The Study Of Structural Characteristic And Its Variation Of Fe-S Series Minerals

Fe-S series minerals are important metal sulfide minerals which abound in polymetallic deposits. The different structures reflect the nature of the crystal and provide a scientific basis for further study of the physical and chemical environment of crystal growth. Fe-S series minerals include pyrite (FeS2), marcasite (FeS2), greigite phase (Fe3S4), pyrrhotite phase (Fe1-xS, x= 0 to 0.223), troilite (FeS) and so on. Pyrite is cubic with the common morphology of cube, pentagonal dodecahedron, octahedron and their shaped poly. Commonly, the pyrrhotite structures are hexagonal; monoclinic; a small amount of orthorhombic and complex super-structures.To determine the structural characteristics of the Fe-S series minerals from different conditions, we integratly use the XRD; TEM; EBSD; Raman and other modern means to analyse the morphology; composition, structural characteristics of natural and synthetic Fe-S series minerals. Then we explore the photovoltaic performance of the samples by using UV-Vis spectrophotometer, analysis the impact of structure on performance.Using modern test technologies, this thesis systematically observe the morphology and composition characteristics of Fe-S series minerals. Then, we utilize the XRD; TEM; EBSD; Raman to determine the structure of the sample; take a comparatively analysis of the structure parameters; use UV-visible-near infrared spectrophotometer to determine the light absorption characteristics of the sample.Through the TEM, we determine the [001], [013], [012], [111], [323], [212], [313], [101], [232], [112], [123] zone of pyrite; the [104], [301], [313], [201], [311], [114], [201], [101] zone of marcasite; the [0001], [1213], [1453], [021], [2423], [1011] zone of hexagonal pyrrhotite and the [110], [010] zone of monoclinic pyrrhotite systhized under hydrothermal conditions.The crystal orientation of pyrite whiskers from Shanxi Gengzhuang is<001>, the growth of the whiskers meet the directional aggregation; The pyrite from the gold mine, Heilongjiang Laozuoshan are cube and grid-like, the Raman spectra are measured as 345.43?354.93cm-1 383.43?389.76cm-1; The different ratios of Fe/S and content of trace elements in laminated pyrite from Wushan copper mine reflect a different degree of hydrothermal metamorphism, the pyrite is formed by the water release of the reductive mineralization fluid; The cell parameters of cube poly-shaped pyrite synthesized under hot and humid conditions are:a= b= c=5.417A, ?=?=?=90°; Through the TEM, we determine the [013], [102], [021], [Oil] zone of sheet pyrite synthesized by hydrothermal;The S/Fe ratio of banded marcasite is larger than 2, the Raman peak positions are 332.76 ?336.13cm-1,370.76?399.26cm-1, the appearance of cube pyrite in banded marcasite is due to the uncompletely conversion from pyrite to marcasite by the changing of environment; The Raman spectra of ring banded is 378-382cm-1,324-328cm-1. The complexity of hydrothermal fluid results in the formation of different morphology.The visible pyrrhotite in Heilongjiang Laozuoshan is hexagonal and monoclinic; we achieve the rare orthorhombic pyrrhotite with spiral growth under hydrothermal conditions, and get the pure hexagonal plate-pyrrhotite at lower temperature.Compare the standard electron diffraction of Fe-S series minerals under different conditions to speculate the arrangement of initial lattice points; Take a classified comparison of the structural parameters of different Fe-S series minerals to inverse the the changement of formation environmental and crystallization degree; Combine with previous studies, we ascertain the conversion of Fe-S series.The samples are cubic pyrite with a certain amount of pyrrhotite (Fe1-xS) synthesized by hydrothermal method. The band gap value is 0.6578eV. The limiting conversion efficiency we achieved is about 15%. The internal structure of mineral is an important factor effecting the photoelectric conversion. The heterostructures of FeS2-Fe1-xS synthesized under hydrothermal conditions can improve the photoelectric conversion efficiency.In summary, the study of structure and variation of nano-micron Fe-S series minerals is of great significance on structure identification; discussion of growing conditions; correlation between crystal structure and properties.