Precipitation of Ba2+ ions in KCl using Eu2+ as an optical probe
Por:
Verdiguel G. H., Hernandez A. J., Flores J. C., Murrieta S. H., Muoz H. G.
Publicada:
1 ene 1991
Resumen:
The results of the precipitation of Ba2+ ions in KCl crystals using Eu2+ as a probe are discussed. The Eu2+-ion concentration used in these studies is about 10% of that of Ba2+. Ionic-thermocurrent (ITC), EPR, and luminescence measurements were carried out in quenched and annealed samples. Quenched samples show one-emission-band peaking at 417 nm, which is characteristic of isolated-Eu2+-vacancy complexes, while the ITC peak corresponds to isolated-Ba2+-vacancy complexes. On the other hand, the EPR spectra correspond to Eu2+-vacancy complexes, in agreement with the luminescence results. Annealing processes at temperatures below 400 K give rise to emission bands at 429 and 441 nm. This result, together with those of the ITC measurements, points out the presence of Eu2+-Ba2+ complexes as well as barium precipitates. In particular, it is worth noting the presence of a cubic phase of BaCl2, stable at room temperature, assigned to the band-emission peaking at 429 nm. This result is supported by EPR measurements that show a typical cubic spectrum. For annealing temperatures between 400 and 500 K, the nucleation of an orthorhombic phase is achieved, besides that of a cubic nature. © 1991 The American Physical Society.
Filiaciones:
Instituto de Física, Universidad Nacional Autanoma de México (UNAM), Apartado Postal 20-364, 01000 México, Mexico
Departamento de Física, Universidad Autanoma Metropolitana (UAM) Iztapalapa, Apartado Postal 55-534, 09340 México, Mexico
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