Patent attributes
This patent covers infrared phosphorescent materials which exhibit extended persistence lifetimes and are composed of mixtures of the elements zinc, antimony, gallium, tellurium, oxygen and nitrogen, and are doped with varying amounts of chromium, neodymium, dysprosium, yttrium or thulium. A typical formula is given by Zn(1-n %-m %-l %)SbxGa2-xTezO4+2z-yNy: n % Cr3+, m % P, l % Q, where Zn is zinc, Sb is antimony, Ga is gallium, Te is tellurium, O is oxygen, N is nitrogen. Additionally, x (0 to 2) y (0 to 0.5) and z (0 to 1) are the molar concentration in the composition. Cr3+ is the doped chromium ion, P is a codopant and Q is a second codopant and n, m, l are the concentration respectively (m,m,l are from 0.1 to 10). An example is the material ZnSbGaTeO5.95N0.05:3% Cr3+, 1% Nd3+, which has an emission peak at 760 nm and a persistent time of over 20 hours (measured with Fluorolog-3 spectrometer with a PMT detector).