Lattice Defects Induce Multiferroic Responses in Ce, La‐Substituted BaFe_0.01Ti_0.99O₃ Nanostructures

Abstract

Single‐phase multiferroic Ba(Fe0.67Ce0.33)0.01Ti0.99O3 (BFTO:Ce) and Ba(Fe0.67La0.33)0.01Ti0.99O3 (BFTO:La) nanostructures were synthesized by a hydrothermal method (180°C/48 h). Rietveld refinement of X‐ray diffraction could confirm crystalline phase and lattice deformation by Ce, La into BFTO. The Ce and La doping induce nanoaggregation‐type BFTO nanostructural product due to their ionic size effect and chemical behavior with OH− ions. Raman active modes show tetragonal phase and defects due to vacancies in the BFTO lattice. Photoluminescence spectrum involves multiple visible emissions due to defects/vacancies. The observed ferroelectric polarization is enhanced due to shape/size effect of nanoparticles, lattice distortion, and filling of d orbital in the perovskite BaTiO3. The room‐temperature magnetic behavior is described due to antiferromagnetic interactions that strengthen by Ce and La doping. The zero‐field cooling and field cooling magnetic measurement at 500 Oe indicates antiferromagnetic to ferromagnetic transition. Dynamic magnetoelectric coupling was investigated, and maximum longitudinal magnetoelectric coefficient is 62.65 and 49.79 mV/cmOe, respectively, measured for BFTO:Ce and BFTO:La. The magnetocapacitance measurements induce negative values that described in terms of magnetoresistance and magnetic phase transition effects. The influence of oxygen vacancy on multiferroicity is evaluated by valance states of O ions.

Tailoring the multiferroic behavior in BiFeO3nanostructures by Pb doping

“…18 The increase in lattice constant, c and decrease a may change in those Fe-O bond lengths and Fe-O-Fe bond angles which have a signicant effect on the multiferroic properties. 19 The values of the distortion ratio, c/a ¼ 2.4851, 2.4911, 2.4951 and 2.4964, and unit cell volume, V (Å 3 ) ¼ 373.5088, 374.2098, 373.996 and 374.3993, respectively, for BFO, BPFO5, BPFO75 and BPFO10. The enhancement in the value of V supports the idea that Pb doping induces strain in the BFO and expands the unit cell.…”

Ferromagnetism in Multiferroic BaTiO3, Spinel MFe2O4 (M = Mn, Co, Ni, Zn) Ferrite and DMS ZnO Nanostructures

“…The magnetoelectric (ME) effect-the induction of magnetization by an electric field and the induction of electric polarization by a magnetic field [1]. Multiferroic nanostructures have given recent advances in new type of memory devices including multistate data storage and spintronics [2]. BaTiO 3 (BTO) is a rare single-phase multiferroic.…”

“…The nano-aggregation type Ba(Fe 0.67 Ce 0.33 ) 0.01 Ti 0.99 O 3 (BFTO:Ce) and Ba(Fe 0.67 La 0.33 ) 0.01 Ti 0.99 O 3 (BFTO:La) product is synthesized by a hydrothermal process [2]. Rietveld refinement of XRD pattern indicates polycrystalline phase with tetragonal BFTO.…”

“…These defects and vacancies are also confirmed with photoluminescence measurement that might be altered due to higher surface-tovolume ratio in nano-aggregation. Figure 4(d and e) shows the ferromagnetic behavior of Ce, La doped BFTO, respectively, by magnetization versus field (M-H dc hysteresis) measured at room temperature [2]. The values of M s (emu g −1 ) = 0.15 and 0.08, and M r (emu g −1 ) = 0.039 and 0.015 with H c (Oe) = 242 and 201, respectively, for BFTO:Ce and BFTO:La.…”

“…(c) ME voltage coefficient (α ME ), (d and e) M-H dc hysteresis at room temperature, (d′ and e′) P-E hysteresis, and (d″ and e″) M(T)following ZFC/FC at H = 500 Oe for Ce, La doped BFTO. Adopted from Refs [2,5]…”