Department of Physics

Permanent URI for this communityhttps://repository.cuilahore.edu.pk/handle/123456789/24

Browse

Author: search.filters.author.Dr. Muhammad Ajmal KhanSubject: search.filters.subject.SP20

Search Results

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Fabrication and Characterization study of Micro Thin Film Electrolyte for the Solid Oxide Fuel Cell (SOFC)
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) RIZWAN ASGHAR; CIIT/SP20-RPH-033/LHR; Dr. Muhammad Ajmal Khan; LHR TP 7691
    In this study, Calcium Doped Ceria (CDC) thin film is prepared by the two steps, in the first step calcium doped ceria (CDC) powder is synthesized by co-precipitation method and in the second step, the slurry of calcium doped ceria (CDC) with ball milling and then thin film is casting with help of Tape casting technique. The fabricated thin films were sintered in the range of temperatures (150-750) ℃, in an air atmosphere. Crystal structure revealed that thin film has a cubic fluorite structure, and its average crystallite size is in the range of (53-42) nm. Raman analysis of the thin film was done in the temperature range of 350-750℃. These results showed that CDC thin films have high oxygen vacancies as sintering temperature rises. Which was depicting the high conductivity of the thin film. These results were also verified by the Conductivity measurements. The increase in FWHM of main peaks of Raman spectra, with an increase in temperature resulting in reduction of the crystallite size. Which was also confirmed by XRD results. FTIR results showed the formation of the Ce-O bonds, OH stretching, etc. Furthermore, FTIR spectra of the thin film at various temperatures indicated that OH stretching decreased as temperature increased, indicating that moisture in the sample reduced. Uv visible analysis was done at two different temperatures, 150 and 750℃. Band gap values decreased with increase in the temperatures. It was 3.22eV at 750oC and 3.3eV at 150℃. The conductivity measurements showed that conductivity of thin film was increasing as sintering temperature rises. which was confirmation of Raman results. Thin-film showed the highest conductivity 0.052 Scm-1 at 750℃, the activation energy and electrical band gap calculated from the Arrhenius plot are 0.25 eV and 0.5 eV for the sample sintered at 750oC, respectively. EIS spectra thin-film sintered at 750℃ and 150℃ showed semicircle, which confirms the ionic behavior of the CDC electrolyte thin film. The ohmic resistance also decreased with an increase in the sintering temperature. These results revealed that the thin film shows high ionic conductivity at intermediate temperatures. Which makes it useful for SOFC application.
  • No Thumbnail Available
    Item
    Synthesis of Bismuth Doped Lanthanum Cobalt Iron Oxide Material as Cathode for Application of Solid Oxide Fuel Cell
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) ZOBIA ARIF; CIIT/SP20-RPH-027/LHR; Dr. Muhammad Ajmal Khan; LHR TP 7714
    To reduce carbon dioxide emissions, which create global warming and climate change, the world is moving toward renewable energy sources. Solid oxide fuel cells are one of the most effective energy generation technologies due to their high energy conversion and low environmental impact. In this project, we are synthesized the bismuth doped lanthanum cobalt iron oxide cathode material. The proposed materials are bismuth doped lanthanum cobalt iron oxide (Bix (La0.5Co0.45 Fe0.05)1-x (BLCF)), where x=0.1, 0.2, 0.3 & 0.4 are prepared by sol gel technique. Different characteristics of cathode materials Bix (La0.5Co0.45Fe0.05)1-x are study in this project are X-ray diffraction (XRD), Raman spectroscopy, Fourier Transformation Infrared Spectroscopy (FTIR) and DC-conductivity by four probe methods. The Bi0.1 (La0.45Co0.405Fe0.045) XRD pattern shows that material has composite phase. The phase of Bismuth Iron oxide (average crystalline size 63.63 nm) has an orthorhombic structure (ICSD card No 96-900-8149), Bismuth Lanthanum Oxide (average crystalline size 50.65) has an orthorhombic crystal structure (ICSD card No 96-100-1472) and Lanthanum Cobalt Oxide (average crystalline size 26.42 nm) having orthorhombic crystal structure (ICSD card No 96-200-2266). In Bi0.2 (La0.4Co0.36Fe0.04) XRD pattern Lanthanum Bismuth Oxide (ICSD card No 96-901-5834) and Bismuth Cobalt Iron Oxide (ICSD card No 96-433-6779) having hexagonal structure with crystalline size 93.4 and 76.1 nm. The 3 rd sample Bi0.3 (La0.35Co0.315Fe0.035) XRD pattern shows Bismuth Cobalt Iron oxide (ICSD card No 96- 433-6780), Lanthanum Cobalt Oxide (ICSD card No 96-200-2266) and Bismuth Lanthanum Oxide (ICSD card No 96-100-1471) having monoclinic, orthorhombic, orthorhombic structure with crystalline size 67.7, 65.8 and 76.3 nm. The XRD pattern of Bi0.4 (La0.3Co0.27Fe0.03) shows that Bismuth Lanthanum Oxide (ICSD card No 96-100-1471), Bismuth Iron Oxide (ICSD card No 96-900-8149) and Cobalt Oxide (ICSD card No 96-900- 5888) have orthorhombic, orthorhombic and cubic with crystalline size 56.2, 61.3 and 91.8 respectively. Raman spectra of all samples [Bi (LCF)] show prominent bands at 128, 281, 320, 374, 486, 595, 621, 645 and 980 cm -1 related to La sit vibration, Fe-O vibration, O-B-O O, CoFeO, Co- O, Ag symmetry, stretching vibrations and Ag and Bg normal modes. FTIR spectra of all xi samples [Bi (LCF)] show the peaks at 1060, 1098, 1117, 1426 and 3500 to 3800 cm -1 having different modes and bond (stretching of C-C, Bi O-H, Co precipitation O= C = O stretching vibrations and vibrational peaks). We use DC four-probe methods to measure conductivity of material at different temperature (300-600) ℃. The sample Bi0.4 (La0.3Co0.27Fe0.03) shows the maximum conductivity (6.9 S/cm) at temperature 650 °C. We use EIS techniques to find the ORR of cathode material at (350 to 650 ℃) in air atmosphere. The sample Bi0.4 (La0.3Co0.27Fe0.03) shows the maximum ORR and good electronic behavior.