文摘
This paper reports the gel combustion synthesis of La x Gd14-em class="EmphasisTypeItalic ">x Ge2B6O34 (x = 3 and 4) germanate borates codoped with Yb3+–Er3+ and Yb3+–Tm3+ active ions. The synthesized compounds are isostructural with Gd14Ge2B6O34 and crystallize in trigonal symmetry (sp. gr. P31). We have determined the unit-cell parameters of the synthesized mixed-cation germanate borates La3Gd9.74Yb0.84Tm0.42Ge2B6O34 (a = b = 9.794 ?, c = 25.7913 ?, V = 2143 ?3) and La3.16Gd10Yb0.7Er0.14Ge2B6O34 (a = b = 9.746 ?, c = 25.7450 ?, V = 2118 ?3) and assessed their thermal stability. The results demonstrate that the La x Gd14-em class="EmphasisTypeItalic ">x Ge2B6O34 (x = 3 and 4) germanate borates codoped with Yb3+–Tm3+ and Yb3+–Er3+ 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 La3.16Gd10Yb0.7Er0.14Ge2B6O34 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 Er3+ 4 F 9/2?4 I 15/2 transition. Original Russian Text ? V.A. Krut’ko, M.G. Komova, S.A. Novikova, D.V. Pominova, 2015, published in Neorganicheskie Materialy, 2015, Vol. 51, No. 12, pp. 1367-373.