Blue cathodoluminescence related to defect center in smithsonite

Abstract

Smithsonite occasionally exhibits a characteristic blue emission, known as cathodoluminescence (CL), which can be assigned to a lattice defect center by CL spectral analysis. The intensity of this emission is reduced at higher temperatures, suggesting a temperature quenching phenomenon. The activation energy in the quenching process was evaluated by a least-square fit of the Arrhenius plots using the integrated intensity of the emission component, and was found to be ∼ 0.03 eV for the defect center. According to the Mott-Seitz model, the quenching process can be interpreted by an increase in non-radiative transition at higher temperatures. The value of the activation energy for a blue emission caused by the defect center corresponds to the vibration energy of the O-Zn-O bending mode in the lattice. It implies that the temperature quenching energy might be transferred as a phonon to the specific lattice vibration.