Preparation And Properties Of RE:GGG (RE=Yb,Nd) Nano-Powders And Ceramics

Gadolinium Gallium Garnet (GGG) is an excellent functional material with good optical and mechanical properties. Active ions doped GGG can also be used as excellent laser materials. It can generate different wavelength laser with corresponding ions. Owing to the outstanding advantages, such as a long storage lifetime, a low quantum defect, a broad absorption bandwidth and less sensitivity to diode wavelength specifications, single crystals of Yb3+-doped gadolinium gallium garnet has been a potential solid state laser material. Nd:GGG has been recognized as one of the most efficient active material for solid state heat capacity laser. But single crystal has some restrictions, such as high-cost, low doping concentration and small size etc. Comparing with single crystal, transparent ceramics become a hot research field because of its characteristics of short producing cycle, low cost, high productivity, and transparent ceramics also possesses uniform optical property and high doping rate.In this paper, preparation method and properties of Yb:GGG and Nd:GGG nano-powders were prepared, the optimum parameters and the influences of fabrication parameters and doping contents of Yb3+ on Yb:GGG ceramic properties were studied. The properties of precursors, nano-powders and ceramics were characterized by TG/DTA, IR, XRD, TEM, SEM, EDS and fluorescence spectrum test. 1. Preparation of Yb:GGG nano-powdersYb:GGG nano-powders were firstly prepared by co-precipitation method using NH4HCO3 as the precipitant. NH4MO(OH)HCO3 (M= Yb3+, Ga3+, Gd3+) precursor was obtained and then calcined at 900℃for 8 h to transform into pure GGG. The influences of dispersant, beginning concentration of reactant, pH value, doping concentration of Yb3+ on the morphology and luminescence properties of powders were studied. The results show that (NH4)2SO4 can improve the dispersitity, and the particles distributed uniformly with diameter of 80nm. The excitation peaks of the samples located at 979nm, corresponding to the transition of 2F7/2→2F5/2, the emission peaks are at 1033nm, corresponding to the IR spectrum line of 2F7/2-2F5/2. The optimum doping contents of Yb3+ is 10.0 at.%.Yb:GGG nano-powder was firstly synthesized by low temperature combustion method, citric acid as the reductive agent. The properties of powders were studied. The precursors were burned at 500℃and transformed into pure GGG after calcined at 900℃for 8 h. The particles size is about 47nm. 2. Preparation of Nd:GGG nano-powders of ceramicsNd:GGG nano-powders was synthesized by co-precipitation and sol-gel low combustion methods. For co-precipitation process, when calcined at 900℃for 8h, the particle size is about 70～90 nm, and morphology is spherical, and there is no intermediate phase. For sol-gel low combustion process, pure GGG phase can be obtained when calcined at 900℃for 8 h. The obtained polycrystalline powders show light agglomerate and have a relatively broad size distribution, but the particle size is less than 100nm. 3. Fabrication of Yb:GGG ceramicsIt can be concluded that the property of samples made by co-precipitation method is better than sol-gel low temperature combustion method. There are great influences of molding pressures, sintering temperature and time on the properties of the samples. The optimum sintering parameters is 1 650℃,5 h. The transmittance of Yb:GGG ceramics sample is about 30%. Yb:GGG ceramics show good luminescence property at 1 033nm. And the results provide the possibility of laser oscillation.