Template‐Engaged Solid‐State Synthesis of Barium Magnesium Silicate Yolk@Shell Particles and Their High Photoluminescence Efficiency

This study presents a new synthetic method for fabricating yolk@shell‐structured barium magnesium silicate (BMS) particles through a template‐engaged solid‐state reaction. First, as the core template, (BaMg)CO 3 spherical particles were prepared based on the coprecipitation of Ba 2+ and Mg 2+ . These core particles were then uniformly shelled with silica (SiO 2 ) by using CTAB as the structure‐directing template to form (BaMg)CO 3 @SiO 2 particles with a core@shell structure. The (BaMg)CO 3 @SiO 2 particles were then converted to yolk@shell barium magnesium silicate (BMS) particles by an interfacial solid‐state reaction between the (BaMg)CO 3 (core) and the SiO 2 (shell) at 750 °C. During this interfacial solid‐state reaction, Kirkendall diffusion contributed to the formation of yolk@shell BMS particles. Thus, the synthetic temperature for the (BaMg)SiO 4 :Eu 3+ phosphor is significantly reduced from 1200 °C with the conventional method to 750 °C with the proposed method. In addition, the photoluminescence intensity of the yolk@shell (BaMg)SiO 4 :Eu 3+ phosphor was found to be 9.8 times higher than that of the conventional (BaMg)SiO 4 :Eu 3+ phosphor. The higher absorption of excitation light by the structure of the yolk@shell phosphor is induced by multiple light‐reflection and ‐scattering events in the interstitial void between the yolk and the shell. When preparing the yolk@shell (BaMg)SiO 4 :Eu 3+ phosphor, a hydrogen environment for the solid‐state reaction results in higher photoluminescence efficiency than nitrogen and air environments. The proposed synthetic method can be easily extended to the synthesis of other yolk@shell multicomponent metal silicates.