No abstract

Magnetoelectric (ME) composites that simultaneously exhibit ferroelectricity and ferromagnetism have recently gained significant attention as evident by the increasing number of publications. These research activities are direct results of the fact that multiferroic magnetoelectrics offer significant technological promise for multiple devices. Appropriate choice of phases with co-firing capability, magnetostriction and piezoelectric coefficient, such as Ni-PZT and NZFO-PZT, has resulted in fabrication of prototype components that promise transition. In this manuscript, we report the properties of Ni-PZT and NZFO-PZT composites in terms of ME voltage coefficients as a function of frequency and magnetic DC bias. In order to overcome the problem of toxicity of lead, we have conducted experiments with Pb-free piezoelectric compositions. Results are presented on the magnetoelectric performance of Ni-NKN, Ni-NBTBT and NZFO-NKN, NZFO-NBTBT systems illustrating their importance as an environmentally friendly alternative.

No abstract

Rapid developments in the area of micro-sensors for various applications such as structural health monitoring, bio-chemical sensors and pressure sensors have increased the demand for portable, low cost, high efficiency energy harvesting devices. In this paper, we describe the scheme for powering a pulse rate sensor with a vibration energy harvester integrated inside a pen commonly carried by humans in the pocket close to the heart. Electromagnetic energy harvesting was selected in order to achieve high power at lower frequencies. The prototype pen harvester was found to generate 3 mW at 5 Hz and 1 mW at 3.5 Hz operating under displacement amplitude of 16 mm (corresponding to an acceleration of approximately 1.14 grms at 5 Hz and 0.56 grms at 3.5 Hz, respectively). A comprehensive mathematical modelling and simulations were performed in order to optimize the performance of the vibration energy harvester. The integrated pen harvester prototype was found to generate continuous power of 0.46–0.66 mW under normal human actions such as jogging and jumping which is enough for a small scale pulse rate sensor.

In this study, we report results on magnetoelectric (ME) core-shell Pb(Zr,Ti)O3 (PZT)-NiFe2O4 (NF) particulate nanocomposites. NF particles forming the shell had size in range of 20–30 nm. The grain size of sintered nanocomposites was found to be in the range of 500–800 nm. The sintered nanocomposite exhibited piezoelectric coefficient (d33) of 60 pC/N, dielectric constant of 865, and ME coefficient of 195 mV/cm Oe. High ME coefficient was observed for wide range of dc bias magnetic field. This approach of fabricating layered composite has a promise to provide large ME coefficients in particulate sintered structures.