Oxoberyllates SrBeO2 and Sr12 Be17 O29 as Novel Host Materials for Eu2+ Luminescence.

Beryllate structures are marginally investigated, but show intriguing structural relations to oxo- and nitridosilicates. A typical feature is the coordination of Be in both trigonal planar and tetrahedral coordination by O. A broad range of structures is accessible by variable combinations of both building units. Three novel ternary Sr-oxoberyllates are characterized by single-crystal X-ray diffraction analysis, density functional theory calculations and investigations on luminescence properties: α-SrBeO2 , β-SrBeO2 and Sr12 Be17 O29 are obtained with oxoberyllate substructures, made up of either BeO3 triangles or BeO4 tetrahedra. The compounds can be described as chain- and layer-type beryllates. When excited with blue light of (In,Ga)N LED chips, β-SrBeO2 and Sr12 Be17 O29 show visible emission in the yellow and orange spectral range, respectively, upon doping with Eu2+ . Exceptional narrow-band yellow emission (λem =564 nm, fwhm=55 nm) makes β-SrBeO2 :Eu2+ a promising phosphor for application in phosphor-converted (pc-)LEDs.