Magnetic, dielectric and calorimetric studies on 0.9BiFeO 3 -0.1BaTiO 3 indicate strong magnetoelectric coupling. XRD studies reveal a very remarkable change in the rhombohedral distortion angle and a significant shift in the atomic positions at the magnetic Tc due to an isostructural phase transition. The calculated polarization using Rietveld refined atomic positions scales linearly with magnetization. Our results provide the first unambiguous evidence for magnetoelectric coupling of intrinsic multiferroic origin in a BiFeO 3 based system.

Uniform 6-13 nm sized 0D superparamagnetic Fe 3 O 4 nanocrystals were synthesized by an aqueous 'coprecipitation method' under a N 2 atmosphere as a function of temperature to understand the growth kinetics. The crystal phases, surface charge, size, morphology and magnetic characteristics of assynthesized nanocrystals were characterized by XRD, Raman spectroscopy, FTIR, TG-DTA, BET surface area, dynamic light scattering along with zeta potential, HR-TEM, EDAX, vibrating sample magnetometry and Mössbauer spectroscopy. TEM investigation revealed highly crystalline spherical magnetite particles in the 8.2-12.5 nm size range. The kinetically controlled as-grown nanoparticles were found to possess a preferential (311) orientation of the cubic phase, with a highest magnetic susceptibility of $57 emu g shows that the particles are ferromagnetic at room temperature with zero remanence and zero coercivity. This method produced highly crystalline and dispersed 0D magnetite nanocrystals suitable for biological applications in imaging and drug delivery.

Never before has electricity been generated out of metal oxides without using any light (UV/IR), acid, or alkali, but it has been achieved by adding a few drops of water on nanoporous metal oxide based Hydroelectric cell (HEC) at room temperature. Electricity generation has been validated and unified for six different metal oxides based on the principle of water dissociation at oxygen deficient nonporous pellet. The presence of oxygen vacancies on the surface of all metal oxide samples has been confirmed by Raman and Photoluminescence spectroscopy techniques. Tin oxide (SnO2) based HEC has delivered maximum power ∼16.6 mW in a 4.48 cm2 cell area with highest current 22.2 mA, approximately 2.075 times higher than reported 8 mA current in ferrite based HEC. Water chemidissociation at metal oxide surface was found to be reinforced predominantly by electronegativity of metal cations and oxygen vacancies on nanoporous surface. Divergent peak current values ranging from 22.2 to 1.1 mA were obtained depending on internal resistance, grain boundary nature, water molecule dissociation capability, and nanopores connectivity in different oxides. Slow diffusion of ions in certain metal oxides due to high impedance of grain boundaries has reduced current as confirmed by dielectric and impedance spectroscopy. Metal oxide HEC provides an ecofriendly, cost-effective, and portable green energy source with almost no running cost.

Fe-doped PbTiO 3 nanoparticles have been synthesized by chemical route using polyvinyl alcohol as a surfactant. The results indicate that the dielectric constant and magnetization value of these nanoparticles depends upon their size and Fe dopents. The x-ray diffraction analysis, and transmission and scanning electron microscopies show that the particle's sizes in the specimens lie in the range of 19-30 nm. It is observed that the magnetization is enhanced with reduction in particle size. The largest value of saturation magnetization ͑M s = 41.6ϫ 10 −3 emu/ g͒ is observed for 1.2 mol % Fe dopents. Dielectric constant and dielectric losses are controlled up to 15 MHz at room temperature.

No abstract