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Growth and characterization of YAl3(BO3)4 single crystal

Simon Ilas 1Alexandra Szemjonov 1Pascal Loiseau 1Gérard Aka 1Takunori Taira 2

1. Ecole Nationale Supérieure de chimie de Paris (ENSCP), 11 rue P. et M. Curie, Paris 75005, France
2. Institute for Molecular Science (IMS), 38 Nishigonaka, Myodaiji, Okazaki 444-8585, Japan

Yttrium aluminum borate (YAB) is a potential candidate for UV applications especially at 266 nm. Many flux can be used to growth YAB: Li2O-B2O3, Li2O-B2O3-Al2O3, Li2WO4-B2O3. Here the flux La2O3-B2Ois presented. Several undoped and Yb doped single crystals were grown. Physical parameters such as: thermal coefficients, absorption coefficent, refractive index and phase matching angles were determined. Moreover 14 % conversion efficiency from 532 to 266 nm were obtained using a YAB single crystal of 3 mm length.

The yttrium aluminum borate YAl3(BO3)4 (YAB) is a very promising nonlinear material for UV applications. YAB crystallizes in the space group R32. Its structure is built from [BO3]3- anionic groups. This material is currently widely studied because of its great potential for UV generation. In fact, it has a lot of good properties such as large NLO coefficient, moderate birefringence and good physical and chemical stability. The intrinsic UV cut-off wavelength was reported to be 160 nm. Nevertheless, one of the drawbacks is the hindered transparency of YAB crystals below 300 nm. Fe3+ ions can enter in the structure in substitution of Al3+ and cause some very efficient charge-transfer transitions between 300 and 200 nm. Moreover, the crystal growth is not well mastered yet. Because of its non-congruent melting, YAB crystals have to be grown using a flux. Many flux can be used: Li2O-B2O3 [1], Al2O3-Li2O-B2O3 [2], Li2WO4-B2O3 [3].

We present here the study of the flux La2O-B2O3. Several undoped and Yb doped crystals with weight of 15-20 g were obtained by cooling under air the melt in the temperature range: 1150 °C - 1100 °C. The average thermal expansion coefficients were determined: α1 = 4,3.10-6 K-1 and α3 = 1,23.10-6 K-1. The absorption coefficient at λ = 266 nm is α ≅ 2,9 cm-1. Measurement of refractive index and phase matching angle were determined. The environement of Yb3+ is studied by EPR and FTIR spectroscopy to evaluate the crystal quality. Moreover, crystals were cut in ZX plane for Type I SHG (532 --> 266 nm) (Fig. 1). 14 % conversion efficiency was obtained using a YAB single crystal of 3 mm length. The infrared source emits 1,6 mJ/pulse with a pulse duration of 500 ps at a frequency of 100 Hz. A 10 mm long type-I LiB3O5 (LBO) was used to obtain green power.YAB_266.JPG

Fig. 1: YAB single crystal cut in the ZX plane for 266 nm generation

[1]X. Yu et al, Journal of Crystal Growth, 312, 3029–3033 (2010)
[2]J. Yu et al, Journal of Crystal Growth, 341, 61-65 (2012)
[3]H. Liu et al, Materials Research Innovations, 15, 102-106 (2011)                                                  

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Related papers

Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 6, by Simon Ilas
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-04-12 14:40
Revised:   2013-07-23 18:23