We have reported the structural, thermal, microscopic, magnetization, polarization, and dielectric properties of BiFeO 3 ceramics synthesized by a rapid liquid-phase sintering technique. Optimum conditions for the synthesis of single-phase BiFeO 3 ceramics were obtained. Temperature-dependent magnetization and hysteresis loops indicate antiferromagnetic behavior in BiFeO 3 at room temperature. Although saturated ferroelectric hysteresis loops were observed in single-phase BiFeO 3 ceramic synthesized at 880°C, the reduced polarization is found to be due to the high loss and low dielectric permittivity of the ceramic, which is caused by higher leakage current.

Chemical and structural heterogeneity and the resulting interaction of coexisting phases can lead to extraordinary behaviours in oxides, as observed in piezoelectric materials at morphotropic phase boundaries and relaxor ferroelectrics. However, such phenomena are rare in metallic alloys. Here we show that, by tuning the presence of structural heterogeneity in textured Co 1 − x Fe x thin films, effective magnetostriction λ eff as large as 260 p.p.m. can be achieved at lowsaturation field of ~10 mT. Assuming λ 100 is the dominant component, this number translates to an upper limit of magnetostriction of λ 100 ≈ 5λ eff > 1,000 p.p.m. microstructural analyses of Co 1 − x Fe x films indicate that maximal magnetostriction occurs at compositions near the (fcc + bcc)/bcc phase boundary and originates from precipitation of an equilibrium Co-rich fcc phase embedded in a Fe-rich bcc matrix. The results indicate that the recently proposed heterogeneous magnetostriction mechanism can be used to guide exploration of compounds with unusual magnetoelastic properties.

ac magnetic field sensors based on thin-film magnetoelectric ͑ME͒ devices operating at room temperature have been fabricated. The ME layers consist of a sol-gel derived Pb͑Zr 0.52 Ti 0.48 ͒O 3 film and a sputter deposited Fe 0.7 Ga 0.3 film on Si cantilevers. The ME coupling is substantially improved by depositing a Pt layer at the interface. The ME coefficient up to 1.81 V / Oe cm is obtained at the mechanical resonant frequency of 333 Hz and at dc bias magnetic field of 90 Oe. Clear reduction in the substrate clamping effect is observed as the Si cantilever thickness is systematically reduced down to 35 m.

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A large increase of diagonal piezo-optic coefficient (up to 3.7×10−13m2∕N at λ=633nm) was observed in Er doped ZnO films under photoinduced treatment by two laser beams with frequencies of 1,060 and 530nm originating from the same Nd:YAG pulsed laser. It was demonstrated that piezo-optic effect is enhanced with increasing film thickness. This may be a consequence of the disturbance of the long range ordering in the nanocrystallites for the film with larger film thickness. The observed effect is explained due to Er ions creating additional local polarizability.