Structural and Thermal Properties of Tetragonal Double Tungstate Crystals Intended for Ytterbium Laser Composites
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- 作者：Xiumei Han ; Alberto Garcí ; a-Corté ; s ; Marí ; a Dolores Serrano ; Carlos Zaldo ; Concepció ; n Cascales
- 刊名：Chemistry of Materials
- 出版年：2007
- 出版时间：June 12, 2007
- 年：2007
- 卷：19
- 期：12
- 页码：3002 - 3010
- 全文大小：241K
- 年卷期：v.19,no.12(June 12, 2007)
- ISSN：1520-5002
文摘
Crystals of undoped and laser active Yb-doped NaT1-xYbx(WO4)2, T = Y (x = 0, 0.1), Lu (x = 0, 0.1,0.5), have been grown by the Czochralski (T = Y) or the top seeded solution growth (T = Lu) methods,depending on their melting nature, congruent or incongruent, respectively. From single-crystal X-raydiffraction analysis, the noncentrosymmetric tetragonal space group I
has been established for all ofthem. The Na+/T3+ (Yb3+) occupancy factors for 2b and 2d sites show the lowest departure from therandom distribution, and thus the largest cationic disorder, in NaLu0.9Yb0.1(WO4)2, namely 0.43/0.57 and0.56/0.44, respectively. The thermal expansion tensors have been determined up to 973 K for the fivecrystals; NaLu(WO4)2 with 
1=8.2(2) × 10-6 K-1 and 3= 17.3(4) × 10-6 K-1 coefficients has loweranisotropy than NaY(WO4)2 with 1= 8.4(2) × 10-6 K-1 and 3=18.5(4) × 10-6 K-1 coefficients. Fromthe point of view of the thermal steadiness, the evaluation of the Yb-doped laser layer/optically inertsubstrate lattice mismatch, about 2.5 times higher for NaY0.9Yb0.1(WO4)2/NY(WO4)2 than for NaLu0.9Yb0.1(WO4)2/NaLu(WO4)2 at temperatures up to 973 K, points out to this last set as the best simplecombination of tetragonal Na-based double tungstates intended for epitaxially grown laser activecomposites. An approach to minimize the laser layer/substrate lattice mismatch derived of the Ybincorporation in the layer is developed through the tailoring of the composition of its optically inertsubstrate.
has been established for all ofthem. The Na+/T3+ (Yb3+) occupancy factors for 2b and 2d sites show the lowest departure from therandom distribution, and thus the largest cationic disorder, in NaLu0.9Yb0.1(WO4)2, namely 0.43/0.57 and0.56/0.44, respectively. The thermal expansion tensors have been determined up to 973 K for the fivecrystals; NaLu(WO4)2 with 1=8.2(2) × 10-6 K-1 and 3= 17.3(4) × 10-6 K-1 coefficients has loweranisotropy than NaY(WO4)2 with 1= 8.4(2) × 10-6 K-1 and 3=18.5(4) × 10-6 K-1 coefficients. Fromthe point of view of the thermal steadiness, the evaluation of the Yb-doped laser layer/optically inertsubstrate lattice mismatch, about 2.5 times higher for NaY0.9Yb0.1(WO4)2/NY(WO4)2 than for NaLu0.9Yb0.1(WO4)2/NaLu(WO4)2 at temperatures up to 973 K, points out to this last set as the best simplecombination of tetragonal Na-based double tungstates intended for epitaxially grown laser activecomposites. An approach to minimize the laser layer/substrate lattice mismatch derived of the Ybincorporation in the layer is developed through the tailoring of the composition of its optically inertsubstrate.