Graphite intercalation compound (GIC) crystal monochromators for cold neutron instruments: Characterization of KC24
Andrew J C Dennison1, Anton Devishvili1, Philipp Gutfreund2
1Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 751 20 Uppsala, Sweden.
The Review of Scientific Instruments
|March 2, 2021
Summary
Graphite intercalation compounds (GICs) are effective cold neutron monochromators. Ensuring GIC crystal purity is crucial for accurate neutron reflectometry data by preventing wavelength mixing.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Neutron Optics
Background:
- Graphite intercalation compounds (GICs) are layered materials.
- KC24 exhibits desirable properties like large lattice spacing (8.74 Å) and high reflectivity for cold neutron monochromators.
- GIC synthesis results in different stages, each with a specific d-spacing.
Purpose of the Study:
- To investigate the impact of GIC crystal purity and stage contamination on neutron reflectometry.
- To establish time-of-flight neutron diffraction as a method for characterizing GIC monochromators.
- To ensure the reliability of reflectometry measurements by accounting for wavelength contamination.
Main Methods:
- Characterization of GIC crystals using time-of-flight neutron diffraction.
- Analysis of neutron wavelength spectra reflected from GIC monochromators.
- Evaluation of GIC crystal purity and stage contamination.
Main Results:
- Impure GICs with multiple stages lead to mixed neutron wavelengths, complicating reflectometry data.
- Time-of-flight neutron diffraction provides an efficient and quantifiable measure of the reflected wavelength spectrum.
- This characterization method allows for the correction of wavelength contaminations.
Conclusions:
- GIC crystal purity is essential for high-quality neutron reflectometry.
- Time-of-flight neutron diffraction is a robust technique for assessing GIC monochromator quality.
- Accurate characterization of GICs enhances the reliability and precision of neutron reflectometry experiments.
