The crystal structure and luminescent properties of nitrogen-rich Ca-α-sialon:Eu with saturated calcium solubility fabricated by the alloy-nitridation method

Nitrogen-rich Ca- -sialon: Eu²⁺ phosphors with saturated calcium solubility are synthesized through a solidstate reaction (SSR) at 2173 K with stable alloy and nitride as the starting materials. The Ca_1.83-1.5xSi_8.34 Al_3.66O_xN_16-x: xEu phosphors have intensive orange emissions, whose peaks are located at approximately 585–600 nm, and the emission wavelengths tend to shift toward the red region when the Eu concentrations increase from 0.5% to 18% (mole percentage). When the Eu concentration is equal to 9%, the phosphors suffer from concentration quenching. The low-temperature photoluminescence properties indicate that Ca_1.83-1.5xSi_8.34Al_3.66O_xN_16-x: xEu phosphors show excellent thermal quenching. The crystal structures of Ca_1.83-1.5xSi_8.34Al_3.66OO_xN_16-x: xEu are also investigated, and are found to have nitrogen-rich compositions with saturated calcium cations at the interstitial sites of the α-sialons. In addition, the influencing factors of -sialons with different compositions on the crystal lattice are discussed in detail.