Lattice effects on the multiferroic characteristics of (La, Ho) co-substituted BiFeO3

The influence of La3+ and Ho3+ co-substitution on the structural, electrical and magnetic properties of rhombohedrally distorted polycrystalline BiFeO3 is reported. The presence of a tiny residual secondary phase of Bi2Fe4O9, Bi25FeO40 is evident in all the samples, while La doping suppresses the impurity phase and favors the grain growth (size of 1-2 mu m) of the pristine compound. A fivefold increase in the dielectric constant (230 at 1 MHz) is achieved for the samples with the highest La content with a remarkable reduction in the dielectric loss. LaxHoyBi1-(x+y)FeO3 ceramics exhibit lossy ferroelectric loops and the magnitude of polarization reduces upon the co-substitution. The antiferromagnetic BiFeO3 transforms to ferromagnetic at low temperatures due to the annihilation of the cycloid-spin structure. The co-substitution effectively improved the magnetic properties. 'Ho' substitution helps in achieving the enhanced magnetization values while 'La' substitution helps in increasing the magnetic coercivity, H-C. The variation of the H-C with the temperature is interpreted by means of the two sublattice model. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The co-substitution of La3+ and Ho3+ in BiFeO3 significantly affects its structural, electrical, and magnetic properties, suppressing impurity phases, promoting grain growth, and notably increasing the dielectric constant. Additionally, the co-substitution improves magnetic properties, with 'Ho' enhancing magnetization values and 'La' increasing the magnetic coercivity.