Demonstration of Low Work Function Perovskite SrVO 3 Using Thermionic Electron Emission

Lin Lin, Ryan Jacobs, Dongzheng Chen, Vasilios Vlahos, Otto Lu‐steffes, Jose A. Alonso, Dane Morgan, John Booske

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13 Scopus citations

Abstract

Engineering a material's work function is of central importance for many technologies and in particular electron emitters used in high-power vacuum electronics and thermionic energy converters. A low work function surface is typically achieved through unstable surface functional species, especially in high power thermionic electron emitter applications. Discovering and engineering new materials with intrinsic, stable low work functions obtainable without volatile surface species would mark a definitive advancement in the design of electron emitters. This work reports evidence for the existence of a low work function surface on a bulk, monolithic, electrically conductive perovskite oxide: SrVO3. After considering the patch field effect on the heterogeneous emitting surface of the bulk polycrystalline samples, this study suggests the presence of low work function (≈2 eV) emissive grains on SrVO3 surface. Emission current densities of 10–100 mA cm–2 at ≈1000 °C, comparable to commercial LaB6 thermionic cathodes, indicative of an overall effective thermionic work function of 2.3–2.7 eV are obtained. This study demonstrates that perovskites like SrVO3 may have intrinsically low work functions comparable to commercialized W-based dispenser cathodes and suggests that, with further engineering, perovskites may represent a new class of low work function electron emitters.

Original languageEnglish (US)
Article number2203703
Pages (from-to)2203703
JournalAdvanced Functional Materials
Volume32
Issue number41
DOIs
StatePublished - Oct 10 2022

Bibliographical note

Funding Information:
This work was funded by the Defense Advanced Research Projects Agency (DARPA) through the Innovative Vacuum Electronic Science and Technology (INVEST) program. The authors gratefully acknowledge use of facilities and instrumentation at the UW-Madison Wisconsin Centers for Nanoscale Technology (wcnt.wisc.edu) partially supported by the NSF through the University of Wisconsin Materials Research Science and Engineering Center (DMR-1720415). Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from the NSF through the MRSEC (Award Number DMR-2011401) and the NNCI (Award Number ECCS-2025124) programs. J.A.A. thanks the Spanish MINECO for funding the Project MAT2017-84496-R. Support for this research was provided by the University of Wisconsin-Madison, Office of the Vice Chancellor for Research and Graduate Education with funding from the Wisconsin Alumni Research Association. The authors gratefully acknowledge useful discussions with Chang-Beom Eom, Jason Kawasaki, Martin Kordesch and Bernard Vancil on the SrVO3 surface chemistry, as well as the support from Martin Kordesch on the heater fixture for thermionic emission testing.

Funding Information:
This work was funded by the Defense Advanced Research Projects Agency (DARPA) through the Innovative Vacuum Electronic Science and Technology (INVEST) program. The authors gratefully acknowledge use of facilities and instrumentation at the UW‐Madison Wisconsin Centers for Nanoscale Technology (wcnt.wisc.edu) partially supported by the NSF through the University of Wisconsin Materials Research Science and Engineering Center (DMR‐1720415). Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from the NSF through the MRSEC (Award Number DMR‐2011401) and the NNCI (Award Number ECCS‐2025124) programs. J.A.A. thanks the Spanish MINECO for funding the Project MAT2017‐84496‐R. Support for this research was provided by the University of Wisconsin‐Madison, Office of the Vice Chancellor for Research and Graduate Education with funding from the Wisconsin Alumni Research Association. The authors gratefully acknowledge useful discussions with Chang‐Beom Eom, Jason Kawasaki, Martin Kordesch and Bernard Vancil on the SrVO surface chemistry, as well as the support from Martin Kordesch on the heater fixture for thermionic emission testing. 3

Publisher Copyright:
© 2022 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH.

Keywords

  • patch field effect
  • perovskites
  • photoelectron spectroscopy
  • thermionic emissions
  • work function

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