STRUCTURAL AND MAGNETIC-PROPERTIES OF THE COMPLEX PEROVSKITE OXIDE BA2HOHFO5.5

The complex cubic perovskite oxide Ba2HoHfO5.5 in the Ho-Ba-Hf-O rare- earth based oxide system has been prepared by a solid-state reaction p rocess. Powder x-ray-diffraction studies show that Ba2HOHfO5.5 has an A(2)BB'O-6 complex cubic perovskite structure. The x-ray-diffraction s pectrum of single-phase Ba2HoHfO5.5 consists of strong peaks character istics of a primitive cubic ABO(3) perovskite plus a few weak reflecti on lines arising from the superlattice. The presence of significant in tensities of superstructure reflections in the x-ray spectrum of Ba2Ho HfO5.5 acts as a signature for an ordered complex cubic perovskite oxi de. Based on the doubling of primitive ABO(3) cubic perovskite unit ce lls, the lattice parameter of Ba2HoHfO5.5 calculated from the experime ntal x-ray diffraction is a=8.316 Angstrom. The real part of the ac ma gnetic susceptibility of Ba2HOHfO5.5, measured in the temperature rang e 5 to 300 K shows a Curie-Weiss behavior. Using a Curie-Weiss law fit ting we obtain an effective magnetic moment per Ho3+ ion in Ba2HoHfO5. 5 of 9.33 mu(B). This value is approximately 10% less than the spin-on ly moment (10.60 mu(B)) expected for an isolated Ho ion. [S0163-1829(9 8)01029-7].