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In present communication, a new Aurivillius family compound K2Bi4Ti4WO18 was synthesized, and the impact of swift heavy ion (SHI), Ni+11 irradiation on its surface and dielectric properties has been studied in detail. The phase formation in this complex oxide, and crystallization to B2cb symmetry was confirmed by the X-ray diffraction. However, post irradiation the XRD, SEM and AFM studies shows the surface amorphization, in agreement with the theoretical calculations. Furthermore, the effect of irradiation was also observed in the bulk dielectric properties as the system transform to a phase with negative dielectric constant above 350 K in the radio frequencies. This transition is in correlation with significant change in other dielectric parameters such enhancement in AC conductivity, a helical Nyquist plot and multiple dielectric relaxations. This conspicuous changes in the dielectric response post irradiation is attributed to the SHI induced defect formation, modification of energy barriers and their consequences on the electronic structure. Thus, current study suggests that the dielectric properties of Aurivillius K2Bi4Ti4WO18 could be tailored by ion irradiation and opens a new possibility of tuning functional properties.

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The most stable oxide of the vanadium oxide family is V2O5. A lot of research effort is focused on it because it has a multitude of functional applications. Here we report on how the heat treatment (600°C, 5 h, air) affects the microstructure and hence, the band gap of V2O5. The V2O5 powders, initially obtained by simple thermal dissociation (500 °C, 3 h, air) of ammonium metavanadate, followed by heat treatment of pellets; were studied. The structural and optical studies performed using X-ray diffraction (XRD), FESEM and UV-Vis techniques, provide uniquely interesting results which indicate the possibility of band gap tuning by controlling the microstructure.