title: Template-Engaged Solid-State Synthesis of Barium Magnesium Silicate Yolk@Shell Particles and Their High Photoluminescence Efficiency.
abstract: 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)CO3 spherical particles were prepared based on the coprecipitation of Ba(2+) and Mg(2+) . These core particles were then uniformly shelled with silica (SiO2 ) by using CTAB as the structure-directing template to form (BaMg)CO3 @SiO2 particles with a core@shell structure. The (BaMg)CO3 @SiO2 particles were then converted to yolk@shell barium magnesium silicate (BMS) particles by an interfacial solid-state reaction between the (BaMg)CO3 (core) and the SiO2 (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)SiO4 :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)SiO4 :Eu(3+) phosphor was found to be 9.8 times higher than that of the conventional (BaMg)SiO4 :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)SiO4 :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.
authors.affiliation: Department of Chemical Engineering, Functional Crystallization Center, Kyung Hee University, Yoing-si Kiheung-ku Seochun-dong, Kyungki-do, 446-701, Republic of Korea.
authors.forename: Xuncai
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Chemical Engineering, Functional Crystallization Center, Kyung Hee University, Yoing-si Kiheung-ku Seochun-dong, Kyungki-do, 446-701, Republic of Korea. wskim@khu.ac.kr.
authors.forename: Woo-Sik
authors.initials: WS
authors.lastname: Kim
keywords: Kirkendall diffusion; luminescence; nanostructures; silicates; template synthesis