Nanostructuring Phenomena in OxygenConducting Complex Oxides of Heavy REE 1

Abstract —In complex oxides of REE (Ln 4 M 3 O 12 (Ln = Tm, Lu; M = Zr, Hf), Ln 2 TiO 5 (Ln = Er–Yb)) andHo 2 TiO 5 , the following phase transitions of the orderdisorder type are studied for different cooling rates: rhombohedral δphase–defective fluorite in Ln 4 M 3 O 12 (Ln = Tm, Lu; M = Zr, Hf), pyrochlorlike phase–defectivefluoride in Ln 2 TiO 5 (Ln = Er–Yb), and hexagonal βphase–pyrochlor in Ho 2 TiO 5 . The presence of nanostructuring phenomena typical of fluoritelike polymorphous modifications of complex oxides in the Ln 2 O 3 –MO 2 (Ln = Ho–Lu; M = Ti, Zr, Hf) systems is confirmed. The conductivity of polymorphous modifications ofLn 4 Zr 3 O 12 (Ln = Tm, Lu;) and Ln 2 TiO 5 (Ln = Ho–Yb) with different thermal prehistory is studied. The comparative studies of the oxygenionic conduc tivity of fluorite and pyrochlorlike Ln 2 TiO 5 (Ln = Ho–Yb), pyrochlor Ho 2 TiO 5 , and βHo 2 TiO 5 and also of the conductivity of fluoritelike compounds and δLn 4 Zr 3 O 12 (Ln =Tm, Lu) are carried out. The oxygenionic conductivity of complex oxides in the Ln