Study on the Solid and Solution Properties of Sc³⁺ and Al³⁺ in (Tb, Sc)₃ (Sc, Al)₅O₁₂ Crystals Grown by the Czochralski Method

It is observed by spherical aberration-correctedtransmissionelectron microscopy that Sc3+ entered into the dodecahedronin the space where Tb3+ was located during the TSAG crystalgrowth. Crystals with a lower Sc content are not easy to crack duringthe growth and have high light transmittance and stronger magneto-opticalproperties. Terbium scandium aluminum garnet crystals (Tb3Sc2Al3O12, TSAG) have excellentopticalcomprehensive properties with unique competitive advantages in theVerdet constant and anti-laser damage threshold. However, the componentsegregation will easily occur during the growth of the TSAG crystaland the distribution habits of elements in crystals have not beensystematically studied. A series of TSAG crystals with different compositionswere grown by the Czochralski method in this work. The behaviors ofSc(3+) and Al3+ in TSAG crystal growth were discussed,and the relationship between TSAG crystal cracking and crystal structurewas deeply studied. The results show that the segregation coefficientof Al in the TSAG melt solid system is 1.02-1.03, while thatof Sc is 0.94-0.97. It is observed by spherical aberration-correctedtransmission electron microscopy that Sc3+ entered intothe dodecahedron in the space where Tb3+ was located duringthe crystal growth, which explains that the composition ratio of Tb:(Al+ Sc) in TSAG crystals was less than the stoichiometric ratio of 3:5.Crystals with a lower Sc content are not easy to crack during thegrowth and have high light transmittance (>80%), excellent thermalstability, and stronger magneto-optical properties.