Condensed Matter & Thermal Physics Group, MPA-10

Mössbauer Spectroscopy for Solid-State Research

R. Dean Taylor - team leader

Moshe Pasternak

Team description:

The Mössbauer Effect (ME), discovered in 1958 and available at LANL since 1959, is the recoil-free emission and absorption of gamma rays.  This surprising nuclear physics event provides a powerful tool to study the environment of certain resonant Mössbauer nuclei in a variety of solid-state hosts.  More than 90 γ-ray transitions in about 75 isotopes of over 42 different elements show some ME, but we currently are using only the ⁵⁷Fe and ¹¹⁹Sn isotopes, mostly in natural abundance absorbers.  Typical controlled variables are sample composition, temperature, pressure, and applied magnetic field.  From the spectra of the ME nucleus in its environment we may obtain detailed local information such as valence and spin states, magnetization, polarization, electric field gradient, lattice dynamics, phase transformations, and non-equivalent sites.  Our recent interests have been focused on the effect of very high applied static pressures on various iron oxides and compounds at pressures up to 1.2 megabars using diamond anvil cells.  In magnetite for example, we have shown that either temperature or pressure can drive the normal ↔ inverse spinel transformation. Two cryostats equipped with ME spectrometers and ancillary equipment are available.  New experiments can be considered.

MPA-10 TEAMS

Thermal Physics

• Thermoacoustics
• Nonlinear Dynamics
• Advanced Fuel Cycle Initiative R&D

Correlated Electrons

• Materials Synthesis and Characterization
• Transport and Thermodynamics
• Novel Materials at Extreme Conditions
• Very Low Temperature Physics

Actinide Chemistry

• Heavy-Element Chemistry

Low Energy Spectroscopy

• Condensed Matter NMR
• Photoelectron Spectroscopy
• Magnetic Resonance Force Microscopy
• Mossbauer Spectroscopy
• Neutron Scattering