Zirconolite-rich ceramics were produced by the cold crucible melting
technique in an air atmosphere, at 1550±50 °C and 1 atm. Four samples with
overall composition (in wt.%): 4.9–14.3 CaO; 19.0–41.3 ZrO2;
24.1–42.6 TiO2; 1.3–11.3 Al2O3; 6.8–30.0
Gd2O3, and 1.1–8.5 SiO2 have been
studied. Total phases in the ceramics consist of major zirconolite and minor
rutile, perovskite, zirconia, aluminium titanate, and glass. The
Gd2O3 content in zirconolite reaches up to 31.4
wt.% corresponding to the formula:
(Cao4,Gd0.7)Zri.0(Tii4,Alo 5)070. The
data on the phase composition agree well with coupled Gd incorporation into
the mineral structure. Ca(H) + Ti(IV) = Gd(III) + Al(III), and 2Gd(III) -
Ca(II) + Zr(IV). The highest Gd contents observed in the other phases are
25.4 % for zirconia, 12.6 % in glass, 8.8 % in perovskite, and 1.4 % for
rutile. The rest of the elements' distribution in the samples are
analyzed.