New red phosphor NaEuBO with an open-window tubular structure.

A new rare-earth polyborate, trisodium europium octaborate, NaEuBO, was prepared using the high-temperature molten-salt method and structurally determined by single-crystal X-ray diffraction analysis. It crystallizes in the triclinic space group P-1 and contains a one-dimensional [BO] tube structure that is constructed from BO and BO polyhedra. The Eu and Na cations reside in this structure to ensure cohesion and neutrality. The excitation spectra, emission spectra, decay time and Commission Internationale de l'Éclairage (CIE) chromaticity index of NaEuBO were studied. Under near-UV light excitation (393 nm), the polyborate shows an intense red emission, which mainly originates from the highest intensities of the D→F and D→F transitions.