Dj. Kim et Si. Pyun, Stress generation and annihilation during hydrogen injection into and extraction from anodic WO3 films, ELECTR ACT, 44(11), 1999, pp. 1723-1732
The present work is aimed at investigating the stress generation and releas
e during hydrogen injection into and extraction from anodic WO3 films in a
0.1 M H2SO4 solution using a laser beam deflection technique, combined with
cyclic voltammetry and potentiostatic current transients, For this purpose
the distribution of donor concentration was measured over the anodic oxide
film using the electrochemical impedance technique. From the experimental
results, it is suggested that the oxygen vacancies are inherently distribut
ed enriched in the 'layer' adjacent to the anodic WO3 film/W metal interfac
e. The attractive interactions operating between hydrogen and trap sites al
most completely release the tensile stresses which would be exerted on the
area adjacent to the oxygen vacancies in the absence of the attractive inte
ractions. The area next to the oxygen vacancies provides reversible and irr
eversible trap sites for hydrogen in the anodic WO3 film. It is concluded t
hat major compressive stresses developed during hydrogen injection into the
film are attributed to hydrogen positioned at reversibly active sites, whi
le minor compressive stresses are caused by hydrogen injection into reversi
ble and irreversible trap sites. (C) 1999 Elsevier Science Ltd. All rights
reserved.