Abstract In this study, we prepared (4.8+x)BaO·CaO·2Al2O3 (0 ≤ x ≤ 1.6) aluminates by calcining the precursors under static air at 1500 °C for 120 min. The precursor powders were prepared using a liquid phase co-precipitation method. The effects of the molar content of BaO on the phase composition (before and after melting), melting properties, environmental stability, evaporation, and emission properties of the aluminates was investigated systematically The results showed that the phase of the aluminates completely transformed from Ba5CaAl4O12 to Ba3CaAl2O7 with an increase in the BaO content. After melting, the phase changed from Ba5CaAl4O12 to a mixed phase of Ba5CaAl4O12 and Ba3CaAl2O7. In the high-temperature molten state, the aluminates were in the ionic state, which generated a relatively low-energy Ba5CaAl4O12 phase during cooling crystallization. With every 0.4 mol increase in the BaO content, the initial melting temperature of the aluminates decreased by 10–20 °C, while the environmental stability deteriorated gradually. When the aluminates reacted with H2O and CO2 in the air, the original phase still existed and the characteristic peaks gradually broadened, but with the formation of Ca(OH)2, CaCO3, and BaCO3. At 1050 °C, with an increase in the BaO content, the evaporation rate of the Ba-W cathodes increased and the emission current density first increased and then decreased. The main components of the Ba-W cathode evaporation were Ba and BaO. At n(BaO):n(CaO):n(Al2O3) = 6:1:2, the Ba-W cathode showed the best emission performance, and its pulse emission current density at 1050 °C was as high as 35.31 A/cm2.

中文翻译：

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BaO对Ba-W正极铝酸盐相组成和性能的影响

摘要 在本研究中，我们通过在静态空气中在 1500 °C 下煅烧 120 分钟制备了 (4.8+x)BaO·CaO·2Al2O3 (0 ≤ x ≤ 1.6) 铝酸盐。使用液相共沉淀法制备前体粉末。系统研究了 BaO 摩尔含量对铝酸盐的相组成（熔化前后）、熔化性能、环境稳定性、蒸发和发射性能的影响 结果表明，铝酸盐的相完全由 Ba5CaAl4O12 转变为Ba3CaAl2O7 随着 BaO 含量的增加。熔化后，相从 Ba5CaAl4O12 转变为 Ba5CaAl4O12 和 Ba3CaAl2O7 的混合相。在高温熔融状态下，铝酸盐呈离子态，在冷却结晶过程中产生相对低能量的 Ba5CaAl4O12 相。BaO 含量每增加 0.4 mol，铝酸盐的初始熔化温度降低 10-20 °C，而环境稳定性逐渐恶化。当铝酸盐与空气中的 H2O 和 CO2 反应时，原相仍然存在，特征峰逐渐变宽，但形成了 Ca(OH)2、CaCO3 和 BaCO3。在 1050 °C 时，随着 BaO 含量的增加，Ba-W 阴极的蒸发速率增加，发射电流密度先增加后减小。Ba-W阴极蒸发的主要成分是Ba和BaO。在 n(BaO):n(CaO):n(Al2O3) = 6:1:2 时，Ba-W 阴极显示出最好的发射性能，其在 1050 °C 下的脉冲发射电流密度高达 35。