A. Namiranian , M. Kalantar,
Volume 8, Issue 3 (september 2011 2011)
Abstract
The process of mullitization of kyanite concentrate was studied at different conditions of heat treatment (1400
– 1600 °C and 0.5 – 3.5 hours) and particle size of raw materials (38-300 ?m). Kyanite concentrate was obtained from
ore-dressing of kyanite deposits of Mishidowan-Bafgh region at 100 km northeastern part of Yazd. The results of
microstructure (shape, distribution and size of the grains) and phase evolution studies by SEM and XRD showed that
total transformation of kyanite to mullite takes place by heat treatment between 1500 –1550 °C during 2.5 hours.. At
temperatures below 1500 °C need-like mullite grains are always produced. At higher temperatures the mullite grains
reveal rounded and platelet morphology. At 1550 °C, the rate of mullitization and densification were improved by
increasing soaking time from 1h to 3h and decreasing particle size of materials from 300 to 38 m
Hussein Ali Jan Miran, Zainab Naji Abdullah, Mohammednoor Altarawneh, M Mahbubur Rahman, Auday Tariq Al-Bayati, Ebtisam M-T. Salman,
Volume 20, Issue 1 (March 2023)
Abstract
This contribution evaluates the influence of Cr doping on the ground state properties of SrTiO3 Perovskite using GGA-PBE approximation. Results of the simulated model infer agreement with the previously published literature. The modification of electronic structure and optical properties due to Cr3+ doping levels in SrTiO3 has been investigated. Structural parameters infer that Cr3+ doping alters the electronic structures of SrTiO3 by shifting the conduction band through lower energies for the Sr and Ti sites. Substituting Ti site by Cr3+ results the energy gap in being eliminated revealing a new electrical case of conducting material for the system. Furthermore, it has been noticed that Cr doping either at Sr or Ti positions could effectively develop the SrTiO3 dielectric constant properties. Consequently, Cr3+ is an effective dopant due to enhancing the optical absorption properties, thus opening up new prospects for optoelectronic applications.
