Thermal stability and electrical transport properties of Ge/Sn-codoped single crystalline β -Zn ₄ Sb ₃ prepared by the Sn-flux method

Abstract

This study prepares a group of single crystalline β -Zn 4 Sb 3 with Ge and Sn codoped by the Sn-flux method according to the nominal stoichiometric ratios of Zn 4.4 Sb 3 Ge x Sn 3 (x = 0-0.15). The prepared samples possess a metallic luster surface with perfect appearance and large crystal sizes. The microscopic cracks or defects are invisible in the samples from the back-scattered electron image. Except for the heavily Ge-doped sample of x = 0.15, all the samples are single phase with space group R 3c. The thermal analysis results show that the samples doped with Ge exhibit an excellent thermal stability. Compared with the polycrystalline Ge-substituted β -Zn 4 Sb 3 , the present single crystals have higher carrier mobility, and hence the electrical conductivity is improved, which reaches 7.48×10 4 S•m −1 at room temperature for the x = 0.1 sample. The change of Ge and Sn contents does not improve the Seebeck coefficient significantly. Benefiting from the increased electrical conductivity, the sample with x = 0.075 gets the highest power factor of 1.45×10 −3 W•m −1 •K −2 at 543 K.

Advances in thermoelectric (GeTe) x (AgSbTe2)100 – x

“…This can be effectively realized by introducing various defects, such as zero-dimensional point defects, [1][2][3][4][5][6] one-dimensional dislocations [7,8] and twodimensional interfaces, [9][10][11][12] for effectively scattering phonons and thereby reducing κ L . Moreover, the features of complex crystal structure, [13,14] liquid-like ions, [15] low sound velocity, [16] and strong lattice anharmonicity [17,18] have been demonstrated to accompany with an intrinsic low κ L , which are utilized as guiding principles for exploring novel thermoelectric materials with a superior zT .…”

Thermal stability and thermoelectric properties of Cd-doped nano-layered Cu2Se prepared using NaCl flux method*

“…[3] Excellent thermoelectric materials should have high Seebeck coefficient and low conductivity and thermal conductivity. [4] Two conventional methods are used to optimize the ZT value of materials. One method is to optimize the energy band structure of materials through doping, which effectively controls the carrier mobility, carrier concentration, and effective mass of state density and then optimizes the electrical transmission characteristics of materials.…”