| The luminescent properties of some quasi-one-dimensional double halide salts with the general formula AMX(,3) (A = a large univalent cation, M = a divalent ion, and X = halide ion) are examined. Part I is concerned with energy transfer between Mn('2+) ion of the host crystal (CsMnBr(,3) or CsMnI(,3)) and a trivalent rare earth dopant ion (Er('3+) or Ho('3+)). Data obtained with a two-dimensional host crystal (Rb(,2)MnCl(,4)) are also included.;Energy transfer, achieved by rapid exciton motion from Mn('2+) ion to Mn('2+) ion along the {MnX(,3)('-)}(,n) chains of the host crystal, is interrupted at impurity centers where it may be radiated or dissipated by a radiationless process. Pure host crystals which are relatively free of quenching traps and which luminesce strongly from 10K to 300K are obtained by addition of excess manganese metal to the melt in preparation of the salts.;Emission spectra of these pure manganese-containing host crystals doped with a trivalent rare earth ion contain features attributable to both Mn('2+) and the rare earth. Monitoring the decrease in intensity of the Mn('2+) emission or increase in intensity of the rare earth ion emissions with increasing temperature gives a reasonable profile of the magnitude of the energy changes involved in the transfer. A model for the energy transfer process is presented.;Part II describes the energy storage and thermoluminescent properties of the double halide salt CsMgI(,3) doped with various rare earth impurities (Sc('3+), In('3+), Ce('3+), Gd('3+), Ho('3+), Tm('3+), or Er('3+)). Cesium magnesium triiodide was found to have properties of a semiconductor with a rather wide band gap (4.8 eV). When CsMgI(,3) is doped with a trivalent rare earth ion, luminescent impurity centers consisting of trivalent ion-vacancy-trivalent ion, replacing three magnesium ions in the lattice, are formed. Alternative type centers consisting of trivalent ion-univalent ion, replacing two Mg('2+) ions, may be formed when a small univalent ion such as Li('+) is a codopant.;When the doped crystals are irradiated at 11K, energy is stored, and when the irradiated crystals are allowed to warm, they display a pronounced thermoluminescence. Glow curves obtained by allowing the irradiated crystals to warm at a constant rate were analyzed by several published methods to provide a quantitative description of their electron trapping and energy storage properties. Data on rare earth doped crystals as well as rare earth - Li('+) doped crystals are presented. |
