Masamitsu Nagano

X-ray photoelectron spectroscopic observation on B–C–N hybrids synthesized by ion beam deposition of borazine

B–C–N hybrid thin films were grown from ion beam plasma of borazine (B3N3H6) on graphite substrate at room temperature, 600 °C, and 850 °C. The films were characterized in situ by x-ray photoelectron spectroscopy (XPS). XPS study suggested that B and N atoms in the deposited films are in a wide variety of chemical bonds, e.g., B–C, B–N, N–C, and B–C–N. The substrate temperature and ion fluence were shown to have a significant effect on the coordination and elemental binding states on the B–C–N hybrids. It was found that B–C–N hybrid formation is enhanced at high temperature, and this component is dominantly synthesized at low fluence. The results imply that it is possible to control the composition of B–C–N hybrid by changing the ion fluence and the temperature during ion implantation.B–C–N hybrid thin films were grown from ion beam plasma of borazine (B3N3H6) on graphite substrate at room temperature, 600 °C, and 850 °C. The films were characterized in situ by x-ray photoelectron spectroscopy (XPS). XPS study suggested that B and N atoms in the deposited films are in a wide variety of chemical bonds, e.g., B–C, B–N, N–C, and B–C–N. The substrate temperature and ion fluence were shown to have a significant effect on the coordination and elemental binding states on the B–C–N hybrids. It was found that B–C–N hybrid formation is enhanced at high temperature, and this component is dominantly synthesized at low fluence. The results imply that it is possible to control the composition of B–C–N hybrid by changing the ion fluence and the temperature during ion implantation.

Studies on Li-Mn-O spinel system (obtained from melt-impregnation method) as a cathode for 4 V lithium batteries. Part V. Enhancement of the elevated temperature performance of Li/LiMn2O4 cells

Abstract Stoichiometric LiMn 2 O 4 , metal-ion doped (Li + and Co 3+ ) spinels, Li 1+ x Mn 2− x − y M y O 4 , and fluorine substituted spinel, Li 1+ x Mn 2 O 4− z F z , are examined as cathodes in Li/organic electrolyte/Li x Mn 2 O 4 cells containing various electrolytes at both room temperature and 50°C. The elevated temperature performance is improved with the metal-ion doped and fluorine substituted spinels in LiBF 4 base electrolyte solution.

Synthesis of PbTiO3 film on LaNiO3-coated substrate by the spray-ICP technique

In an attempt to utilize LaNiO3 as a bottom electrode for PbTiO3 ferroelectric film, PbTiO3 and LaNiO3 films were prepared by the spray-ICP technique under atmospheric pressure. The dense LaNiO3 films crystallized with preferred (1 1 1) and (1 0 0) orientations on sapphire (0 0 1) and MgO (1 0 0), respectively. Resistivities of the LaNiO3 films deposited above 600 °C were about 4 × 10−6 Ωm. The PbTiO3 film with preferred (001) orientation was successfully prepared on LaNiO3-coated MgO (1 0 0). Its dielectric constant and dissipation factor were about 200 and 0.02, respectively, at 1 kHz. The Curie temperature suggested that PbTiO3 films were free from contamination by LaNiO3.

Growth of SnO2 whiskers by VLS mechanism

SnO2 recrystallized on SnO2 rod crystals based on the reversible reaction SnO2(s) = SnO(g)+12 O2 (g). SnO2 whiskers with globule at the tip grew perpendicular to the a-axis of the rod crystal. Sn was the principal constituent of the globule, which was essential for the growth by the VLS mechanism and considered to be melted during the growth process. Zn, Cu and other metals detected as impurities in the whiskers appeared to have no appreciable effects on the whisker growth. The decrease in the partial pressure of oxygen in the ambient gas favored the whisker growth. It was suggested that Sn(1) was formed according to the disproportionation: 2 SnO(g) = Sn(1)+SnO2(s).

Chemical vapor deposition of SnO2 thin films on rutile single crystals

Abstract Thin films of SnO 2 were deposited on the (110) surface of TiO 2 , rutile single crystals by chemical vapor deposition (CVD) using SnCl 4 and O 2 . The depositions were carried out using N 2 as a carrier gas at a substrate temperature of 900–1300°C for 0.5–60 h. The flow rate of SnCl 4 varied from 0.08 to 1.3 cm 3 min −1 while oxygen flow was at a constant rate of 12 cm 3 min −1 . There were some differences in morphology among the SnO 2 films deposited at varying temperatures. The SnO 2 films had the same crystallographic orientation as the rutile substrates in both the parallel and the perpendicular directions while the SnCl 4 flow was slow (0.08 cm 3 min −1 ). As the SnCl 4 flow was faster, SnO 2 crystalites composing the films were slight tilted with respect to each other.

Deposition of LaMO3 (M=Ni,Co,Cr,Al)-Oriented Films by Spray Combustion Flame Technique

LaMO3 (M=Ni,Co,Cr,Al) films were prepared on sintered alumina, sapphire (001) and MgO(100) at 500–900°C by spraying ultrasonically atomized aqueous solutions of nitrates into a combustion flame (spray combustion flame technique). LaNiO3 and LaCoO3 on MgO(100) crystallized in high-temperature phases (cubic) while LaCrO3 and LaAlO3 crystallized in room-temperature phases. LaMO3 (M=Ni,Co,Cr,Al) films on MgO(100) were highly oriented to (100), (100), (001) and (100), respectively, while the films on sintered alumina and sapphire were not. The electric resistivities of the dense LaMO3 (M=Ni,Co,Cr) films were as low as those of bulk ceramics. LaNiO3 film deposited on MgO above 700°C showed the lowest resistivity of about 6×10-6 Ω m. It was suggested that the reactivities of the constituent metal atoms with OH in the flame are associated with the preferred phase and the morphology of the films.

Plasma production with DC discharge planar magnetron device for thin film preparation

Plasma production is studied with a planar magnetron device using permanent magnets in a DC discharge for thin film preparation. The minimum value of discharge threshold voltages is found to lie in a wide region of pressure*gap length in comparison to that in the normal discharge without the magnets, resulting in a more stable discharge. Strongly inhomogeneous ion density in the radial direction is observed in a region close to the magnetics under the cathode to form a visible ring. Primary electrons and high electron temperatures are observed around the cathode, while the ion temperature is spatially homogeneous. The drift velocity caused by the effect of the electric and magnetic fields is directly measured to keep the value roughly constant in the longitudinal direction. A typical thin film of SnO2 prepared by the plasma CVD technique in this device is presented.

Deposition of LaMO3 (M=Co, Cr, Al) films by spray pyrolysis in inductively coupled plasma

Abstract LaMO 3 (M=Co, Cr, Al) films were prepared on substrates by introducing ultrasonically atomized metal nitrate solutions into an inductively coupled plasma under atmospheric pressure (spray-ICP technique). Dense perovskite-type oxide films of LaCoO 3 and LaCrO 3 were obtained at 600–900°C, while the LaAiO 3 films consisted of loosely packed aggregates. Deposition rates of the films were 6–35 nm/min at 600–900°C. The high temperature phases (cubic) of LaCoO 3 and LaAlO 3 crystallized due to effect of grain size. LaCrO 3 film crystallized in the room temperature phase (orthorhombic). LaCoO 3 was highly oriented to (100) on MgO(100), and LaCrO 3 to (011) and (101) on sapphire(001). Lowest electric resistivities of LaCoO 3 and LaCrO 3 film on MgO were 9.8X10 -3 and 2.7X10 -1 Ω m, respectively, at room temperature.

Synthesis of BaTiO3/LaNiO3 and PbTiO3/LaNiO3 multilayer thin films by spray combustion flame technique

In an attempt to utilize LaNiO3 thin film as a bottom electrode for ferroelectric BaTiO3 and PbTiO3 thin films, PbTiO3/LaNiO3 and BaTiO3/LaNiO3 multilayer thin films were prepared on MgO(100) by spraying an ultrasonically atomized nitrate solution into a combustion flame (spray combustion flame technique). Highly oriented BaTiO3(100)/LaNiO3(100) and PbTiO3(001)/LaNiO3(100) multilayer thin films were obtained on MgO(100). BaTiO3 film was pseudocubic while PbTiO3 film was tetragonal. Curie temperature measurement of the PbTiO3 film suggested that the films were free from contamination when LaNiO3 was used as a bottom electrode.

Effects of organometallic compounds introduced to plasma on diamond synthesis

Volatile organometallic compounds were introduced to feed gas (CH4/H2) during the synthesis of diamond by microwave plasma chemical vapor deposition. Addition of Si(CH3)4, Sn(CH3)4, Sn(CH3)4, Fe(AA)3, TiO(AA)2 or Zr(AA)4 increased nucleation density of diamond particles to 2-10 times that without additives. Addition of Zr(AA)4 and TiO(AA)2 made the grain sizes smaller. Most additives lowered atomic hydrogen temperature, increased concentration of C2 in plasma and seemed therefore to degrade the crystallinity of the diamonds. Some additives shifted the A band cathodoluminescence to a higher energy region. In the case of Si(CH3)4, the GR-1 center cathodoluminescence was observed as well as the A-band, and adhesion of the diamond film was markedly improved.