CZOCHRALSKI GROWTH OF PURE AND PR3-DOPED CATISIO5 AND CA2ZNSI2O7()

Pure and Pr3+-doped titanite (GaTiSiO5) single crystals of cm-size wer e obtained by the Czochralski method. Go-doping with Na+ was necessary to prevent a partial reduction of Ti4+ to Ti3+. The effective distrib ution coefficients k(eff) were 0.06 for Pr3+ and 0.008 for Na+, respec tively. Maximum doping levels of 0.07 mol% Pr3+ and 0.1 mol% Na+ were achieved. Growth of pure hardystonite (Ca2ZnSi2O7) yielded single crys tals of 40 mm in length and 10 mm diameter. In this case the evaporati on of ZnO led to CaSiO3 inclusions in the core of Pr3+-doped crystals. A k(eff) of 0.03 and a maximum doping level of 0.01 mol% were obtaine d. The phase diagram near the composition Ca2ZnSi2O7 of the quasi-bina ry system ZnO-CaSiO3 was reinvestigated by visual determination of the liquidus curve. Titanite and hardystonite crystals were characterized by optical absorption measurements, electron microprobe and inductive ly coupled plasma optical emission spectroscopy (IGP-OES) analyses.