Yttria-stabilized zirconia (Zr0.92Y0.08O2- :YSZ) thin films have prepared on Al2O3 substrates by RF magnetron sputtering. The asdeposited YSZ thin films prepared at 500 ºC exhibits the (020) peak at 2 ~34.8  , which corresponds to the peak position of the YSZ single crystal. The Zr 4+ , Y 3+ and valence-band states were confirmed by photoemission spectroscopy (PES). The YSZ thin film at wet air exhibits higher conductivity and lower activation energy than that at dry air. The obtained PES spectra demonstrate the O-H bond and Fermi level shift of the YSZ thin film at wet air are observed by PES spectra. These results indicate that the YSZ thin film exhibits proton conduction at wet air in the intermediate temperature (IMT) region of 300~500 ºC.

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The in-plane-oriented BaPrO3-δ thin film with mixed valence states has been prepared on an Al2O3 (0001) substrate by RF magnetron sputtering. The lattice constant decreases with increasing film thickness. The thin film has the mixed valence states of Pr 4+ and Pr 3+. The ~168 nm thickness film with small lattice constant exhibits high electrical conductivity and low activation energy of 0.58 eV at dry atmosphere. The wet-annealed thin film shows high proton conduction, which is required as electrolyte of solid oxide fuel cell, at 300 ~ 600 C.

The in-plane-oriented BaPrO 3-δ thin film with mixed valence states has been prepared on an Al 2 O 3 (0001) substrate by RF magnetron sputtering. The lattice constant decreases with increasing film thickness. The thin film has the mixed valence states of Pr 4+ and Pr 3+ . The ~168 nm thickness film with small lattice constant exhibits high electrical conductivity and low activation energy of 0.58 eV. The thin film at wet air shows hole-ion mixed conduction and proton conduction, which is required as anode electrode of solid oxide fuel cell, at 300 C.

Resonant photoemission spectroscopy (RPES) and X-ray absorption spectroscopy (XAS) were used to investigate the effect of lithiation on the electronic structure of Fe 3 O 4 thin film relevant to the operation mechanism of nanoionic devices to enable magnetic property tuning. Comparison of the Fe 2p XAS spectrum for lithiated Fe 3 O 4 (Li-Fe 3 O 4 ) with that for pristine Fe 3 O 4 clearly demonstrated that the number of Fe 2+ ions at octahedral B sites is increased by lithiation. The valence band RPES spectra of Li-Fe 3 O 4 further showed that lithiation increases the density of states near the Fermi level originating Fe 2+ ions at octahedral B sites. These findings agree well with the observed decrease in the saturation magnetization in the magnetization-magnetic field (M-H) loop of Li-Fe 3 O 4 thin film, indicating that minority spins (down spins) increase (i.e., total spins decrease) due to lithiation. The variation in the number of Fe 2+ ions at B sites is suggested to be an underlying operating mechanism of a nanoionics-based magnetic property tuning device.