Thermoelectric Composites on the Base of PbTe with Nanoiclusions of Colloidal Silver

Formation of thermocouples by pressing powder of thermoelectric material with micro- and nano- size range creates large internal borders for additional phonon scattering. However, it need not only reduce the thermal conductivity, but also increase the Seebeck coefficient to improve the thermoelectric properties of material. For this case, around thermoelectric grain PbTe of the size of (0.5-1.0) micrometers prompted to create nano-channels for the stream of an electric current. In this paper was development technology of the conductive nano-channels on the base of colloidal Silver. It was finding that the introduction of Ag nanoparticles (size 50 nm), not only reduces the thermal conductivity, but also increases the Seebeck coefficient after additional throttling of electrons on the barriers of Silver nanoparticles. Thermal conductivity of (0.06-0.2) W/(m·K) has been achieved in the case of the scattering of medium-wave phonons (MWP). The absolute value of Seebeck coefficient in these conditions increases up to 340 V/K

Thermoelectric Composites on the Base of PbTe with Nanoiclusions of Colloidal Silver

Formation of thermocouples by pressing powder of thermoelectric material with micro- and nano- size range creates large internal borders for additional phonon scattering. However, it need not only reduce the thermal conductivity, but also increase the Seebeck coefficient to improve the thermoelectric properties of material. For this case, around thermoelectric grain PbTe of the size of (0.5-1.0) micrometers prompted to create nano-channels for the stream of an electric current. In this paper was development technology of the conductive nano-channels on the base of colloidal Silver. It was finding that the introduction of Ag nanoparticles (size 50 nm), not only reduces the thermal conductivity, but also increases the Seebeck coefficient after additional throttling of electrons on the barriers of Silver nanoparticles. Thermal conductivity of (0.06-0.2) W/(m·K) has been achieved in the case of the scattering of medium-wave phonons (MWP). The absolute value of Seebeck coefficient in these conditions increases up to 340 V/K

Синтез і властивості високоефективних термоелектричних матеріалів на основі систем Pb-Ag-Sb-Te

The paper presents the results of research of X-ray diffraction and thermoelectric parameters (thermoelectric coefficient α, electrical conductivity σ and thermal conductivity coefficient k) of materials based on Lead Telluride: PbTe, PbTe:Sb, PbTe-Sb2Te3, Pb18Ag1Sb1Te20, Pb18Ag2Te20 and PbTe-Ag2Te. Established that the highest values of thermoelectric figure of merit have samples of PbTe:Sb (0,3 at.%) and system Pb18Ag1Sb1Te20, Pb18Ag2Te20. For PbTe:Sb is due to a significant increase of the electrical conductivity. For the other two materials is due to a increase the thermoelectric coefficient and a significant decrease of thermal conductivity compared to pure PbTe.У роботі представлено результати рентгенографічних досліджень та вимірювань термоелектричних параметрів (коефіцієнта термо-ЕРС α, питомої електропровідності σ та коефіцієнту теплопровідності k) матеріалів на основі плюмбум телуриду: PbTe, PbTe:Sb, PbTe-Sb2Te3, Pb18Ag1Sb1Te20, Pb18Ag2Te20 та PbTe-Ag2Te. Встановлено, що найбільш високими значеннями термоелектричної добротності володіють PbTe:Sb (0,3 ат.% Sb) та системи Pb18Ag1Sb1Te20 , Pb18Ag2Te20, що у першому випадку зумовлено значним ростом електропровідності матеріалу, а у двох інших – як збільшенням коефіцієнта термо-ЕРС, так і значним зниженням теплопровідності у порівнянні з бездомішковим PbTe

Thermodynamic Parameters of PbTe Crystals: DFT-Calculations

Based on the analysis of the crystal NaCl type and electronic structure of cubic phase CdS crystals the cluster models have been built for calculation of the geometric and thermodynamic parameters. According to density functional theory (DFT) and using the hybrid valence base set B3LYP the temperature dependence of the energy ΔE and the enthalpy ΔH of formation, Gibbs free energy ΔG, entropy ΔS, specific heat at constant volume CV and pressure CP of the crystals have been found. The analytical expressions of the temperature dependences of presented thermodynamic parameters which was approximated from the quantum- chemical calculations data and with using mathematical package Maple 14 have been received. Keywords: DFT, cluster models, the thermodynamic parameters, lead telluride.</blockquote