Review—Photoluminescence Properties of Cr3+-Activated Oxide Phosphors

Abstract

The Cr3+-activated phosphor properties are discussed in detail from an aspect of spectroscopic point of view. The host materials considered here are a various kind of oxide compounds. The photoluminescence (PL) and PL excitation spectra of the Cr3+-activated oxide phosphors are analyzed based on Franck−Condon analysis within the configurational-coordinate model. A new method is proposed for obtaining reliable crystal-field (Dq) and Racah parameters (B and C) based on a general ligand field theory with paying an attention to difficulty in the exact estimation of such important ligand field parameters. The intra-d-shell Cr3+ states, such as 2 E g (2 G), 4 T 2g (4 F), and 4 T 1g (4 F), in various oxide hosts are determined and plotted against Dq in the Tanabe−Sugano energy-level diagram. The results obtained are summarized in graphical and tabular forms. A comparative discussion of Cr3+ ion as an efficient activator in oxide and fluoride hosts is also given. The present analysis method can be used to predict an energy of Cr3+ emission and/or to check a validity of the Racah parameter values for a variety of Cr3+-activated phosphors and related optical and optoelectronic device applications.