Browsing by Author "Yadav K."

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Effect of doping on optical properties in BiMn1−x (TE) x O3 (where x = 0.0, 0.1 and TE = Cr, Fe, Co, Zn) nanoparticles synthesized by microwave and sol-gel methods
(Springer Verlag, 2017) Bhardwaj N.; Gaur A.; Yadav K.
The structural, optical, and dielectric properties of polycrystalline BiMn1−x TE x O3 (x = 0, 0.1 and TE = Cr, Fe, Co, and Zn) samples synthesized by microwave-assisted synthesis, and sol-gel techniques have been studied. It is found from the XRD data for samples synthesized by both the methods that the lattice volume and average grain size of the prepared samples decrease with doping Cr, Fe, Co, and Zn, consequently. Furthermore, the optical properties obtained from FTIR confirmed that bandgap increases and refractive index decreases on doping transition element in the same order as Cr, Fe, Co, and Zn for samples synthesized by both the methods. The grain sizes obtained for the samples in case of sol-gel method are less than the samples synthesized by microwave method. It is due to less agglomeration of particles in the samples prepared by sol-gel method. P–E loops are measured at room temperature. The variations of dielectric constant and loss tangent with the frequency are plotted. The value of dielectric constant increases for Zn doped sample and then decreases for Cr, Co, and Fe doped samples, respectively. The correlation between the observed structural, optical, and dielectric properties has been described in this paper.
Morphological, optical and thermal properties of (TiO2)xembedded (PVC/PE)1?x(where X = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) blend nanocomposites
(Springer Science and Business Media, LLC, 2017) Thakur A.; Thakur P.; Yadav K.
Present study deals with the dispersion of TiO2 nanoparticles in PVC/PE blends. The prepared blend nanocomposites have been characterized using FESEM, FTIR, UV-Visible spectroscopy, TGA, and EDX to study the morphology, optical and thermal properties of prepared samples. FESEM confirms the dispersion of nanoparticles in polymer blend and formation of blend nanocomposites. Decrease in optical band gap has been observed by addition of TiO2 content. Variation in melting point is studied by TGA. Thermal stability is enhanced with increasing TiO2 content in polymer blend.
Study of optical properties of BaMn1-xCrxO3 (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) manganites using microwave synthesis method
(American Institute of Physics Inc., 2015) Rani R.; Yadav K.
Barium manganite (BaMnO3), a perovskite based material, has been studied extensively. BaMnO3 properties can be changed by doping different elements at manganese (Mn) lattice site. We have prepared BaMnO3 and BaMn1-xCrxO3 (x=0.1, 0.2, 0.3, 0.4, 0.5) by Microwave Synthesizer. Data obtained from Fourier Transform Infrared Spectroscopy (FTIR) that the band gap of pure BaMnO3 is less as compare to the Cr doped BaMnO3. It is also clear from the FTIR that the band gap decreased with increasing the concentration of chromium. Broaden peak at 3201 cm-1 correspond to the stretching vibration of hydroxyl group (OH or H2O). The peaks appear on 724, 863 and 974 cm-1 is corresponding to the stretching vibration of metal oxide (M-O) bonds in the BaMnO3. BaMnO3 have applications in memory storage devices. - 2015 AIP Publishing LLC.
Study of variation in the band gap with concentration of TiO2In (LaMnO3)1-x / (TiO2)x (where x = 0.0,0.1,0.2,0.3 and 0.4) nanocomposites
(American Institute of Physics Inc., 2016) Thakur P.; Thakur A.; Yadav K.
In this paper(LaMnO3)1-x/ (TiO2) x (where x = 0.0, 0.1, 0.2, 0.3 and 0.4) nanocomposite are prepared by mixing the LaMnO3 and TiO2 (Sigma Chemicals, particle size ?21 nm) nanoparticle in appropriate ratio. These samples were characterized by using FESEM, EDS and FTIR to study the optical properties. Field Emission Scanning Electron Microscopy (FESEM) image of pure LaMnO3 sample shows that the uniform particle size distribution is observed. The average particle size of the LaMnO3 nanoparticles is 43 nm. The crystallite size increases from 16-24 nm with increasing the weight percentage of TiO2 in LaMnO3/TiO2 nanocomposite up to x = 0.4. The Fourier transform infrared spectroscopy (FTIR) spectra show that the absorption peaks appear at 450 cm-1 and 491 cm-1 which represent the Mn-O bending and Ti-O stretching mode respectively. The broadening of these peaks with increasing the concentration of TiO2 is also observed. It gives an evidence for the formation of metal oxygen bond. The absorption band at 600 cm-1 corresponds to the stretching mode, which indicates the pervoskite phase present in the sample. The values of band gap are found 2.1, 1.9, 1.5, 1.3 and 1.2 eV for the x = 0.0, 0.1, 0.2, 0.3, and 0.4 respectively. Thus, the decrease in band gap and increase in refractive index with increasing concentration of TiO2 has been observed. These prepared nanocomposites can be used in the energy applications, to make the electrical devices and as a catalyst for photocatalytic processes e.g. hydrogenation.