Gel combustion synthesis of LaxGd14–xB6Ge2O34 (x = 3 and 4) codoped with Yb3+–Er3+ and Yb3+–Tm3+ active ions

• Published in: Inorganic materials 2015, Vol.51 (12), p.1270-1276
• Main Authors: Krut’ko, V. A., Komova, M. G., Novikova, S. A., Pominova, D. V.
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Materials Science
• ISSN: 0020-1685; 1608-3172
• DOI: 10.1134/S0020168515120031

This paper reports the gel combustion synthesis of La x Gd 14– x Ge 2 B 6 O 34 ( x = 3 and 4) germanate borates codoped with Yb 3+ –Er 3+ and Yb 3+ –Tm 3+ active ions. The synthesized compounds are isostructural with Gd 14 Ge 2 B 6 O 34 and crystallize in trigonal symmetry (sp. gr. P 3 1 ). We have determined the unit-cell parameters of the synthesized mixed-cation germanate borates La 3 Gd 9.74 Yb 0.84 Tm 0.42 Ge 2 B 6 O 34 ( a = b = 9.794 Å, c = 25.7913 Å, V = 2143 Å 3 ) and La 3.16 Gd 10 Yb 0.7 Er 0.14 Ge 2 B 6 O 34 ( a = b = 9.746 Å, c = 25.7450 Å, V = 2118 Å 3 ) and assessed their thermal stability. The results demonstrate that the La x Gd 14– x Ge 2 B 6 O 34 ( x = 3 and 4) germanate borates codoped with Yb 3+ –Tm 3+ and Yb 3+ –Er 3+ active ions melt congruently at T = 1660 and 1700 K and crystallize with undercooling at T = 1620 and 1660 K, respectively. We have obtained an upconversion luminescence spectrum of the La 3.16 Gd 10 Yb 0.7 Er 0.14 Ge 2 B 6 O 34 germanate borate. The spectrum shows two bands. The stronger band (in the green region) corresponds to two transitions: 2 H 11/2 → 4 I 15/2 (λ = 525 nm) and 4 S 3/2 → 4 I 15/2 (λ = 550 nm). The weaker band (in the red region) corresponds to the Er 3+ 4 F 9/2 → 4 I 15/2 transition.