Growth of Oxide Laser Crystals by Czochralski Method

The growth of series of actual laser crystals belonging to different structural types by the Czochralski method is presented. The primary attention is given to single crystalline compounds and their solid solutions with garnet structure (scandium-containing rare-earth garnets with general formula ${LnSc}_3[ScMe]_2Me_3O_{12}$, Me = Al, Ga) as well as with olivine (forsterite $Mg_2SiO_4$) and scheelite structure (double tungstates and molybdates with formula $NaLn(TO_4)_2$, where T = Mo or W). The broad bands of luminescence and absorption produced by activator ions in these laser hosts that appear either as a result of structural disorder (garnets, scheelites) or due to the doping by transition metal ions (chromium in forsterite) join together these representatives of different structural classes and determine their application in photonics. The paper considers the problems of growing of large crystals with uniform distribution of components and dopants, determination of congruently melting composition, especially in compounds with complex isomorphism. The mutual influence of components and dopants, redistribution of ions along crystallographically non-equivalent sites in the structure, alteration of valency of transition metal ions accompanied with the change of their segregation coefficients under variation of redox conditions is discussed.