Titanium dioxide (TiO2 ) nanocrystals are prepared by a hydrolysis process of tetrabutyl titanate. Nanocrystal samples with various sizes of 6.8-27.9 nm are obtained after annealing from 100 to 650 °C. The crystal structures and the average particle sizes are examined using x-ray diffraction. Raman scattering was employed to investigate the evolution of the anatase phase in the nanocrystals during annealing. Phonon confinement and non-stoichiometry effects are responsible for the blueshift and broadening of the lowest-frequency E g Raman mode. The influence of interfacial vibrations on the Raman linewidth is also discussed.

Nanosize crystalline silicon films are fabricated by using highly hydrogen-diluted silane as the reactive gas and activated with rf+dc double-power sources, in a conventional plasma-enhanced chemical-vapor-deposition system. The structure of the deposited films as studied by means of high-resolution electron microscopy, Raman scattering spectra, x-ray-diffraction pattern, IR transmission spectra, and ultraviolet ray analysis. The results show that there are many novel structural features and new physical properties for these nanosize crystalline silicon films. In particular, it is found that the optical-absorption coefficient α is higher than that of a-Si:H and μc-Si:H films, the room-temperature conductivity σd has the value of 10−3–10−1 Ω−1 cm−1, and the hydrogen content CH in nc-Si:H films is higher than 30 at. %. The nc-Si:H films have their peculiar features which are different from both a-Si:H and μc-Si:H films.

Most potassium-ion battery (PIB) cathode materials have deficient structural stability because of the huge radius of potassium ion, leading to inferior cycling performance.W e report the controllable synthesis of an ovel low-strain phosphate material K 3 (VO)(HV 2 O 3 )(PO 4 ) 2 (HPO 4 )(denoted KVP) nanorulers as an efficient cathode for PIBs.The as-synthesized KVP nanoruler cathode exhibits an initial reversible capacity of 80.6 mAh g À1 under 20 mA g À1 ,with alarge average working potential of 4.11 V. It also manifests an excellent rate property of 54.4 mAh g À1 under 5Ag À1 ,w ith ah igh capacity preservation of 92.1 %o ver2 500 cycles.T he outstanding potassium storage capability of KVP nanoruler cathode originates from al ow-strain K + uptake/removal mechanism, inherent semiconductor characteristic,a nd small K + migration energy barrier.The high energy density and prolonged cyclic stability of KVP nanorulers//polyaniline-intercalated layered titanate full battery verifies the superiority of KVP nanoruler cathode in PIBs.

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