We show that the anomalous thermal expansion behavior of Pu-Ga alloys can be explained by an invar effect, which is modeled by assuming the thermal transfer of Pu atoms from a lower-energy, higher-volume δ1 state to a higher-energy, lowervolume δ2 state. From a fit to the available neutron diffraction data on the lattice constants of Pu-Ga alloys, the energy separation of these states is found ...

We have investigated the vibrational anharmonicity and quantum effects in the Invar alloy Fe64.6Ni35.4 which shows anomalously small thermal expansion. We have performed Fe and Ni K-edge EXAFS spectroscopic measurements and computational simulations based on the path-integral effective-classical-potential theory. The first nearest-neighbor (NN) shells around Fe showed almost no thermal expansio...

We report thermal expansion measurements on Ca(Fe 1−x Co x) 2 As 2 single crystals with different thermal treatment, with samples chosen to represent four different ground states observed in this family. For all samples, thermal expansion is anisotropic with different signs of the in-plane and c-axis thermal expansion coefficients in the high temperature, tetragonal phase. The features in therm...

We have investigated the anharmonicity and quantum effects in the Invar alloy Fe(64.6)Ni(35.4) that shows anomalously small thermal expansion. We have performed Fe and Ni K-edge extended x-ray-absorption fine-structure spectroscopic measurements and the computational simulations based on the path-integral effective-classical-potential theory. The first nearest-neighbor (NN) shells around Fe sho...