Department Of Physics

Permanent URI for this communityhttps://kr.cup.edu.in/handle/32116/57

Browse

Subject: search.filters.subject.Optical properties

Search Results

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Effects of Dy3+-doping on the band-gap widening and formation of mixed cubic and monoclinic phases of Sm2O3 nanoparticles
    (Springer Science and Business Media Deutschland GmbH, 2023-10-30T00:00:00) Sain, Rachana; Roy, Ayan; Kumar, Ajay; Anu; Deeksha; Kour, Pawanpreet; Singh, Ravi Pratap; Yadav, Kamlesh
    We synthesized Sm2?xDyxO3 (where X = 0.00, 0.03, 0.06, 0.09, and 0.12) nanoparticles using a co-precipitation method and investigated their structural and optical properties. X-ray diffraction (XRD) results reveal that Dy3+-doping in Sm2O3 nanoparticles leads to the formation of a monoclinic polymorphic phase along with the cubic phase of Sm2O3 and its fraction increases with increasing Dy3+-doping concentration. The substitution of Dy3+ at the Sm3+ site converts the cubic Sm2O3 unit cells into distorted monoclinic Sm2?XDyXO3 unit cells. The average crystallite and nanoparticle sizes decrease with increasing Dy3+-doping concentration. Dy3+-ions act as particle size inhibitors, which is attributed to an increase in the segregation of Dy3+-dopant ions at the surface of the nanoparticles with increasing Dy3+-doping content. The peak appearing at 851�cm?1 in the Fourier transform infrared spectroscopy (FTIR) spectra confirms the formation of Sm2O3. Widening of the band gap (Eg) above the band gap of pure cubic Sm2O3 with Dy3+-doping concentration has been observed for X > 0.06, which is due to the Moss-Burstein and quantum size effects. � 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.
  • No Thumbnail Available
    Item
    Effects of interfacial interactions on structural, optical, thermal degradation properties and photocatalytic activity of low-density polyethylene/BaTiO3 nanocomposite
    (Elsevier Ltd, 2023-04-10T00:00:00) Roy, Ayan; Panda, Sambit; Gupta, Jaya; Anu; Singh, Ravi Pratap; Deeksha; Kour, Pawanpreet; Sharma, M.P.; Yadav, Kamlesh
    Barium titanate (BaTiO3) filled low density polyethylene (LDPE), (LDPE)100?x/(BaTiO3)x (where x = 0, 2, 4, 6 and 10) nanocomposites are prepared via a solvent-free melt-mixing method. The effects of nano-sized BaTiO3 (nBT) on the structural, optical and thermal degradation properties of LDPE are investigated to address the qualitative interfacial interaction effects due to the spatial distribution of nBT particles in the LDPE matrix. X-ray diffraction (XRD) results confirm the uniform dispersion of nBT nano-fillers in the LDPE polymer matrix. The crystallite size of LDPE increases with increasing the nBT content. Fourier transform infrared spectroscopy (FTIR) results indicate the enhancement in interfacial physical interactions between the polymer and nano-fillers with increasing nano-filler content. The band gap energy of the nanocomposites decreases with increasing nano-filler content, which suggests chemical imperfections close to the interfaces. DSC results depict higher Tm values for the composites which is attributed to the heterogeneous nucleating effects of the nBT particles. Thermo-gravimetric analysis (TGA) results indicate an increase in the decomposition temperature (TD), thermal stability and good dispersibility probability of nBT with increasing nBT. The photocatalytic decomposition of MB is highest (73.52%) for the 10% nBT incorporated LDPE nanocomposite sample. These results correlate with the effect of the interfacial interactions between the nBT fillers and the LDPE polymer matrix. � 2023 Elsevier Ltd
  • Thumbnail Image
    Item
    Optical properties of nanocrystallite films of ?-Fe2O3 and ?-Fe2-xCrxO3 (0.0 ? x ? 0.9) deposited on glass substrates
    (Institute of Physics Publishing, 2017) Kumar, Ajay; Yadav, Kamlesh
    ?-Fe2O3 films are deposited on fluorine-doped tin oxide (FTO) and indium-doped tin oxide (ITO) substrates for 1, 4 and 6 min using a spray pyrolysis technique. We also deposited ?-Fe2-xCrxO3 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.7 and 0.9) films on the FTO substrate for a deposition time of 35 s. The structural and optical properties of these films were then studied. The x-ray diffraction (XRD) patterns show that all the films are crystalline in nature with a hexagonal crystal structure. The average grain size and unit cell volume were calculated using XRD data. It is found that the average grain size and unit cell volume increase with an increasing film thickness and Cr-doping concentration. The value of strain decreases with an increasing film thickness and Cr-doping content. It is also found that films with the same deposition time on the ITO substrate are more crystalline than on the FTO substrate. Furthermore, the average grain size is obtained from field emission scanning electron microscopy (FESEM) images. FESEM analysis confirms that the average grain size increases with the film thickness and Cr-doping concentration. The optical absorption spectra of the films show that the absorbance increases with an increasing deposition time and Cr concentration. The energy band gap (Eg) of all the films has been calculated using Tauc's relation. A narrowing of the band gap was observed with an increase in film thickness and Cr-doping content. The reduction of the band gap with the increase in film thickness of the films deposited on the ITO substrate is larger than for the film deposited on the FTO substrate. The refractive index is also obtained from the absorption spectra of the films using the Moss relation: n = 4 (k/Eg), where k =108 eV. The refractive index decreases with an increase in the optical band gap. The band gaps of the films are also calculated from the FTIR spectra. This is in good agreement with the UV data. The correlation between the structural and optical properties of the deposited films has been discussed.