Crystal structure, growth and characterization of LiPbB9O15: A new congruent melting nonlinear optical crystal

• A new congruent-melt NLO crystal LiPbB9O15 (LPBO) has been grown.
• The basic structural unit of LPBO is B3O7 group same as that found in LiB3O5.
• LPBO is phase matchable with SHG signal 10 times that of its Ba-analog.
• LPBO is highly transparent within 410–1700 nm with a UV cut-off of 261 nm.

A new congruent-melting crystal LiPbB9O15 (LPBO) has been grown and its structure was determined by single crystal X-ray diffraction. LPBO crystallizes in a polar space group R3c with a large unit cell of a=b=21.649(11) Å, c=17.193(11) Å, and Z=24. The basic anionic unit, (B3O7)5− group, is connected by terminal O atoms to build an infinite [(B3O5)−]n helical chain along the c axis. Second harmonic generation (SHG) measurements of the title compound indicate that LPBO can be phase matchable and its SHG coefficient is almost equal to that of KDP, which is about 3.3 times that of its analog BaLiB9O15. This significant enhancement of the SHG effect can be tentatively attributed to the lone pair Pb2+ cations with severely distorted coordination. LPBO has a wide transparent region from 410 to 2500 nm with a UV absorption edge about 261 nm according to the reflectance spectra.

The crystal structure of LiPbB9O15 composed of the (B3O7)5− anionic group and the lone pair Pb and Li polyhedra along c axis.Figure optionsDownload as PowerPoint slide