Synthesis and Characterization of Pb(Fe 1/2 Ta 1/2 )O 3
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Synthesis and Characterization of Pb(Fe1/2Ta1/2)O3 R. Martinez, R. Palai, and R.S. Katiyar Department of Physics, University of Puerto Rico, San Juan, 00931-3343, Puerto Rico ABSTRACT: We report synthesis, and characterization for structural, microstructural, dielectric, electrical, magnetic, and spectroscopic (Raman) properties of lead iron tantalate Pb(Fe1/2Ta1/2)O3. The dielectric properties of PFT showed a typical relaxor ferroelectric behavior with long-range disorder, while the magnetoelectric properties of Pb(Fe1/2Ta1/2)O3 showed an interesting multiferroic behavior (coexistence of the ferroelectric and magnetic orders) in the single-phase. Keywords: lead iron tantalate, relaxor ferroelectric, Raman spectroscopy, and multiferroic, magnetoelectric. INTRODUCTION Pb(Fe1/2Ta1/2)O3 (PFT) is a compound of the family of Pb-based complex perovskites with the general formula AB’xB”1-xO3. It was first prepared as a ceramic by Smolenskii et al. [1] in 1959. PFT has a partially ordered perovskite structure with relaxor ferroelectric behaviour and a broad ferroelectric phase transition [2]. PFT is one of the first perovskites in which magnetic Fe3+ (3d5, S= 5/2) and a nonmagnetic Ta5+ (3d0, S= 0) ions share the B site of the simple perovskite structure and the compound shows simultaneous magnetic and electric orders in the same phase, which is very rare. The physics of such materials is strongly influenced by the underlying chemical distribution of B cations in the octahedral sublattice of the perovskite structure and in this compound both the Fe3+ and Ta5+ cations are randomly distributed on octahedral sites. PFT possesses a cubic crystal structure (a = 4Å) with space group Pm 3 m at room- temperature (RT) [3]. The excellent dielectric, ferroelectric, and electrostrictive properties of this compound is attracting more attention and a significant amount of work [2-7] has been carried out on the preparation and characterization of this material for device applications using different techniques, such as sol-gel and solid state processing [4-5]. Nevertheless, the sol-gel technique was not very successful to avoid the nucleation of pyrochlore phase [2-7]. In the present work, we report the dielectric, electrical, magnetic, and Raman spectroscopic studies of PFT compound synthesized by using solid-state reaction technique. −
EXPERIMENTAL DETAILS Polycrystalline samples of Pb(Fe1/5Ta1/2)O3 were prepared using high purity PbO, Fe2O3, and Ta2O5 as starting materials. The powders of materials were mixed in the stoichiometric ratio, together with 10 wt. % excess of PbO to compensate Pb deficiency during processing at high temperature, followed by high-energy ball-milling, using tungsten balls in methanol medium for 16 h. The mixture was dried in the oven to 50 oC. After powders were ground again in a mortar for several minutes, to break up some agglomerates and calcined in air the powders to 950 oC in covered crucibles with intermediate grinding and ball-milling for 5h, and finally, pressed into pellets of 7.25 mm di
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