Synthesis, crystal structures and photoluminescence properties of new oxyborates, Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3}, with novel warwickite-type superstructures

Journal Article · Thu Sep 15 00:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.07.022· OSTI ID:21580245

Kawano, Tetsuya ^[1]; Yamane, Hisanori ^[1]

---

1. Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

Single crystals of new oxyborates, Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3}, were prepared at 1370 deg. C in air using B{sub 2}O{sub 3} as a flux. They were colorless and transparent with block shapes. X-ray diffraction analysis of the single crystals revealed Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3} to be isostructural. The X-ray diffraction reflections were indexed to the orthorhombic Pnma (No. 62) system with a=9.3682(3) A, b=9.4344(2) A, c=9.3379(3) A and Z=4 for Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and a=9.3702(3) A, b=9.4415(3) A, c=9.3301(2) A and Z=4 for Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3}. The crystal structures of Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3} are novel warwickite-type superstructures having ordered arrangements of Mg and Nb/Ta atoms. Polycrystals of Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} prepared by solid state reaction at 1200 deg. C in air showed broad blue-to-green emission with a peak wavelength of 470 nm under 270 nm ultraviolet excitation at room temperature. - Graphical abstract: Single crystals of new oxyborates, Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3}, were synthesized by a self flux method. They crystallize in novel warwickite-type superstructures having ordered arrangements of Mg and Nb/Ta atoms. Highlights: > Single crystals of two new oxyborates, Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3}, were prepared using B{sub 2}O{sub 3} as a flux. > Both oxyborates crystallize in isotypic novel warwickite-type superstructures with seven-fold coordinated Nb/Ta atoms. > Polycrystalline sample of Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} was prepared by solid state reaction. > Polycrystalline Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} exhibits broad blue-to-green emission with a peak wavelength of 470 nm under 270-nm excitation.

• OSTI ID: 21580245
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 9; Other Information: DOI: 10.1016/j.jssc.2011.07.022; PII: S0022-4596(11)00400-2; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BORATES
BORON OXIDES
EXCITATION
MAGNESIUM
MONOCRYSTALS
NIOBIUM
ORTHORHOMBIC LATTICES
PHOTOLUMINESCENCE
POLYCRYSTALS
SOLIDS
SYNTHESIS
TANTALUM
X-RAY DIFFRACTION
ALKALINE EARTH METALS
BORON COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DIFFRACTION
ELEMENTS
EMISSION
ENERGY-LEVEL TRANSITIONS
LUMINESCENCE
METALS
OXIDES
OXYGEN COMPOUNDS
PHOTON EMISSION
REFRACTORY METALS
SCATTERING
TRANSITION ELEMENTS