Dowa Electronics Materials Co., Ltd.

The University of Tokyo

Canon Kabushiki Kaisha

Shiro Kuroki

Shin-ichi Ohkoshi

Shunsuke Sakurai

Shinya Sasaki

Kazuhito Hashimoto

Shinya Yachi

Kimitaka Sato

Kazumi Yoshizaki

Takeshi Kaburagi

Kenichi Nakayama

Asuka Namai

Hideki Kaneko

Nobuhisa Abe

Shin-Ichi Ohkoshi

Disclosed is a magnetic material comprising a crystal of &#x3b5;-GaFeO(wherein 0&#x3c;x&#x3c;1) prepared by substituting a part of Gaion sites of an &#x3b5;-FeOcrystal with Feions and having X-ray diffraction peaks corresponding to the crystal structure of &#x3b5;-FeO. The coercive force of the magnetic material lowers in accordance with the Ga content thereof, and the saturation magnetization thereof has a maximum value.

Magnetic material

Disclosed is a magnetic crystal for electromagnetic wave absorbing materials, having a structure of &#x3b5;-MFeOwith 0&#x3c;x&#x3c;1, which has the same space group as that of an &#x3b5;-FeOcrystal and which is derived from an &#x3b5;-FeOcrystal by substituting a part of the Fe site therein with M. In this, M is a trivalent element having an effect of lowering the coercive force Hc of &#x3b5;-FeOcrystal by the substitution. Concretely, the element M includes Al and Ga. An electromagnetic wave absorber having a packed structure of particles having such a substituent element M-added 'M-substituted &#x3b5;-FeOcrystal' as the magnetic phase may control the electromagnetic wave absorption peak frequency depending on the degree of substitution with the element M, and for example, the invention gives an electromagnetic wave absorber applicable to a 76 GHz band for on-vehicle radars.

Magnetic crystal for electromagnetic wave absorbing material and electromagnetic wave absorber

A magnetic material is provided that has an iron oxide phase whose principal phase is a crystal of a structure which has the same space group as &#x3b5;-FeOcrystal and in which Al is substituted for a portion of the Fe sites of the &#x3b5;-FeOcrystal. The molar ratio of Al to Fe in the iron oxide phase, when expressed as Al:Fe=x:(2&#x2212;x), satisfies 0&#x2266;x&#x2266;1. The value of x is preferably in the range of 0.3 to 0.7. The average particle diameter of the powder determined from a TEM image is preferably 5 to 200 nm, more preferably 10 to 100 nm. The magnetic material has very high practical value because it enables the extremely high coercive force Hc of the &#x3b5;-FeOcrystal to be regulated to a level enabling utilization in magnetic recording medium and various other applications. The magnetic powder can be produced by a method combining the reverse micelle method and the sol-gel method.

A magnetic material composed of &#x3b5;-InFeO(wherein 0&#x3c;x&#x2266;0.30) crystal in which In is substituted for a portion of the Fe sites of the &#x3b5;-FeOcrystal. The crystal exhibits an X-ray diffraction pattern similar to that of an &#x3b5;-FeOcrystal structure and has the same space group as that of an &#x3b5;-FeO. The In content imparts to the magnetic material a magnetic phase transition temperature that is lower than that of the &#x3b5;-FeOand a spin reorientation temperature that is higher than that of the &#x3b5;-FeO. The In content can also give the magnetic material a peak temperature of the imaginary part of the complex dielectric constant that is higher than that of the &#x3b5;-FeO.

Magnetic material, and memory and sensor using same

Growing community of inventors

Tokyo, Japan

Shiro Kuroki