PREPARATION, CRYSTAL-STRUCTURE, DIELECTRIC-PROPERTIES, AND MAGNETIC-BEHAVIOR OF BA2FE2TI4O13

The preparation, crystal structure, dielectric properties, and magneti c behavior of the new compound Ba2Fe2Ti4O13 are reported. Structural s tudies carried out by single-crystal X-ray diffraction and neutron pow der diffraction show that this phase is isostructural with K2Ti6O13 an d Ba2ZnTi5O13 (C2/m (No. 12); a = 15.216(1), b = 3.8979(3), c = 9.1350 (6) Angstrom, beta = 98.460(7)degrees; V = 535.90(8) Angstrom(3); Z = 2). The cations Fe3+ and Ti4+ are partially ordered among distorted oc tahedral sites with Ba2+ occupying eleven-coordinated polyhedra. Ba2Fe 2Ti4O13 exhibits TE(0) resonance near 10 GHz with a dielectric constan t of similar to 28 and a dielectric loss tangent of 2 x 10(-3). The co mpound displays complex paramagnetic behavior with marked field depend ence; the magnetization at 80 kA/m is several orders of magnitude smal ler than that of most ferrites. Spin-glass effects have not been obser ved; however, weak collective interactions are clearly present. No mag netic ordering has been detected by neutron diffraction down to 13 K. (C) Academic Press,Inc.