Growth and characterization of Fe:Ti:Al2O3 single crystal by floating zone method

• Floating zone growth of Fe:Ti:Al2O3 single crystals in different atmospheres.
• The crystal growth procedure and the best growth conditions are well characterized.
• The 646 cm−1 Raman peak is the evidence similar to the natural blue sapphire.
• The EPMA proves that iron is the main coloring element.
• The transmittance analysis exhibits high transmission (higher than 60% in argon).

Fe:Ti:Al2O3 single crystals were successfully grown by the floating zone (FZ) method in different atmospheres. The grown crystals, typically about 7–8 mm in diameter and 50–70 mm in length, have been obtained from the materials of Al2O3 doped with FeTiO3 and Fe2O3. The effect of the atmosphere on the growth was studied, and the obtained single crystals presented the best crystal quality when grown in argon. The optimum growth parameters by the FZ method for this single crystal were also studied in order to grow the highest quality single crystal. The crystal has been characterized by means of X-ray diffraction (XRD) and X-ray single crystal diffraction. Meanwhile, the Raman spectroscopy indicates that the single crystal grown in argon is similar to the natural blue sapphire. The transmittance was also measured by ultraviolet and visible spectrophotometry. Coloration mechanism in the single crystals of Fe:Ti:Al2O3 was analyzed by an electron probe X-ray microanalyser (EPMA). It is proved that iron is the main coloring element.