Promising Zn₃Ta₂O₈:Pr³⁺ red phosphor for low voltage cathodoluminescence applications

Zn₃Ta₂O₈ is a promising host for low voltage cathodoluminescence (CL) applications. Surface chemical stability during low voltage electron beam excitation is a prime concern for phosphors to be used in various new generation information displays. Photoluminescence (PL) and CL characteristics of the Zn₃Ta₂O₈ host doped with Pr³⁺ are presented. The phosphors were synthesized via solid-state reaction route at 1100°C. Red CL or PL with a maximum at 611 nm, attributed to the ¹D_2-³H₄ transition of the Pr³⁺ ion, was observed at room temperature under high energy electron (2 keV, 12 μA) or a monochromatic xenon lamp (257 nm) irradiation. Electron stimulated chemical changes on the surface of the Zn ₃Ta₂O₈:Pr³⁺ phosphor during an electron beam exposure from 0-350 C/cm² was monitored using Auger electron spectroscopy. The CL exhibited only a 20% loss in the original intensity during the continuous electron beam exposure. X-ray photoelectron spectroscopy (XPS) was used to estimate the redox states of the chemical constituents and a comparison of binding energies was made with the standard Ta₂O₅ and ZnO compounds. A correlation between the structural configuration of Zn₃Ta₂O₈ and the XPS data is also established.