L. Niinistö

EXAFS study of terbium activated zinc sulfide thin films

This paper reports that in order to establish the nature of luminescent centers in green-emitting electroluminescent thin film structures based on terbium-activated zinc sulfide, extended x-ray absorption fine structure (EXAFS) measurements were carried out using x-ray radiation from the 1.85 GeV-200 mA DCI storage ring in Orsay. Analysis of the EXAFS spectra at the Tb L{sub III} edge gives direct evidence for the presence of Tb-containing clusters in films prepared by the Atomic Layer Epitaxy process. The polycations TbO{sup +} forming the cluster are very similar to those found in the crystal structure of Tb{sub 2}O{sub 2}S.

Extended X‐ray Absorption Fine Structure Studies of Luminescent Centers in II – VI Thin Films

Extended x-ray absorption fine structure (EXAFS) was used to determine the local structure of luminescent centers in electroluminescent thin films: in Mn- and Tm-doped zinc sulfide as well as in Tb- and Ce-doped calcium sulfide and strontium sulfide. EXAFS measurements were carried out using the electron-yield detection method. While Mn enters a substitutional site, the larger Tm ion is associated with oxygen and forms TmO + polycations. In CaS the rare-earth dopants replace Ca 2+ ions in the lattice and no oxygen was found in their environment

Thermoanalytical Study on Fertilizer Components and Their Mixtures

Thermal decomposition of several fertilizer components and their most important mixtures has been studied by simultaneous recording of the TG, DTG, and DTA curves up to 900 °C. The seven mixtures studied were NH4NO3+(NH4)2SO4, NH4NO3+KN03, 0.7NH4NO3•0.3KNO3+2NH4NO3;(NH4)2SO4, 0.7NH4NO•0.3KNO3 +NH4H2PO4, and (K, NH4)2(NO3)2SO4 with 2NH4NO3 • (NH4)2SO4, NH4H2PO4 or 0.7NH4NO3 • 0.3KN03. In addition to simple mixtures, synthetic and industrial compound fertilizers with varying N:P:K ratios were studied.