title: Temperature and pressure dependence of the optical properties of Cr3+-doped Gd3Ga5O12 nanoparticles.
abstract: Since the crystal-field strength at the Cr(3+) site is very close to the excited-state crossover (ESCO), this work investigates the optical properties of Cr(3+)-doped Gd(3)Ga(5)O(12) (GGG) nanoparticles as a function of temperature and pressure in order to establish the effect of the ESCO on the optical behaviour of nanocrystalline GGG. Luminescence, time-resolved emission and lifetime measurements have been performed on GGG:0.5% Cr(3+) nanoparticles in the 25-300 K temperature range, as well as under hydrostatic pressure up to 20 GPa. We show how low temperature and high pressure progressively transforms Cr(3+)(4)T(2) --> (4)A(2) broadband emission into a ruby-like (2)E --> (4)A(2) luminescence. This behaviour together with the lifetime dependence on pressure and temperature are explained on the basis of the spin-orbit interaction between the (4)T(2) and (2)E states of Cr(3+).
authors.affiliation: Departamento Física Aplicada, Facultad de Ciencias, Universidad de Cantabria, Santander, Spain. rosa.martin@unican.es
authors.forename: R
authors.initials: R
authors.lastname: Martín-Rodríguez
authors.forename: R
authors.initials: R
authors.lastname: Valiente
authors.forename: F
authors.initials: F
authors.lastname: Rodríguez
authors.forename: M
authors.initials: M
authors.lastname: Bettinelli