Correlation between structural, magnetic and ferroelectric properties of Fe-doped (Ba-Ca)TiO3 lead-free piezoelectric

Abstract

The effect of iron (Fe) doping modification on the structure and properties of Ba 0.92 Ca 0.08 TiO 3 (BCT8) lead-free ferroelectrics is investigated in detail. Intrinsic BaTiO 3 (BT) and Ba 0.92 Ca 0.08 TiO 3 (BCT8) lead-free polycrystalline ceramics were synthesized by conventional solid-state chemical reaction method. The crystal structure, morphology, chemical composition and valence state, magnetic and ferroelectric properties of BCT8 ceramics were evaluated as a function of variable Fe-content (0-5 wt%). X-ray diffraction measurements coupled with Rietveld refinement analyses indicate that the BT, BCT8, and Fe-BCT8 ceramics crystallize in single phase tetragonal structure. Phase transformation occurs with higher Fe doping; Fe-BCT8 ceramics with 5 wt.% Fe exhibits fully transformed orthorhombic structure. The crystal structure and phase formation of these ceramics was further confirmed by the Raman spectroscopic (RS) measurements. The RS data coupled with high-resolution X-ray photoelectron spectroscopic (XPS) analyses also confirm the formation of single phase materials without any presence of secondary or impurity phases. Microstructure imaging analyses indicate that the grain size was ~ 1 μm, while agglomeration and inhomogeneous distribution were observed with Fe doping. Polarization-electric field (P-E) hysteresis and strainelectric field (S-E) hysteresis measurements revealed the ferroelectric and piezoelectric nature of the ceramics. Ferroelectric and piezoelectric properties were observed to be suppressed for Fe doped BCT8 ceramics due to the partial replacement of Ti 4+ by Fe 3+ as confirmed by the chemical analyses made using XPS. Temperature dependent dielectric measurements for Fe doped BCT8 show a drastic decrease in ferroelectric Curie temperature (T c), along with a decrease in dielectric constant compared to that of undoped BCT8. Magnetization (M-H) measurements confirm the presence of long-range magnetic ordering for 5% Fe-doped BCT8 3 sample. The results demonstrate that addition of 5% Fe in lead-free BCT8 perovskite induces the magnetic ordering and a switchable ferroelectric state, which evidences the presence of multiferroic nature that can be used for four-bit memory and switching applications.

Fe and Co-doped (Ba, Ca)TiO3 Perovskite as Potential Electrocatalysts for Glutamate Sensing

“…An observation related to agglomeration in Fe-doped (Ba,Ca)TiO3 powders was reported. According to Keswani et al and Medeiros et al, an increase in agglomeration was attributed to highly reactive nature of Fe ions [27][28]. Size uniformity with narrower particle size distribution were also observed in Fe and Co-doped BaTiO3 and CaTiO3 powders, as shown in Fig.…”

Strong electro-optically active Ni-substituted Pb(Zr0.35Ti0.65)O3 thin films: toward integrated active and durable photonic devices

“…Similar magnetic coupling behaviours were reported in Fe-doped PZT and PbTiO 3 nanocrystals. 56,57 There are several mechanisms that can explain the origin of ferromagnetism in magnetic metal-doped PZT thin films. Firstly, the secondary phase formation such as the magnetoplumbite phase is attributed to the presence of magnetism.…”

Impact of transition metal oxidation state on the multiferroic properties and magnetoelectric coupling strength of BST ceramics

“…In the case of BSTF3 sample, the XPS data had shown the presence of both Fe 2+ and Fe 3+ states. The pronounced M-H loop in the case of BSTF3 sample can be due to the presence of multivalent Fe states (Fe 2+ /Fe 3+ ) which result in stronger double-exchange interaction [4,15,30]. The interaction is a consequence of electron hopping between the two Fe atoms in different oxidation states (2+ and 3+).…”

“…Owing to its high performance and utility for various applications, it is one of the most preferred lead-free ferroelectric materials. Attempts have been made to further improve its performance and applicability as a multiferroic by making its solid solutions with many transition metals and rareearth oxides [3][4][5][6][7][8][9][10]. The word multiferroic refers to the simultaneous existence of multiple ferroic orders (like ferroelectricity and anti/ferromagnetism) in the same material.…”