No abstract

Herein, we present a methodology based on constrained density functional theory and vibrational mode computations to simulate and interpret the luminescence spectra of periodic solids. A multi-dimension harmonic model is used to combine electronic and vibrational contributions into an overall vibrationally resolved emission spectrum. We applied it to Ti-doped BaZrO3 to accurately reproduce its blue luminescence and unambiguously assign the observed luminescence to a Ti3+ + O– → Ti4+ + O2– charge transfer.

This article reviews blue shortwave-excited luminescence (BSL) in natural minerals and synthetic materials. It also describes in detail the emission of seven minerals and gems displaying BSL, as well as three references in which BSL is caused by titanate groups (TiO6): benitoite, Ti-doped synthetic sapphire and spinel. Emission (under 254 nm shortwave excitation) and excitation spectra are provided, and fluorescence decay times are measured. It is proposed that BSL in beryl (morganite), dumortierite, hydrozincite, pezzotaite, tourmaline (elbaite), some silicates glasses, and synthetic opals is due to titanate groups present at a concentration of 20 ppmw Ti or above. They all share a broad emission with a maximum between 420 and 480 nm (2.95 to 2.58 eV) (thus perceived as blue), and an excitation spectrum peaking in the short-wave range, between 230 and 290 nm (5.39 to 4.27 eV). Furthermore, their luminescence decay time is about 20 microseconds (from 2 to 40). These three parameters are consistent with a titanate emission, and to our knowledge, no other activator.