Intrinsic and impurity-induced emission bands inSrHfO3

Abstract

To better understand the scintillation mechanism in ${\text{SrHfO}}_{3}$-based scintillators we investigate in detail their x-ray excited radioluminescence (RL) emissions. The Gaussian decomposition of the undoped ${\text{SrHfO}}_{3}$ RL spectra manifests the presence of four emission bands peaking at 3.0, 4.0, 4.6, and 5.1 eV. Based on corresponding photoluminescence emission and excitation spectra we tentatively associate the observed bands with excitonic or defect-related emissions. When doped by ${\text{Ce}}^{3+}$ or ${\text{Pb}}^{2+}$ luminescent activators, the RL spectra feature two or three new bands, respectively. The temperature dependence of all RL spectra demonstrates a competition between activators and intrinsic or defect centers in carrier capture. Around room temperature the emission process is completely dominated by recombination at activator centers. In the case of ${\text{Pb}}^{2+}$ activator we also study in detail the concentration dependence of the RL spectra below room temperature exhibiting an optimal value around $0.3\text{ }\text{mol}\text{ }\mathrm{%}$.