Pressure and temperature dependence of hyperfine field parameters of iron and its compounds by Synchrotron Mössbauer Spectroscopy

The pressure and temperature dependence of the hyperfine interaction parameters like internal hyperfine magnetic field, isomer shift, and quadrupole splitting have been measured with high precision using a pulsed synchrotron radiation source. The pressure range varied between ambient to 30 GPa, and the temperature range between 10 to 600 K. Taking advantge of a special "hybrid" filling mode of the Advanced Photon Source, we observed the nuclear decay of pure iron and several compounds over 6 lifetimes, reaching an accuracy of better than 0.1%. Relative isomer shift between bcc-iron and hcp iron is also measured with high precision, provining a direct measure of s-electron density at the iron nucleus due to phase change.