Chemical modification of B4C films and B4C/Pd layers stored in different environments

Abstract

B4C/Pd multilayers with small d‐spacing can easily degrade in the air, and the exact degradation process is not clear. In this work, we studied the chemical modification of B4C films and B4C/Pd double layers stored in four different environments: a dry nitrogen environment, the atmosphere, a dry oxygen‐rich environment, and a wet nitrogen environment. The XANES spectra of the B4C/Pd layers placed in a dry oxygen‐rich environment showed the most significant decrease in the σ* states of the B–C bonds and an increase in the π* states of the B–O bonds compared with the other samples. X‐ray photoelectron spectroscopy (XPS) measurements of the samples placed in a dry oxygen‐rich environment showed more intensive B‐O binding signals in the B4C/Pd layers than in the single B4C film. The results of the Fourier‐transform infrared spectroscopy (FTIR) showed a similar decrease in the B–C bonds and an increase in the B–O bonds in the B4C/Pd layers in contrast to the single B4C film placed in a dry oxygen‐rich environment. We concluded that the combination of palladium catalysis and the high content of oxygen in the environment promoted the oxidization of boron, deteriorated the B4C composition.