Composition of the first atomic layers of (0 0 1)-oriented AuCu 3 crystal measured with the use of directional Auger electron spectroscopy at 400 K< T

Abstract

Changes of the composition of the first, second, and third atomic layers of (0 0 1)-oriented AuCu 3 crystal having the bulk order–disorder transition at T c =663 K were determined with the use of Auger peak heights for Au and Cu M 23VV transitions recorded with the retarding field analyzer for the incidence angle of the primary electron beam equal to 8° and 60°, for the sample temperature ranging from 400 to 1000 K. The relative atomic concentration of gold in the first atomic layer (Au1) remains almost constant from 630 K (Au1≈0.47) to 900 K (Au1≈0.45). Above 900 K the decrease is much faster and Au1 approaches 0.35 at 1000 K. The relative atomic concentration of gold in the second atomic layer (Au2) remains constant and equal to about 0.17 from 630 to 900 K. Above 900 K it increases up to 0.31 at 1000 K. However, a large systematic error is possible in Au2 determination. No specific changes of Au1 and Au2 are observed in the vicinity of the bulk order–disorder transition temperature T c . The relative atomic concentration of gold in the third atomic layer Au3 starts to decrease in the vicinity of T c and this decrease lasts up to 900 K. The presented results are compared with the theoretical and experimental literature data. Apart from some common general trends, appreciable quantitative differences are indicated.