Structural and multiferroic properties of La-modified BiFeO3 ceramics

Abstract

The coexistence of the magnetic and the electrical properties in lanthanum (La)-modified bismuth ferrite (Bi1−xLaxFeO3, x=0.05, 0.1, 0.15, and 0.2) ceramics was studied and compared with those of bismuth ferrite (BiFeO3). The presence of a small secondary phase of BiFeO3 (arises due to excess Bi2O3) was removed on La substitution at the Bi site, as observed in x-ray diffraction (XRD). The effect of La substitution on dielectric constant, loss tangent, and remnant polarization of the samples was studied in a wide range of temperature (77–400K) and frequency (1kHz–1MHz). The variation of magnetization, coercive field, and exchange bias with temperature (2–300K) and La concentration were investigated. These changes in the magnetic parameters with La doping along with those of the electron magnetic resonance parameters measured at 300K and 9.28GHz are understood in terms of increase in the magnetic anisotropy and magnetization. These results also show that stabilization of crystal structure and nonuniformity in spin cycloid structure by La substitution enhances the multiferroic properties of BiFeO3.

Development of microcontroller based thermogravimetric analyzer

“…11) results and XRD pattern (Fig. 12) results are in good agreement with the results published [6][7][8][9][10].…”

“…The standalone (manual) mode or PC mode can be selected by using one more switch (SW4). Transmit (RC 6 ) and receive (RC 7 ) pins of the microcontroller are connected to receive and transmit pins of the serial port of PC via RS232C interface.…”

Spin-cycloid instability as the origin of weak ferromagnetism in the disordered perovskiteBi0.8La0.2Fe0.5Mn0.5O

“…While the ferroelectric polarization can be controlled through an applied voltage, the magnetic degree of freedom in BiFeO 3 is difficult to measure directly as it exhibits antiferromagnetic (AFM) order with a related incommensurate spin-cycloidal structure [4]. A promising avenue of research to induce a sizable ferromagnetic component necessary for technical applications is cation substitution [5][6][7][8][9][10], which has been shown to both establish measurable weak-ferromagnetic (wFM) behavior and enhance ferroelectric properties. However, it is only comparatively recently that the mechanisms responsible for the magnetic ground state of pure BiFeO 3 have been investigated in detail, enabling a more systematic approach to improve the properties of BiFeO 3 [11][12][13][14].…”

“…Cation substitution of either the Bi A site or Fe B site affects both the electric and magnetic polarization components, indicating a complex array of competing interactions [6][7][8][9]. While experimentally it is known that the cycloid can be perturbed through modifications of the BiFeO 3 chemical and structural properties via cation substitution or strain fields [24,25], it remains unclear as to what magnetic perturbations are required to drive the BiFeO 3 system to a canted spin structure and release latent wFM.…”

Atomic scale structure and chemistry of anti-phase boundaries in (Bi0.85Nd0.15)(Fe0.9Ti0.1)O3ceramics

“…Nevertheless, there are significant issues to be addressed before applications for bulk ceramics may be countenanced; the magnetic ordering is antiferromagnetic (AFM) but canted over long range, and the electrical conductivity is too high to access the dielectric or ferroelectric properties. Recent work has concentrated on using donor doping on the B-site of the ABO 3 perovskite sublattice to prevent oxygen vacancy (V O ) formation and thereby reduce conductivity [1][2][3], together with rare earth (RE) A-site site to modify the magnetic ordering [1][2][3][4][5]. Combining such A-and B-site doping results in the formation of a low conductivity ceramic with stable AFM ordering [6][7][8][9].…”