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The multiferroic magnetoelectric 2–2 laminated composite systems with BaTiO3 and NiFe2O4 as the ferroelectric and ferrimagnetic phases were successfully fabricated by co-firing technique. For this phase, pure BaTiO3 and NiFe2O4 were successfully synthesized by sol–gel and polyol method, respectively. The structural, microstructural, multiferroic and magnetoelectric coupling properties of phase pure and co-fired systems were investigated using X-ray diffraction, HR-TEM, SEM–EDX, P–E Loop, VSM and magnetoelectric coupling analysis. The multiferroic and magnetoelectric coupling properties of the laminated systems were compared with the mixed system having similar weight percentage of BaTiO3 and NiFe2O4. The fabricated composite systems show good multiferroic and magnetoelectric properties. Compared to mixed composite systems, the laminated structure has an enhanced magnetoelectric (ME) coupling of 6.42 mV/cm.Oe. This variation in ME coupling is attributed to the low leakage current effects in the laminated systems. The ME coupling in the laminates varies with the nature and number of layers. For laminated composite systems, the ME coupling coefficient is found to increase from 6.42 mV/cm.Oe to 10.48 mV/cm.Oe with increase in the number of layers. [ABSTRACT FROM AUTHOR]

Lead-free multiferroic magnetoelectric mixed and core shell composites of BaTiO3 and NiFe2O4 were synthesised by a two-step process. The structural, morphological, electrical, magnetic and dielectric properties of the as prepared samples were investigated in detail. XRD—Rietveld refinement (using JANA 2006 program) confirms the co-existence of two phases in the composite. The dielectric, ferroelectric and ferromagnetic properties of the systems was studied. The enhanced remanent polarization of core shell composite compared to pure BaTiO3 is the direct evidence of formation of core shell structure. The decrease in saturation values of composites can be attributed to the presence of nonmagnetic BaTiO3. The magnetoelectric coupling studies on BaTiO3@NiFe2O4 core–shell system exhibits enhancement due to the well-defined interface between the two phases. The sensitivity of electric properties to the applied magnetic field enables the systems for possible applications in magnetoelectric sensors. [ABSTRACT FROM AUTHOR]

Kinetics of magnetoelectric coupling in bismuth ferrite (BiFeO3) with the substitution of aliovalent calcium ion is investigated. The resulting structural, dielectric, magnetic, and magnetoelectric (ME) coupling properties are explained in terms of chemical pressure originating from the substituent ion. Substitution of calcium finds to reduce the oxygen vacancies. Two important substitution concentrations find to be critical in ferroelectric (FE) and ME coupling properties. At 10 at% calcium, highest remanent polarization is obtained and maximum ME coupling coefficient is observed at 20 at%, which suggests calcium concentration between 10% and 20% can be optimized to obtain good electrical and ME coupling properties of BiFeO3. Maximum ME coupling coefficient at calcium concentration 20 at% is close to numerical calculations reported in the literature. Magnetic properties are also favorably modified by the substitution; a coupled antiferromagnetic and weak ferromagnetic ordering is obtained. Also, a variation in blocking temperature and spin relaxation is observed with respect to the substituent ion concentration. [ABSTRACT FROM AUTHOR]

Fe–Ni based amorphous thin films were prepared by thermal evaporation. These films were irradiated by 108 MeV Ag8+ ions at room temperature with fluences ranging from 1×1012 to 3×1013 ions/cm2 using a 15 UD Pelletron accelerator. Glancing angle x-ray diffraction studies showed that the irradiated films retain their amorphous nature. The topographical evolution of the films under swift heavy ion (SHI) bombardment was probed using atomic force microscope and it was noticed that surface roughening was taking place with ion beam irradiation. Magnetic measurements using a vibrating sample magnetometer showed that the coercivity of the films increases with an increase in the ion fluence. The observed coercivity changes are correlated with topographical evolution of the films under SHI irradiation. The ability to modify the magnetic properties via SHI irradiation could be utilized for applications in thin film magnetism. [ABSTRACT FROM AUTHOR]

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The development of catalyst materials with significant potential and multifunctional applicability is essential for sustainable energy and environmental applications. The present work reports the preparation of nitrogen doped reduced graphene oxide supported Co 3 O 4 nanoparticles (NGCO) via a simple and cost effective one pot synthesis method, at a relatively low temperature. The prepared NGCO composites were employed for the first time as active bifunctional catalysts in the reduction of 4-nitrophenol (4NP) and NaBH 4 hydrolysis. The NGCO catalyst exhibited excellent catalytic activity and stability for the 4NP conversion with a mass normalized rate constant of 97.8 min−1g−1 at 303 K. The concentration (0.7 mM) and volume (20 mL) of the 4NP solution used in this study was higher than most of the works in the literature and that signifies the novelty of the prepared NGCO catalyst materials. The NGCO catalysts also showed potential activity and durability in liberating hydrogen from NaBH 4 , via hydrolysis, with a maximum specific hydrogen generation rate of 2090.6 mL min−1 g Co −1. The kinetics of the catalytic NaBH 4 hydrolysis reaction was investigated using zero order and first order kinetic models. The experimental data was well-described with the zero-order kinetic model. The improved catalytic activity of the NGCO composites relative to the unsupported Co 3 O 4 nanoparticles is due to the excellent dispersibility of the active sites and the synergetic action of both Co 3 O 4 and N doped graphene support in NGCO. [Display omitted] • Nitrogen doped graphene supported Co 3 O 4 (NGCO) composites were prepared through a simple one pot synthesis route. • The NGCO composites exhibited excellent catalytic activity in 4-Nitrophenol (4NP) reduction and NaBH 4 hydrolysis. • The introduction of nitrogen doped reduced graphene oxide support enhanced the catalytic performance of NGCO. • The NGCO catalysts displayed good stability and reusability in both 4NP reduction and NaBH 4 hydrolysis reactions. [ABSTRACT FROM AUTHOR]

Kinetics of magnetoelectric coupling in bismuth ferrite (BiFeO3) with the substitution of aliovalent calcium ion is investigated. The resulting structural, dielectric, magnetic, and magnetoelectric (ME) coupling properties are explained in terms of chemical pressure originating from the substituent ion. Substitution of calcium finds to reduce the oxygen vacancies. Two important substitution concentrations find to be critical in ferroelectric (FE) and ME coupling properties. At 10 at% calcium, highest remanent polarization is obtained and maximum ME coupling coefficient is observed at 20 at%, which suggests calcium concentration between 10% and 20% can be optimized to obtain good electrical and ME coupling properties of BiFeO3. Maximum ME coupling coefficient at calcium concentration 20 at% is close to numerical calculations reported in the literature. Magnetic properties are also favorably modified by the substitution; a coupled antiferromagnetic and weak ferromagnetic ordering is obtained. Also, a variation in blocking temperature and spin relaxation is observed with respect to the substituent ion concentration. [ABSTRACT FROM AUTHOR]