Titanium Iodates with a Second-Harmonic-Generation Response.

Nonlinear-optical (NLO) crystal is an important photoelectric functional material. In this work, a new NLO titanium iodate, (HO)Ti(IO), along with Ti(IO) has been synthesized under facile conditions. The space group of (HO)Ti(IO) is the chiral noncentrosymmetric group 3 (No. 146), with an interesting three-dimensional framework, while that of Ti(IO) is the centrosymmetric space group 1̅ (No. 2) containing one-dimensional chains. Thermogravimetric analysis shows that (HO)Ti(IO) and Ti(IO) have no weight loss below 220 and 390 °C, respectively. In addition, (HO)Ti(IO) not only is thermally stable up to 200 °C in an air atmosphere but also is stable in water. (HO)Ti(IO) has a moderate-intensity second-harmonic-generation (SHG) response (1.4×KDP), a large laser-induced damage threshold (46×AgGaS), and high transmittance in the wavelength ranges of 0.5-1.4 and 2.5-10 μm. Both local dipole moment and systematic theoretical calculations reveal that the SHG response of (HO)Ti(IO) is mainly because of the combined effect of [TiO] octahedra and IO and IO units. In a word, (HO)Ti(IO) exhibits good NLO performances, as well as water resistance and facile growth of a single crystal with high quality, indicating its potential application as NLO materials in the visible and mid-IR regions, especially the visible region.