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LiF–NixMn1−xO composites are prepared by the mechanical milling of LiF and NixMn1−xO (x ≤ 1) solid solution for 72 h. The obtained composites are examined by XRD, charge–discharge measurements, CV, and XPS. X-ray diffraction peaks of LiF–NixMn1−xO are broadened by milling. The diffraction peaks of NixMn1−xO in x

LiF–NiO composites are synthesized by the mechanical milling of LiF and Li-doped NiO (d_NiO) for 72 h. Li-d_NiO is prepared by the calcination of a mixture of Li2CO3 and NiO. The X-ray diffraction peaks of NiO are shifted by the doping and milling processes, while those of LiF disappear after milling. Rietveld analysis shows that the composites obtained by milling form solid solutions and that the Li+ and Ni2+ ions in them are disordered. LiF and Li-d_NiO samples milled individually do not exhibit a noticeable discharge capacity, while the composites show large values. The composite formed using undoped NiO without ball-milling shows a discharge capacity of 144 mA h g−1 at 0.05 C between 2.0 and 5.0 V, while the composite of LiF and 20% Li-d_NiO exhibits a discharge capacity of 247 mA h g−1. The rate capabilities of the composites increase with the Li content, and the discharge capacity of the LiF–Li-d_NiO (20%) is 146 mA h g−1 at 1 C for voltages of 2.0–4.8 V.

4LiF-NiMn 2 O 4 composites are synthesized by the mechanical milling of LiF and NiMn 2 O 4 in a molar ratio of 4: 1 for 36–192 h. The synthesized composites are investigated by XRD, charge-discharge measurements, and XPS. A broad XRD peak of 4LiF-NiMn 2 O 4 was observed and those of LiF and NiMn 2 O 4 disappear after the milling of 144 h and more. The discharge capacity of the 4LiF-NiMn 2 O 4 composites changes with the milling time, with the composite prepared by milling for 144 h exhibiting a discharge capacity of 256 mA h g −1 at 0.1 C for voltages of 2.0–4.8 V. With a cut-off voltage of 4.8 V or more, decomposition of the electrolyte proceeds along with the charge process, so the charge-discharge current efficiency deteriorates and the discharge voltage decreases. In the charge-discharge measurement without the capacity limit, although the charge-discharge efficiency was low due to the decomposition of the electrolyte, the high discharge capacity of 310 mA h g −1 was obtained. The XPS data suggests that the Ni 2+ ion and Mn 3+ ion are oxidized to Ni 3+ and Mn 4+ ion in charge process up to 4.8 V and are reduced to Ni 2+ ion and Mn 3+ ion during the discharge process.

MgAl2X8 (X = Cl, Br) was synthesized from MgX2 and AlX3, and the physical properties were evaluated by XRD, AC conductivity, and NMR. MgAl2Br8 has the same crystal structure as MgAl2Cl8 and belongs to the space group C2/c. MgAl2Cl8-yBry was also synthesized in the same manner as MgAl2Br8. MgAl2Cl8-yBry was found to have the same crystal structure as MgAl2Cl8 and forms a solid solution in all the synthesized compositions. From the Rietveld analysis of the XRD pattern, it was found that the arrangement of Cl and Br in the crystal had no order and occupied the halogen sites almost randomly. The AC conductivity of the obtained compound was lowest for MgAl2Cl8 and highest for MgAl2Cl2Br6. The conductivity of MgAl2Cl2Br6 at 400 K is 1.3 × 10−6 S/cm, and the Nyquist plot suggests that MgAl2Cl8-yBry is a magnesium ionic conductor. In the temperature range from room temperature to 412 K, there was no significant change in the 27Al NMR spectra of a MgAl2Br8 single crystal, and the effects of Mg2+ ionic conduction and the reorientation motion of AlX4ˉ anion were not observed.

ZnO 1− x S x films were deposited on quartz substrates by pulsed laser deposition (PLD) of ZnO 1− x S x targets. The ZnO 1− x S x films with S-contents of 0.03–0.17 were grown from the ZnO 1− x S x targets sulfured at temperatures of 200 and 500 °C. The resistivity of the ZnO 1− x S x films is slightly increased with the S-content. An increase of the O 2 -partial pressure in an atmosphere reduces the S-content in the films and drastically enhances the resistivity of the films. However, the carrier type of the films is still n-type. In order to incorporate excess S atoms into films, evaporation of Sulfur was performed during the PLD process. As a temperature of the S-evaporation is raised, the resistivity of the films is significantly enhanced and hole-conductivity appears in the films grown by the S-evaporation at 80 and 90 °C. By X-ray photoelectron spectroscopic measurements, the presence of SO x species is confirmed for the p-type ZnO 1− x S x film. Both interstitial SO 3 or SO 4 clusters and complexes of Zn-vacancy with H are considered to be appropriate acceptors responsible for the hole-conductivity at room temperature.

LiF-NiO composites in a molar ratio of 1:1 are synthesized by the mechanical milling of equal amounts of LiF and NiO for 12–144 h. The synthesized composites are investigated by XRD, charge-discharge measurements, and XPS. The XRD peaks of NiO broaden with an increase in the milling time, while those of LiF disappear. Rietveld analysis shows that the LiF-NiO composites prepared by milling for more than 72 h form a solid solution and that the arrangement of Li + and Ni 2+ ions in them is disordered. The LiF and NiO samples milled individually do not exhibit a noticeable discharge capacity, while the composites show a large one. Further, the discharge capacity of the LiF-NiO composites increases with the milling time, with the composite prepared by milling for 144 h exhibiting a discharge capacity of 216 mA h g −1 and an average voltage of 3.53 V at 0.05 C for voltages of 2.0–5.0 V. The XPS data suggest that the Ni ions are probably oxidized and reduced repeatedly during the charge-discharge process and that the Ni 2+ ions are partially oxidized to Ni 3+ ions during charging to 5.0 V.

MgAl2-xGaxCl8 and MgGa2Cl7Br was synthesized from MgCl2, MgBr2, AlCl3, and GaCl3, and the physical properties were evaluated by XRD, AC conductivity, and X-ray fluorescence. MgAl2-xGaxCl8 has the same crystal structure as MgAl2Cl8, belongs to the space group C2/c, and forms a solid solution in all the synthesized compositions. We attempted to MgGa2Cl8-yBry synthesize in the same manner as MgAl2Cl8, but only obtained MgGa2Cl7Br as a single-phase compound. The AC conductivity of MgAl2-xGaxCl8 was lowest for MgAl2Cl8 and highest for MgGa2Cl8. The conductivity of MgGa2Cl8 at 400 K was 1.7 &times, 10&minus, 6 S/cm. The conductivity of MgGa2Cl7Br was higher than that of MgAl2-xGaxCl8 with a value of 1.6 &times, 5 S/cm at 400 K. The formation of Mg metal was observed at the surface of the cathode electrode in an experiment of flowing a direct current using an electrochemical cell, indicating that this compound is a magnesium ion conductor.

Hexagonal BN (h-BN) films codoped with Mg and O atoms were grown on n-type Si and quartz substrates heated at 500 °C by the sputtering of h-BN targets containing MgO. It is confirmed from Fourier transform infrared spectroscopic measurements that h-BN films are formed by sputtering h-BN targets containing 0.25 mol% MgO in an atmosphere of Ar + 1% O 2 . Absorption is seen at wavelengths 2 . The calculated energy levels of defects and impurities of O and Mg indicate that the absorption near 400 nm is originated from nitrogen vacancies, and that the absorption near 220 nm is ascribed to O N –Mg B –O N complexes, where O N and Mg B denote O atoms at N sites and Mg atoms at B sites, respectively. The film prepared from the h-BN target (0.5 mol% MgO) in an Ar atmosphere exhibits a low turn-on electric field of 2.2 V/μm and a gentle slope in the Fowler–Nordheim plots. The gentle slope in the Fowler–Nordheim plots is not ascribed to an increase of a field-enhancement factor, but to a decrease of the work function.

Films have been prepared at substrate temperatures of 125 to 200 °C by chemical vapor deposition. As a substrate temperature decreases, the grain sizes of the films are decreased. From transmission electron microscopic observation, the film grown at 125 °C is found to be constructed from ZnO quantum dots with 5 nm in diameter. Photoluminescence spectra in ultraviolet region at 40 K or less are assigned to both free electron-acceptor and donor-acceptor pair emissions, whereas photoluminescence spectra at temperatures higher than 50 K are due to the free electron-acceptor emission. The peak energy of the free electron-acceptor emission for the film deposited at 125 °C is 0.143 eV larger than that for the film deposited at 200 °C. The blue shift of the emission peak is ascribed to the quantum confinement effect. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Composites of mesoporous SiO2and LiAlCl4were synthesized, and the change in ionic conductivity due to the formation of the composites was investigated. The electrical conductivity of the composite with the SiO2: LiAlCl4of 2 : 3 was the highest with a value of 2 x 10-6S/cm at room temperature. A higher order of conductivity was observed for the composite compared to the non-composite LiAlCl4. In addition, it was found that the conductivity of the composites depends on the pore size of the mesoporous SiO2.

ron fluoride (III) anhydrate fine particle was prepared by drying in vacuum from FeF3·3H2O, a mechanical milling process and a calcination at 473 773 K. Particle size of FeF3·3H2O was ca. 3 5 μm and that of FeF3 anhydrate was 100 500 nm after drying and milling. FeF3 sample only after drying and milling was hygroscopic and became FeF3·3H2O under atmosphere. FeF3 became stable under atmosphere after oxidation at 673 K for more than 20 minutes. It was found that Fe2O3 was produced by calcination and covered the surface of FeF3 particles. In Charge-discharge measurements, the discharge capacity of these FeF3 samples was 150 - 200 mAh/g at a discharge rate of 0.1 C. The oxidation could improve the discharge properties of FeF3 cathode.

A p-type ZnO film was successfully obtained by the alternate deposition of ZnO and Mg3N2 in radio-frequency (RF) magnetron sputtering process. ZnO and Mg3N2 (or Mg-oxynitride) films were alternately deposited on a substrate rotated above ZnO and Mg3N2 targets, where ZnO and Mg3N2-sputtering were carried out at RF power of 30 W and 0–90 W, respectively. In the case of the alternate deposition, where the substrate was kept for 0.2 s above the Mg3N2 target, p-type ZnO films were grown by Mg3N2-sputtering at 50–70 W, whereas an n-type ZnO film was grown at 90 W. The c-axis lengths of the films prepared by Mg3N2-sputtering at 0–50 W increase with RF power, and oppositely the c-axis lengths of the films prepared by Mg3N2-sputtering at 60–90 W decrease with RF power. p-type ZnO films were grown by Mg3N2-sputtering at 50 W for 2 and 5 s, whereas insulative ZnO films were grown by Mg3N2-sputtering at 70 W for 2 and 5 s. The band-gap energies of the p-type ZnO films prepared by Mg3N2-sputtering at 50 W for 0.2 and 5 s are estimated to be 3.31 and 3.39 eV, respectively. The increase of the band-gap energies of the p-type ZnO films is caused by the intermixing of ZnO and Mg-oxynitride films.

Films were deposited on a glass substrates heated at 100 °C by alternate deposition of ZnO and Mg3N2 films in an atmosphere of N2 + 0.2% O2. p-type ZnO films with the resistivity of 9.9×103 - 4.5×103 Ωcm were grown by Mg3N2 sputtering for 0.2 s at 50-70 W, whereas an n-type ZnO film was grown for 0.2 s at 90 W. Appearance of the n-type ZnO film is caused by a decrease of O2-partial pressure in an atmosphere. The contraction of the c-axis due to the incorporation of Mg atoms is found in these p-type and n-type ZnO films. When the Mg3N2-depostion period was extended to 5 s, p-type ZnO films were grown in the alternate sputtering at 50 W, whereas only insulator films were grown in the alternate sputtering at 70 W. The optical band gap of the films increases with both a RF power and a period of Mg3N2-deposition.

The iron oxide/polyaniline electrode was prepared from the photoanodic deposition of polyaniline film on the iron oxide electrode. The two linear relations of Mott-Schottky plots were obtained on the iron oxide/polyaniline electrode in HClO4 aqueous solution. This electrode showed a stable photoanodic current under visible light irradiation and also a linear dependence of photoanodic current on glycolic acid concentration.

We have enhanced the stability of a flavylium dye, a model compound of a natural anthocyanin dye, by the incorporation into the interlayer of a natural clay, bentonite. The composite of the flavylium and the bentonite shows excellent stability under increased temperature (up to 353 K) or alkaline environment (pH ∼ 9) compared to the original flavylium dyes. This material can be candidate of an environmentally friendly coloring material. Increased amount of dye causes a muddy color due to the formation of dye aggregate. Samples with brilliant color can be obtained with the loading amount less than 0.25 mmol dye per g-clay.

Undoped and Li-doped NiO films have been prepared by radio frequency sputtering and electron-beam evaporation techniques. These sputtered films prepared at a lower pressure of 2.6 × 10 − 1 Pa show no diffraction peaks and their surfaces are smooth. These films are p-type semiconductors and their resistivity is dependent on an O 2 -partial pressure. A minimum resistivity of 0.39 Ω cm is attained for a Li-doped NiO film prepared at RF power of 20 W in 50% O 2 atmosphere. In contrast, Li-doped NiO films prepared by electron-beam evaporation exhibit no diffraction peaks, but their surface is not smooth. The fabrication of pn-junction is carried out between NiO films and amorphous n-type transparent oxide films, e.g., In–Zn–O and In–Ga–Zn–O. No rectification characteristic is seen at an interface of In–Zn–O and Li-doped NiO films, while the rectification characteristic is achieved in In–Zn–O/In–Ga–Zn–O/NiO/Au device. The threshold voltage of 2.3 V is estimated from the current vs. voltage characteristic.

ZnO films codoped with Al and N have been prepared by radio frequency magnetron sputtering in an Ar atmosphere, using targets of mixtures of ZnO and AlN powders. The Al-doped ZnO films are transparent, whereas the films codoped with Al and N are colored. The Al- and N-concentrations in the colored films are estimated to be 4–7 at.% and 1–2 at.%, respectively. No enhancement of the carrier density is seen in the colored ZnO films, whereas the colored films exhibit lower etching rates of 3–5 nm/s in a 0.1 M HCl solution, in comparison with the Al-doped ZnO films. For the colored film, the anisotropic grain growth occurs, and cubic grains are produced after etching. The low etching rates of the colored films are ascribed to the epitaxial growth of AlN films on the surfaces of ZnO grains, rather than the incorporation of Al–N and Al–O bonds into the ZnO lattice.

ZnO films prepared from the ZnO target containing 2% AlN are transparent irrespective of radio frequency (RF) power. The obtained ZnO films have the carrier density of 3.8 × 1020 cm−3 or less and the low mobility of 5.3–7.8 cm2/(V s). In the case of 5% AlN target, ZnO films prepared at 40, 60 and 80 W are transparent, whereas ZnO films prepared at 100 and 120 W are colored. As RF power increases from 40 to 120 W, the carrier density increases straightforwardly up to 5.5 × 1020 cm−3 at 100 W and is oppositely reduced to 3.2 × 1020 cm−3 at 120 W. In the case of 10% AlN target, ZnO films prepared at 60 W or more are colored, and have the carrier density of 4 × 1020 cm−3 or less. The N-concentration in these colored films is estimated to be 1% or less. The Al-concentration in the ZnO films prepared from the 5 and 10% AlN targets is higher than 2%. The carrier density of the ZnO films containing Al and N atoms is nearly equal to that of ZnO films doped with Al atoms alone. There is no evidence in supporting the enhancement of the carrier density via the formation of N-AlxZn4−x clusters (4 ≥ x ≥ 2).

We have enhanced the stability of some derivatives of a flavylium dye, a model compound of a natural anthocyanin dye, by incorporating them between the interlayer of a clay mineral, montmorillonite K10. The incorporation procedure is simply mixing the solution of the flavylium dyes with the clay powder. The resulting colored powder shows excellent stability under increased temperature (up to 353 K), alkaline environment (pH ∼ 9), and visible light irradiation, compared to the original flavylium dyes. This material can be a candidate for an environmentally friendly coloring material.

ZnO films doped with Li and Cl atoms have been prepared by organometallic chemical vapor deposition method. In photoluminescence spectra of the doped ZnO films, strong emission appears at 376 nm which is slightly longer than that of free-excitons. As excitation intensity increases, a peak wavelength of the emission is shifted toward a shorter value. The emission near band-gap edge is assigned to radiative recombination via Li-Cl pairs.

ZnO films containing both Be and N atoms were deposited on (0001)-sapphire substrates heated at 250 °C, by using a target consisting of Be sheets placed on ZnO powders. There are only ZnO (0002) peaks observed in the X-ray diffraction (XRD) patterns of the ZnO films. As the power of radio frequency (RF) in sputtering increases, the c-axis lengths of the sputtered ZnO films decrease significantly, and the concentration of Be atoms in the ZnO films increases remarkably. The presence of Be and N atoms is confirmed in the ZnO film prepared at 70 W, from X-ray photoelectron spectroscopic (XPS) measurements. For the ZnO film prepared at 70 W, the binding energy of Be 1s and of N 1s is evaluated to be 114.0 and 398 eV, respectively. The concentration of N atoms is as low as 1% for the ZnO film containing no Be atoms, whereas the high concentration of 7% N atoms is attained in the ZnO film containing 4% Be atoms. The ZnO films prepared at 120 W or more are insulators, and the ZnO film doped with N atoms alone is an n-type semiconductor. The ZnO film containing both 4% Be and 7% N atoms is a p-type semiconductor with a resistivity of 45 Ω cm.

Amorphous InGaZnO4 (IGZO) films codoped with Al and N atoms were prepared by sputtering of targets consisting of IGZO and AlN powders in Ar + O2 atmospheres. No hole-conductivity is seen in films deposited at 2×10-3 Torr, whereas hole-conductivity is found in films deposited at 2×10-2 Torr at radio frequency powers of 60-80 W in 0.3-0.6% O2 atmospheres. The amorphous p-type IGZO film has the resistivity of 210 Wcm, hole-density of 7.5×1017 cm-3, and mobility of 0.4 cm2/Vs. The rectification characteristic is obtained for a device constructed from Au, amorphous p-type IGZO, and amorphous n-type IGZO. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

NMR, NQR, powder X-ray diffraction, DTA and AC conductivity were measured in RMBr4 (R = Ag, Cu; M = Al, Ga) and RM2Br7 (R = Li, Ag; M = Al, Ga). In RMBr4 , the activation energy of Cu+ diffusion was evaluated from 63Cu NMR and was in good agreement with that from 81Br NQR. In CuAlBr4 , the e2Qq/h value of 63Cu NMR and the η value of 27AI NMR changed linearly with decreasing temperature, although the e2Qq/h value of 27AI NMR did not change so much. These temperature dependences are supposed to be due to Cu+ diffusion and not to a variation of the lattice constants. In RM2Br7 , the activation energy was obtained from the spin-lattice relaxation time T1 of 81Br NQR and is ascribed to a modulation of the cation diffusion. The line width of 7Li NMR in LiAl2Br7 was about 5.9 kHz in the low-temperature phase and 0.4 kHz for the high-temperature phase. The 27AlNMR spectrum was broadened by the quadrupole interaction and unchanged up to 400 K, suggesting that diffusion of Li+ ions occurs in the high-temperature phase.

Upheavals of adsorbed oxygen molecules are formed on the TiO2 (110) surface by applying a negative bias voltage between the TiO2 and a tip. The heights of upheavals corresponding to the state density of O2- increase with a bias voltage. The letters "YT" constructed from O2- are drawn on the TiO2 surface. The letters have the line width of 22 nm and the height of 6 nm. The letter "T" is selectively deleted by applying a positive voltage under ultraviolet illumination. It is found that the adsorption of O2 and the photodesorption of O2 are controlled in a nanometer scale. A stearic-acid film deposited on the TiO2 (110) is selectively decomposed at the area where a bias voltage of 10 V is applied under ultraviolet illumination. Using AFM-based photocatalysis, several patterns are formed in a thick stearic-acid film. The letters "YT" are drawn in the thin stearic-acid film. The spatial resolution of the photocatalytic decomposition is estimated to be 30 nm from a line width of the letters "YT".