Valence Regulation and Optical Properties of Cr-Doped YAG Transparent Ceramics
Cr4+∶YAG crystal materials have been proved to be an ideal passive Q-switched material in recent years.Using MgO and CaO as sintering aid and charge compensation agent,0.25％Cr4+∶YAG(molar concentration)transparent ceramics with high optical quality were successfully prepared by low-temperature vacuum sintering combined with hot isostatic pressing(HIP)sintering.Effect of MgO,CaO,and MgO-CaO co-added divalent oxides on the transmittance,absorption spectra,and fluorescent properties of Cr4+∶YAG ceramics were investigated.It is found that,compared with CaO and MgO-CaO series,MgO exhibits the most significant effect on the densification of Cr4+∶YAG ceramics when the vacuum-sintering temperature is 1 550℃.Especially when the molar concentration of MgO is 0.25％,the relative density reaches 98％.After HIP sintering at 1 680℃,the corresponding in-line transmittance of the densified Cr4+∶YAG ceramics reaches as high as 84.4％at the wavelength of 1 400 nm.Moreover,by annealing at 1 400℃for 20 h,the absorption coefficient of Cr4+at 1 030 nm reaches the highest value of 3.0 cm-1,though some Cr3+still remain in the Cr4+∶YAG ceramics.
Cr4+∶YAG ceramicsvalence regulationoptical propertytransparent ceramicssintering aid
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