A re-investigation of the crystal structure and luminescence of BaCa{sub 2}MgSi{sub 2}O{sub 8}:Eu{sup 2+}

Journal Article · Wed Jun 15 04:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.04.030· OSTI ID:21580119

Park, Cheol-Hee ^[1]; Kim, Tae-Hoon ^[1]; Yonesaki, Yoshinori; Kumada, Nobuhiro ^[2]

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1. LG Chem Research Park, Daejeon 305-380 (Korea, Republic of)
2. University of Yamanashi, Miyamae-Cho 7-32, Kofu 400-8511 (Japan)

Barium calcium magnesium silicate (BaCa{sub 2}MgSi{sub 2}O{sub 8}), a compound whose space group was obtained via X-ray diffraction data, was re-investigated using neutron diffraction techniques. A combined powder X-ray and neutron Rietveld method revealed that BaCa{sub 2}MgSi{sub 2}O{sub 8} crystallizes in the trigonal space group P3-bar (Z=1, a=5.42708(5) A, c=6.79455(7) A, V=173.310(4) A{sup 3}; R{sub p}/R{sub wp}=5.52%/7.63%), instead of the previously believed space group P3-bar m1. The difference in the two structures arises from the displacement of the O2 atom. Blue emission from Ba{sub 0.98}Eu{sub 0.02}Ca{sub 2}MgSi{sub 2}O{sub 8} under 325-nm excitation is ascribed to the 4f{sup 6}5d{sup 1}{yields}4f{sup 7} transitions of Eu{sup 2+} ions at Ba sites and Ca sites. Site assignment of Eu{sup 2+} ions in the titled compound was performed by analysis of emission spectra at temperatures in the range of 4.2-300 K. - Graphical abstract: A combined powder X-ray and neutron Rietveld method reveals that BaCa{sub 2}MgSi{sub 2}O{sub 8} crystallizes in the trigonal space group P3-bar , instead of the previously believed space group P3-bar m1 from X-ray diffraction data. Highlights: > Re-investigation of the structure using neutron diffraction data. > The correct space group is P3-bar , not P3-bar m1. > Identification of Eu{sup 2+} sites using temperature-variable luminescence.{yields} The emission at the shorter wavelength corresponds to the Ba site in the compound.

• OSTI ID: 21580119
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 6 Vol. 184; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
BARIUM
BARYONS
CALCIUM
CHARGED PARTICLES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ELEMENTS
EMISSION
EMISSION SPECTRA
ENERGY-LEVEL TRANSITIONS
EUROPIUM IONS
EXCITATION
FERMIONS
HADRONS
IONIZING RADIATIONS
IONS
LUMINESCENCE
MAGNESIUM COMPOUNDS
MAGNESIUM SILICATES
METALS
NEUTRON DIFFRACTION
NEUTRONS
NUCLEONS
OXYGEN COMPOUNDS
PHOTON EMISSION
RADIATIONS
SCATTERING
SILICATES
SILICON COMPOUNDS
SPACE GROUPS
SPECTRA
SYMMETRY GROUPS
TRIGONAL LATTICES
X RADIATION
X-RAY DIFFRACTION