Various Structures Of MnS Nanocrystals Through Solvothermal Synthesis

Semiconductor nanomaterials have emerged as a type of material in people's learning and life, nano-structure with much related to people's lives. As the quantum size effects of nanomaterials, it has good tunable optical properties. In recent years, as a function of nano-composite materials are actively used in chemical devices, biomedical, optoelectronics, nano-electronics and other subject areas.Manganese sulfide isⅦB-ⅥA important dilute magnetic semiconductors. The band gap energy is 3.7eV. MnS is a typical wide band gap semiconductor. There are three types of manganese sulfide structure:the rock-salt structure (a-MnS), the sphalerite structure (β-MnS), and the wurtzite structure (y-MnS). The three structures can be distinguished from the appearance. The sphalerite structure and the wurtzite structure were tested pink. The rock-salt structure is rather special.Its colour is green. The sphalerite structure and the wurtzite structure is a metastable state exists only in the lower temperature range. And two kinds of metastable state can transform irreversibly to the stable a type at 100-400℃. It is inferred that the metastable type manganese sulfide compared with the stable type has more specific chemical properties. For example:electrical, optical, magnetic and other properties. Manganese sulfide in electronic devices and solar cells has potential applications.In this paper, with a simple change in temperature we obtained three types of manganese sulfide nanocrystals. The PL peak position of Manganese sulfide is about the 400-500nm, thus which makes manganese sulfide as the short wavelength of electronic devices possible. Manganese sulfide phase transition accompanied with the evolution of morphology. That phase transitions and morphology evolution is simultaneously. Sphalerite is generated at lower temperatures.It's morphology similar to the spherical. With an increasing temperature, the wurtzite structure of y-MnS is obtained. Morphology of the crystal can be seen from the TEM with great changes. The TEM image is bipod. When changing the ligand, we also received a sheet of a-MnS.The combined of temperature and ligand effect the phase transition of manganese sulfide. If the solution to form a nucleus, it must maintain the reaction kinetics and thermodynamic equilibrium. In the Schlenk system, only the oleylamine as the ligand, the reaction only generated the wurtzite structure of manganese sulfide, and the reaction has not been much change between the structures. Then we added the oleic acid to the reaction, at this time both of the oleic acid and oleylamine is the ligand in the reaction. They work together. When change the injection temperature at this time, we get the phase transition from the sphalerite to the wurtzite structure of manganese sulfide. Therefore only in certain temperature and the appropriate ligand interaction, the manganese sulfide phase transition will occur.