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Proceedings ArticleDOI

Improvement of magnetic and ferroelectric properties of BiFeO3 nanoparticles on Tb and Co substitution

10 May 2016-Vol. 1728, Iss: 1, pp 020644
TL;DR: In this article, the authors improved the ferroelectric properties of BiFeO3 by substitution of Tb3+ ions in Bi3+ site and magnetic properties of Co2+ in Fe3+ sites.
Abstract: Tb and Co substituted bismuth ferrite nanoparticles (NPs) with chemical composition Bi1-xTbxFe1-yCoyO3 (x = 0, 0.05; y = 0, 0.05) have been synthesized by a sol-gel method and characterized by x-ray diffraction (XRD), Mossbauer spectroscopy, dc magnetization and electric polarization measurements. The aim of the present work is to improve ferroelectric properties of BiFeO3 by substitution of Tb3+ ions in Bi3+ site and magnetic properties by substitution of Co2+ in Fe3+ site. The XRD patterns of all prepared samples show formation of the desired phase along with a small amount of impurity. Room temperature Mossbauer spectroscopic studies reveal that all samples are in magnetically ordered state. Magnetic hysteresis loops of all samples indicate a significant enhancement of magnetic moment and coercivity whereas electric polarization measurements at room temperature reveal an improvement of ferroelectric properties in the co-substituted sample.
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Journal ArticleDOI
TL;DR: In this paper , the effects of low-level Ba(5%)-Cr(1-5%) co-incorporation on room temperature structural and functional properties of sol-gel synthesized bismuth ferrite (BiFeO3) nanoparticles were reported.
References
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Journal ArticleDOI
TL;DR: In this article, a modified Scherrer equation (MSE) method was proposed to calculate the nano-scale size of bovine bone using XRD radiation of wavelength λ (nm) from measuring full width at half maximum of peaks (β) in radian located at any 2π in the pattern.
Abstract: Scherrer Equation, L=Kλ/β.cosθ, was developed in 1918, to calculate the nano crystallite size (L) by XRD radiation of wavelength λ (nm) from measuring full width at half maximum of peaks (β) in radian located at any 2θ in the pattern. Shape factor of K can be 0.62 - 2.08 and is usually taken as about 0.89. But, if all of the peaks of a pattern are going to give a similar value of L, then β.cosθ must be identical. This means that for a typical 5nm crystallite size and λ Cukα1 = 0.15405 nm the peak at 2θ = 170° must be more than ten times wide with respect to the peak at 2θ = 10°, which is never observed. The purpose of modified Scherrer equation given in this paper is to provide a new approach to the kind of using Scherrer equation, so that a least squares technique can be applied to minimize the sources of errors. Modified Scherrer equation plots lnβ against ln(1/cosθ) and obtains the intercept of a least squares line regression, ln=Kλ/L, from which a single value of L is obtained through all of the available peaks. This novel technique is used for a natural Hydroxyapatite (HA) of bovine bone fired at 600°C, 700°C, 900°C and 1100°C from which nano crystallite sizes of 22.8, 35.5, 37.3 and 38.1 nm were respectively obtained and 900°C was selected for biomaterials purposes. These results show that modified Scherrer equation method is promising in nano materials applications and can distinguish between 37.3 and 38.1 nm by using the data from all of the available peaks.

1,418 citations

Journal ArticleDOI
TL;DR: In this article, the authors highlight the physical concepts of multiferroicity and the current challenges to integrate the magnetism and ferroelectricity into a single-phase system and summarize various strategies used to combine the two types of order.
Abstract: Multiferroics, defined for those multifunctional materials in which two or more kinds of fundamental ferroicities coexist, have become one of the hottest topics of condensed matter physics and materials science in recent years. The coexistence of several order parameters in multiferroics brings out novel physical phenomena and offers possibilities for new device functions. The revival of research activities on multiferroics is evidenced by some novel discoveries and concepts, both experimentally and theoretically. In this review, we outline some of the progressive milestones in this stimulating field, especially for those single-phase multiferroics where magnetism and ferroelectricity coexist. First, we highlight the physical concepts of multiferroicity and the current challenges to integrate the magnetism and ferroelectricity into a single-phase system. Subsequently, we summarize various strategies used to combine the two types of order. Special attention is paid to three novel mechanisms for multiferroicity generation: (1) the ferroelectricity induced by the spin orders such as spiral and E-phase antiferromagnetic spin orders, which break the spatial inversion symmetry; (2) the ferroelectricity originating from the charge-ordered states; and (3) the ferrotoroidic system. Then, we address the elementary excitations such as electromagnons, and the application potentials of multiferroics. Finally, open questions and future research opportunities are proposed.

1,243 citations

Journal ArticleDOI
TL;DR: As-prepared, single-crystalline bismuth ferrite nanoparticles show strong size-dependent magnetic properties that correlate with increased suppression of the known spiral spin structure with decreasing nanoparticle size and uncompensated spins and strain anisotropies at the surface.
Abstract: As-prepared, single-crystalline bismuth ferrite nanoparticles show strong size-dependent magnetic properties that correlate with: (a) increased suppression of the known spiral spin structure (period length of ∼62 nm) with decreasing nanoparticle size and (b) uncompensated spins and strain anisotropies at the surface. Zero-field-cooled and field-cooled magnetization curves exhibit spin-glass freezing behavior due to a complex interplay between finite size effects, interparticle interactions, and a random distribution of anisotropy axes in our nanoparticle assemblies.

1,129 citations

Journal ArticleDOI
TL;DR: In this article, the authors highlight the physical concepts of multiferroicity and the current challenges to integrate the magnetism and ferroelectricity into a single-phase system, and summarize various strategies used to combine the two types of orders.
Abstract: Multiferroics, defined for those multifunctional materials in which two or more kinds of fundamental ferroicities coexist, have become one of the hottest topics of condensed matter physics and materials science in recent years. The coexistence of several order parameters in multiferroics brings out novel physical phenomena and offers possibilities for new device functions. The revival of research activities on multiferroics is evidenced by some novel discoveries and concepts, both experimentally and theoretically. In this review article, we outline some of the progressive milestones in this stimulating field, specially for those single phase multiferroics where magnetism and ferroelectricity coexist. Firstly, we will highlight the physical concepts of multiferroicity and the current challenges to integrate the magnetism and ferroelectricity into a single-phase system. Subsequently, we will summarize various strategies used to combine the two types of orders. Special attentions to three novel mechanisms for multiferroicity generation: (1) the ferroelectricity induced by the spin orders such as spiral and E-phase antiferromagnetic spin orders, which break the spatial inversion symmetry, (2) the ferroelectricity originating from the charge ordered states, and (3) the ferrotoroidic system, will be paid. Then, we will address the elementary excitations such as electromagnons, and application potentials of multiferroics. Finally, open questions and opportunities will be prospected.

1,088 citations

Journal ArticleDOI
TL;DR: In this article, the transport properties of aliovalent-ion-doped BiFeO3 (BFO) thin films have been studied in order to identify the cause of high leakage currents.
Abstract: Transport properties of aliovalent-ion-doped BiFeO3 (BFO) thin films have been studied in order to identify the cause of high leakage currents Doping of 2at% Ti4+ ions increased the dc resistivity by more than three orders of magnitude In contrast, doping of 2+ ions such as Ni2+ reduced the dc resistivity by two orders of magnitude Current–voltage (I–V) characteristics indicated that the main conduction mechanism for pure and Ni2+ doped BFO was space charge limited, which was associated with the free-carriers trapped by the oxygen vacancies, whereas in the Ti4+ doped BFO, field-assisted ionic conduction was dominant

970 citations