Fig. 3: High-pressure Mössbauer spectroscopy results at ambient and low temperature.
From: Correlated electron physics near a site-selective pressure-induced Mott transition in α-LiFe5O8
Selected Fe Mössbauer spectra of α-LiFe5O8 at various pressures and temperatures; at room temperature a, c and low temperatures b, upon compression a, b and decompression (c). Empty circles represent experimental data points whereas the black solid line through the data points represents the overall fit to the data from the sum of sub-components shown. Gray and pink shaded sub-components refer to the P4332 phase tetrahedral and octahedral sites, respectively, whereas olive dark-yellow and red sub-components represent the Cmcm phase HP1, HP2, and HP3 components, respectively. Pressure dependence of the isomer shift (IS), hyperfine field (HF) and abundances or area percentage extracted from best fits to the Mössbauer spectra of α-LiFe5O8 for (d) compression and (e) decompression cycles at RT. In (d) black squares and pink diamonds refer to parameters for the octahedral and tetrahedral sites of the P4332 phase, respectively, whereas dark yellow triangles, olive asterisks and red spheres in both (d) and (e) represent HP1, HP2 and HP3 components for the Cmcm phase, respectively. We note that in the case of SMS measurements (panel b) there is an appreciable delay in the HP1 to HP3 transformation compared to in-house measurements (panel a): even at 90 GPa the abundance of the HP1 component remains rather high, ~ 20%. This may be attributed to the different pressure transmitting media used and how the degree of non-hydrostaticity (strain and stress) affects the electronic transition58.
