Electrical, Thermal, and Magnetic Characterization of Natural Tetrahedrites–Tennantites of Different Origin

Abstract

Naturally occurring sulfosalt minerals of the tetrahedrite-tennantite series ((Cu,Fe,Zn,Ag,Hg) 12 (Sb,As) 4 S 13 ) are studied because of their potential use as basic components in the manufacture of thermoelectric devices for moderatetemperature applications. In the work reported herein, the chemical, crystallographic, thermoelectric, and magnetic properties of four specimens from different ores from Europe and America were exhaustively characterized. Our study revealed that these natural tetrahedrites usually behave as low-tomoderately doped p-type semiconductors with low mobility. Their carrier charge transport is thus located at the edge between hopping and itinerant mechanisms. The magnetic study, probing the behavior of the constituent iron species, revealed that an insignificant part of the iron occurs as ferromagnetic impurities. The dominant iron species is Fe 2+ ions with antiferromagnetic interactions. The maximum value of ZT observed was 0.13 at 700 K; this value is impaired, primarily, by high electrical resistivity.

The influence of self-doping of stibnite ore with impurities on the preparation, heat capacity, magnetic and transport properties of tetrahedrite Cu12Sb4S13

“…The reported χ value for Cu 12 Sb 4 S 13 at low temperature (T < 25 K), was a bit larger than the value for Cu 12 Sb 4 S 13 reported in the literature [12] (0.0041 emu/mol), [30] (less than 0.001 emu/mol) and [18] at 2 K but was similar to χ values of natural tetrahedrite-tennantite (above 0.15 emu/mol) [15]. It might be attributed to Fe impurities.…”

“…For Cu 12 Sb 4 S 13 and Cu 11.9 Sb 4 S 13 , both C and θ are smaller, which is related to the valence of Fe ion ( Table 1). The influence of Fe content on χ and θ depends on the Fe valence (antiferromagnetic for Fe 2+ ions) in the natural tetrahedrites [15,31].…”

“…Natural tetrahedrite minerals are potential starting materials for the preparation of Cu 12 Sb 4 S 13 . However, the maximum ZT value of Cu 12 Sb 4 S 13 synthesized from four sulfosalt minerals of tetrahedrite-tennantite series was low (ZT value about 0.13 at 700 K) [15] due to tetrahedritetennantite electrical resistivity, which was far less than that of Cu 12 Sb 4 S 13 (ZT value about 1 at 700 K [4][5][6]16]). Single phase Cu 12 Sb 4 S 13 was obtained from natural minerals such as the "seed matrix" [4,16] which demonstrated a novel route for the preparation of Cu 12 Sb 4 S 13 [4,16].…”

Research Update: Cu–S based synthetic minerals as efficient thermoelectric materials at medium temperatures

“…13,[56][57][58] It should be noted that the natural minerals showed rather low ZT's due to excessive ρ. 13,59 For Cu 12−x Tr x Sb 4 S 13 , various synthesis techniques have been examined for large-scale TE application. 50,58,[60][61][62] The Te substituted system Cu 12 Sb 4−x Te x S 13 (0 ≤ x ≤ 1) has also been examined.…”

Tetrahedrites: Prospective Novel Thermoelectric Materials

“…Further investigations aiming at determining the inluence on the chemical composition of the mineral on the thermoelectric properties will be interesting to undertake. In this regard, a preliminary study carried out on minerals from various geographical origins has shown that all of them show semiconducting-like properties despite diferences in their chemical composition [51].…”