Showing papers by "Sampat Raj Vadera published in 2017"
TL;DR: In this paper, the synthesis and catalytic activity of a novel nanocatalyst (CuO@mTiO2@CF), consisting of CuO nanoparticles, mesoporous titanium oxide and Cobalt ferrite have been reported for the first time.
Abstract: Here, synthesis and catalytic activity of a novel nanocatalyst (CuO@mTiO2@CF), consisting of CuO nanoparticles, mesoporous titanium oxide and Cobalt ferrite have been reported for the first time. The catalyst was synthesized using a simple aqueous solution based chemical methodology. Synthesized CuO@mTiO2@CF showed excellent catalytic activity towards various organic reactions such as (i) Epoxidation of styrene, (ii) Click reaction, (iii) Biginelli reaction, (iv) Reduction of 4-Nitrophenol and trifluralin in presence of excess NaBH4. Moreover, this novel nanocatalyst offered easy magnetic separation after the catalysis reaction and excellent reusability. Easy synthesis methodology, versatility, good reusability and easy separation make the nanocatalyst attractive in the field of heterogeneous catalysis.
27 citations
TL;DR: In this article, the effect of percentage loading of nanosize carbon black (CB) on DC conductivity, dielectric and microwave absorption properties and electromagnetic Shielding Effectiveness (SE) of silicone rubber composites is studied.
Abstract: In this paper, studies on broadband microwave absorption and electromagnetic shielding effectiveness are reported in flexible rubber composites with low filler content of nanosize conducting carbon over 8–18 GHz frequency range of electromagnetic spectrum. Rubber based composites are prepared by loading of 1–15 wt% nanosize conducting Carbon Black (CB) in silicone rubber matrix. Effect of percentage loading of nanosize CB on DC conductivity, dielectric & microwave absorption properties and electromagnetic Shielding Effectiveness (SE) of silicone rubber composites is studied. The percolation threshold is achieved at low concentration (3 wt%) of CB in composites. The observed complex permittivity values revealed that composites with concentration of 5wt% CB can provide more than 90% microwave absorption (Reflection Loss > −10 dB) over 8–18 GHz at composite thickness of 1.9–2.7 mm. Further, composites with concentration of 15 wt% of CB shows −40 dB SE over the broad frequency range 8–18 GHz at thickness 2.8 mm. The effect of composite thickness on microwave absorption properties and shielding effectiveness is also analyzed. Thus, the prepared rubber composites with suitable concentration of nanosize CB as filler may be used as microwave absorber in stealth applications as well as for EMI shielding of electronic equipments in various civilian and military areas.
19 citations
TL;DR: The gel to carbonate precipitate route has been used for the synthesis of Ni1−xZnxFe2O4 bulk inverse spinel ferrite powder samples and the optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent.
Abstract: The gel to carbonate precipitate route has been used for the synthesis of Ni1−xZnxFe2O4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδm) > −1.2 over the entire 2–10 GHz frequency range with an optimum value ~−1.75 at 6 GHz. Ni0.5Zn0.5Fe2O4- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni0.5Zn0.5Fe2O4/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (fm1) and destructive interference at λm/4 matched thickness near ~10 GHz (fm2) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni0.5Zn0.5Fe2O4/NBR composite samples for possible microwave absorption applications.
16 citations
TL;DR: In this paper, the phase pure rhombohedral structure of prepared powder was confirmed by X-ray diffraction and Fourier transform infrared studies, which confirmed that the ferroelectric properties of multiferroic BiFeO3 are contributing significantly for the observed MW absorption with respect to the magnetic contribution.
Abstract: Nanostructured multiferroic BiFeO3 powder has been synthesized using sol–gel route followed by optimized post-annealing treatment. The phase pure rhombohedral structure of prepared powder was confirmed by X-ray diffraction and Fourier transform infrared studies. The room temperature weak ferromagnetic nature (~ 0.15 emu/g) exhibited by the nanocrystalline BiFeO3 sample (~ 50 nm) is attributed to the canted spin ordering in the sample. The BiFeO3/NBR rubber composites, with 50–80 wt% filler loading fractions, show the dual band resonating microwave (MW) absorption behavior. The reflection loss (R.L.) values enhanced and required absorber thickness reduced simultaneously with increasing BiFeO3 loading fraction in composite samples. These results confirm that the ferroelectric properties of multiferroic BiFeO3 are contributing significantly for the observed MW absorption with respect to the magnetic contribution.
5 citations