The electronic states of Mn2+ are derived from excitation spectra for five green‐emitting phosphors: (i) MgGa2O4:normalMn , (ii) Zn2SiO4:normalMn , (iii) ZnAl2O4:normalMn , (iv) Zn2GeO4:normalMn , and (v) Li2ZnGe3O8:normalMn . Only MgGa2O4:normalMn is found to give a spectrum consistent with octahedral (or tetrahedral) symmetry of Mn2+; the other four phosphors show spectra typical of Mn2+ in symmetry lower than octahedral. Solution of the Tanabe‐Sugano energy matrices using the MgGa2O4:normalMn levels as input gave Racah parameters of B=624 cm−1 and C=3468 cm−1 .

The synthesis and photoluminescence mechanism of ZnGa204:Mn 2 § are presented. Monitored at 450 nm, ZnGa204 exhibits an absorption band at 245 nm; monitored at 506 nm ZnGa204:Mn ~ § exhibits absorption bands at 245 and 283 nm. Under 254 nm excitation ZnGa204 exhibits a broad-band emission extending from 360 to 610 nm, peaking at 450 nm. This emission is gradually quenched, as a new band emerges, peaking at 506 nm, as Mn 2 § is incorporated into the lattice (Zn~_~Mn~Ga2Q), where x = 0.006 at maximum intensity. Activator sensitization and host-to-activator energy transfer are suggested.

ZnGa2Q and Znl_~Mn~Ga~O4 were investigated as potential low voltage cathodoluminescence phosphors for use in vacuum fluorescent displays. A low-voltage cathodoluminescence spectrophotometer was developed for phosphor characterization. Brightness was measured as a function of anode voltage (10 to 300 V). The effects of activator concentration, phosphor layer thickness, deposition process, and internal pressure were examined. The stability of these oxide phosphors in high vacuum and absence of corrosive gas emission under electron bombardment, offer advantages over commonly used sulfide phosphors.

The electronic states of Mn2+ are derived from excitation spectra for eight orange‐to‐red emitting phosphors: (i) ZnF2:normalMn , (ii) normalZnS:normalMn , (iii) Zn3false(PO4)2:normalMn , (iv) CaSiO3:normalPb,normalMn , (v) CdSiO3:normalMn , (vi) Cd10Cl2false(PO4)6:normalMn , (vii) Ca10F1.8Cl0.2false(PO4)6:normalSb,normalMn , and (viii) Sr10F1.8Cl0.2false(PO4)6:normalSb,normalMn . All eight phosphors show complete splitting of at least one electronic level. The observed splittings are compared to the expected splittings from crystal field theory. New assignments of the normalZnS:normalMn levels are given.

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