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Titanium Iodates with a Second-Harmonic-Generation Response.

Authors :: Fang YB
Fu RB
Tang HX
Shui QR
Ma ZJ
Wu XT
Source :: Inorganic chemistry [Inorg Chem] 2021 Apr 19; Vol. 60 (8), pp. 5821-5828. Date of Electronic Publication: 2021 Mar 29.
Publication Year :: 2021
Abstract: Nonlinear-optical (NLO) crystal is an important photoelectric functional material. In this work, a new NLO titanium iodate, (H <subscript>3</subscript> O) <subscript>2</subscript> Ti(IO <subscript>3</subscript> ) <subscript>6</subscript> , along with Ti(IO <subscript>3</subscript> ) <subscript>4</subscript> has been synthesized under facile conditions. The space group of (H <subscript>3</subscript> O) <subscript>2</subscript> Ti(IO <subscript>3</subscript> ) <subscript>6</subscript> is the chiral noncentrosymmetric group R 3 (No. 146), with an interesting three-dimensional framework, while that of Ti(IO <subscript>3</subscript> ) <subscript>4</subscript> is the centrosymmetric space group P 1̅ (No. 2) containing one-dimensional chains. Thermogravimetric analysis shows that (H <subscript>3</subscript> O) <subscript>2</subscript> Ti(IO <subscript>3</subscript> ) <subscript>6</subscript> and Ti(IO <subscript>3</subscript> ) <subscript>4</subscript> have no weight loss below 220 and 390 °C, respectively. In addition, (H <subscript>3</subscript> O) <subscript>2</subscript> Ti(IO <subscript>3</subscript> ) <subscript>6</subscript> not only is thermally stable up to 200 °C in an air atmosphere but also is stable in water. (H <subscript>3</subscript> O) <subscript>2</subscript> Ti(IO <subscript>3</subscript> ) <subscript>6</subscript> has a moderate-intensity second-harmonic-generation (SHG) response (1.4×KDP), a large laser-induced damage threshold (46×AgGaS <subscript>2</subscript> ), 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 (H <subscript>3</subscript> O) <subscript>2</subscript> Ti(IO <subscript>3</subscript> ) <subscript>6</subscript> is mainly because of the combined effect of [TiO <subscript>6</subscript> ] octahedra and IO <subscript>3</subscript> and IO <subscript>4</subscript> units. In a word, (H <subscript>3</subscript> O) <subscript>2</subscript> Ti(IO <subscript>3</subscript> ) <subscript>6</subscript> 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.