It has been shown that the optical and electrical properties of
Sr0.95±xEu0.05Al2O4±x
depend on composition. A composition with excess alumina was found to have the highest CR efficiency, photoconductivity, and a long‐lasting persistence. A mechanism is proposed which assigns the delayed luminescence to a process involving the conduction of charged particles. Evidence is presented which indicates that holes are trapped at lattice defects and the Eu2+ emission is associated with thermal deactivation of these traps.
The luminescence of Yb2+ in alkaline earth phosphates and vanadates is reported. Particular attention has been given to those compositions possessing apatite and spodiosite structures. Emissions from Yb2+ are broad and sensitive to host composition. Single and double emission bands are observed which exhibit a variety of temperature dependent relationships. The decay of the Yb2+ fluorescence, under cathode‐ray excitation, is short.
The optical absorption spectra of Yba+ in CdF2 and of Yba+ in CdF2 in the presence of various codopants such as Na+, ya+, and Eu3+ were recorded, and the oscillator strengths of the main absorptions of the Yb a + in the 10 OOO-cm-1 region were calculated. Also, the electron spin resonance (ESR) spectra of W+ in CdF2 and Yb'+ in CdF2 in the presence of Na+, 2% ya+, and 10% ya+ were recorded. Noncubic spectra were observed only in the case of the Yba+-Na+-CdF2 and Yba+-10% ya+-CdF2 samples. The former noncubic spectrum was interpreted assuming a rhombic distortion with the major distortion axis along the [110J direction, while the latter could not be interpreted due to the broadeness of the absorptions. From the results of these measurements and the comparison to the optical spectra of Yba+ in other systems, it has been concluded that the previous interpretation of the optical spectrum of Yba+ in CdF 2 is incorrect. It is suggested that the main absorption line at 10 250 cm-1 is not due to an intemalf-f transition but is due to some other mechanism. Possible mechanisms are proposed based on some of the unusual physical properties of trivalent rare-earth ions in CdF2• The interpretation of the optical spectra assuming the absorptions at 10395 and 10 870 cm-1 are the main f-f transitions gives a reasonable fit to the theoretical calculations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.