Sapphire crystals doped with transition metals such as chromium, vanadium and titanium have attracted the attention of scientists and engineers for many years primarily because of their applicability as high-power laser media and secondarily because of there marketability as synthetic gemstones. As a tunable laser medium, for example, transition-metal-doped sapphire crystals must exhibit a uniform trivalent dopant distribution. High quality titanium-doped sapphire single crystals, for instance, can produce high-power tunable lasers in the wavelength range of 670-1100 nm, and also provide pink synthetic gem stone.
Presently, Ti: Sapphire crystals are produced primarily by a method known as melt growth at very high temperatures often exceeding 2000° C. Melt growth inherently produces low quality crystals with high defect densities attributable to the high growth temperature. Additional drawbacks attendant to melt growth include high stress within the crystal and non-uniform distribution of the selected dopant(s).
Accordingly, there exists a need for a method, alternative to melt growth, for synthesizing sapphire crystals doped with trivalent transition metals including at least one of chromium, vanadium and titanium.