-3- Res. Reports Asahi Glass Co., Ltd., 62 (2012) 12CaO・7Al2O3エレクトライドはサブナノポーラスな籠状結晶に電子を包接したユニークな酸 化物セラミックスである。包接された電子に由来して、仕事関数が2.4 eVとアルカリ金属並みに低 く、また、最大1.5×10 5 S/mの導電性を有する。本稿では、12CaO・7Al2O3エレクトライドを蛍光 ランプの陰極に応用し、ランプ特性の改善を検討した。12CaO・7Al2O3エレクトライドを使った 冷陰極蛍光ランプ(CCFL)は、一般的なニッケル製の陰極を用いたCCFLと比べて大電流(20 mA)で駆動でき、かつ、低消費電力であった。これは、スパッタ耐性や二次電子放出係数(γ係 数)が高いことに起因する。また、放電電流を増加すると電流密度18 mA/mm 2 で熱陰極モードへ 遷移することが確認され、DC 100mAで駆動した熱陰極蛍光ランプ(HCFL)は、1500時間以上 の連続点灯を達成した。 UDC:628.972:666.651.6 12CaO・7Al2O3 electride is unique oxide ceramics, having electrical conductivity up to 1.5x10 5 S/m and low work function as low as 2.4 eV which is almost at the same level as alkaline metals. In this report, cold and hot cathode fluorescent lamps using 12CaO・7Al2O3 electride cathode are introduced. CCFL with 12CaO・7Al2O3 electride is able to operate at high current as 20mA due to its high sputtering resistance. Moreover, power consumption of this lamp is lower than the lamp with nickel cathodes by higher secondary electron emission coefficients (γ) . Additionally, cold cathode - hot cathode transition is observed when current density is 18mA/mm 2 . HCFL with 12CaO・7Al2O3 electride cathode achieved continuous DC100mA operation for 1500 hours or more. 蛍光ランプ用 C12A7 エレクトライド陰極 12CaO・7Al 2 O 3 Electride Cathode for Fluorescent Lamps 渡邉俊成*・渡邉暁**・伊藤和弘***・宮川直通**** Toshinari Watanabe, Satoru Watanabe, Kazuhiro Ito and Naomichi Miyakawa *中央研究所 主席(E-mail: [email protected])Senior Researcher of Research Center **中央研究所 主席(E-mail: [email protected])Senior Researcher of Research Center ***中央研究所 主席(E-mail: [email protected])Senior Researcher of Research Center ****中央研究所 主幹(E-mail: [email protected])Principal Researcher of Research Center
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12CaO・7Al2O3 electride is unique oxide ceramics, having electrical conductivity up to 1.5x105 S/m and low work function as low as 2.4 eV which is almost at the same level as alkaline metals. In this report, cold and hot cathode fluorescent lamps using 12CaO・7Al2O3 electride cathode are introduced. CCFL with 12CaO・7Al2O3 electride is able to operate at high current as 20mA due to its high sputtering resistance. Moreover, power consumption of this lamp is lower than the lamp with nickel cathodes by higher secondary electron emission coefficients (γ). Additionally, cold cathode - hot cathode transition is observed when current density is 18mA/mm2. HCFL with 12CaO・7Al2O3 electride cathode achieved continuous DC100mA operation for 1500 hours or more.
蛍光ランプ用C12A7エレクトライド陰極
12CaO・7Al2O3 Electride Cathode for Fluorescent Lamps
渡邉俊成*・渡邉暁**・伊藤和弘***・宮川直通****Toshinari Watanabe, Satoru Watanabe, Kazuhiro Ito and Naomichi Miyakawa
*中央研究所 主席(E-mail: [email protected])Senior Researcher of Research Center**中央研究所 主席(E-mail: [email protected])Senior Researcher of Research Center***中央研究所 主席(E-mail: [email protected])Senior Researcher of Research Center****中央研究所 主幹(E-mail: [email protected])Principal Researcher of Research Center
Fig.4 Sputtering yields obtained by simulation for C12A7, Ni, and Mo.
Fig.5 Ion-induced secondary electron emission coefficients measured with Ne and Xe for C12A7 electride cathodes having an electron density of 1021 cm-3.
Fig.6 Schematic illustration of electronic structure of C12A7 electride, and ion-induced potential emission.
Fig.11 I-V property of HCFL with C12A7 electr ide electrode sealed at 60 torr of Ar gas. Electrode distance is 100 mm.
Fig.12 Voltage change of HCFL with C12A7 electride electrode. Discharge current is 100 mA in direct current.
Fig.13 Arc spot on C12A7 electride cathode when discharge current is 100 mA, and discharge gas is Ar at 60 torr. (a)Temperature change after discharge. (b)Appearance of arc spot at discharge.
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参考文献
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Fig.14 Current density of arc spot on C12A7:e- as a function of the temperature.