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bismuth-ferrite
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BiFeO3 Thin Films Deposition by Sol-Gel and Dip Coating Process
, M.Sc. Thesis Sharif University of Technology ; Nemati, Ali (Supervisor) ; Alizadeh, Masoud (Supervisor)
Abstract
Dark and light conductivity has been investigated in Ca-doped bismuth ferrite thin films. Higher conductivity in the order of 105 magnitude of pure Bismuth ferrite has been observed for Bi0.85Ca0.15FeO3-δ. Structural analysis using Rietveld refinement showed a deviation from volume reduction for Bi0.85Ca0.15FeO3-δ that could be the reason of the abnormally high conductivity for this compound. Although higher calcium doping reduced conductivity but photoresponse could be revived. Atomic Forec Microscopy investigations showed that surface roughness decreases with increasing calcium concentration. Enhanced photoconductivity is reported for Bi0.7Ca0.3FeO3-δ with ~2.9 eV direct optical band gap...
Synthesis of Piezoelectric Nanomaterials and Kinetics Investigation of Their Performance for Degradation of Organic Pollutants Under Ultrasonic Vibrations
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
In this research, BiFeO3/Bi2WO6 nanocomposite was synthesized by hydrothermal method and utilized for piezocatalytic degradation of methyl orange dye. This nanocomposite was characterized by XRD, FE-SEM, FT-IR, DRS, PL and Raman spectroscopy. The results of XRD patterns confirmed the rhombohedral crystal structure of BiFeO3 nanoparticles and orthorhombic crystal structure of Bi2WO6 nanosheets. FT-IR and Raman spectroscopy approved the existence of chemical bonds and non-centrosymmetric structure of catalysts. The FE-SEM images displayed the formation of BiFeO3 nanodisks and the Bi2WO6 nanosheets and the decoration of BiFeO3 nanodisks on the Bi2WO6 nanosheets. By using the data of DRS...
Experimental Study and Modelling of Ultrafine Particles Formation by Using the Supercritical Fluids
, Ph.D. Dissertation Sharif University of Technology ; Gotbi, Cyrus (Supervisor) ; Khanchi, AliReza (Supervisor) ; Farhadpour, Farhad (Co-Advisor) ; Dorkoosh, Farid (Co-Advisor)
Abstract
In this research, we focused on demonstration of features and advantages of supercritical fluids technology to formation of fine particles (nano and micro scales) from bulk materials (solid) and synthesized metal oxides nanoparticles. Therefore, using two different fluids, carbon dioxide and water, and two completely different methods, the Rapid expansion of supercritical solution and supercritical hydrothermal, were used to produce fine particles of drug (acetaminophen) and nano metal oxide (zirconium dioxide and bismuth ferrite). The summary of this research are as follows:1. The solubility of acetaminophen in SuperCritical-Carbon Dioxide (SC-CO2) with and without menthol as a cosolvent...
Investigation of dark and light conductivities in calcium doped bismuth ferrite thin films
, Article Materials Letters ; Volume 65, Issue 19-20 , October , 2011 , Pages 3086-3088 ; 0167577X (ISSN) ; Ahadi, K ; Nemati, A ; Sharif University of Technology
2011
Abstract
Electrical conductivities in dark and light were investigated in Calcium doped Bismuth Ferrite thin films. Higher dark conductivity, in the order of 10 times higher than conductivity of bismuth ferrite, was observed for Bi 0.85Ca0.15FeO3 - δ. Structural analyses using Rietveld refinement showed a deviation from volume reduction for Bi 0.85Ca0.15FeO3 - δ which could be the reason of abnormally high conductivity for this compound. Although higher calcium doping reduced conductivity, photoconductivity was observed again. Atomic Force Microscopy investigations showed that surface roughness and grain size decreased with increasing calcium concentration. Enhanced photoconductivity is reported for...
Photoconductivity and diode effect in Bi rich multiferroic BiFeO 3 thin films grown by pulsed-laser deposition
, Article Journal of Materials Science: Materials in Electronics ; Volume 22, Issue 7 , 2011 , Pages 815-820 ; 09574522 (ISSN) ; Mahdavi, S. M ; Nemati, A ; Kianinia, M ; Sharif University of Technology
2011
Abstract
Bismuth ferrite, BiFeO 3, is almost the only material that is simultaneously magnetic and a strong ferroelectric at room temperature. As a result it is the most investigated multiferroic material. In this study, bismuth ferrite thin films were deposited on silicon wafer (100) and glass by pulsed-laser deposition and their structural, optical, and electrical properties were measured. Our study indicates that Bi richness in these films can stimulate formation of oxygen vacancy in the system which in its turn leads to delocalization of carriers and a more intensified photoconductivity response. X-ray diffraction analysis revealed formation of BiFeO 3 (BFO), but it also showed formation of Bi 2O...
Tunable magneto-optical and interfacial defects of Nd and Cr-doped bismuth ferrite nanoparticles for microwave absorber applications
, Article Journal of Colloid and Interface Science ; Volume 608 , 2022 , Pages 1868-1881 ; 00219797 (ISSN) ; Lu, Y ; Hu, E ; Wang, B ; Niaz Akhtar, M ; Noor, A ; Akbar, M ; Yousaf Shah, M. A. K ; Wang, F ; Zhu, B ; Sharif University of Technology
Academic Press Inc
2022
Abstract
Tunable microwave absorption characteristics are highly desirable for industrial applications such as antenna, absorber, and biomedical diagnostics. Here, we report BiNdxCrxFe1-2xO3 (x = 0, 0.05, 0.10, 0.15) nanoparticles (NPs) with electromagnetic matching, which exhibit tunable magneto-optical and feasible microwave absorption characteristics for microwave absorber applications. The experimental results and theoretical calculations demonstrate the original bismuth ferrite (BFO) crystal structure, while Nd and Cr injection in the BFO structure may cause to minimize dielectric losses and enhance magnetization by producing interfacial defects in the spinel structure. Nd and Cr co-doping plays...