• ARMAN SEDGHI

      Articles written in Bulletin of Materials Science

    • Effect of chemical composition and alumina content on structure and properties of ceramic insulators

      Arman Sedghi Nastaran Riahi-Noori Naser Hamidnezhad Mohammad Reza Salmani

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      In the present work, six electrical porcelain compositions with different amount of alumina and silica have been prepared and fired in an industrial furnace at 1300°C. Density, porosity, bending strength and electrical strength were measured in the samples. In order to find a relationship between properties and sample microstructures, samples were analyzed by scanning electron microscope (SEM) and x-ray diffraction (XRD) techniques. The results showed that, with chemical composition of 53.5 wt.% SiO2 and 37.5 wt.% alumina, highest electrical strength of 21.97 kV/mm was achieved in fabricated electrical porcelains. Increasing amount of alumina up to 30 wt.% decreases quartz and cristobalite phases, but increases corundum phase 3 to 5 times. SEM observation revealed that dense particles and uniform distribution of long and thin needle shaped mullite are predominant in sample microstructures with highest electrical strength.

    • Investigation of the effect of MAI and PbI$_2$ concentrations on the properties of perovskite solar cells

      ALI MEHDIKHANI ARMAN SEDGHI ROOZBEH SIAVASH MOAKHAR NASTARAN RIAHI-NOORI

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      Here, the effect of perovskites layer quality on the performance of compact-TiO$_2$/mesoporous-TiO$_2$/CH$_3$NH$_3$PbI$_3$/carbon solar cells was investigated. Different perovskite layers were prepared by varying concentrationsof PbI$_2$ and CH$_3$NH$_3$I, while reaction temperature and dipping time were fixed. The range of concentrations for PbI$_2$ and methylammonium iodide (MAI) were 1–1.4 M and 6–10 mg ml$^{−1}$, respectively. Fabricated perovskite layers were first coated by carbon electrodes (5-layer) and then, the champion one was coated by Spiro-OMeTAD (as a hole transport material) andAu-evaporated layer as a cathode (6-layer). Fabricated films were fully characterized by field emission scanning electron microscopy, X-ray diffraction analysis, UV–Vis spectroscopy and photoluminescence spectrum. Photovoltaic properties were measured under AM 1.5. Output currents of 5-layer cells were in the range of 228–476 $\mu$A, of which the highest one was obtained by using 1.2M PbI$_2$ and 8 mg ml$^{−1}$ MAI. Ultimately, the maximum power conversion efficiency of 9.1% was obtained with 6-layer cell.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

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      Posted on July 25, 2019

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