Particle size dependence of magnetization and noncentrosymmetry in nanoscale BiFeO3

Abstract

The saturation magnetization (M S ), antiferromagnetic transition point (T N ), and the off-center displacements of Bi and Fe ions have been measured as a function of particle size in nanoscale BiFeO 3 . T N decreases down to $550 K for particles of size $5 nm from $653 K in bulk, while M S rises by more than an order of magnitude. Analysis of crystallographic structure from Rietveld refinement of x-ray diffraction patterns shows significant rise in off-center displacements of Bi (d Bi ) and Fe (d Fe ) ions within a unit cell with the decrease in particle size. The net unit-cell polarization P S too, is found to be larger in nanoscale regime.

Large magnetoelectric coupling in nanoscaleBiFeO3from direct electrical measurements

“…Interestingly, the structural noncentrosymmetry ap- pears to have improved as the particle size is brought down from bulk to a scale of ∼30 nm -it increases from ∼1.48Åin bulk to ∼1.67Åin ∼100 nm particles to, finally, ∼1.73Åin particles of size ∼30 nm. This could result from enhanced lattice strain of the finer particles [8]. The strain has increased from 0.015% to 0.1% as the particle size reduces from bulk to nanoscale.…”

“…The nanoparticles of BiFeO 3 were prepared by sonochemical synthesis route [8] while the bulk sample was prepared by solid-state reaction process. The high resolution powder neutron diffraction patterns were recorded at the multi-position-sensitive detector based focusing crystal diffractometer set up by UGC-DAE-CSR Mumbai Centre at the National Facility for Neutron Beam Research (NFNBR), Dhruva Reactor, Mumbai and also at the D20 diffractometer of the Institute Laue-Langevin, Grenoble, France.…”

A training effect on electrical properties in nanoscale BiFeO3

“…The nanochains of BiFeO 3 system have been fabricated from solution chemistry route [13]. The chains have been patterned in a two-probe configuration with tungsten wires by focused ion beam (FIB) milling and deposition.…”

Spontaneous exchange bias in a nanocomposite of BiFeO3-Bi2Fe4O9

“…7 The volume fraction of the Bi 2 Fe 4 O 9 phase has been varied from <3% to $10%. The exchange bias is maximum for a composite of $6 vol.…”