Preparation And Properties Of ?-?₂-?-?4 Polysulfide Magnetic Semiconductors

Magnetic semiconductors have attracted wide attention because of their electronic charge and spin characteristics.However,the low Curie temperature of magnetic semiconductors has been restricting the development of this field.Therefore,the development of magnetic semiconductors with high Curie temperature is still the focus of development.Due to the diversity and flexibility of its composition and structure,multi-chalcogenide compounds have gradually come into people's vision.After years of research,they have also made great progress.However,most of the prepared compounds are mainly in ordered systems,and the research on disordered systems is limited,mainly in I-III-VI₂,I₂-IV-VI₃ and I₂-II-IV-VI₄ compounds.Recently,I-II₂-III-IV₄ compounds with disordered wurtzite structure have been successfully prepared.Therefore,this kind of disordered diamond-like chalcogenides has great potential for development.I-II₂-III-IV₄ compounds were prepared by thermal injection method,and their related properties were studied,which further enriched the content of the system.The main research contents include:?1?CuNi₂InS₄,a hexagonal wurtzite type,was prepared by thermal injection using oleic acid as coordinating agent,dodecyl mercaptan as sulfur source and self-made acetylacetone salt as precursor.The shape of the bullet is uniformly distributed,the length is about 15 nm,and the width is within the range of 5-10 nm.Each element exists in the chemical valence states of Cu⁺,Ni²⁺,In³⁺,and S^2-,respectively.After annealing,CuNi₂InS₄ of hexagonal wurtzite decomposed at 400 ^oC to form hexagonal CuInS₂ and Ni₃S₄,and CuInS₂ transformed from hexagonal to tetragonal at 600^oC.The extrapolated optical band gap is 1.45 eV.As for magnetism,it shows ferromagnetism at low temperature and paramagnetism at room temperature.Nickel temperature is 12K,at which magnetic transition takes place.?2?CuNi₂InS₄,a tetragonal phase,was prepared by thermal injection with oleamine as coordinating agent,dodecyl mercaptan as sulfur source and acetylacetone salt as precursor.The results showed that CuNi₂InS₄ had good crystallinity,irregular circular morphology and uniform dispersion,and its size was nanometer and its diameter varied from 15 to 25 nm.The extrapolated optical band gap is 1.58 eV.As for magnetism,it shows ferromagnetism at low temperature and paramagnetism at room temperature.Nick temperature is 14 K,at which magnetic transition takes place.?3?CuNi_x Zn_?2-x?InS₄ of hexagonal wurtzite type was prepared by thermal injection method using oleic acid as coordinating agent,dodecyl mercaptan as sulfur source and self-made acetylacetone salt as precursor.Characterization analysis showed that the samples prepared according to different doping ratios of Zn and Ni were hexagonal wurtzite structure,and no impurity was formed.Zn and Ni ions occupied the same crystal lattice position.With the increase of doped Zn ions,the interplanar crystal spacing becomes larger because of its larger radius,and the XRD peak shifts to a lower angle.With the increase of doped Zn ions,the morphology and size become smaller.The absorption intensity of hexagonal wurtzite CuNi_xZn_?2-x?InS₄doped with different proportions is different.With the decrease of x,that is,the content of Ni in the experimental sample decreases gradually,the content of Zn increases gradually,and the absorption intensity increases.The optical band gap increases with the decrease of x.