Finite‐Size Effects in Nanoscaled Multiferroics

Abstract

We present studies of single-phase multiferroic materials in nanoparticle or nanoplate form, where size effects modify the long range magnetic structure and hence influence the magnetic properties. Size effects as isolated here, are of particular relevance to understand the interplay between magnetic and ferroelectric properties in heterogeneous, multi-phase multiferroic structures. Bulk multiferroic BiMnC>3 shows ferromagnetic ordering below 105 K, but few characterization attempts have been performed on nanoscaled material. We have synthesized BiMnC>3 nanoplates and characterized the structure, composition, morphology and magnetic properties. Ferromagnetic behavior is not observed in the nanoplates, in contrast to the bulk, indicative of finite size effects. We have also synthesized BiFeCb nanoparticles (characterized by XRD, EDS and magnetometry), which exhibit ferromagnetism with spin-glass-like behavior, as a result of reduced dimensionality. Bulk perovskite BiFeCh instead shows antiferromagnetism. The difference in magnetic behavior for nanoparticles compared to bulk behavior, is, in both cases, attributable to finite-size effects.

Characterization of the BFO-BZN-based electroceramic composite for application as DRA

“…All peaks were in-line with the diffraction pattern ICSD PDF 84-0757. XRD pattern of BZNα sample showed the formation of the α-BZN (Bi 1.5 ZnNb 1.5 O 7 ) phase with space group Fd3m, α=β=γ=90°, a=b=c=10.557 Å, density of 7.044 g/cm 3 and unit cell volume of 1176.6 Å 3 , which conformed to the standard ICSD PDF 00-052-1770, and also the formation of a small amount of the phases BiNbO 4 (ICSD PDF 00-016-0295) and ZnO (ICSD PDF 00-003-0752) [8]. These remaining phases were precursor phases of α-BZN, according to the reaction indicated in Eq.…”

“…XRD pattern of BZNβ sample showed the formation of β-BZN (Bi 2 Zn 2/3 Nb 4/3 O 7 ) phase with the C2/c space group, α=γ=90.0°, β=101.256°, a=13.119 Å, b=7.671 Å, c=12.165 Å, density of 7.719 g/cm 3 , and volume of the unit cell of 1200.7 Å 3 , which were in accordance with the ICSD standard PDF 00-052-0141, and two remaining phases, Bi 5 Nb 3 O 15 (ICSD PDF 00-016-0293) and BiNbO 4 (ICSD PDF 01-071-1518), following the reaction path shown in Eq. E [8].…”

“…Ceramic composites are attractive for telecommunications because of the flexibility of features that can be obtained by the mixture of two or more phases, providing new materials with a wide range of properties (mechanical, magnetic, optical and dielectric properties) that can be controlled through phase composition to meet the desired specifications necessary for a particular application. There are several applications such as capacitors, substrates for encapsulation of electronic circuits, antennas, sensors, high voltage insulation, and fuel cells [3,4].…”