Raw data for the manuscript entitled "Direct evidence of low work function on SrVO₃ cathode using thermionic electron emission microscopy and high-field ultraviolet photoemission spectroscopy"

Electrically conductive perovskite oxide SrVO₃ with its low work function and facile synthesis process has become a very promising electron emission cathode candidate. The SrVO₃ cathode in polycrystalline pellet form has been reported to show a reproducible effective work function of about 2.7 eV, suggesting the presence of some fraction of even lower work function patch on the polycrystalline cathode surface. In this study, we used thermionic electron emission microscopy (ThEEM) to study the spatial local work function distribution on the partial [110] SrVO₃ cathode surface. ThEEM with a high applied electric field cancels the patch field effect and uncovers the lowest local work function of just 2.1 eV, which is much lower than [001] LaB₆ single crystal cathodes (2.7 eV) and comparable to B-type dispenser cathodes (2.1 eV). ThEEM measurement under high applied field also reveals observable electron emission at a very low temperature of just 750 ^oC. Overall, this study demonstrates that high applied electric field can uncover the lowest work function of SrVO₃ cathode surface, comparable to the DFT-predicted value of 2.3 eV of (110) SrVO₃ surface. And, if the areas of the low work function patches are increased, it can provide high emission current at reduced temperature and applied electric field which could significantly advance the electron emission cathode research field.This file contains all the raw data of the ThEEM measurement, thermionic and photoemission current measurements using ultra violet photo emission spectroscopy, electron backscatter diffraction (EBSD) measurement, field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) study on the SrVO3 cathode surface.<br>导电钙钛矿氧化物SrVO₃凭借其较低的功函数与简便的合成工艺，成为极具应用前景的电子发射阴极候选材料。已有研究报道，多晶颗粒形态的SrVO₃阴极可展现出约2.7 eV的可重复有效功函数，这表明该多晶阴极表面存在部分功函数更低的局域区域（功函数补丁）。本研究采用热电子发射显微镜（thermionic electron emission microscopy, ThEEM），对部分[110]取向的SrVO₃阴极表面的空间局域功函数分布展开研究。当施加外加高电场时，ThEEM可抵消功函数补丁带来的场效应，揭示出仅为2.1 eV的最低局域功函数——这一数值远低于[001]取向的六硼化镧（LaB₆）单晶阴极（2.7 eV），且与B型浸渍阴极（2.1 eV）相当。外加高电场下的ThEEM测量还发现，仅在750 ℃的极低温度下即可观测到明显的电子发射。综上，本研究证实，外加高电场可揭示SrVO₃阴极表面的最低功函数，该数值与密度泛函理论（DFT）预测的(110)晶面SrVO₃表面功函数（2.3 eV）基本一致。若提升低功函数补丁区域的占比，便可在更低的温度与外加电场条件下获得更高的发射电流，这将极大推动电子发射阴极领域的研究进展。本数据集包含SrVO₃阴极表面的热电子发射显微镜（ThEEM）测量、热电子与紫外光电子能谱（ultra violet photo emission spectroscopy）光电流测量、电子背散射衍射（EBSD）、场发射扫描电子显微镜（FESEM）以及能量色散X射线光谱（EDS）分析的全部原始数据。