Hydrothermal growth of Ti:sapphire (Ti3+: Al2O3) laser crystals

Titanium(III)-doped sapphire single crystals (Ti3+:Al2O3) have been grown by the hydrothermal technique for the first time. Due to Ti3+ instability, Ti:sapphire could not easily be grown in alkaline solution. Instead, we grew the crystals in acidic solutions. The solubility of Ti3+:Al2O3 in HCl hydrothermal solutions was found to exhibit a negative temperature coefficient. The grown crystals were characterized by X-ray diffraction, elemental analysis, and electron paramagnetic resonance (EPR). The results indicated that the grown crystals have a uniform distribution of Ti(III) (about 2×1020 atoms/cc) and are of high quality.