V. R. Palkar

Ferroelectricity in a pure BiFeO3 ceramic

The difficulties in synthesizing phase pure BiFeO3 are well known. In this letter we are reporting the optimized synthesis conditions for obtaining phase pure BiFeO3 ceramic. The oxide mixing technique followed by leaching with dilute nitric acid has been used for the synthesis. X-ray diffraction pattern indicated that the sample is phase pure. Scanning electron microscopy along with energy dispersive x-ray fluorescence analysis confirmed the chemical homogeneity of the sample. No segregation of the impurity phase in the matrix was detected. Moreover, Bi/Fe atomic ratio is observed to be ∼1. The ferroelectric transition of the sample at 836 °C has been detected by differential thermal analysis.

Observation of saturated polarization and dielectric anomaly in magnetoelectric BiFeO3 thin films

We report here synthesis of phase-pure magnetoelectric BiFeO3 thin films with controlled oxygen stoichiometry on Pt/TiO2/SiO2/Si substrate using pulsed-laser deposition technique. Saturated ferroelectric hysteresis loop has been observed in phase-pure and highly resistive BiFeO3 thin films. The dielectric response study of the films with temperature indicates an anomaly in dielectric constant e(T), in the vicinity of Neel temperature (∼380 °C). This anomaly in e(T) is explained as an influence of vanishing magnetic ordering on electric ordering of magnetoelectric BiFeO3 sample.

Observation of magnetoelectric behavior at room temperature in Pb(FexTi1-x)O3

Abstract The co-existence of ferroelectric and ferromagnetic properties at room temperature is very rarely observed. We have been successful in converting ferroelectric PbTiO3 into a magnetoelectric material by partly substituting Fe at the Ti site. The Pb(FexTi1−x)O3 system exhibits ferroelectric and ferromagnetic ordering at room temperature. Even more remarkably, our results demonstrate a coupling between the two order parameters. Hence it could be a futuristic material to provide cost effective and simple path for designing novel electromagnetic devices.

Effect of Mn substitution on magnetoelectric properties of bismuth ferrite system

The effect of Mn substitution on ferroelectric and antiferromagnetic properties of the Bi0.9La0.1Fe1−xMnxO3 system has been studied. It is seen that, with the increase in Mn content, there is a contraction in unit cell volume. Since the cell volume contraction is isotropic, lattice distortion (c/a) remains the same and so is the ferroelectric transition temperature TC. Further, it is observed that the presence of Mn does not affect the loss tangent (tan δ) of the samples. On the contrary, with increase in Mn content, a small but linear enhancement in the magnetization is observed.

High quality zinc oxide films by pulsed laser ablation

Abstract We have investigated the structural, electrical and optical properties of thin films of zinc oxide deposited by laser ablation. We find that even at room temperature the films are c-axis oriented on both crystalline and amorphous substrates. The electrical dc resistivity is independent of substrate temperature and is about 2–3 mΩ cm−1. The films have low absorption coefficient in the visible part of the spectrum and represent some of the best ZnO films deposited at low temperature.

Observation of room-temperature magnetoelectric coupling in pulsed-laser-deposited Bi0.6Tb0.3La0.1FeO3 thin films

Magnetoelectrics, characterized by simultaneous ferroelectric and magnetic ordering, have potential applications in information storage, sensors, etc. However, there are very few materials exhibiting the coexistence of ferroelectric and ferromagnetic ordering at room temperature. Hence, in normal practice, desired magnetoelectric effect is achieved by growing heterostructures of ferroelectric and magnetic materials. Realization of heterostructures with desired properties is not only difficult but also involves complicated lengthy procedures. BiFeO3 is weakly ferroelectric and antiferromagnetic at and above room temperature. We have been successful in enhancing both the ferroelectric and the magnetic properties of BiFeO3 by partial substitution of Tb at Bi site. Thin films of Bi0.6Tb0.3La0.1FeO3, integrated on Si/SiO2/TiO2/Pt substrate by using pulsed laser deposition technique, show good ferroelectric and magnetic properties and also coupling between them. Single step growth of thin films with desired mag...

Scanning probe imaging of coexistent ferromagnetism and ferroelectricity at room temperature

Room temperature coexistence of ferromagnetism and ferroelectricity in a thin film of nominal composition PbTi0.5Fe0.5O3−δ is probed by standard ferroelectric and ferromagnetic hysteresis loop measurements and by scanning probe microscopy. Both magnetic domains and ferroelectric domains are observed in the same spatial region of the material, implying phase coexistence in this system. Sample morphology strongly affects the roughness of the domain walls for both order parameters.

Dielectric properties of oriented thin films of PbZrO3 on Si produced by pulsed laser ablation

PbZrO3 is an antiferroelectric perovskite with TC≈230 °C. We have deposited single phase, perfectly c-axis oriented thin films of PbZrO3 on Si(100) substrates by pulsed laser ablation at 700 °C. The growth conditions (substrate temperature, ambient oxygen pressure, and laser energy density) have been optimized and the morphology of the films studied by scanning electron microscopy and atomic force microscopy. From a study of the dielectric hysteresis of the films and a measurement of the temperature dependence of their capacitance, we find that films thicker than ≈300 nm are antiferroelectric, while thinner films (<300 nm) appear to exhibit ferroelectric behavior.

c‐axis oriented ferroelectric thin films of PbTiO3 on Si by pulsed laser ablation

We have deposited single phase c‐axis oriented ferroelectric thin films of PbTiO3 on Si(100) by pulsed laser ablation technique in situ. It has been shown that the formation of a nonferroelectric, Pb2Ti2O6 pyrochlore phase at the interface could be avoided by raising the substrate temperature.

Ferroelectric thin films of PbTiO3 on silicon

The advantages offered by ferroelectric films deposited directly onto silicon in memory applications, field effect devices and pyroelectric detectors have stimulated intense research activity. This review covers work carried out during the last several years on their growth, characterization and device fabrication using ferroelectric thin films of on single-crystalline Si substrate with and without buffer layers.