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Thermoelectric materials may be used in devices as thermoelectric "air conditioner" in a smart house for improved energy efficiency. Energy harvesting uses ambient energy to generate electricity. It provides potentially low-cost, maintenance-free, long-life equipment by reducing the need for batteries or power chords. Energy harvesting (EH) is also known as power harvesting or energy scavenging. EH is considered to give benefits related to environmental friendliness, safety, security, convenience and affordability. EH can be used for brand enhancing. Technically, it can be used to make new things possible depending on visionary engineering. The variety of thermoelectric (TE) materials that can be used in energy harvesting is quite large, and the optimal material for a given application depends mainly on the temperature range in which the material is to be used. In this work we study the development and characterization of thermoelectric materials which were prepared by two different method, which were: a) ball-milling followed by sintering and b) ball-milling, microwave synthesis, high energy planetary ball milling, and sintering. Finally, we study the thermoelectric properties, calculate the band gaps and the ZT for the thermoelectric materials.

Hydrogen is a promising alternative fuel since it can be used pollution-free and can readily be produced from renewable energy resources, eliminating the production of greenhouse gases. Its storage is a great subject of intensive research for many years. Metal hydrides have the potential for reversible on-board hydrogen storage and release at low temperatures and pressures. In this work materials with nominal composition Zr 1-x Ti x Cr 2y-z V y Ni z were investigated. The samples were prepared by arcmelting under Ar-atmosphere from pure metals. The structure and microstructure of the alloys were examined by X-ray diffraction analysis and high resolution scanning electron microscopy (HR-SEM), respectively. Morphology and quantitative measurement were made using the energy dispersive X-ray. A two phase system of hexagonal Laves MgZn 2 (C14)-and MgCu 2 (C15)type of structure has been found for all samples. Increasing the V concentration in the stoichiometry leeds to development of a dentritic-type of microstructure. P-C-T curves were obtained after crucial activation procedure. The alloys were found to be more active under hydrogen while the desorbed amount of hydrogen has been measured in the temperature range of (20 to 30)°C by using a Sieverts'-type apparatus.

In this work we report on opportunities for a colossal reduction in lattice thermal conductivity (LTC) of graded micro-nanoporous structures with inhomogeneous porosity which leads to the considerable improvement in thermoelectric figure of merit ZT. We employ the effective medium theory to calculate the LTC of a porous media with hole pores of variable radius and show that porous materials with inhomogeneous porosity are expected to have stronger reduction (about 30 times!) in thermal conductivity than those with pores of equal sizes. Such a reduction is caused by enhanced scattering of thermal phonons with the pore boundaries. We have studied the variations of the LTC as a function of porosity, pore sizes, geometry and the number of pore groups with different sizes. Our theoretical results show excellent agreement with experimental data.