Piezoelectricity and Its Applications

The piezoelectric effect is extensively encountered in nature and many synthetic materials. Piezoelectric materials are capable of transforming mechanical strain and vibration energy into electrical energy. This property allows opportunities for implementing renewable and sustainable energy through power harvesting and self-sustained smart sensing in buildings. As the most common construction material, plain cement paste lacks satisfactory piezoelectricity and is not efficient at harvesting the electrical energy from the ambient vibrations of a building system. In recent years, many techniques have been proposed and applied to improve the piezoelectric capacity of cement-based composite, namely admixture incorporation and physical. The successful application of piezoelectric materials for sustainable building development not only relies on understanding the mechanism of the piezoelectric properties of various building components, but also the latest developments and implementations in the building industry. Therefore, this review systematically illustrates research efforts to develop new construction materials with high piezoelectricity and energy storage capacity. In addition, this article discusses the latest techniques for utilizing the piezoelectric materials in energy harvesters, sensors and actuators for various building systems. With advanced methods for improving the cementations piezoelectricity and applying the material piezoelectricity for different building functions, more renewable and sustainable building systems are anticipated

Densification, Grain Growth and Microstructure of Ni-Zn Ferrites

Ni0.65 Zn0.35 Fe2 O4, with high density and fine grain size, is a desirable composition for applications of high frequency switching power supplies. This composition has been studied under different sintering conditions. Observed changes in density, grain size and microstructure in these ferrites have been correlated to the volatilization of zinc from the samples at elevated sintering temperatures. Densification and grain growth are observed to be Arrhenius controlled rate processes with activation energies of 63.9 and 64.4 Kcal/mole respectively

Structural, electrical and electrochemical studies of copper substituted layered LiNi1/3Co1/3Mn1/3O2 cathode materials

The copper substituted in LiNi1/3Co1/3Mn1/3O2 cathode materials are synthesized by the solid state reaction method. Here, we are presenting the details of synthesized LiNi1/3Co(1/3-x)Mn1/3CuxO2 (0, 0.05, 0.1 and 0.15) as an alternative cathode material for lithium-ion batteries. The powder X-ray diffraction (XRD) is used for confirmation of phase formation. Morphology and topography of the materials are investigated through a scanning electron microscope (SEM). The chemical composition is identified by techniques of energy dispersive X-ray spectroscopy (EDS) that is integrated with SEM. The Fourier transform infrared spectroscopy (FT-IR) technique is used to characterize the stretching and bending vibrational modes of different functional groups exist in the materials. At low frequencies, the dispersion of real parts of dielectric constant is due to space charge polarization which is observed for all the temperatures. More over charge/discharge studies are carried out to study the performance of the synthesized cathode materials. Keywords: Layered structure, Lithium nickel manganese cobalt oxides, XRD, SEM, Impedance, Charge-discharg