Preface

Hyperfine Interactions -     

Magnetic Properties of Nanocrystalline Fe x Cu1−x Alloys Prepared by Ball Milling

Hyperfine Interactions - X-ray diffraction, Mössbauer and magnetization measurements were used to study Fe x Cu1?x alloys prepared by ball-milling. The X-ray data show the formation of a...     

Mössbauer Studies of Fe0.7−x Si0.3Mn x Alloys

Hyperfine Interactions - In this work we present Fe57 Mössbauer study for the alloy system Fe0.7?x Si0.3Mn x , where 0≤x≤0.3. Mössbauer spectroscopic results show that...     

Atmospheric corrosion of mild steel in Oman

A systematic study has been made of the initial corrosion products which form on mild steel capons exposed near the coastal region of Oman and at some industrial areas. The phases and compositions of the products formed at different periods of exposure were examined by using Mössbauer spectroscopy (295 and 78 K) and X-ray diffraction (XRD) techniques. The results show that lepidocorcite and maghemite are early corrosion products and goethite starts to form after 2 months of metal exposure to the atmosphere. Akaganeite is an early corrosion product but it forms in marine environments only, which reflects the role of chlorine effect in the atmosphere. The 12 months coupons showed the presence of goethite, lepidocorcite and maghemite, but no akaganeite being seen in the products of one of the studied areas.     

Isomer shift,hyperfine field and magnetic structure in bcc Fe−Si alloys

The electronic and magnetic structures of disordered bcc Fe−Si alloys are calculated using the first principle discrete variational method. The contact charge density and hyperfine field are determined. It is concluded that the isomer shift results mainly from the screening by 3d electrons. The average magnetic moment is calculated and compared with experimental results.     

A structural and Mössbauer study of Y3Fe5O12 nanoparticles prepared with high energy ball milling and subsequent sintering

The influence of ball milling and subsequent sintering of a 3:5 molar mixture of Y₂O₃ and α-Fe₂O₃ on the formation of nanocrystalline Y₃Fe₅O₁₂ (YIG) particles is studied. Pre-milling the mixture for 100 h lowers the onset temperature at which the material forms to 900°C which is 200°C lower than that reported when a similar mixture of reactants was premilled for shorter times. A single-phased nanocrystalline Y₃Fe₅O₁₂ phase develops as a sole product when the pre-milled mixture is heated at 1,000°C (12 h). This temperature is ~300–400°C lower than those used to prepare the material conventionally. The bulk and surface crystal structure of the nanoparticles is studied with X-ray diffraction, Mössbauer spectroscopy, Atomic Force Microscope (AFM) and X-ray photoelectron spectroscopy.     

Magnetic and Mössbauer study of Mg0.9Mn0.1Cr x Fe2−x O4 ferrites

The ferrites Mg_0.9Mn_0.1Cr _x Fe_2?x O₄ ( The ferrites Mg_0.9Mn_0.1Cr _x Fe_2−x O₄ () were prepared using the conventional double sintering method. The XRD showed that the samples maintain a single spinel cubic phase. The M?ssbauer measurements were carried out at room and liquid nitrogen temperatures. From the area ratios of the A and B sites, it was found that the Fe cation population of the A and B sites decreases in proportion to Cr concentration. The contact hyperfine fields at the A and B sites were found to decrease with increasing Cr contents. This was found to be in approximate agreement with the results of magnetization measurement. The distributions of Mg and Mn cations versus Cr concentration were also determined using the M?ssbauer and magnetization results. The Curie temperatures were determined and found to agree with the reported values. As the Cr contents increases the relative magnetization, was found to increase at low temperatures and decreases at higher temperatures.     

The Formation of Lithiated Ti-Doped α-Fe2O3 Nanocrystalline Particles by Mechanical Milling of Ti-Doped Lithium Spinel Ferrite

Perturbed Angular Correlation method has been used to study the hyperfine magnetic field in the Heusler alloy Pd₂MnSb(Sn). Ion implantation of the recoil ¹¹¹In nuclei following heavy ion nuclear reactions ¹⁰⁸Pd(⁷Li, 4n)¹¹¹In and ¹⁰⁸Pd(⁶Li, 3n)¹¹¹In has been used to great advantage in the present case resulting in large implantation efficiency. Only a few hours of irradiation time with moderate beam current of the order of 400–500 nA resulted in sufficient implanted ¹¹¹In activity on the sample for good quality measurements. The hyperfine field was measured at ¹¹¹Cd probe nuclei substituting Mn and Sb(Sn) sites as a function of temperature. The fraction of ¹¹¹Cd nuclei occupying Mn atom sites was found to increases with the annealing of sample at higher temperatures.     

The hyperfine properties of a hydrogenated Fe/V superlattice

We study the effect of hydrogen on the electronic, magnetic and hyperfine structures of an iron-vanadium superlattice consisting of three Fe monolayers and nine V monolayers. The contact charge density (ρ), the contact hyperfine field (B_hf) and the electronic field gradient (EFG) at the Fe sites for different H locations and H fillings are calculated using the first principle full-potential linear-augmented-plane-wave (FP-LAPW) method. It is found that sizeable changes in the hyperfine properties are obtained only when H is in the interface region.     

Identification of Corrosion Products Due to Seawater and Fresh Water

Hyperfine Interactions - Mössbauer and X-ray diffraction (XRD) measurements were performed on corrosion products extracted from the inner surface of two different metal tubes used in a...