Surface defects of ZnO nanoparticles were induced via mechanical stressing using a Turbula shaker mixer and a planetary ball mill, and the possibilities for surface modification and functionalization of the ZnO nanoparticles were exemplified by sulfur doping of activated ZnO. Raman spectroscopy reveals that the formation of oxygen vacancies (V_O) does not only occur under high stressing conditions in a planetary ball mill but even upon rather ‘mild stressing’ in the shaker mixer. The temporal evolution of the vacancy concentration in ZnO stressed under different conditions can be described by a model that accounts for stress number and vacancy diffusion with diffusion coefficients of V_O of 3.7 × 10⁻²¹ m² s⁻¹ and 2.4 × 10⁻²⁰ m² s⁻¹ for stressing in the shaker and the planetary ball mill, respectively. The thickness of the V_O layer was estimated to be about 1 nm. Thiourea was mixed with defective ZnO particles, and then heated at various temperatures for sulfur-doping. A linear relationship between the amount of induced V_O and the level of sulfur doping was found. Remarkably, mechanical activation is indispensable in order to control the level of sulfur doping quantitatively. High-angle annular dark field scanning transmission electron microscopy (HAADF STEM) observations with energy dispersive X-ray spectroscopy (EDX) analysis clearly revealed that the doped sulfur atoms are concentrated at the particle surface. Thus, ZnO (core)/ZnS (shell) structures are obtained easily via mechanochemical activation and subsequent thermal treatment.

Sol-gel-derived <mml:math display="inline"><mml:msub><mml:mo>P</mml:mo><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mo>O</mml:mo><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub><mml:mo>­</mml:mo><mml:msub><mml:mi mathvariant="normal">SiO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>P2O5­SiO2 glasses were investigated to prepare high proton conductors for fuel cell electrolyte. Glasses with a pore size of 2-30 nm diam were prepared using <mml:math display="inline"><mml:mi mathvariant="normal">Si</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:msub><mml:mo>OC</mml:mo><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mo>H</mml:mo><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mo stretchy="false">)</mml:mo><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo></mml:math>Si(OC2H5)4, colloidal silica, <mml:math display="inline"><mml:mo>PO</mml:mo><mml:mo stretchy="false">(</mml:mo><mml:msub><mml:mo>OCH</mml:mo><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mo stretchy="false">)</mml:mo><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo></mml:math>PO(OCH3)3, <mml:math display="inline"><mml:msub><mml:mo>H</mml:mo><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mo>PO</mml:mo><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo></mml:math>H3PO4, and <mml:math display="inline"><mml:msub><mml:mi mathvariant="normal">POCl</mml:mi><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo></mml:math>POCl3, the pore properties of which were discussed to relate with the water absorption and proton conduction from conductivity measurements and relaxation of proton transfer. In the glasses with pores larger than 10 nm, high humidity is needed to absorb the water in pores, resulting in low proton conductivity. As the pore size decreases, the pores are filled with the water molecules at low humidity, which act to form the pathways of the proton transfer. The <mml:math display="inline"><mml:msub><mml:mo>P</mml:mo><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mo>O</mml:mo><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub><mml:mo>­</mml:mo><mml:msub><mml:mi mathvariant="normal">SiO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>P2O5­SiO2 glasses having 2 nm diam pores exhibited high conductivity of ∼100 mS/cm at 50°C and above 50% relative humidity. © 2004 The Electrochemical Society. All rights reserved.

A proposed reaction scheme for in situ controlled low-temperature formation of metallic-Co at the early stage of pyrolysis of perhydropolysilazane (PHPS) coordinated with CoCI ₂ .

A novel polyethoxysilsesquiazane ([EtOSi(NH)_1.5]_n, EtOSZ) was synthesized by ammonolysis at −78 °C of ethoxytrichlorosilane (EtOSiCl₃), which was isolated by distillation as a reaction product of SiCl₄ and EtOH. Attenuated total reflection-infra red (ATR-IR), ¹³C-, and ²⁹Si-nuclear magnetic resonance (NMR) spectroscopic analyses of the ammonolysis product resulted in the detection of Si–NH–Si linkage and EtO group. The simultaneous thermogravimetric and mass spectrometry analyses of the EtOSZ under helium revealed cleavage of oxygen-carbon bond of the EtO group to evolve ethylene as a main gaseous species formed in-situ, which lead to the formation at 800 °C of quaternary amorphous Si–C–N with an extremely low carbon content (1.1 wt %) when compared to the theoretical EtOSZ (25.1 wt %). Subsequent heat treatment up to 1400 °C in N₂ lead to the formation of X-ray amorphous ternary Si–O–N. Further heating to 1600 °C in N₂ promoted crystallization and phase partitioning to afford Si₂N₂O nanocrystallites identified by the XRD and TEM analyses. The thermal stability up to 1400 °C of the amorphous state achieved for the ternary Si-O-N was further studied by chemical composition analysis, as well as X-ray photoelectron spectroscopy (XPS) and ²⁹Si-NMR spectroscopic analyses, and the results were discussed aiming to develop a novel polymeric precursor for ternary amorphous Si–O–N ceramics with an enhanced thermal stability.

Polysilazanes functionalized with alkoxy groups were designed and synthesized as single source precursors for fabrication of micro and mesoporous amorphous silica-based materials. The pyrolytic behaviors during the polymer to ceramic conversion were studied by the simultaneous thermogravimetry-mass spectrometry (TG-MS) analysis. The porosity of the resulting ceramics was characterized by the N₂ adsorption/desorption isotherm measurements. The Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopic analyses as well as elemental composition analysis were performed on the polymer-derived amorphous silica-based materials, and the role of the alkoxy group as a sacrificial template for the micro and mesopore formations was discussed from a viewpoint to establish novel micro and mesoporous structure controlling technologies through the polymer-derived ceramics (PDCs) route.