X-ray structural determination of a multilayered magnetic dielectric ceramic Ba42Ti51Fe20O174 in the BaO-TiO2-Fe2O3 system

摘要

Crystallographic studies and refinement of a native multilayered phase (Ba42Ti51Fe20O174), occurring in the BaO-TiO2-Fe2O3 System for a Ba:Ti:Fe composition close to 2:2:1, were undertaken using synchrotron X-ray powder diffraction. In this area of the BaO-TiO2-Fe2O3 phase diagram, numerous ternary compounds were found for extremely close chemical and thermal conditions and multilayered phases were always prepared together with a few adjacent phases. The structure of the multilayered compound (Ba42Ti51Fe20O174: space group C2/m, a = 9.9512(2) Angstrom, b = 17.2366(4) Angstrom, c = 42.5272(2) Angstrom, alpha = 90degrees, beta = 94.4949(5)degrees, gamma = 90degrees, V = 7272.04 Angstrom(3), rho = 5.62 g/cm(3), Z = 2) has been solved by Rietveld analysis of a multiphase pattern containing two other known phases (Ba12Ti15Fe28O84: space group. C2/m, a = 9.9792(2) Angstrom, b = 17.2883(6) Angstrom, c = 19.1714(4) Angstrom, alpha = 90degrees, beta = 99.7253(6)degrees, gamma = 90degrees, V = 3260.04 Angstrom(3), rho = 5.30 g/cm(3), Z = 2, and c-Ba-Ti0.925Fe0.075O3: space group Pm (3) over barm, a = 4.00779(1) Angstrom, alpha = beta = gamma = 90degrees, V = 64.38 Angstrom(3), rho = 6.04 g/cm(3), Z = 1). This multilayered structure adopts a 54-layer close-packed structure built with a (chcehhhhcchhhhcchc)(3) (Ba,O) stacking along the c-axis to give rise to a very long (c(rh) = 127.19 Angstrom) rhombohedral c-axis. Octahedral sites are occupied by a mixture of Ti4+ and Fe3+ cations and tetrahedral ones by Fe3+ cations. (C) 2002 Elsevier Science (USA). [References: 21]