Structural study of an amorphous NiZr2 alloy by anomalous wide angle X-ray scattering and Reverse Monte Carlo simulations

The local atomic structure of an amorphous NiZr2 alloy was investigated using the anomalous wide-angle x-ray scattering (AWAXS), differential anomalous scattering (DAS) and reverse Monte Carlo (RMC) simulations techniques. The AWAXS measurements were performed at eight different incident photon energies, including some close to the Ni and Zr K edges. From the measurements eight total structure factor S(K,E) were derived. Using the AWAXS data four differential structure factors DSFi(K,Em,En) were derived, two about the Ni and Zr edges. The partial structure factors SNi-Ni(K), SNi-Zr(K) and SZr-Zr(K) were estimated by using two different methods. First, the S(K,E) and DSFi(K,Em,En) factors were combined and used in a matrix inversion process. Second, three S(K,E) factors were used as input data in the RMC technique. The coordination numbers and interatomic distances for the first neighbors extracted from the partial structure factors obtained by these two methods show a good agreement. By using the three-dimensional structure derived from the RMC simulations, the bond-angle distributions were calculated and they suggest the presence of distorted triangular-faced polyhedral units in the amorphous NiZr2 structure. We have used the Warren chemical short-range order parameter to evaluate the chemical short-range order for the amorphous NiZr2 alloy and for the NiZr2 compound. The calculated values show that the chemical short-range order found in these two materials is similar to that found in a solid solution.Comment: Submitted to Phys. Rev. B, 8 figure

Investigation of the ferromagnetic order in crystalline and amorphous Fe2Zr alloys

We present the study of the ferromagnetic behaviour of crystalline and amorphous samples with identical composition Fe2Zr. The crystalline sample was obtained by arc melting. The two amorphous samples were obtained by mechanical grinding from the intermetallic crystalline phase and by mechanical alloying starting from the elements, respectively. We investigated the magnetic properties of the alloy using Mössbauer spectroscopy and superconducting quantum interference device magnetometry. The values of the Mössbauer parameters are reported and discussed. We present the initial magnetization curves and hysteresis loops. The magnetization behaviour is marked by saturation at low field values with very small values of remanent magnetization and coercive field, indicating that the samples are soft ferromagnets; this feature is more sharpened in the crystal. The mechanically grinded sample is more similar to the crystalline compound than the mechanically alloyed sample

Investigation of the ferromagnetic order in a crystalline Fe2Zr alloy

We present the study of the ferromagnetic behaviour of a crystalline Fe2Zr sample obtained by arc melting. Mossbauer spectroscopy measurements show that the sample is magnetically ordered at room temperature with ferromagnetic order. The magnetization behaviour obtained by superconducting quantum interference device magnetometry measurements indicates that the sample is a soft ferromagnet

anomalous X-Ray scattering on Sr and Sr-Eu metaphosphate glasses

The results of an Anomalous X-ray Scattering experiment performed on Sr(PO3)2 and Eu0.1Sr0.9(PO3)2.1 glasses are presented. These are the first measurements carried out on GILDA (General purpose Italian beamLine for Diffraction and Absorption) diffractometer, located at the European Synchrotron Radiation Facility (ESRF), Grenoble. To obtain detailed information about the local order on pure and Eu-doped Sr-metaphosphate glasses both samples were investigated near the Sr K-edge (16.107 KeV), while the latter was also studied near the Eu K-edge (48.517 KeV)