Lead palladium titanate: A room-temperature multiferroic

Abstract

There have been a large number of papers on bismuth ferrite (BiFeO 3 ) over the past few years, trying to exploit its room-temperature magnetoelectric multiferroic properties.Although these are attractive, BiFeO 3 is not the ideal multiferroic, due to weak magnetization and the difficulty in limiting leakage currents. Thus there is an ongoing search for alternatives, including such materials as gallium ferrite (GaFeO 3 ). In the present work we report a comprehensive study of the perovskite PbTi 1-x Pd x O 3 with 0 < x < 0.3. Our study includes dielectric, impedance and magnetization measurements, conductivity analysis and study of crystallographic phases present in the samples with special attention paid to minor phases, identified as PdO, PbPdO 2 , and Pd 3 Pb. The work is remarkable in two ways: Pd is difficult to substitute into ABO 3 perovskite oxides (where it might be useful for catalysis), and Pd is magnetic under only unusual conditions (under strain or internal electric fields).The new material, as a PZT derivative, is expected to have much stronger piezoelectric properties than BiFeO 3 .

Lead palladium zirconate titanate: A room temperature nanoscale multiferroic thin film

“…At room temperature, dielectric constant, and loss tangent values were found to be ~1780, and ~0.52, respectively, measured at the frequency of 1 kHz. The dielectric constant, ɛ, was found to be larger than those reported for ceramics samples PZTPd (ɛ ~300) 16 , and PbPdT (ɛ ~500) 17 . One can notice that a moderate decrease in dielectric constant and a nearly constant loss tangent values up to as high as frequency of 10 5 Hz.…”

“…Remarkably, density functional theory (DFT) calculations support ferromagnetism arising from Pd cation substitution in PZT. 16,17 The results of these calculations revealed that isoelectric cationic substitution, such as Pd 4+ on B-site cations and/or Pd 2+ on Asite (Pb 2+ cation) do not produce magnetism. However, anisoelectric Pd 4+ substitution at A-site (Pb 2+ cation) establishes magnetism in the ferroelectric PZT matrix.…”

“…The polarization maximum P max and the remanent polarization P r were found to increase with increasing electric field up to 1200 kV/cm and are likely to reach a saturation at larger electric field. Other possibility for non-saturation of P-E loops is that the lossy ferroelectric behavior of thin films originating from oxygen vacancies and other involved ionic conduction processes 17 . Several Pd-based perovskites have shown larger conductivity due to Pd cation effects 17,28,29 .…”

“…Other possibility for non-saturation of P-E loops is that the lossy ferroelectric behavior of thin films originating from oxygen vacancies and other involved ionic conduction processes 17 . Several Pd-based perovskites have shown larger conductivity due to Pd cation effects 17,28,29 . In fact, our studies on the leakage current behavior in these thin film capacitors (I-V curve) support significant conductivity with bias voltage (shown below).…”

Magnetic and electronic properties of the ferroelectric-photovoltaic ordered double perovskiteCaMnTi2O6investigated by x-ray absorption spectroscopies

“…On the other hand, the strikingly low entropy value found in the PM phase of CMTO would support the presence of short-range magnetic order that could see its correlation length enhanced under particular external conditions. Further efforts to overcome the limitations currently found in the production of CMTO may open the door to explore chemical substitutions or mechanical strain with the aim of modifying the optical gap or enhancing the FM correlations, as recently seen in other promising titanates [38].…”