A newly designed ferromagnetic, ferroelectric compound, Bi(2)NiMnO(6), was prepared by high-pressure synthesis at 6 GPa. The crystal structure, as determined by synchrotron X-ray powder diffraction, is a heavily distorted double perovskite with Ni(2+) and Mn(4+) ions ordered in a rock-salt configuration. The presence of 6s(2) lone pairs of Bi(3+) ions and the covalent Bi-O bonds give ferroelectric properties with T(CE) of 485 K, while -Ni(2+)-O-Mn(4+)-O-Ni(2+)- magnetic paths lead to a ferromagnetism with T(CM) of 140 K. This simple material design to distribute two magnetic elements with and without e(g) electrons on B sites of Bi- and Pb-based perovkites can be applied to other Bi(2)M(2+)M'(4+)O(6) and Pb(2)M(3+)M'(5+)O(6) systems to search for newer ferromagnetic ferroelectrics.

No abstract

Epitaxial thin films of Bi 2 NiMnO 6 were synthesized on SrTiO 3 substrates by pulsed laser deposition. The resulting film had the rock-salt-type arrangement of Ni 2+ and Mn 4+ ions in a double-perovskite unit cell. The films clearly showed multiferroic properties, both ferromagnetic behavior with a Curie temperature of about 100 K and ferroelectric behavior with a saturated polarization of about 5 C/cm 2 .

Unter 15 GPa bei 1300 K entsteht CaCuII3FeIV4O12, das bei 210 K eine Ladungsdisproportionierung eingeht (2 FeIV→FeIII+FeV) und seine elektrischen und magnetischen Eigenschaften sowie seine Struktur verändert. Die FeIIIO6‐ und FeVO6‐Oktaeder sind wie die Ionen einer Steinsalzstruktur angeordnet (siehe Bild; Ca grau, O blau, Cu rot); die Tieftemperaturphase CuII(S=1/2,↓)3FeIII(S=5/2,↑)2 FeV(S=3/2,↑)2 ist ferrimagnetisch.