 film resulted in marked decreasing of the resistivity of the ITO film.

The relation between electrical and structural properties of indium tin oxide (ITO) films prepared by pulsed laser deposition with and without in situ laser irradiation is examined. The residual stresses of the films were estimated from x-ray diffraction patterns measured by grazing-incidence asymmetric Bragg and grazing-incidence x-ray diffraction geometries. For the films prepared without in situ irradiation, the residual stress depended on oxygen pressure (PO2) during deposition and had minimum around PO2 of 1.3 Pa, which coincided with the optimum PO2 for growing the lowest resistivity films. The resistivity was only slightly improved with an increase of substrate temperature (Ts) because a large residual stress was introduced. In contrast, the ITO films prepared with in situ laser irradiation showed very low resistivity (ρ

The electrical and optical properties of pulsed laser deposited amorphous indium tin oxide films at room temperature are discussed. The films were grown from indium oxide (In 2 O 3 ) targets of different tin (Sn) doping content (0, 5 and 10 wt%) at different oxygen pressures ( P O 2 ) ranging from 1×10 −3 to 5×10 −2 Torr. The electrical and optical properties of the films were examined by Hall measurements and optical spectrophotometry. It was found that high conductivity amorphous films could be prepared at room temperature irrespective of the Sn doping content. The properties of these films deposited from 0, 5, 10 wt% Sn-doped In 2 O 3 targets show a similar response to changes in P O 2 . The maximal conductivity of (4.0, 2.1 and 1.8)×10 3 S/cm and optical transmittance (visible) higher than 90% were obtained at P O 2 region of (1–1.5)×10 −2 Torr. An undoped In 2 O 3 film produced the highest conductivity of 4×10 3 S/cm in these studies.

Molybdenum and graphite powders were mechanically alloyed. Carbon K X-ray emission spectra of the mechanically alloyed powders were measured using electron probe microanalyzer (EPMA) in order to investigate the solid state reaction process. In the early stage of the mechanical alloying (∼36ks), graphite did not react with molybdenum, but particle size of graphite became smaller. In the next stage of mechanical alloying (36 ∼ 144 ks), graphite react with molybdenum gradually as the time increases. Molybdenum carbides were formed on mechanical alloying for 288 ks. The mechanically alloyed powders for 288 ks were heat-treated in a vacuum. Mo-33 at%C system heat-treated at 1273 K was a mixture of Mo2C and molybdenum, while Mo-50at%C system heat-treated was a mixture of Mo 2 C, mechanically ground graphite and graphite.

High quality indium tin oxide (ITO) films of thickness 80±20 nm grown by laser irradiation of the glass substrates during pulsed laser deposition are reported. Films were deposited from a 5 wt.% SnO 2 -doped In 2 O 3 target at substrate temperatures ( T s ) ranging from room temperature (RT) to 400°C and oxygen pressure (PO 2 ) of 1.3 Pa. The energy of the laser beam focused unto the middle of the glass substrate during coatings was about 70 mJ cm −2 . The structural, electrical and optical properties of the laser-irradiated and the nonirradiated parts of the ITO films were studied as a function of T s . Crystalline films with 〈1 1 1〉 preferred orientation and crystal sizes⪢200 nm were obtained at all T s . At RT, the resistivity of the laser-irradiated part of one film was 1.2×10 −4 Ω cm compared with 2.3×10 −4 Ω cm for a nonirradiated part. At 300°C, a low resistivity value of 8.5×10 −5 Ω cm was achieved for both the laser-irradiated and the nonirradiated parts of the ITO film. The achievement of low resistivity resulted from the high carrier concentration ∼1.2×10 21 cm −3 and the high Hall mobility (40–57) cm 2 V −1 s −1 . The films also exhibited high optical transmittance (∼90%) to visible light.

The effects of stress in pulsed laser deposited (PLD) indium-tin-oxide (ITO) films formed on glass substrate at 200 °C and oxygen pressures (Po2) ranging from 0.1 to 2.7 Pa are discussed. Grazing incidence X-ray diffraction (GIXRD) investigations of the ITO films show splitting of the diffraction peaks and significant changes in the lattice constants for films deposited at low Po2 and when the thickness of the films is larger than 150 nm. These features were due to intrinsic stress caused by the incidence of energetic particles on the substrate during growth. The splitting of the peaks only occurred in the bulk of the films, while near the surface, single peaks were evidenced, indicating the existence of two layers. No apparent splitting of the diffraction peaks or shifts in peak positions occurred in the ITO layers with thickness less than 100 nm. In spite of the presence of stress in the ITO films, resistivity less than 3 10, -4 Ωcm was obtained. © 2001 Kluwer Academic Publishers

Pure indium oxide (In2O3) and SnO2-doped In2O3 (5 and 10 wt %) films were deposited on glass at different substrate temperatures (Ts) ranging from room temperature (RT=25 °C) to 350 °C using pulsed laser deposition. At low Ts (RT to 100 °C), pure In2O3 films yielded the lowest resistivity of (1.8–2.5)×10−4 Ω cm and the resistivity increased sharply with an increase in Ts, and the rise in the resistivity of pure In2O3 films resulted mainly from a decrease in carrier concentration and Hall mobility. For SnO2-doped In2O3 films, the resistivity decreased from 3.5×10−4 to 1.3×10−4 Ω cm with increasing Ts from RT to 350 °C and the reduction in the resistivity is associated with thermal activation of Sn leading to an increase in carrier concentration. Amorphous films were obtained at RT, but from Ts of 100 °C, the films appeared polycrystalline with orientation in the 〈111〉 plane. From atomic force microscopy, minimum surface roughness (Ra)⩽1.3 nm was obtained at RT and Ts>200 °C. Between 100 and 150 °C, Ra was maximum (2.5–4.9 nm). The films also exhibited high optical transmittance (>85%) to visible light.

The DV-Xa molecular orbital (MO) calculation method was applied to the B K‐V x-ray emission spectra of hexagonal (h-), cubic (c-) and wurtzite (w -) type boron nitrides (BN). The calculated B 2p density of states (DOS) was in good agreement with the B K‐V x-ray emission. The main peaks and low-energy satellite peaks in the B K‐V x-ray emission spectra are due to the B 2p and the B 2p hybridized with N 2s, respectively. The high-energy satellite peak in the B K‐V x-ray emission spectra clearly corresponds to the p sub-band of the B 2p DOS in h-BN. However, the high-energy satellite peak observed in w -BN is not in agreement with the B 2p DOS. It is considered that the high-energy satellite peaks are due to less than four-coordinated B atoms such as have dangling bonds and defects in w -BN. In the B K‐V x-ray emission spectra of h-BN, the synthesizing p and s sub-bands of B 2p DOS could explain the polarized emission spectra very well. Copyright ” 1999 John Wiley & Sons, Ltd.

X-ray emission and absorption spectra of carbon nitride films prepared by laser ablation were measured. The carbon x-ray spectra of films obtained in a nitrogen atmosphere were different from those of a film prepared in vacuum. It was found from DV-Xα molecular orbital calculations on x-ray spectra that the films obtained in a nitrogen atmosphere contained bonding between carbon and nitrogen atoms. This was supported by the Fourier transform IR spectra.

Highly conducting and transparent indium tin oxide (ITO) thin films were prepared on SiO2 glass and silicon substrates by pulsed laser ablation (PLA) from a 90 wt.% In2O3-10 wt.% SnO2 sintered ceramic target. The growths of ITO films under different oxygen pressures (PO2) ranging from 1×10 −4 –5×10 −2 Torr at low substrate temperatures (Ts) between room temperature (RT) and 200°C were investigated. The opto-electrical properties of the films were found to be strongly dependent on the PO2 during the film deposition. Under a PO2 of 1×10 −2 Torr, ITO films with low resistivity of 5.35×10 −4 and 1.75×10 −4 Ω cm were obtained at RT (25°C) and 200°C, respectively. The films exhibited high carrier density and reasonably high Hall mobility at the optimal PO2 region of 1×10 −2 to 1.5×10 −2 Torr. Optical transmittance in excess of 87% in the visible region of the solar spectrum was displayed by the films deposited at P o 2 ≥1×10 −2 Torr and it was significantly reduced as the PO2 decreases.

Niobium or tungsten and graphite powders were mechanically alloyed. Carbon K X–ray spectra of the mechanically alloyed powders were measured using an electron probe microanalyzer (EPMA) in order to investigate the solid state reaction process. In the early stage of the mechanical alloying (10 hours), graphite did not react with metal, but particle size of graphite became smaller. In the next stage of the mechanical alloying (2–4 hours), micro–crystalline graphite powder reacted with metal. Polarization of the X–rays were measured for Nb 2 C and W 2 C, because a single crystal WC emitted polarized X–rays. The measurement of X–ray emission spectra was useful for the structural and chemical analysis of mechanical alloying reaction processes.

The DV-Xα molecular orbital (MO) calculation method has been applied to the carbon K-V X-ray emission spectra of graphite. The calculated 2p density of states (DOS) of a larger model cluster, which avoided the influence of dangling bonds of the cluster edge, was in excellent agreement with the X-ray emission spectra. The calculated π and σ subbands of 2p DOS explained the polarized behavior of the spectra. The orientation of graphite was quantitatively discussed by means of polarization of the spectra. These results were applied to the analysis of the structural change of mechanical milled graphite; the structure change of the ball-milled graphite was studied by the X-ray spectroscopy and MO calculation. It was shown that the refinement of graphite powder occurred for up to 1000 h of milling, keeping the graphite structure, and that a further milling changed the C-C bonding within the graphite layer network.

C K–emission spectra of carbons (graphite, diamond) and graphite fluoride ((CF)n) are calculated with the discrete–variational–Xα method. The numerical recipes are used to get the polarized C K–emission spectra. The results of graphite and diamond are in good agreement with the observed spectra. The difference in intensity between the calculated and observed spectra of graphite fluoride is suggested to be due to the decomposition of (CF)n during the measurement.

Camphene has been studied over ranges of pressure up to 9.5 GPa and temperature up to 1300 °C by in situ resist-volumetric, x-ray diffraction, and Raman scattering measurements as well as by postcompression analyses on retrieved samples. In the solid state, polymerized and amorphous phases appeared. The melting temperature was found to increase with increasing pressure and the melting line showed a small deflection at about 4 GPa, which was attributed to a triple point among the two solid phases and the liquid. Another amorphous phase was retrieved from a region right above the melting line. Heat treatment at temperatures beyond the melting line by about 200 °C and higher yielded turbostratic and graphitic carbons.

Soft X-ray emission and absorption (SXEA) spectroscopy is presented as a possible method for electronic structure analysis. To demonstrate its feasibility, the electronic structure of silicon backbones in a cubic silicon cluster (octasilacubane) and its related clusters was analyzed by measuring the SXEA spectra in the Si K-shell threshold. Three discrete levels are observed in both Si3p occupied and unoccupied orbitals of octasilacubane, which may be caused by the large degree of degeneracy of the orbitals due to the high symmetry of the cubic silicon backbone structure. The measured narrow energy gap of 2.3 eV between the highest occupied and the lowest unoccupied orbitals of octasilacubane shows that Si3p σ-electrons in octasilacubane are more widely conjugated than those in the related clusters.

The B K X-ray emission spectrum of h-BN can be approximately reproduced by the DV-Xα calculation, using the two-dimensional model cluster constructed of a mono-layer of the planar hexagonal network. In order to verify the polarized B K X-ray emission spectrum of h-BN, the contributions of the σ, π and π ∗ subbands to its spectral feature were estimated at different take-off angles for the c axis of an h-BN crystal. The high-energy satellite band increases its intensity, remarkably, due to the contribution of the π ∗ subband with increase in take-off angle, whereas the low-energy satellite band decreases its intensity due to the contribution of the σ subband. The measured B K X-ray emission spectrum of the ion-plated h-BN thin film is in good agreement with the calculated one at a take-off angle of 90°.

Ball-milling of graphite powder was performed by the use of a stainless steel ball-mill and an agate ball-mill. The crystal structure of the ground graphite was studied by transmission electron microscopy and X-ray diffractometry. A spectrometric approach to the change of structure during the milling process was also carried out by the carbon Kα X-ray-emission band spectroscopy (XES). The carbon Kα XES spectra were compared with those of carbon materials such as ball-milled diamond powder, i-diamond film and amorphous carbon powder. In the case of the stainless steel ball-milling, microcrystalline and/or onion-like structure were formed. The XES spectrum suggested that sp3 hybrid orbital was formed after 2000 h of milling. While, in the case of an agate ball-milling, it was suggested that the 2p orbital became narrow as a result of further finely-ground pulverization of graphite crystallite after 1750 h of milling.

Mechanical alloying (MA) of iron and graphite was performed for C-10 at%Fe alloy by the use of a conventional ball mill. The structure of mechanically alloyed samples were examined by X-ray diffraction, transmission electron microscopy. A spectrometric approach to the change of structure during the milling process was carried out by carbon Kα X-ray-emission band spectroscopy and electron energy loss spectroscopy. Finely dispersed iron particles with a grain size of about 10 nm into graphite powder particles were obtained after 1000 h of MA. Spectrometric results suggested that fracturing of graphite of graphite crystal progressed by three steps ; fracturing along the hexagonal plane, fracturing the hexagonal networks and amorphization. The electron state of carbon atom in the ball milled sample was energized to form sp 3 hybrid orbital, after applying pressuring.

The effect of zirconia on crystallization of glasses with lepidolite composition and properties of glass-ceramics obtained have been investigated. The batches of 7LiF⋅15KF⋅28Al2O3⋅50SiO2 (wt%) were melted at 1500°C for 10min and the melts were quenched by pressing the melt with platinum plate. The obtained glasses were heated at a constant heating rate, and the precipitated crystals were found to be lepidolite and β-eucryptite by X-ray diffraction analysis. The crystallization temperatures of lepidolite and β-eucryptite were 600 and 800°C, respectively at the heating rate of 10°C⋅min-1. However, in order to precipitate the lepidolite in the glass containing no ZrO2 by isothermal heat-treatment, the crystallization of lepidolite required heating the glass at 500°C for more than 1h. One percent ZrO2 was sufficient for the crystallization of lepidolite. The activation energy for crystal growth of the glass was 268kJ/mol. The thermal conductivity of glass-ceramics heated at 500°C for 1h and then 800°C for 2h was 0.033W/cm⋅°C, which was larger than lepidolite glass-ceramics, and its thermal expansion coefficient and dielectric properties were similar to those of lepidolite glass-ceramics.

The fluorination of highly oriented pyrolytic graphite (HOPG), powdery and flaky natural graphites, and carbon fiber (P 100) has been performed in a fluorine atmosphere with HF gas (5.3 × 103−4.8 × 104 Pa), or by flowing fluorine gas in anhydrous liquid hydrogen fluoride (AHF) at ambient temperature. The obtained CxFs were the stage 1 to 2 compounds with composition of C1.9F to C7.0F. The stage 1 phases prepared from HOPG and pyrolytic graphite have shown large IC values of 1.12 nm to 1.18 nm. This result has coincided with the model that the stage 1 phase with large IC values is a bi-intercalation phase in which two kinds of almost ionically and semi-covalently bonded fluorine atoms with different C-F bond lengths are inserted in every other carbon layer. However, stage 1 CxF samples prepared from natural graphite powder and carbon fiber showed only one strong (001) diffraction line in most cases. X-ray powder diffraction and electron diffraction have revealed the absence of an in-plane superlattice at all stages.

Elemental Al, Nb and B powders with the composition of Al3Nb-xvol%NbB2 (x=10-30) were mechanically alloyed (MA) in an Ar gas atmosphere. The results of X-ray diffraction indicated that an Al3Nb phase and a NbB2 phase, which was considered to be NbB2-x (with lesser stoichiometrical B content), were obtained in 72.0ks MA powders. The sintered compacts with high density were obtained by vacuum heating of the compacts of 72.0ks MA powders. Fine NbB2-x dispersed uniformly in the sintered compacts and its content increased according to the x value in A13Nb-xvol%NbB2. A part of NbB2-x obtained in the sinterd compacts was like a rod in shape. Many rod-like NbB2-x were formed in HIPed compacts which were processed at lower temperature than the sinterd compacts. TEM observation of the HIPed compacts revealed that rod-like NbB2-x, which was as small as nano-meter, precipitated on nano-sized Al3Nb matrix. The hardness of the HIPed compacts was about Hv1000 which was higher than that of Al3Nb.

Carbon K-V x-ray-emission spectra of solid C 70 and C 60 are measured, and the partial electron densities of states (DOS) are calculated by the discrete-variational (DV) Hartree-Fock-Slater (Xα) molecular-orbital (MO) method. The measured x-ray line shapes are compared with the calculated 2p DOS of C 70 and C 60 . The agreement between theory and experiment is satisfactory without any adjustable parameters in the DV-Xα MO calculations

X‐ray emission spectra of buckminsterfullerene (C60) and alkali‐metal fullerides (M3C60, where M denotes alkali‐metal) are calculated with the discrete‐variational (DV)‐Xα method. The calculated x‐ray emission spectra of C60 agree well with experimental x‐ray spectra. This indicates that the x‐ray emission spectrum of M3C60 calculated with the same method provides a good prediction of fulleride spectra which have not been measured yet. The calculated x‐ray emission spectra are proposed to be used as standards of the electron probe microanalyzer (EPMA) spectra of fullerene and related compounds for searching the existence of such compounds in carbon mixtures.

Fluorine-graphite intercalation compound (CxF) has been synthesized from HOPG by electrochemical method using solid electrolyte PbSnF4 in a fluorine atmosphere. The compositions of the obtained CxF samples were between stage 7+4, C16.5F and stage 1, C2.4F. Fluorination was highly promoted by charging and, the fluorine content in the sample increased with increase of the charge. Two types of stage 1 bi-intecalation phases, and the in-plane superlattice with a0=2ag and b0=√3ag were observed for stage 1, C2.4F, for which the c-axis and in-plane structure models have been proposed. The calculated intensity of X-ray diffraction lines is in good agreement with observed one.

Hard BN films with cubic BN (c-BN) phase and soft BN films without c-BN phase were deposited on Si wafer by a reactive ion plating process with a hot cathode plasma discharged within parallel magnetic field. These BN films were left in air with relative humidity of about 30%, 65-85% and 100% for about 3000 hours. The atmospheric degeneration of these BN films was investigated by SEM observation and EPMA measurements. Small particles such as boron oxide, boric acid or ammonium borate were formed at the surface of soft BN films left in air. All BN films were cracked after leaving in air. The cracking became faster with an increase in the relative humidity of air. The cracking of soft BN films occurred more rapidly than that of hard BN films. The cracking of hard BN films was retarded by post annealing.

X‐ray emission spectra of buckminsterfullerene (C60) and alkali‐metal fullerides (M3C60, where M denotes alkali‐metal) are calculated with the discrete‐variational (DV)‐Xα method. The calculated x‐ray emission spectra of C60 agree well with experimental x‐ray spectra. This indicates that the x‐ray emission spectrum of M3C60 calculated with the same method provides a good prediction of fulleride spectra which have not been measured yet. The calculated x‐ray emission spectra are proposed to be used as standards of the electron probe microanalyzer (EPMA) spectra of fullerene and related compounds for searching the existence of such compounds in carbon mixtures.

Fluorine-graphite intercalation compounds have been prepared from HOPG and natural graphite powder in the presence of a fluoride such as AgF, WF 6 , or SbF 5 at room temperature. The C x F samples obtained were quasi stage 1, 2, and 3 compounds with compositions of C 2.7 F-C 9.6 F. The stage 1 phases in the admixtures of stages 1 and 2 prepared from HOPG show large I c values of 10.5 to 11.9 A. X-ray powder diffraction indicates the existence of an in-plane superlattice with a 0 = 2 a g in the stage 3 and 2 compounds, but no superlattice at quasi stage 1. Electron diffraction for the same samples also reveals an in-plane superlattice at stages 3 and 2. Based on these results, c -axis and inplane structure models have been proposed for sage 1 through 3, C x F. The phase with a large I c value is a bi-intercalation phase in which two kinds of ionically and semi-ionically bonded fluorines with different sizes are inserted between every other carbon layer. For the in-plane structures, the proposed models are that stage 3 and 2 compounds consist of C 4n F and C 2.7n F with a 0 = 2 a g , which lead to the C 2n F structure and/or some disordered one with a 0 = a g at stage 1.

Low-resistivity (ρ) and highly transparent pure indium oxide (In2O3) thin films grown on glass substrates by pulsed laser deposition at substrate temperature (Ts) between room temperature and 200 °C are reported. As-deposited films with resistivity (ρ) of ∼3×10−4 Ω cm and transmittance (visible), above 87% were obtained within a narrow range of PO2 (1×10−2–1.5×10−2 Torr). Hall effect measurements showed that the low ρ resulted from the high carrier concentration (n)∼7×1020 cm−3, whereas modest Hall mobility (μ

Electrical and magnetic properties of (La1−xSrx)2CuO4+δ annealed in high pressure oxygen gas up to 400 bar are studied. The superconducting La2CuO4+δ includes two separate phases: one is the superconducting phase with extra oxygen, and the other is the well known antiferromagnetic phase with Neel temperature TN at 240–300 K depending on the annealing atmosphere. The superconducting phase in the undoped sample becomes unstable by Sr doping. In the high pressure oxygen annealed La2CuO4+δ, a temperature dependent paramagnetism is observed even below TN, and spontaneous vortices are considered to be induced in the zero magnetic field cooling.

In the superconducting La2CuO4+δ obtained by annealing in high pressure mixture gas of oxygen and argon, nuclear quadrupole resonance (NQR) signals of 63Cu and 65Cu have been observed around 33.1 and 36.0 MHz together with the antiferromagnetic Cu NMR signal around 70–100 MHz. The ratio of the resonance frequency of 63Cu and 65Cu is the same as that of the quadrupole moment of each Cu nucleus, indicating no internal magnetic field (paramagnetic) at Cu site. The nuclear spin-lattice relaxation time, T1, of Cu NQR indicates that the paramagnetic phase is in the superconducting state at low temperatures. The NQR intensity is roughly proportional to the partial pressure of the oxygen gas. The NQR result suggests that the volume fraction of paramagnetic phase in La2CuO4+δ increases with increasing oxygen content.

Enhanced resonant x-ray emissions were observed from mechanically milled hexagonal boron nitride nanoclusters in boron K-shell excitation using quasimonochromatic undulator radiation. The resonant x-ray emission intensity increases with decrease in size of the milled clusters. Comparison of the measured x-ray emission spectra with the calculated spectra using the discrete-variational Xa methods showed enhanced resonant x-ray emissions originate from the B1 s - n p B1 s 2 1 electron transition, with n p an unoccupied nonbonding orbital of twofold-coordination boron atoms with dangling bonds. X-ray emissions excited to n p orbitals may be possible for detecting dangling bonds in nanoclusters. [S0031-9007(96)00198-6]

To investigate the local structure of carbon black (CB) crystallites, soft X-ray absorption spectra (XAS) in the CK region of CB were measured using synchrotron radiation, and the π* peak profile in the CK-XAS was analyzed by the discrete variational (DV) Xα method. Compared to highly oriented pyrolytic graphite (HOPG), CB exhibits a broader π* peak profile where the intensity of the broad portion in CB is proportional to the hydrogen occluded in the CB. However, the broad portion cannot be reduced even in H2-degassed CB by thermal desorption. These findings on the broad π* peak profile can be simulated by the unoccupied C2p density of states (DOS) of the carbon atoms that form the nonbenzenoid rings and hydrogenated edge carbon atoms. Therefore, plausible origins for the broad π* peak in the CK-XAS of CB are the nonbenzenoid structure and/or hydrogenated edge carbon atoms in the graphitic crystallites.

Boron 2p density of states are calculated and compared with X-ray fluorescence spectra of h-BN. The high energy satellite, which was assigned to resonance X-ray scattering peak, is found to be 1s electron scattered by nonbonding unoccupied orbitals. Thus it is concluded that the resonance peak intensity is a measure of the density of dangling bonds in a nanocrystal.