Electromagnetic wave absorber and film forming paste
AssigneesThe University of Tokyo, Tokyo Ohka Kogyo Co., Ltd.
InventorsShin-ichi Ohkoshi, Asuka Namai, Marie Yoshikiyo, Takashi Ono
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Abstract
A radio wave absorber provided with a radio wave absorbing film formed on a substrate, the radio wave absorber being capable of absorbing radio waves over a broad frequency band and exhibiting superior radio wave absorbing properties even with a radio wave absorbing film thinner than 1 mm. A film forming paste suitable for forming a radio wave absorbing film that is provided in the radio wave absorber. In a radio wave absorber provided with a radio wave absorbing film formed on a substrate, a particular epsilon-type iron oxide is employed in the radio wave absorbing film and relative permittivity of the radio wave absorbing film is set to 6.5 to 65.
Claims9
A radio wave absorber comprising a radio wave absorbing film formed on a substrate, wherein:
- the radio wave absorber has a peak radio wave absorption in a frequency selected from a band of 60-270 GHz;
- the radio wave absorbing film comprises an epsilon-type iron oxide and a carbon nanotube;
- the epsilon-type iron oxide is at least one selected from the group consisting of an ε-Fe2O3 crystal and a crystal in which a crystalline structure and space group are the same as those of the ε-Fe2O3 crystal, wherein a portion of Fe sites in the ε-Fe2O3 crystal is substituted by an element M other than Fe, wherein the crystal is represented by a formula ε-MxFe2-xO3 wherein x is greater than 0 and less than 2;
- a relative permittivity of the radio wave absorbing film is 6.5 to 65;
- and
- the content of the epsilon-type iron oxide relative to total amount of the radio wave absorbing film is at least 30 mass %,
- wherein an amount of the carbon nanotube relative to the total amount of the radio wave absorbing film is in a range from 1 to 10% by mass.
A film forming paste comprising an epsilon-type iron oxide and a carbon nanotube, wherein the epsilon-type iron oxide is at least one selected from the group consisting of an ε-Fe2O3 crystal and a crystal in which a crystalline structure and space group are the same as those of the ε-Fe2O3 crystal, wherein a portion of Fe sites in the ε-Fe2O3 crystal is substituted by an element M other than Fe, wherein the crystal is represented by a formula ε-MxFe2-xO3 wherein x is greater than 0 and less than 2,
- wherein the film forming paste is capable of forming a film having a relative permittivity of 6.5 to 65, and
- wherein the content of the epsilon-type iron oxide relative to total amount of the radio wave absorbing film is at least 30 mass %,
- wherein an amount of the carbon nanotube relative to the total amount of the radio wave absorbing film is in a range from 1 to 10% by mass.
Dependencies are inferred from the claim text.