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A single-step synthetic method was developed to obtain ultrafine MgO nanocrystals by ultimately simple solvothermal treatment of a precursor solution containing magnesium acetylacetonate in acetonitrile at 400 °C for 10 min. HRTEM images and calculations based on Scherer equation showed that the average size of obtained ultrafine MgO nanocrystals was ca. 7 nm.

A simple synthetic approach to Al2O3–TiO2 and ZnO–TiO2 mesoporous hollow composite assemblies consisting of homogeneously mixed primary particles at the nano scale was demonstrated. The composites, Al2O3–TiO2 and ZnO–TiO2, have a large specific surface area (250–600 m2 g–1) and were synthesized by high-temperature and high-pressure treatment of precursor solutions containing Al(OiPr)3 or Zn(OAc)2, Ti(OiPr)4, and phthalic acid in methanol. Aggregated, fused spherical, and individual spherical morphologies of the hollow assemblies with amorphous Al2O3 and anatase TiO2 were obtained, depending on the Al/Ti ratio of the precursor solutions. Hollow spherical composite assemblies with amorphous ZnO and anatase TiO2 phases were obtained by treating precursor solutions with lower Zn contents (5–25 %). A phase transition from anatase to rutile was not observed for the Al2O3–TiO2 composite assemblies (50 % Al) even at 1000 °C. The band gap energies of the ZnO–TiO2 hollow assemblies were tuned (3.12–3.21 eV) by changing their Zn content.

CeO_2-ZrO_2 composite nanoparticles with mesoporous and spherical morphologies were assembled into different homogeneously dispersed, domain, and core-shell structures by changing the reaction conditions, such as the heating rate, acid, and solvent, in supercritical alcohols. Ce_xZr_O_2 with homogeneous structures were prepared from Ce(NO_3)_3 and ZrO(NO_3)_2 in the presence of formic acid in methanol by rapid heating (500℃/min) to 300℃, while CeO_2–ZrO_2 with domain structures were obtained by slow heating (5.4℃/min). Treatment of mesoporous and spherical ZrO_2 nanoparticles with a Ce(NO_3)_3 solution in supercritical conditions yielded CeO_2-ZrO_2 nanocomposites with core-shell morphologies, while solvents playing a key role in controlling the thickness of the outer shell; methanol produced a very thin outer shell (

The ZnO thin film phosphor was prepared on conductive ITO substrate directly combining radio frequency sputtering and a novel multi-reducing annealing method. The vertically aligned ZnO nanorods with much oxygen vacancies were formed during the annealing processes. The intense photoluminescence from ZnO nanorods was obtained.

In equilibrium reaction processes, the precise control of composition ratios in multi-component thin films is problematic due to the changes in the state of precursor materials, which are caused by differences in metal ion stabilities. We have identified a strategy to resolve this problem by first developing a theory and then constructing a fine-channel type mist chemical vapor deposition (mist-CVD) system with two solution chambers and a mist-mixing chamber. Zn1-x Mg x O thin films were fabricated using the conventional and the developed mist-CVD systems to verify the theory. The properties of the Zn1-x Mg x O thin films produced using the two systems were significantly different. The Mg composition ratio in the film was clearly influenced by the Mg ion stability and all the measurement results support the theory.

Transparent conducing antimony doped tin oxide (SnO x :Sb) thin films were fabricated by solution-processed atmospheric-pressure 3rd generation mist chemical vapor deposition (3rd G mist CVD) system with two solution chambers and one mixing chamber to control the atmosphere in reaction area. To study how to reduce the resistivity, the effects of each additive component in dopant solution were investigated; this was followed by identification of components contributing to the fabrication of SnO x :Sb films. Experimentally, the HNO3 clearly affected the resistivity and the formation of SnO2 thin films through a change in the valence state of N derived from HNO3 promoting the transformation of Sn (II) and Sb (III) to Sn (IV) and Sb (V). Moreover, the values of electron and hole effective mass were defined using the specified referred parameters to confirm the band diagram of SnO x :Sb thin films fabricated by 3rd G mist CVD system.

A MoS2 layered thin film was grown by atmospheric-pressure solution-based mist CVD on a 30 mm2 large-area substrate at 400 °C, which is a significantly lower growth temperature than that of conventional CVD. The film formation was reliably confirmed by Raman spectroscopy, grazing incidence X-ray diffraction (GIXD), and transmission electron microscope (TEM). Possibly, film formation energy was decreased by dissolving (NH3)6Mo7O24 4H2O in methanol owing to formation of an intermediate product, whose decomposition temperature was lower than 760 °C — the decomposition temperature observed in thermogravimetric-differential thermal analysis (TG-DTA). Optical constants were derived by spectroscopic ellipsometry measurements, whose results indicate the reasonably good quality of MoS2 and the suitability of mist CVD in response to the large-area low-temperature growth request from industry.

Yttrium iron garnet (YIG) thin films were deposited on c-plane sapphire substrates under atmospheric pressure by a mist CVD technique, and their chemical composition and optical properties were examined. The thin films deposited at 450 °C showed an [Y]/[Fe] ratio of 0.57, indicating the deposition of yttrium iron oxide, while the molar ratio of [Y]/[Fe] in the precursor solution was set at 1.5. A thermodynamic model was developed to explain the reaction paths of the YIG thin film fabrication process using thermogravimetric differential thermal analysis (TG-DTA) results. The model indicates that the decomposition rate of yttrium acetylacetonate [Y(acac)3 nH2O] was much lower than that of iron acetylacetonate [Fe(acac)3], providing a plausible explanation for the large difference between the composition ratio of the thin films and that of the precursor solutions.

ZnO nanorods were grown up from as-deposited ZnO film on which the zinc self-catalysts generated by a novel reducing method. Well aligned ZnO nanorods with a uniform high aspect ratio were grown up on multi-annealed samples. The length of nanorods depended significantly on the reaction time in the hydrothermal synthesis.