Thermoelectric Properties of Cu-Doped Bi2Te2.7Se0.3 Fabricated by Hot Pressing.

Owing to the energy and environmental issues, energy recovery technologies attract an increasing interest. Thermoelectric power generation is a recycling technology, which directly converts heat energy into electric energy by reusing waste heat. In this study, n-type Bi2Te2.7Se0.3 thermoelectric materials doped with Cu were fabricated by hot pressing. The Bi-Te system has excellent thermoelectric properties in the middle- and low-temperature ranges; when a certain amount of Cu dopant is added, the thermoelectric properties are improved. The thermoelectric properties of the samples doped with Cu were compared with those of the intrinsic Bi-Te-based sample without Cu doping. In addition, the effects of the Cu concentration on the thermoelectric-material structures were investigated.

Intermetallic Growth Mechanism and Mechanical Properties of Post-Annealed SAC305 Solder Joints on Cu-Based Electrode Interfaces.

Intrinsic Cu- and Ni-added Cu electrodes were prepared to study Sn-3Ag-0.5Cu lead-free solder joints. Our work focused on three categories: (1) formation and role of intermetallic compounds, (2) structural and compositional change of intermetallic compounds due to thermal aging effects, and (3) mechanical bonding strength of solder joints. A series of SEM, EDX, and bonding test analyses were performed on two electrode types to study joint morphologies, the types of intermetallic compounds formed, and bonding strengths, respectively. As a result, after heat treatments at 150 °C for 10 h, 100 h, and 300 h, Cu6Sn5 and (Ni, Cu)3Sn4 were obtained at the interfaces of the intrinsic Cu electrode and the Ni-added Cu electrode, respectively. In the Ni-added Cu electrode samples, the growth rate of the intermetallic compounds was reduced, but the mechanical bonding strength had a higher value compared to that of the intrinsic Cu electrode. The bonding characteristics under different heat treatment conditions are also discussed.

Influence of the Sintering Temperature of Al-Doped Higher Manganese Silicide for Improved Thermoelectric Properties.

Higher manganese silicide is generally used in thermoelectric devices between 700 K and 900 K. MnSi1.73Al0.005 samples were fabricated by two continuous solid-state reactions followed by hot pressing because the electrical conductivity of all the samples is strongly dependent on Al doping, showing superior thermoelectric performance to the as-synthesized higher manganese silicide. The solid-state-reaction was performed at 1173 K for 6 hours. The effects of the sintering temperature were examined by sintering at three different temperatures: 1273 K, 1323 K and 1373 K. For the surface, microstructural, and electrical properties, scanning electron microscopy, X-ray diffraction, and a series of electric conductivity, Seebeck coefficient, and thermal conductivity analyses were conducted, respectively. As a result, the optimal process temperature for Al-doped higher manganese silicide using a hot-press technique was determined.