Fabrication And Properties Of Yb: Yag And Yb:yag/yag Polycrystalline Transparent Ceramics

Yb3+ doped yttrium aluminum garnet (Yb:Y3Al5O12, Yb:YAG) became one of the most potential laser ceramics in application because of its wide absorption and emission band, long fluorescent lifetime and good thermodynamic and mechanical property, and the most important thing is that a high doping content can be achieved in Yb:YAG ceramics. So it can be processed into flake as gain transmitter, which can be used in solid-state laser. However, when crystal plate work as operation material, just a part of the pumping energy translates into laser, the dump energy translates into radiationless transition of host material or lattice energy absorption. It must induce non-homogeneous of heating in laser medium which create distortion of crystal and consequently create thermal lens effect. It will influence the quality of output laser beam and laser efficiency. People put forward an idea to prepare laser operation material into composite structure which has already made a successful use in solid-state laser. In this dissertation, (Y1-x,Ybx)3Al5O12 (x=0.01,0.02,0.05,0.1,0.2,0.3) ceramics were fabricated by solid-state reaction method from commercial nano-sized Y2O3, Yb2O3 andγ-Al2O3 powder. And on this basis, dry-pressed and centrifugal casting were used to prepared Yb:YAG/YAG composite ceramics.High-purity nano-sized Y2O3, Yb2O3 andγ-Al2O3 powder were used as starting materials. The starting materials were mixed by ball-milling in ethanol with an addition of 0.5wt% tetraethyl orthosilicate (TEOS) as sintering aid. The mixtures were dried, sieved and calcined at 1200℃to obtain the mixture powders containing YAG and YAP. The mixtures powders were two-direction dry-pressed, then pre-sintered at 1300℃for 4h. The compacts were sintered at 1700℃for 5h in vacuum. After sintered at 1700℃for 5h in vacuum. With the increased content of Yb3+ ion, the average grain size had a trend of grain growth, and was homogeneous. The in-line transmittance of 1mm thick sample is about 75.6% (700nm).YAG and Yb:YAG powder (Ybat%=1%,2%,5%,10%,20%,30%) were prepared in same technology, then pre-sintered Yb:YAG/YAG body at 1300℃for 4h which had been dry-pressed. The compacts were sintered at 1700℃for 5h. The sample had low light-admitting quality because of the Al2O3 precipitated phase in Yb:YAG.The calcined Yb:YAG(Yb 10at%) powders were milled with 0.1 wt%,0.5wt%, 1wt%, 2wt% and 5wt% polyelectrolyte for 6h.Viscosimetriced after ultrasonic dispersion for 5min.At the same time, made a settlement observation on the five groups of slurry. Then the body was prepared with centrifugal casting. After drying the body was pre-sintered then sintered in vacuum. The optimal content of dispersant agent was 1wt%. And YAG/Yb: YAG/YAG composite ceramics were prepared with the same centrifugal casting technology.