Study On The Preparation Method And Properties Of Silver Selenide Doped By Magnetic Impurity

The magnetoresistance of non-stoichiometric silver chalcogenide presents a good linear relation with the applied magnetic field and keeps a nonsaturating state under higher magnetic field, the magnetoresistance can be comparable with colossal magnetoresistance materials. This nature for nonmagnetic silver chalcogenide is precious and shows a great application prospect in magnetic technology and information storage, causing extensive concern for the researchers, through the experiment, the physic principle of LMR produced by a series of low-temperature ?-phase self-doped silver chalcogenide and the application prospect have been explored. The linear magnetoresistance mechanism of this type of materials, mainly has the following three views: Abrikosov quantum magnetoresistance effect, Parish and Littlewood random resistor network model theory and Zhang et al, topological insulator's point of view. However, the physical mechanism behind also can't be explained by a clear and reasonable generally accepted theory. So for the doping silver chalcogenide compound system also needs more experiments and further theories to explore.Firstly, this article used two-step synthesis method to prepare Mn- doped Ag2 Se system to improve the feature. Through comparison and analysis of a series of experimental powder samples prepared at different reaction conditions to determine the optimized experimental process of solvent thermal method to prepare Mn doped Ag2 Se system,KBH4 as the catalyst, diethylamine as the reaction solvent, heating for 12 h at 180?.Summary analysis of the chemical reaction mechanism of the doped system under diethylamine strong alkaline solution has been acted. The optimized temperature in the solid phase reaction determined through the thermogravimetric test result of the obtained powder samples is 370 ? to 550 ?.Then we analyse the microscopic physic and optic properties of a series of Mn-dopedAg2 Se powder prepared under the optimum process using relative test means. The study found that the composition of sample is pure, the Mn atoms exists in the form of Mn2+ion in Ag2 Se lattice, formed the solid solution, its solid solution limit reached to 22%. The mainly exist form of Ag is Ag+, Ag elemental valence may exist. From the microscopic morphology, nanoparticles and little nanowires have been found, part nanoparticles cluster gather to be layer-like chunks. Using uv-visible spectrophotometer to analyse the absorption spectrum of the sample, the energy band gap is 0.62 ~ 0.75 eV, slightly lower than 1.56 eV reported by literature, this may be caused by the doping of Mn icon in the crystal.Finally, the preparation procedure of magnetic icon Ni-doped Ag2 Se solid solution prepared through solvent thermal method and Cu-doped CuAg Se ternary compound system and relative characterization of the samples have been explored respectively. By analyzing and comparing the samples prepared under different reaction condition through relative testing means to determine the optimum preparation parameter. As to a series of Ni-doped Ag2 Se powder system, the samples were similar with Mn-doped Ag2 Se system,Ni2+substitute Ag+in Ag2 Se lattice to form solid solution, the solid solution limit could reach to 12%. As to Cu-doped pure phase CuAg Se system, the optimized ratio of raw material was originally determined to be Cu:Ag=1.5.