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Co/C multilayers were prepared using DC triode sputtering with different Co thicknesses (tCo), and their magnetic properties were investigated using a vibrating sample magnetometer. It is found that the magnetization of Co layers decreases with decreasing tCo, at thicknesses below 6 nm, which can be understood by the presence of a magnetically dead layer, due to intermixing between Co and C layers, i.e., the alloy formation around the former interface. A model based on the spin-wave theory was utilized to explain the change of the magnetization as function of temperature, and estimate the coupling exchange interaction. Ab initio calculations were utilized to explain the decrease of the magnetic moment within the interfacial layer (Co1-xCx). In addition, the influence of pressure on the magnetic properties of the Co1-xCx layer was studied as well.

Fe/C multilayers with different Fe thicknesses ( t Fe ) were prepared using triode sputtering with a fixed C layer thickness of 20 A, while the Fe film thickness was changed from 30 to 300 A. The magnetization strongly decreases with decreasing t Fe when t Fe was smaller than 60 A. This is attributed to the existence of a magnetically dead layer due to the presence of Fe 1 − x C x alloys at the Fe/C interface due to the diffusion of carbon in iron. First-principles calculations based on Density Functional Theory (DFT) were performed to investigate the magnetic and electronic structures of the interfacial Fe 1 − x C x alloys. It is shown that the C insertion reduces the magnetization, which becomes significant with increasing C content. In addition, the influence of pressure by changing volume on the magnetic properties was investigated as well, where the pressure reduces significantly the interfacial magnetization.

Magnetic and electronic properties of LiVOPO4 and VOPO4 cathodes have been studied using ab initio calculations, high temperature series expansions (HTSEs) calculations and Monte Carlo simulations (MCSs). Self-consistent ab initio calculations, based on Density Functional Theory approach (DFT) and using Full Potential Linear Augmented Plane Wave (FLAPW) method, were performed to investigate both electronic and magnetic properties of the LiVOPO4. Polarized spin and spin–orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent V plans. Magnetic moments considered to lie along (010) axes are computed. Average equilibrium voltage over a full cycle ([Formula: see text]) of the LiVOPO4, battery have been estimated. Computed magnetic moments are used as input for HTSEs to compute other magnetic parameters using the mean field theory, MCSs and HTSEs. The obtained results by HTSEs and MCSs are comparable with experiments results.

Recent trends in electromechanical conversion using alternative materials, have demonstrated the advantages of using piezoelectric composites for energy generation. There have been several papers on ceramic/polymer composites in which the fillers have high piezoelectric constant. Basically, the energy harvested depends on the proportion of the piezoelectric properties of composite. The fillers size within the composites is also an important criterion of the composites properties. Thus, in this paper 0–3 composites, made of lead zirconate titanate (PZT) ceramic powder and polyurethane (PU) were prepared. Different sizes of ceramic grains were used: grains with average size of 10 μm, size under 80 μm and size under 100 μm. Sizes of the PZT grains was determined according to the homogenization efficiency of the composite. Piezoelectric (piezoelectric coefficient d33) and dielectric properties (dielectric constant) were investigated. They have shown an interesting improvement with the increasing grains size up to 20 pC/N and 100, respectively. In order to understand the composite behavior on the microscopic scale, a simulation was carried out by mean of a finite element method (FEM) software. Finally, an estimation of the harvested voltage was modeled according to the grains size.