Preprints of Annual Meeting of The Ceramic Society of Japan<br> Preprints of Fall Meeting of The Ceramic Society of Japan

The borate glasses containing F and S element were perapered and the hole burning properties were measured. The partially crsytallied glasses showed the interesting hole burning properties.

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The synthesis of monodisperse iron oxide nanoparticles has long been of scientific and technological interest. Its particle dispersions have been widely used as ferrofluid. The use of coated iron oxide nanoparticles in clinical medicine has also intensified. All these applications require that the nanoparticles are superparamagnetic with sizes smaller than 20 nm and narrow overall particle size distribution so that the particles have uniform physical and chemical properties. Here we report two simple routes to monodisperse iron oxide nanoparticles. One is the high-temperature reaction of iron (III) acetylacetonate in organic solvents, and the other is the bionic synthesis in side the apo-ferritin.

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Usually, in the system of AlN with Y₂O₃ additive, first of all, yttrium aluminate is produced as a grain boundary phase. And, by further heat treatment in nitrogen-reducing atmosphere, it is found that yttrium aluminate at grain boundary is transformed into conductive material from the surface. As a result, fortunately, we found AlN containing conductive material as a grain boundary phase showed electrical conductivity. The purpose of this study is to fabricate electrically conductive AlN ceramics with high thermal conductivity, and to control the electrical conductivity by addition of a small amount of CeO₂, which is easily reduced compared with Y₂O₃. In this presentation, we will report the effect of fabrication conditions on properties of electrically conductive AlN ceramics.

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For magnetoelectric effect --- induction of magnetization by anelectric field or of polarization by a magnetic field, although it waspredicted thereotically early in the 1894 and demonstrated inexperiments twenty years later, the developments were very much slowowing to very few systems of magneticferroelectrics in nature\cite{fiebig,hill}. In the recent five years, it comesinto a revival accompanying the development of materialsciences. Besides magnetic/ferroelectric composites, manysingle phase materials with linear magnetoelectric effect arefound\cite{fiebig}. In order to obtain excellent high temperaturemagnetoelectric effect, one of strategies is to make use of solid solutionof magnetic and ferroelectric materials. Here, we reported several solid solution systems ofBiFeO$_3$(LaFeO$_3$,LaCrO$_3$)-Bi$_4$Ti$_3$O$_{12}$,Bi$_5$Fe$_2$Ti$_2$O$_{15}$, Bi$_3$FeTiO$_9$, andBi$_2$FeCrO$_6$ prepared with various methods ofconventional solid state reaction, sol-gel, coprecipitation, andhydrothermal. X-ray diffraction and magnetic succeptibilitymeasurements indicated that their homogeneous single phases wereobtained successfully. The magnetic properties were discussed from the viewpoint of superexchangeinteraction. Except the case of Bi$_2$FeCrO$_6$, they are not goodcandidates for magnetoelectric materials as expectedpreviously\cite{singh,james,zhang}. For the case of Bi$_2$FeCrO$_6$,it exhibits one magnetic transition at about 140K, which is alsodifferent from recent thereotical calculations\cite{spaldin:bf,spaldin:bcf}.

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