Crystal structure and Eu 3+/Tb 3+ doped luminescent properties of a new borate Ba 3BiB 9O 18

Abstract

Undoped and doped either by Eu 3+ or Tb 3+ bismuth borate Ba 3BiB 9O 18 was structurally characterized and analyzed by fluorescence spectroscopy. Belonging to synthetic borate member of the family Ba 3XB 9O 18, layers of planar triangular B 3O 6 groups connecting with deformed BaO 6 hexagons are interleaved by 9-coordinate Ba atoms, and 6-coordinate Bi atoms. Its crystal structure was determined and refined from powder X-ray diffraction data by the Rietveld method and the results showed that Ba 3BiB 9O 18 belongs to space group P6 3/ m with unit cell dimensions of a = 7.1999(2) Å, c = 17.3567(6) Å, and z = 2. Curves of differential thermal analysis and thermogravimetric analysis showed that Ba 3BiB 9O 18 is a congruent melting compound and chemically stable above 728 °C. Ba 3Bi 1− x Eu x B 9O 18 and Ba 3Bi 1− x Tb x B 9O 18 form a continuous solid solution from x = 0.01 to x = 0.9. The ultraviolet excited photoluminescence intensity increased with both Eu 3+ and Tb 3+ concentration in the matrix of Ba 3BiB 9O 18. There may be an interesting correlation between spectroscopic properties and lattice structural features of doped Ba 3BiB 9O 18.