Neutron Reflectometry

In-Situ Polarized Neutron Reflectometry Study of the Passive Film Growth on Fe-20Cr Alloy

“…For the PNR experiments, a neutron beam with a wavelength of 0.237 nm was polarized and the spin of the neutron beam was controlled using a spin flipper. 13,14,22 A magnetic guide field was provided along the neutron path to maintain the polarization of the neutron beam. The polarized neutron beam travelled through the Si wafer before it reached the alloy/electrolyte interface at a small grazing angle.…”

“…The polarized neutron beam travelled through the Si wafer before it reached the alloy/electrolyte interface at a small grazing angle. The intensity of the specular reflected beam was recorded at different grazing angles θ and the reflectivity curves were plotted as a function of the scattering vector Q which is related to the incident beam angle and the neutron wavelength by the following expression: 13,16…”

“…10 One of the challenges with the aforementioned in-situ techniques lies in their limited depth resolution that prevents the techniques from accessing more detailed information of the passive film composition and structure in the sub-nanometer regime. Polarized neutron reflectometry (PNR) which has been used to study thin films from the sub-nanometer regime up to about 200 nm thickness 13,14 is a nondestructive examination method and can be combined with electrochemical techniques to perform in-situ characterization of the passive film under controlled chemical and electrochemical conditions. The scattering length density (SLD) profile obtained from the measured reflectivity curves provides information about the thickness of layers in the sample, interfacial roughness, material density, and composition depth profile.…”

“…The scattering length density (SLD) profile obtained from the measured reflectivity curves provides information about the thickness of layers in the sample, interfacial roughness, material density, and composition depth profile. [13][14][15][16][17][18][19][20][21] In this study, we use PNR to study the passive film growth on an Fe-Cr alloy thin film in an alkaline environment.…”

Polarized Neutron Reflectometry of Metal Consumption and Passive Film Growth on Nickel Exposed to an Alkaline Deuterium Oxide (D2O) Solution

“…43,45,46 This technique provides a unique method to study the dissolution of metals and alloys in the passive state 47 and the evolution of passive films on metals and alloys in-situ.…”