Structure And Performance Of Co Doped ZnO Nano-powder By Sol-gel Method

The rapid development of micro-nano technology gave birth to using electron’s spin to design for quantum devices, which is spintronics. In recent years, the transition metal-doped ZnO-based diluted magnetic semiconductor materials have shown an increasingly important research value in spintronics basic theory and applications of spintronic devices. The in-depth study on Co-doped ZnO diluted magnetic semiconductor nanopowder materials has significance in scientific and application value.This thesis is to study on the effect of process parameters and doping content on the structure and magnetic properties of Zn1-XCoXO nanopowders prepared by sol-gel calcine method and sol-gel auto-combustion method. The main contents and conclusions of the thesis are as follows.Preparing Zn1-XCoXO nanopowders using sol-gel calcine method is to study the effect of aging conditions and calcining temperature on structure and magnetic properties of Zn0.95Co0.05O nanopowders, and the effect of doping content on microstructure and magnetic properties of Zn1-XCoXO nanopowders. The results showed that the sol need a temperature of100℃, suitable for the aging time is3days; Zn0.95Co0.05O nano-powder calcination and calcination temperature was below700℃, there were Co3O4impurity phase peak, when calcined Co2+form again when the temperature reaches800℃, Co3O4decomposed into CoO solid solution into the ZnO lattice form Zn0.95Co0.05O single-phase; when the Co doping content and more than7%, calcined at800℃the nanometer powder Zn1-XCoXO Co3O4impurity phases; sol-gel calcine method prepared the Zn1-XCoXO of nano-powders of Co solid solubility of slightly more than5%. The show room docile magnetic powder calcined at800℃the Zn1-XCoXO nano and Co doping concentration increased, the nano-powder paramagnetic enhancement.Preparing Zn1-XCoXO nanopowders using sol-gel auto-combustion method is to study the effect of doping content and calcining temperature on structure and magnetic properties of Zn1-XCoXO nanopowders. The study found that slightly more than7%, the degree of solid solution of Co doping content reaches and exceeds 10%, the Co single sample quality; the Zn1-XCoXO nanopowders, heat treatment is subsequently calcined, nano Zn0.93Co0.07O Powders still pure phase Co doped Co elemental oxide content greater than or equal to10%of the samples generated Co3O4, the calcination temperature reaches800℃, a small amount of the powders of Zn0.9Co0.1O nm Co3O4again decomposition of Co2+form solid solution into the ZnO lattice. The sol-gel auto-combustion method prepared Zn0.93Co0.07O nano exhibit ferromagnetism at room temperature, but with the calcination temperature, reduced ferromagnetic and paramagnetic, when the calcination temperature of800℃, the sample showed only obvious paramagnetic magnetic transition is likely to be derived from the changes in carrier transport characteristics of the sample.Making a comparative study on Zn1-XCoXO nanopowders prepared by sol-gel calcine method and sol-gel auto-combustion method, it is can be found that due to the difference of the reaction process, the solid solubility of Co ions and the impurity phase in Zn1-XCoXO nanopowders prepared by two different methods are different from each other. Sol-gel auto-combustion rapidly response, likely to cause hypoxic environment, Co elemental impurity phase; sol-gel calcine is taken place in oxygen-rich environment, Co3O4impurity phase. The differences in the reaction of the two methods resulted in carrier transport characteristics which leads to the differences in magnetic properties of Zn1-XCoXO nanopowders prepared by two different methods.