perature. The ferroelectric ferromagnets reported previously have anisotropic crystal structures and their polycrystalline form causes light to scatter. Conversely, in cubic structures, the scattering of light is suppressed and, hence, the present (PLZT) x (BiFeO 3 ) 1ยฑx solid solutions will allow optical properties to be studied.
In summary, we have succeeded in preparing (PLZT) x -(BiFeO 3 ) 1ยฑx solid solutions by the conventional solid-state reaction. The solid solutions for x = 0.10ยฑ0.45 exhibited both ferromagnetic and ferroelectric properties at room temperature. Their spontaneous magnetizations are due to the weak ferromagnetism resulting from the distortion of the antiparallel spin arrangement of unpaired electrons on Fe 3+ ions. The structures of the present solid solutions remained cubic over a wide compositional region. The present system is a suitable system for the study of optical properties because light can propagate through the cubic structure. Therefore, the present materials may allow us to develop novel types of optical devices based on the interaction between magnetic and electric properties.
Experimental
The (PLZT) x (BiFeO 3 ) 1ยฑx solid solutions were prepared by the conventional solid-state reaction with BiFeO 3 and PLZT(10/65/35) powders by the following procedures. The BiFeO 3 powder was prepared by mixing Bi 2 O 3 and a-Fe 2 O 3 powders via wet ball milling and heating at 800 C in a furnace for 2 h. The PLZT(10/65/35) powder was prepared by the co-precipitation method using PbO, La 2 O 3 , ZrO(NO 3 ) 2 , and TiCl 4 . The precipitated powder was calcined at 800 C in a furnace for 2 h. The mixed powders of BiFeO 3 and PLZT at various compositions were uniaxially pressed into disks with 1 mm thickness and 15 mm diameter. The disks were then sintered in a PbO atmosphere at 900 and 950 C in a furnace for 5 h, to obtain (PLZT) x (BiFeO 3 ) 1ยฑx solid solutions.
The crystal structures of the samples were identified by a Rigaku RINT 2100 X-ray diffractometer. Silicon powder was used as a reference material for the XRD spectra. Magnetization measurements were carried out using a Quantum Design MPMS 5 superconducting quantum interference device magnetometer (SQUID). Ferroelectric properties were measured by a Radiant Technologies RT66A Ferroelectric Test System at a constant applied field up to ยฑ 50 kV/cm at room temperature. For electrical measurements, the disks of the samples were mechanically thinned with 1000-grid Al 2 O 3 and then Pt electrodes were sputtered onto their surfaces.