Growth and structure redetermination of a nonlinear BaAlBO3F2 crystal

Self-organized homo-epitaxial growth in nonlinear optical BaAlBO3F2 crystal crossing lines patterned by laser in glass

“…(1) BaAlBO 3 F 2 is an excellent candidate for high power ultra-violet (UV) solid state laser because of its high second and third harmonic optical nonlinearities, deep UV absorption edge, and high thresholds for laser-induced damage [29][30][31][32][33][34]. (2) BaAlBO 3 F 2 crystals are formed easily in 50BaF 2 -25Al 2 O 3 -25B 2 O 3 glass corresponding to the stoichiometric composition of BaAlBO 3 F 2 by heat treatment in an electric furnace, In order to clarify the orientation state of BaAlBO 3 F 2 crystals at the crossing, bending, and curved points in laser-patterned lines, we also need to select good experimental techniques.…”

“…In particular, when compared with other techniques such as TEM observations, the birefringence imaging enables to determine the crystal orientation in the wide range of crystal lines including bending and curved points. A nonlinear optical BaAlBO 3 F 2 crystal has a hexagonal structure (lattice constant a = 0.48770 nm and c = 0.93824 nm) and has a birefringence value of Dn = 0.046 at 532 nm (Dn = n o (1.6346) À n e (1.5890)) [31,34], and thus it is possible to apply the birefringence imaging technique to examine crystal orientation in laser-patterned lines. In this study, we use mainly the birefringence imaging obtained by POM observations.…”

“…Because the crystal structure of BaAlBO 3 F 2 is hexagonal, the crystal plane of the side of the first crystal line would correspond to the plane of ð10 10Þ or ð01 10Þ. Furthermore, the lattice constants of BaAlBO 3 F 2 crystal are a = 0.48770 nm and c = 0.93824 nm [34], and thus the following lattice missmatch is expected. The lattice miss-match for the combination of 10Þ//(0 0 0 1) because of the large strain energy arising from the large lattice miss-match.…”

“…BaAlBO 3 F 2 is a layered compound, in which AlO 3 F 2 trigonal bipyramids and [BO 3 ] 3À triangles are alternately arranged in a trigonal pattern and connected via common oxygen corners to generate a two-dimensional infinite [AlBO 3 F 2 ] layer parallel to the ab plane. Ba 2+ ions are located between these layers to balance charge and also to hold the layers together through the coordination with oxygen and fluorine atoms [34]. The average linear thermal expansion coefficients of the a-axis (i.e., along the a-axis direction) and of the c-axis (i.e., along the c-axis direction) in the temperature range of 30-800°C are 6.3 Â 10 À6 1/K and 48.1 Â 10 À6 1/K, respectively [33], indicating that two-dimensional infinite [AlBO 3 F 2 ] layers are stacked along the c-axis direction with relatively small bonding energy when compared with the a-axis direction.…”

Photoluminescence in cerium doped barium aluminium borate difluoride—BaAlBO3F2 glass ceramics

“…BaAlBO3F2 is nontoxic and also excellent material for high power UV light generation [13][14][15]. Recently Shionozaki et.al.…”