The Relationship between Natural Pyrite and Impurity Element Semiconductor Properties: A Case Study of Vein Pyrite from the Zaozigou Gold Deposit in China

Abstract

Pyrite is a common sulfide mineral in gold deposits, and its unique thermoelectricity has received extensive attention in the field of gold exploration. However, there is still a lack of detailed research and direct evidence about how impurity elements affect mineral semiconductor properties. In this paper, combined with first-principles calculations, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) mapping technology and in situ Seebeck coefficient scanning probe technology were used to study the law of changing semiconductor properties in pyrite containing impurity elements such as As, Co, Ni, and Cu. The results showed that pyrite containing arsenic is a P-type semiconductor, and pyrites containing Ni, Co, Cu, and other elements are N-type semiconductors. When P-type pyrites containing As were supplemented with Ni, Cu, and other elements, the semiconductor type changed to N-type. However, Co addition did not change the semiconductor type of arsenic-rich pyrite. Pyrite formed under different temperature conditions tended to be enriched with different combinations of impurity elements, leading to the relative accumulation of P-type or N-type pyrites.

Controlled p-Type Doping of Pyrite FeS2

“…While large enough to confirm diffusive transport, the relatively low hole mobility of ∼2 cm 2 V –1 s –1 , which is reasonably consistent with prior reports, − is worthy of comment. This is, in fact, ∼30 times smaller than the peak electron mobility in Figures c,f ,− , and far smaller than the maximum electron mobility reported at any T in pyrite .…”

“…In bulk crystals, p -doping is also on shaky ground. As, Sb, and P have been suggested to be p -dopants, ,− but the evidence is limited, scattered, and frequently contradictory, with controlled p -doping not established. In naturally occurring pyrite crystals, findings are widely variable, and most observations indicate n -type behavior, although occasional p -type behavior is reported, often associated with As or P impurities. − In synthetic crystals, deliberate doping with P and As has been performed in attempts to p -dope pyrite, but with widely varying outcomes. ,,,− Both n - and p -type behaviors are reported, typically based on Hall or Seebeck effect data alone. ,,,− In cases where both are measured, the signs of the two effects often do not agree on p -type majority carriers .…”

“…As, Sb, and P have been suggested to be p -dopants, ,− but the evidence is limited, scattered, and frequently contradictory, with controlled p -doping not established. In naturally occurring pyrite crystals, findings are widely variable, and most observations indicate n -type behavior, although occasional p -type behavior is reported, often associated with As or P impurities. − In synthetic crystals, deliberate doping with P and As has been performed in attempts to p -dope pyrite, but with widely varying outcomes. ,,,− Both n - and p -type behaviors are reported, typically based on Hall or Seebeck effect data alone. ,,,− In cases where both are measured, the signs of the two effects often do not agree on p -type majority carriers . Dopant concentrations are also often not quantified, , surface conduction is often not considered (meaning that any p -type behavior is difficult to associate with the pyrite bulk), − and the possibility of the typically low p -type mobilities − artificially inverting Hall and/or Seebeck effects , was not considered.…”

Iron Sulfide Phases: A Brief Review

“…Co addition did not change the semiconductor type of As-rich pyrite. It is interesting to mention that, pyrite formed under different temperature conditions are enriched with different combinations of impurity elements, leading to the relative accumulation of p-type or ntype pyrites [10].…”

“…The effects of environmental factors on marcasite oxidation, such as [dissolved oxygen], [Fe(III)] and [Fe(II)] or pH have been reported by a number of authors. Few investigations have focused on the dissolution kinetics of marcasite [10].…”