Imperial College London
Portrait Picture

Nicholas M Harrison

Faculty of Natural Sciences, Department of Chemistry

Chair of Computational Materials Science
 
 
 
//

Contact

 

+44 (0)20 7594 5884nicholas.harrison Website

 
 
//

Location

 

401LMolecular Sciences Research HubWhite City Campus

//

Summary

 

Publications

Citation

BibTex format

@article{Napier:2019:10.1103/PhysRevApplied.11.064061,
author = {Napier, IA and Chang, V and Noakes, TCQ and Harrison, NM},
doi = {10.1103/PhysRevApplied.11.064061},
journal = {Physical Review Applied},
pages = {064061--1--064061--13},
title = {From electronic structure to design principles for photocathodes: Cu-Ba alloys},
url = {http://dx.doi.org/10.1103/PhysRevApplied.11.064061},
volume = {11},
year = {2019}
}
Download

RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Producing a metal photocathode with a low work function (WF), low emissivity, and high quantum efficiency is a matter of importance in the design of the next generation of free-electron laser facilities. General rules for the design of appropriate materials are currently unclear and difficult to elucidate from observations of structure-composition relationships of known photocathodes. In this work, high-quality density-functional-theory electronic structure calculations and a simple physical model are employed to develop design rules for photocathodes based on metallic alloys. A theoretical study of metal alloys for photocathode applications is presented, in which high WF, stable copper is paired with low WF, unstable barium in two alloys, Cu13Ba and CuBa. Surfaces terminating in a plane of Ba atoms have a lower computed surface energy than those terminating in Cu atoms due to surface segregation of the larger Ba atoms. This results in a significant surface dipole due to the interatomic charge transfer from the differences in electronegativity of the species. The details of the surface structure determine the direction of the dipole and thus have a strong influence on the computed WF. The computed WF of the Cu13Ba Ba-terminated (100) surface is even lower than that of pure Ba, at 1.95 eV. The computed quantum efficiency (QE) of the best-performing pure Cu surface is 5.86×10−6, whereas the best-performing Cu13Ba surface terminates in a plane of Ba atoms and has a significantly increased QE of 5.09×10−3. A surface terminating in two planes of Ba atoms, the (001) surface of CuBa, has an even higher computed QE of 1.38×10−2.
AU  - Napier,IA
AU  - Chang,V
AU  - Noakes,TCQ
AU  - Harrison,NM
DO  - 10.1103/PhysRevApplied.11.064061
EP  - 1
PY  - 2019///
SN  - 2331-7019
SP  - 064061
TI  - From electronic structure to design principles for photocathodes: Cu-Ba alloys
T2  - Physical Review Applied
UR  - http://dx.doi.org/10.1103/PhysRevApplied.11.064061
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000473042900002&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.11.064061
UR  - http://hdl.handle.net/10044/1/72093
VL  - 11
ER  -
Download