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Presents information on a study which measured the phonon density of states in thin films of polycrystalline alpha-iron by inelastic nuclear resonant scattering of synchrotron radiation. Experimental details; Results and discussion; Conclusions.

A new method is presented to calibrate an X-ray energy scale with sub-meV relative accuracy by using the detailed-balance principle of the phonon creation and annihilation. This method is conveniently used to define or verify the energy scale of high-energy-resolution monochromators that are used in inelastic X-ray scattering and nuclear resonant inelastic X-ray scattering instruments at synchrotron radiation facilities. This method does not rely on sample properties and its precision only depends on the statistical data quality. Well calibrated instruments are essential for reliable comparison of data sets obtained at different synchrotron radiation beamlines, of data with theoretical predictions, and of data from other techniques such as neutron or light scattering. The principle of the detailed-balance method is described in this paper and demonstrated experimentally. [ABSTRACT FROM AUTHOR]

Inelastic nuclear resonance scattering measurements, utilizing a submilli eV monochromator, were performed on natural Dy metal, dysprosium oxide, and intermetallic Laves and Chevrel phase dysprosium compounds. The inelastic spectrum directly yields the partial phonon density of states, and thus provides a wealth of information about the modes of vibration occurring in a lattice at the Mössbauer Dy site. The extraction of the partial phonon density of states from a broad range of materials containing dysprosium demonstrates the feasibility of material science studies. [ABSTRACT FROM AUTHOR]

We have measured the phonon density of states (PDOS) of isolated bcc and fcc FexAu1-x alloy nanoclusters (NCs) by nuclear resonant inelastic x-ray scattering. Drastic deviations were observed with respect to the PDOS of bulk Fe–Au alloys. Important information on the structure and thermodynamic properties of these NCs was obtained. [ABSTRACT FROM AUTHOR]

The 57Fe phonon partial density of states (PDOS) in L12-ordered Pd3Fe was studied at high pressures by nuclear resonant inelastic x-ray scattering (NRIXS) measurements and density functional theory (DFT) calculations. The NRIXS spectra showed that the stiffening of the 57Fe PDOS with decreasing volume was slower from 12 to 24 GPa owing to the pressure-induced Invar transition in Pd3Fe, with a change from a high-moment ferromagnetic (FM) state to a low-moment (LM) state observed by nuclear forward scattering. Force constants obtained from fitting to a Born-von Kármán model showed a relative softening of the first-nearest-neighbor (1NN) Fe-Pd longitudinal force constants at the magnetic transition. For the FM low-pressure state, the DFT calculations gave a PDOS and 1NN longitudinal force constants in good agreement with experiment, but discrepancies for the high-pressure LM state suggest the presence of short-range magnetic order. [ABSTRACT FROM AUTHOR]