Crystallization of langasite-type phases in gallium germanate glasses and optical properties of crystallized glasses

摘要

Langasite-type crystals such as Ba_3Ga_2Ge_4O_(14) and BaGa_4La_2Ge_2O_(14) are formed through the crystallization of gallium germanate glasses with stoichiometric compositions corresponding to langasite-type phases and optical properties of crystallized glasses are clarified. It is found that the single langasite-type phase is easily formed in each corresponding glass. The crystallized glasses with highly oriented langasite-type crystals at the surface are fabricated using an ultrasonic surface treatment method. The crystallized glasses with Ba_xGa_(5-x)La_(3-x)Ge_(1+x)O_(14) phases show moderate second harmonic (SH) intensities of 5-75 times as large as α-quartz, and it is found that the SH intensity of Ba_xGa_(5-x)La_(3-x)Ge_(1+x)O_(14) phases increases with the increase of the La~(3+)/Ba~(2+) ratio. The feature of fluorescence spectra of Eu~(3+) ions incorporated into langasite-type crystals is also discussed.