Nanocrystalline V 2 O 5 thin films were deposited by dc-magnetron sputtering at various substrate temperatures keeping O 2 to Ar ratio at 1:8. The microstructural features were studied by XRD and Raman measurements while the surface topography and grain size of the films by AFM. The films deposited at 250 ˚C exhibited predominant (001) orientation representing the orthorhombic crystal structure with Pmmn space group. The observation of well resolved vanadyle mode at 993 cm-1 and very strong vibrational mode at 142cm-1 in Raman spectrum confirms the formation of layered like structure. The surface of the film is comprised of nanocrystallites with an average grain size of 32 nm and surface roughness of 14 nm. The V 2 O 5 thin films deposited on Ni substrates exhibited good electrochemical performance with high specific capacitance of 238 F/g current density of 1 mAcm-2 with good cycling stability.
Vanadium pentoxide (V 2 O 5 ) thin films have been prepared onto ITO coated flexible Kapton substrates by electron beam evaporation technique. The influence of substrate temperature on the structural, morphological, optical and electrical properties has been investigated. The XRD results reveals that the films prepared at lower temperatures are amorphous in nature and the films prepared at 300 o C is exhibited predominant (001) orientation with an orthorhombic crystal structure. AFM study showed that the grain size varies from 80 nm to 150 nm. The optical studies revealed that the transmittance decreased with increasing substrate temperature. The optical absorption coefficient '' determined from the experimentally measured transmittance and reflectance data for V 2 O 5 films was found to give a better fit for the exponent n = 3/2 suggesting the direct forbidden transitions with an estimated optical band gap of 2.31 eV for the films prepared at 300 o C. The electrical conductivity has been observed to be increased from 2 x 10 -6 S/cm to 3 x 10 -2 S/cm by varying temperature from 30 o C to 300 o C. The electrochemical experiments exhibited the discharge capacity of about 60 μAh/(cm 2 -μm) for the films deposited at 300 o C. Copyright
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