A re-investigation of the crystal structure and luminescence of BaCa2MgSi2O8:Eu2+

✍ Scribed by Cheol-Hee Park; Tae-Hoon Kim; Yoshinori Yonesaki; Nobuhiro Kumada

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 741 KB
• Volume: 184
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2011.04.030

✦ Synopsis

BaCa 2 MgSi 2 O 8 Crystal structure Neutron diffraction data Eu 2 þ luminescence Site assignment a b s t r a c t Barium calcium magnesium silicate (BaCa 2 MgSi 2 O 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 2 MgSi 2 O 8 crystallizes in the trigonal space group P3 ¯(Z ¼ 1, a ¼ 5.42708(5) Å, c ¼ 6.79455(7) Å, V ¼ 173.310(4) Å3 ; R p /R wp ¼ 5.52%/7.63%), instead of the previously believed space group P3 ¯m1. The difference in the two structures arises from the displacement of the O2 atom. Blue emission from Ba 0.98 Eu 0.02 Ca 2 MgSi 2 O 8 under 325-nm excitation is ascribed to the 4f 6 5d 1 -4f 7 transitions of Eu 2 þ ions at Ba sites and Ca sites. Site assignment of Eu 2 þ ions in the titled compound was performed by analysis of emission spectra at temperatures in the range of 4.2-300 K.