Luminescence

Abstract

This chapter is devoted to the luminescence of inorganic compounds. Luminescence characteristics are strongly host‐dependent. This is illustrated by various examples of the influence of covalency, crystal field, phonon energies, and structural features. The chapter is organized as follows. Section 2 describes the fundamentals of luminescence: probability of electronic transitions, shape of emission bands, quantum efficiency, energy transfer, and factors governing the position of the emitting level (nephelauxetic effect and crystal field splitting). Section 3 reviews the main families of luminescent ions: transition metal ions, lanthanide ions, and s 2 ions. The various types of electronic transitions responsible for the luminescence of transition and lanthanide ions are presented: nd → nd, (n + 1)s → nd, and charge transfer (CT) transitions for the former, 4f → 4f, 5d → 4f, and CT transitions for the latter. Data are given on the luminescence wavelength range, excited‐state lifetimes, thermal stability, and concentration quenching. Section 4 deals with donor‐acceptor transitions in ZnS. Section 5 presents the luminescence mechanisms for excitation through the host lattice. Vacuum ultraviolet (VUV), electron beam, X‐ray, and γ‐ray excitation are considered. The most efficient luminescent materials are given for the various types of excitation. Section 6 deals with electroluminescent materials.

Synthesis of GAGG:Ce3+ powder for ceramics using mechanochemical and solution combustion methods

“…The excited Ce 3+ ion then nonradiatively relaxes to the lowest‐energy crystal‐field level of the 5d state. From this position, it decays radiatively to the 2 F 7/2 and 2 F 5/2 4f multiplets of Ce 3+ …”