[en] Photo-galvanic effects were studied in a photo-galvanic cell containing oxalic acid as reductant and Brilliant Cresyl as photosensitizers. The photo potential and photo current generated were 320.0 mV and 80.0 uA, respectively. The effects of different parameters on the electrical output of the cell were observed and a mechanism has also been proposed for the generation of a photocurrent in a photo-galvanic cell. (author)

[en] Synroc mineral specifically zirconolite has been proven a potential candidate for the immobilization of high level radio-active wastes released from nuclear weapons and nuclear reactors due to its superior properties viz. high radiation and aqueous resistance and high waste loading. It is being studied since decades to isolate the environment from hazardous effects of α-decay events by simulating with low energy heavy (1-1.5 MeV Kr⁺ and Xe⁺) and light (30-200 keV He⁺) ions. In present study, single phase zirconolite samples prepared by solid state reaction method, were irradiated using 120 MeV Au⁺ ions. In-situ XRD along with micro-Raman spectroscopy techniques were employed to investigate the induced effects of swift heavy ions. Disappearance of characteristic diffraction peaks and appearance of broad diffuse scattering bands, confirmed the amorphization of zirconolite. Also, trend of amorphization with fluence was linear at lower fluences followed by a saturation at the higher fluences, inferring the formation of ion tracks. The ion fluence dependent Raman investigation was also in accordance with the XRD observations. In summary, swift heavy ion produced columnar defects, vacancies and induced micro-strains which led to the bonds distortion and eventually amorphization of the zirconolite. (author)

[en] Present study reports the structural and dielectric properties of Ce_1_-_xMn_xO_2 (0 ≤ x ≤ 0.15) compounds synthesized by solid state reaction method. X-ray diffraction and Raman measurements confirm the formation of cubic phase corresponding to Fm3m space group for all these compositions investigated. The transition metal Mn ions exhibit multivalency nature in oxides and doping these ions at Ce sites in CeO_2 which is also known to exist in 3+ and 4+ valency state is expected to modify the physical properties. The crystallite size was found to decrease with Mn concentration up to 7%, however, it increases at higher Mn concentration i.e., x = 0.15 which is also confirmed by the images from Scanning Electron Microscope. Raman study reveals red shift in peaks at ∼462.9 cm"−"1 and ∼572.9 cm"−"1 upto x = 0.07, whereas the blue shift was observed from these peaks for x = 0.15. The electrical resistivity measured as a function of temperature (200 K–380 K) indicates an increase in resistivity with Mn doping. Furthermore, the dielectric measurements performed with varying frequency as well as temperature shows an enhancement in dielectric constant and decrease in the dielectric loss with Mn concentration. - Highlights: • Influence of Mn ions on the structural, electrical and dielectric properties of CeO_2 was investigated. • The crystallite size and grain size decreases with Mn doping into CeO_2 matrix. • The dielectric constant and resistivity of samples increases with Mn doping into CeO_2 lattice. • The dielectric loss decreases with Mn doping into CeO_2.

[en] ZnO/NiO thin film heterojunctions of film thickness 100/100 nm respectively deposited on Si(100) by Pulsed Laser Deposition (PLD) method were irradiated with 200 MeV Ag ions. The evolution of electrical property of the film with ion fluence was probed though in-situ I-V measurement at room temperature. The pristine heterojunction showed rectifying behaviour. Irradiation suppressed the rectifying nature and the junctions became ohmic at high ion fluences. The reverse biased leakage current showed a monotonic increase with irradiation fluence, while the ideality factor obtained from the I-V characteristics of the diode structure, showed an increase followed by a decrease and then saturation with increasing irradiation fluence. The mechanism of electrical conduction in our case seems to follow the power law model. The calculated barrier height decreased exponentially with increasing ion fluence. However, in the present work, the cause of exponential suppression of the barrier height with ion fluence is attributed to the implantation of ion track in the sample. We extracted the radius of ion track to be ~ 3 nm from the variation of barrier height with ion fluence. (author)