Please use this identifier to cite or link to this item: http://hdl.handle.net/10266/4363
Title: Multiferroic properties of doped-BiFeO3 nanoparticles
Authors: Dhir, Gitanjali
Supervisor: Verma, N. K.
Uniyal, Poonam
Keywords: multiferroic;nanoparticles;Ferromagnetism;BiFeO3
Issue Date: 17-Oct-2016
Abstract: With the semi-conductor industry facing threats of reaching fundamental limits further miniaturization is not possible. Current trends toward device miniaturization and high-density data storage system thus necessitate integration of multifunctions into a single material. Multiferroics, the rare class of compounds exhibiting co-existence of two or more ferroic orders serves the contemporary demands. Significant advancements in the atomic and nanoscale growth and characterization techniques achieved with the developments in the field of nanotechnology pave the way for multifunctional nanostructural materials. These nanostructured multiferroics offer plenty of horizons for future technology because of the tunability of properties with size and morphology. Bismuth ferrite (BiFeO3) – the most widely studied single phase multiferroic system in the literature displays room temperature ferroelectric (1100 K) and magnetic (640 K) order that makes it unique of its kind. Though this feature being promising for utilization in devices however, has failed hitherto. Its application is hampered by several serious issues that involve high leakage currents (mainly arising due to oxygen and bismuth vacancies, non-stoichiometery, secondary phase impurities and defects caused by the volatile nature of Bi), and no net magnetization (mainly arising due to incommensurate spin spiral structure of wavelength 62 nm superimposed over G-type antiferromagnetic ordering), which thus leads to low magnetoelectric coupling in BiFeO3. Many studies are devoted to eradicate these problems over the time. Reviewing the literature one observes the rare earth and alkaline earth metal ions-doping and reduction of the size to nanoscale are helpful in addressing these issues. 13 Particle size plays a crucial role in deciding the overall multiferroic properties of BiFeO3 nanoparticles. Various aspects (structural, magnetism, dielectric behaviour, magnetic transition temperature, photocatalytic activity, etc.) of BiFeO3 nanoparticles scrutinizing their influence on particle size have been studied in details. However, it has been found that not much of studies have been carried out to investigate the influence of the particle size on the multiferroic properties of rare earth and alkaline earth metal ions doped BiFeO3 nanoparticles. In a nutshell, the present thesis attempts to study the influence of particle size on rare earth and alkaline earth metal ions-doped BiFeO3 nanoparticles . Altogether, six combinations (rare earth (Tb, Dy, Gd) and alkaline earth (Ca, Sr, Ba) metal-doped BiFeO3 nanoparticles) have been studied, which are synthesized using sol-gel method. Their structural, morphological, magnetic, dielectric and ferroelectric analyses have been done by X-ray diffractometer (XRD), Scanning electron microscope/Transmission electron microscope (SEM/TEM), Vibrating sample magnetometer (VSM), LCR meter and P-E loop tracer, respectively. Remarkable influence of particle size on magnetic, dielectric and ferroelectric properties of rare earth and alkaline earth metal ions-doped BiFeO3 has been witnessed. Rare earth metals in comparison to alkaline earth metals have been found to display enhanced magnetic, dielectric and ferroelectric values. Amongst the six ions, Dy3+ ions - doped BiFeO3 nanoparticles have been observed to exhibit the maximum enhancement of multiferroic (desirable for device application) properties owing to its smallest ionic radii and highest magnetic moment.
URI: http://hdl.handle.net/10266/4363
Appears in Collections:Doctoral Theses@SPMS

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