Thermoelectric SnS and SnS-SnSe solid solutions prepared by mechanical alloying and spark plasma sintering: Anisotropic thermoelectric properties

Abstract

P–type SnS compound and SnS1−xSex solid solutions were prepared by mechanical alloying followed by spark plasma sintering (SPS) and their thermoelectric properties were then studied in different compositions (x = 0.0, 0.2, 0.5, 0.8) along the directions parallel (//) and perpendicular (⊥) to the SPS–pressurizing direction in the temperature range 323–823 Κ. SnS compound and SnS1−xSex solid solutions exhibited anisotropic thermoelectric performance and showed higher power factor and thermal conductivity along the direction ⊥ than the // one. The thermal conductivity decreased with increasing contents of Se and fell to 0.36 W m−1 K−1 at 823 K for the composition SnS0.5Se0.5. With increasing selenium content (x) the formation of solid solutions substantially improved the electrical conductivity due to the increased carrier concentration. Hence, the optimized power factor and reduced thermal conductivity resulted in a maximum ZT value of 0.64 at 823 K for SnS0.2Se0.8 along the parallel direction.

Hydrothermal transformation of SnSe crystal to Se nanorods in oxalic acid solution and the outstanding thermoelectric power factor of Se/SnSe composite

“…Figure 2b shows the XRD patterns of the SnSe powders before (pristine SnSe) and after the reaction (Se/SnSe). Pristine SnSe powder shows diffraction patterns typical of the orthorhombic Pnma crystal structure (JCPDS #48-1224) with no additional XRD peak 21 – 23 , indicating the existence of pure phase of SnSe. In contrast, the sample collected after the reaction exhibits a second pattern of XRD peaks in addition to the primary diffraction pattern of Pnma crystal, originating from the pristine Se (shown in Fig.…”

Revealing anisotropy and thickness dependence of Raman spectra for SnS flakes

“…Its large absorption coefficient ($10 5 cm À1 ), 9,10 as well as the predicted high carrier mobility, 7 renders it a great of potential applications in optoelectronic and electronic devices. 2,4,[11][12][13][14][15][16][17][18] Moreover, similar to the black phosphorous (BP) with puckered honey-comb crystal structure, SnS also possesses anisotropic electronic, 19,20 thermoelectric, [21][22][23] piezoelectric 24 and optical 25,26 properties. Given the strongly anisotropic properties of SnS, the SnS-SnS x Se 1Àx core-shell heterostructure with anisotropic photoresponse and the SnS-based photodetector with highly anisotropic performance of near-infrared have been achieved.…”

Lattice dynamics of Pnma Sn(S1–xSex) solid solutions: energetics, phonon spectra and thermal transport

“…There has therefore been significant effort devoted to alternative systems including the more earth-abundant SnS [2] and metal oxides [7][8][9][10].Alloying is commonly used as a means to enhance thermoelectric performance, as a suitable choice of components can maintain or improve a favourable electronic structure while reducing k latt by introducing variation in atomic masses and chemical bond strength to promote stronger phonon scattering [11]. Pb(S, Se, Te), Sn(S, Se) and (Bi, Sb) 2 (Se, Te) 3 alloys have all been studied as thermoelectrics and the alloying shown to improve ZT [12][13][14][15][16][17]. Due to the record-breaking high-temperature ZT of SnS, the Te-free Sn(S, Se) alloys are of particular interest, and experimental studies have demonstrated a reduction in the thermal conductivity of mixed compositions [12,14].Thermoelectricity is unique in that all four of the terms in the figure of merit ZT are amenable to calculation using first-principles electronic-structure methods such as density-functional theory (DFT) [18].…”

“…Alloying is commonly used as a means to enhance thermoelectric performance, as a suitable choice of components can maintain or improve a favourable electronic structure while reducing k latt by introducing variation in atomic masses and chemical bond strength to promote stronger phonon scattering [11]. Pb(S, Se, Te), Sn(S, Se) and (Bi, Sb) 2 (Se, Te) 3 alloys have all been studied as thermoelectrics and the alloying shown to improve ZT [12][13][14][15][16][17]. Due to the record-breaking high-temperature ZT of SnS, the Te-free Sn(S, Se) alloys are of particular interest, and experimental studies have demonstrated a reduction in the thermal conductivity of mixed compositions [12,14].…”