Eu2+ as the structural probe in the phase transformation of CMSA by site-selective occupancy and adjustable multimode white luminescence in Ca2(Mg0.5Al0.5)(Si1.5Al0.5O7) akermanite based on high-aluminum blast furnace slag.

Abstract

A tunable multimode white emission Ca2(Mg0.5Al0.5)(Si1.5Al0.5O7):Eu2+/Eu3+ phosphor was prepared by doping Eu2O3 in molten high-aluminum blast furnace slag. The structural probe Eu2+ was studied during phase transformation between the glassy state and Ca2(Mg0.5Al0.5)(Si1.5Al0.5O7) crystals based on site-selective Eu2+ occupancy. When the doped Eu2+ ions occupied two different Ca2+ sites in the matrix, blue light (421 nm) and green light (516 nm) emissions were observed corresponding to two types of Eu2+Ca2+, namely Eu2+Ca2+ (Mg2+ → Al3+) and Eu2+Ca2+ (Si4+ → Al3+). The effects of Eu concentration (0.1-2.0 mol%), heat treatment temperature (800-1000 °C), and thermal quenching temperature (30-150 °C) on the structural evolution of the emission unit were studied by differential scanning calorimetry (DSC), photoluminescence spectroscopy (PL) and X-ray diffraction (XRD) analyses. The Eu2+Ca2+ (Mg2+ → Al3+) structure formed by site-selective Eu2+ occupancy possessed better structural stability in the Ca2(Mg0.5Al0.5)(Si1.5Al0.5O7) crystal matrix, in favour of light-emitting diode (LED) illumination and plasma display panels (PDPs).