Preparation and Luminescence Properties of Glass Ceramics Precipitated With $hbox{M}_{bf 2}hbox{MgSi}_{bf 2}hbox{O}_{bf 7}{:},hbox{Eu}^{bf 2+}$ (M = Sr, Ca) Phosphor for White Light Source

$hbox{Eu}^{2+}$-doped silicate glasses were prepared in the system $42hbox{SiO}_{2}$– $gamma hbox{CaO}$– $(38gamma)hbox{SrO}$–$20hbox{MgO}$– $0.2hbox{EuO} (gamma = 0, 10, 20, 30, 38)$ by melting under reducing atmosphere. Glass ceramics precipitated with $hbox{M}_{2}hbox{MgSi}_{2}hbox{O}_{7}{:}hbox{Eu}^{2+}$ (M = Sr, Ca) phosphor were obtained by heat-treatment of the glass. They showed broad emission band due to the 5d $rightarrow$ 4f transition of $hbox{Eu}^{2+}$. The peak wavelength shifted from 470 to 530 nm with increasing CaO content. Their emission wavelength can be controlled by changing the compositional ratio of Ca and Sr. Their color coordinates were widely changed from blue to yellowish green region. We have successfully obtained glass ceramic phosphors with excellent durability for a high-power white LED based on near-UV LED.