Luminescence analysis and subsequent revision of the crystal structure of triclinic L-EuBO3

The structure of L-EuBO3 is revised by using the centric P-1 space group wi th two crystallographic sites for Eu3+, in perfect agreement with the lumin escence results (site A and site B). The structure, refined from single cry stal X-ray diffraction data, is triclinic, space group P-1, Z = 4, with a = 6.468(7) Angstrom, b = 6.477(7) Angstrom, c = 6.220(7) Angstrom, alpha = 1 07.78(6)degrees, beta = 108.00(7)degrees, gamma = 93.07(4)degrees, R-1 = 0. 025, wR(2) = 0.062. The three-dimensional network is built up from corrugat ed sheets of EuO8 polyhedra, approximately parallel to the ((1) over bar (1 ) over bar 1) planes. Luminescence analysis indicates that site to site ene rgy transfer is efficient at 77 K and is phonon assisted from site B to sit e A. At 12 K, this site B to site A phonon coupling disappears. (C) 1999 El sevier Science S.A. All rights reserved.