ZnAl2O4:Mn2+ transparent phosphor ceramic with narrow-band green emission by spark plasma sintering

Narrow-band green emitting ZnAl2O4:Mn2+ transparent ceramics were fabricated by the spark plasma sintering (SPS) method. The occupancy of Mn2+ in ZnAl2O4:Mn2+ transparent ceramics was investigated, and it was determined through fitting calculations that the concentration quenching of Mn2+ is caused by dipole-quadrupole interactions. Additionally, two thermal quenching mechanisms, namely non-radiative transitions and electron-phonon coupling were compared. Under the 450 nm excitation, the ZnAl2O4:0.5%Mn2+ ceramics exhibit a narrow-band green emission at 510 nm, with a full-width at half-maximum (FWHM) of 18 nm. This emission is attributed to the 4T1(4G)-6A1(6S) transition of Mn2+ in the [ZnO4] tetrahedral site. The thermal conductivity of the ceramics was measured to be 17.2 W m−1 K−1 at room temperature and remained at 11.5 W m−1 K−1 at 225 °C. As a result, the photoluminescence (PL) intensity at 150 °C was maintained at around 70% compared to its initial value at room temperature. These findings suggest that ZnAl2O4:Mn2+ transparent ceramics have potential applications in high brightness and wide gamut display backlights.