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High-temperature stability and saturation magnetization of superparamagnetic nickel nanoparticles in microporous polysilazane-derived ceramics and their gas permeation properties

: Seifollahi Bazarjani, Mahdi; Müller, Mathis; Kleebe, Hans Joachim; Jüttke, Yvonne; Voigt, Ingolf; Baghaie Yazdi, Mehrdad; Alff, Lambert; Riedel, Ralf; Gurlo, Aleksander


ACS applied materials & interfaces 6 (2014), Nr.15, S.12270-12278
ISSN: 1944-8244
ISSN: 0013-936X
ISSN: 1944-8252
Fraunhofer IKTS ()
mebrane; Ni / polysilazane; superparamagnetic; Ni / SiCNO

Superparamagnetic Ni nanoparticles with diameters of about 3 nm are formed in situ at room temperature in a polysilazane matrix, forming Ni/polysilazane nanocomposite, in the reaction between a polysilazane and trans-bis(aceto-kO) bis(2-aminoethanol-k2N,O)nickel(II). The thermolysis of the Ni/polysilazane nanocomposite at 700 °C in an argon atmosphere results in a microporous superparamagnetic Ni/silicon oxycarbonitride (Ni/SiCNO) ceramic nanocomposite. The growth of Ni nanoparticles in Ni/SiCNO ceramic nanocomposite is totally suppressed even after thermolysis at 700 °C, as confirmed by HRTEM and SQUID characterizations. The analysis of saturation magnetization of Ni nanoparticles in Ni/polysilazane and Ni/SiCNO nanocomposites indicates that the saturation magnetization of Ni nanoparticles is higher than expected values and infers that the surfaces of Ni nanoparticles are not oxidized. The microporous superparamagnetic Ni/SiCNO nanocomposite is shaped as a free-standing monolith and foam. In addition, Ni/SiCNO membranes are fabricated by the dip-coating of a tubular alumina substrate in a dispersion of Ni/polysilazane in THF followed by a thermolysis at 700 °C under an argon atmosphere. The gas separation performance of Ni/SiCNO membranes at 25 and 300 °C is assessed by the single gas permeance (pressure rise technique) using He, H2, CO2, N2, CH4, n-propene, n-propane, n-butene, n-butane, and SF6 as probe molecules. After hydrothermal treatment, the higher increase in the hydrogen permeance compared to the permeance of other gases as a function of temperature indicates that the hydrogen affinity of Ni nanoparticles influences the transport of hydrogen in the Ni/SiCNO membrane and Ni nanoparticles stabilize the structure against hydrothermal corrosion.