Sc_2O_3掺杂对Y_2O_3-Gd_2O_3-HfO_2难熔稀土氧化物直热式阴极热发射性能的影响
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摘要
Y_2O_3-Gd_2O_3-HfO_2难熔稀土氧化物直热式阴极具有制备工艺简单,热发射电流密度大,次级电子发射系数大,寿命长等优点,在大功率连续波磁控管中具有很好的应用潜力。为进一步提高Y_2O_3-Gd_2O_3-HfO_2阴极的热发射性能,本文对该阴极的发射物质进行了不同比例Sc_2O_3的掺杂,结果表明,Sc_2O_3的掺杂能有效提高Y_2O_3-Gd_2O_3-HfO_2阴极的热发射电流密度,其中,掺杂10%(质量比)Sc_2O_3的Y_2O_3-Gd_2O_3-HfO_2阴极热发射电流密度在1500℃下达到5.3 A/cm~2,比未掺杂时提升了35.5%。由于在阴极激活过程中Sc_2O_3与Y_2O_3形成了固溶体,合成氧化物中Sc得到电子并释放出游离Sc,增强了涂层的导电性,所以,Sc_2O_3掺杂Y_2O_3-Gd_2O_3-HfO_2难熔稀土氧化物直热式阴极热发射性能具有显著提高。
The Sc_2O_3-doped Y_2O_3-Gd_2O_3-HfO_2 coatings,an advanced direct-heating cathode material with excellent thermal emission properties,were synthesized via solid state reaction of refractory and rare-earth metal oxides.The influence of the Sc_2O_3-doping on the thermal emission properties of Y_2O_3-Gd_2O_3-HfO_2 coatings was investigated with scanning electron microscopy and energy dispersive spectroscopy.The results show that the Sc_2O_3-doping effectively increased the emission current density of the cathode.To be specific,doping with 10%(wt) Sc_2O_3 increased the emission current density up to 5.3 A/cm~2 at 1500℃,35.5% higher than that of the un-doped cathode.The free Sc atoms,possibly released in formation of Sc_2O_3 and Y_2O_3 solid solution and considerably increasing the conductivity of Y_2O_3-Gd_2O_3-HfO_2 coatings,explained the mechanism responsible for the significant enhancement of thermal emission current density.
The Sc_2O_3-doped Y_2O_3-Gd_2O_3-HfO_2 coatings,an advanced direct-heating cathode material with excellent thermal emission properties,were synthesized via solid state reaction of refractory and rare-earth metal oxides.The influence of the Sc_2O_3-doping on the thermal emission properties of Y_2O_3-Gd_2O_3-HfO_2 coatings was investigated with scanning electron microscopy and energy dispersive spectroscopy.The results show that the Sc_2O_3-doping effectively increased the emission current density of the cathode.To be specific,doping with 10%(wt) Sc_2O_3 increased the emission current density up to 5.3 A/cm~2 at 1500℃,35.5% higher than that of the un-doped cathode.The free Sc atoms,possibly released in formation of Sc_2O_3 and Y_2O_3 solid solution and considerably increasing the conductivity of Y_2O_3-Gd_2O_3-HfO_2 coatings,explained the mechanism responsible for the significant enhancement of thermal emission current density.
引文
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