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The optical spectroscopic properties of Mn5+ doped into ten host lattices have been studied. The influence of both chemical variation [phosphates(V), arsenates(V), and vanadates(V)] and structural variation (spodiosites, apatites, and Li3PO4-type salts) on the luminescence properties is studied in detail. By varying the host lattice, the position of the sharp luminescence band can be varied from 8300 to 8960 cm−1. Excited state splittings, luminescence lifetimes, and sideband intensities are correlated with the geometrical distortion of the MnO3−4 tetrahedron. In all the host lattices, the luminescence originates from the 1E excited state at all temperatures. It is essentially unquenched at room temperature in apatite and Li3PO4-type lattices, whereas in spodiosites up to 90% of the luminescence may be quenched at room temperature.

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The room-temperature photoluminescence spectrum of SiO2 glass: 0.1% Cr prepared by sol–gel method is reported. It consists of a broad band centered at 14 900 cm−1 with a width of 4200 cm−1 and a lifetime in the μs order and is attributed to the d–d transition of Cr5+ ions (3d1 electron configuration). Absorption and emission spectra give no evidence for the presence of Cr3+ or Cr4+ ions.