Text this: Calculation of the isomorfic mixture limit in the system Ln<sub>3</sub>[M]<sub>2</sub>M<sub>3</sub>O<sub>12</sub> - Ln<sub>3</sub>[Sc]<sub>2</sub>M<sub>3</sub>O<sub>12</sub> (Ln = La-Lu,Y; M = Ga, Al)