Pragati Kumar; Nupur Saxena; Avinash Agarwal; Vinay Gupta
Abstract
Influence of growth temperature on swift heavy ion (SHI) induced structural and optical functionality in CdS thin films is explored for photonic applications. Intense green emission is observed in nanocrystalline CdS thin films grown by pulsed laser deposition (PLD) at two different substrate temperatures ...
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Influence of growth temperature on swift heavy ion (SHI) induced structural and optical functionality in CdS thin films is explored for photonic applications. Intense green emission is observed in nanocrystalline CdS thin films grown by pulsed laser deposition (PLD) at two different substrate temperatures (Ts): room temperature (RT) and 200 ºC. The role of Ts and its implications on the effect of dense electronic excitation provoked by swift heavy ion irradiation (SHII) on various optical and structural properties of CdS films is investigated under the influence of 70 MeV 58 Ni +6 ion beam. It reveals from the present studies that Ts may crucially affect the crystalline structure, vibrational and electronic states of the film and thereafter the functionality induced by ion beam. It is found that ion beam is capable to transform structural phase from mixed phase of cubic and hexagonal structure to either pure cubic or pure hexagonal phase of CdS depending upon the pre-existing preferred orientation in pristine film. The modification in crystallite size and band gap due to impact of ion beam is found to be strongly dependent on pre-existing structural phase, as determined by Ts. The studies presented here confirm that initial growth conditions play a key role even after post deposition SHII treatment in selecting precisely the functional behavior of the films.
Jasneet Kaur; Jaspreet Kaur; R. K. Kotnala; Vinay Gupta; Kuldeep Chand Verma
Abstract
In the present work, the self-assembly of Co 2+ and Fe 3+ doped SnO2 nanoparticles (Co and Fe = 5 mol% each) into nanorods by co-doping of Ce 3+ (4 mol%) ions is studied. The nanorods are prepared by a chemical route using polyvinyl alcohol as surfactant with the composition Sn0.91Co0.05Ce0.04O2 (SCC54) ...
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In the present work, the self-assembly of Co 2+ and Fe 3+ doped SnO2 nanoparticles (Co and Fe = 5 mol% each) into nanorods by co-doping of Ce 3+ (4 mol%) ions is studied. The nanorods are prepared by a chemical route using polyvinyl alcohol as surfactant with the composition Sn0.91Co0.05Ce0.04O2 (SCC54) and Sn0.91Fe0.05Ce0.04O2 (SFC54). The X-ray diffraction (XRD), transmission electron microscopy (TEM), magnetic and electrical measurements are used to characterize these nanorods. The XRD pattern show the tetragonal rutile and polycrystalline nature of SnO2 nanorods which is also confirmed by TEM. The TEM images exhibit that the diameter of SCC54 nanorods lie in the range of 15-20 nm, length~100-200 nm whereas for SFC54 specimen, diameter ~5-15 nm and length ~50-100 nm. In our previous work, we fabricated Co and Fe (3 and 5 mol% each) doped SnO2 nanoparticles which exhibited high ferromagnetism. It is observed that on Ce 3+ co-doping, nanoparticles assembled themselves into rod like structures and the values of saturation magnetization and dielectric properties have further enhanced. Thus the nature and the concentration of dopants are found to play crucial role in tuning the morphology, magnetic and electrical properties of nanostructures. The values of saturated magnetization (Ms) are 1.14 and 0.14 emu/g and coercive field are 112 and 42 Oe, in SCC54 and SFC54 specimen, respectively, at room temperature. The variation in dielectric behavior is attributed due to the interface polarization. However, in lower frequency regime, the decreasing trend of dielectric permittivity with increasing frequency is explained by the Maxwell-Wagner theory and Koops’ model, whereas, in higher frequency region, the resonant behavior is observed due to nano size effect.
Jaspreet Kaur; Jasneet Kaur; Jyoti Shah; R.K. Kotnala; Vinay Gupta; Kuldeep Chand Verma
Abstract
In the present work, structural, microstructural and magnetoelectric (ME) coupling of multiferroic Ba(Fe0.01Ti0.99)O3 (BFT1) nanowires have been studied. BFT1 nanowires were prepared by a hydrothermal method with reaction temperature 180 o C for 48 hours. The X-ray diffraction shows that BFT1 is polycrystalline ...
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In the present work, structural, microstructural and magnetoelectric (ME) coupling of multiferroic Ba(Fe0.01Ti0.99)O3 (BFT1) nanowires have been studied. BFT1 nanowires were prepared by a hydrothermal method with reaction temperature 180 o C for 48 hours. The X-ray diffraction shows that BFT1 is polycrystalline with cubic phase. The calculated value of distortion ratio (c/a) is ~ 1. No impurity or extra phase is observed. The micrographs by transmission electron microscopy reveal nanowires like structure of BFT1with diameter lie in the range of ~ 40 - 50 nm and length greater than 1.5 μm. The ME coefficient measurement shows that the ME coupling under the effect of both ac and dc bias. It shows strong dependence on ac and dc bias applied field. The value of linear coefficient (α) called ME coefficient is calculated as ~ 16 mV/Oecm at a fixed frequency of 850 Hz. This ME coefficient α corresponds to induction of polarization by a magnetic field or of magnetization by an electric field. The observed optimum dc bias field at which the maximum magneto-electric coupling occurs is ~ 750 Oe. The magnetization hysteresis shows strong ferromagnetism.