ABSTRACT The authors studied deposits from combustion chambers of high-pressure engines supplied ... more ABSTRACT The authors studied deposits from combustion chambers of high-pressure engines supplied with standard fuel (SO) and ecological fuel of City-Diesel type. Chemical analysis, X-ray diffractograms, Mössbauer absorption and additionally Raman wavenumber measurements were made. The wearing of some engine elements was examined by the profilometric method. By using ecological fuel, the deposits were shown to contain four to five times less iron compounds than standard fuel supply. This accounts for a smaller attrition of the combustion chamber elements, and thus longer durability of the engine.
ABSTRACT The authors studied deposits from combustion chambers of high-pressure engines supplied ... more ABSTRACT The authors studied deposits from combustion chambers of high-pressure engines supplied with standard fuel (SO) and ecological fuel of City-Diesel type. Chemical analysis, X-ray diffractograms, Mössbauer absorption and additionally Raman wavenumber measurements were made. The wearing of some engine elements was examined by the profilometric method. By using ecological fuel, the deposits were shown to contain four to five times less iron compounds than standard fuel supply. This accounts for a smaller attrition of the combustion chamber elements, and thus longer durability of the engine.
Nanoparticles of manganese ferrite were obtained by the impregnation of highly ordered mesoporous... more Nanoparticles of manganese ferrite were obtained by the impregnation of highly ordered mesoporous MCM-41 silica support. The investigated sample contained 20% wt. Fe. The obtained nanocrystallites were strongly dispersed in silica matrix and their size was about 2 nm. The sample annealing at 500°C led to increase of particle size to about 5 nm. The Mössbauer spectroscopy investigations performed at room temperature show on occurrence of MnFe2O4 nanoparticle in superparamagnetic state for the sample annealed in all temperatures. The coexistence of superparamagnetic and ferromagnetic phase was observed at liquid nitrogen temperature. The sample annealed at 400°C and 500°C has bigger manganese ferrite particle and better crystallized structure. One can assign them the discrete hyperfine magnetic field components.
The intermetallic pseudobinary compounds Sc(Fe1−xNix)2 exhibit the C15 cubic Laves phase structur... more The intermetallic pseudobinary compounds Sc(Fe1−xNix)2 exhibit the C15 cubic Laves phase structure over the whole concentration range except for x = 0. Pure ScFe2 shows either the hexagonal C14 or the dihexagonal C36 structure when it crystallizes at high temperatures (1473 < T < 1838 K) [3]. From our earlier investigations, it is known that ScFe2 with the C36 structure (hP24, space group P63/mmc) is ferromagnet with TC = 642 K. In this structure, Fe atoms occupy three non-equivalent positions: 6g, 6h and 4f (Wyckoff notation) and have magnetic moments equal to 1.31(1), 1.78(1) and 1.52(1) μB at RT, respectively. The mean value of hyperfine magnetic field in this compound amounts to 18.2(2) T. The theoretical calculations of band structure for ScFe2 with the C15 cubic structure give the magnetic moment of Fe atom of 1.56 μB and predict occurrence of antiparallel induced magnetic moments of about 0.52 μB at Sc atoms [1]. NMR Sc measurements in the polymorphic C15 form of ScFe2 ...
The diversity of magnetic phenomena due to 3d-3d exchange interactions present in alloys and inte... more The diversity of magnetic phenomena due to 3d-3d exchange interactions present in alloys and intermetallic compounds was a matter of interest for a long time [4]. Among the large number of such materials, the binary Laves phases with comparatively simple crystal structure give the possibility of substituting the 3d metals with each other or non-magnetic sp elements without changing the crystal structure over a wide range of compositions. This appears to be one of the main advantages of pseudobinary alloy systems compared with binary alloys to investigate the onset of magnetism as a function of alloy composition. For example, it is known that Cu has a very low solubility in metallic Fe of the order of 2 at.% at 600 K [1] and the Cu solubility in Sc not exceeds 0.5% at 865 K [10]. In the quasibinary system Sc-Fe-Cu, where Fe atoms are gradually substituted for Cu atoms, an initial ScFe2 compound belongs to the Laves phases. It has hexagonal C36 structure (hP24, space group P63/mmc) an...
Systems of the (T1−xT’ x)Fe2-type (where T = Y, Nb, Ti and T’ = Sc, Zr) have been extensively inv... more Systems of the (T1−xT’ x)Fe2-type (where T = Y, Nb, Ti and T’ = Sc, Zr) have been extensively investigated. In many such pseudobinary systems interesting magnetic and structural properties were observed [6, 8, 11]. In the cubic C15 YFe2 phase (MgCu2-type, space group Fd3m) Fe atoms (16d positions) create a sublattice of corner sharing regular tetrahedrons (see Fig. 1a). Six Fe atoms and six Y (8a positions) atoms surround each Fe atom composing its nearest neighbourhood. The Y atoms create a sublattice of the diamond type. These two sublattices penetrate each other. In the hexagonal C14 TiFe2 phase (MgZn2-type, space group P63/mmc) Fe atoms create a sublattice of regular tetrahedrons linked alternately by apexes (2a positions) or by their bases (6h positions). In this structure the population ratio of 6h and 2a sites is 3:1. The Ti atoms create a sublattice of the wurcite type. The compound YFe2 is a ferrimagnet (TC = 542 K) with a saturation magnetization of 2.9μB per formula unit ...
Measurements of X-ray diffraction and Mössbauer effect were made on a series of Y1-xScxFe2 polycr... more Measurements of X-ray diffraction and Mössbauer effect were made on a series of Y1-xScxFe2 polycrystalline samples (x = 0.0, 0.2, 0.5, 0.7, 0.8, 1.0). It was found that the system has the cubic MgCu2 structure except for x = 1.0 where hexagonal MgZn2 structure type is stable. The lattice constant decreases with increasing x. The results of Mössbauer effect study at room temperature show that the easy axes of magnetization remain in the <111> direction for the cubic samples and <100> for the hexagonal one. Curie temperatures TC were determined from temperature dependence of the hyperfine magnetic fields. The concentration dependence of the hyperfine fields and TC show similar trends, exhibiting a maximum at x = 0.8. The magnetic and structural behaviour show that, in spite of being isoelectronic, the substitution of Y by Sc induces clear changes in the structural and magnetic properties of the compounds under investigation.
ABSTRACT The authors studied deposits from combustion chambers of high-pressure engines supplied ... more ABSTRACT The authors studied deposits from combustion chambers of high-pressure engines supplied with standard fuel (SO) and ecological fuel of City-Diesel type. Chemical analysis, X-ray diffractograms, Mössbauer absorption and additionally Raman wavenumber measurements were made. The wearing of some engine elements was examined by the profilometric method. By using ecological fuel, the deposits were shown to contain four to five times less iron compounds than standard fuel supply. This accounts for a smaller attrition of the combustion chamber elements, and thus longer durability of the engine.
ABSTRACT The authors studied deposits from combustion chambers of high-pressure engines supplied ... more ABSTRACT The authors studied deposits from combustion chambers of high-pressure engines supplied with standard fuel (SO) and ecological fuel of City-Diesel type. Chemical analysis, X-ray diffractograms, Mössbauer absorption and additionally Raman wavenumber measurements were made. The wearing of some engine elements was examined by the profilometric method. By using ecological fuel, the deposits were shown to contain four to five times less iron compounds than standard fuel supply. This accounts for a smaller attrition of the combustion chamber elements, and thus longer durability of the engine.
Nanoparticles of manganese ferrite were obtained by the impregnation of highly ordered mesoporous... more Nanoparticles of manganese ferrite were obtained by the impregnation of highly ordered mesoporous MCM-41 silica support. The investigated sample contained 20% wt. Fe. The obtained nanocrystallites were strongly dispersed in silica matrix and their size was about 2 nm. The sample annealing at 500°C led to increase of particle size to about 5 nm. The Mössbauer spectroscopy investigations performed at room temperature show on occurrence of MnFe2O4 nanoparticle in superparamagnetic state for the sample annealed in all temperatures. The coexistence of superparamagnetic and ferromagnetic phase was observed at liquid nitrogen temperature. The sample annealed at 400°C and 500°C has bigger manganese ferrite particle and better crystallized structure. One can assign them the discrete hyperfine magnetic field components.
The intermetallic pseudobinary compounds Sc(Fe1−xNix)2 exhibit the C15 cubic Laves phase structur... more The intermetallic pseudobinary compounds Sc(Fe1−xNix)2 exhibit the C15 cubic Laves phase structure over the whole concentration range except for x = 0. Pure ScFe2 shows either the hexagonal C14 or the dihexagonal C36 structure when it crystallizes at high temperatures (1473 < T < 1838 K) [3]. From our earlier investigations, it is known that ScFe2 with the C36 structure (hP24, space group P63/mmc) is ferromagnet with TC = 642 K. In this structure, Fe atoms occupy three non-equivalent positions: 6g, 6h and 4f (Wyckoff notation) and have magnetic moments equal to 1.31(1), 1.78(1) and 1.52(1) μB at RT, respectively. The mean value of hyperfine magnetic field in this compound amounts to 18.2(2) T. The theoretical calculations of band structure for ScFe2 with the C15 cubic structure give the magnetic moment of Fe atom of 1.56 μB and predict occurrence of antiparallel induced magnetic moments of about 0.52 μB at Sc atoms [1]. NMR Sc measurements in the polymorphic C15 form of ScFe2 ...
The diversity of magnetic phenomena due to 3d-3d exchange interactions present in alloys and inte... more The diversity of magnetic phenomena due to 3d-3d exchange interactions present in alloys and intermetallic compounds was a matter of interest for a long time [4]. Among the large number of such materials, the binary Laves phases with comparatively simple crystal structure give the possibility of substituting the 3d metals with each other or non-magnetic sp elements without changing the crystal structure over a wide range of compositions. This appears to be one of the main advantages of pseudobinary alloy systems compared with binary alloys to investigate the onset of magnetism as a function of alloy composition. For example, it is known that Cu has a very low solubility in metallic Fe of the order of 2 at.% at 600 K [1] and the Cu solubility in Sc not exceeds 0.5% at 865 K [10]. In the quasibinary system Sc-Fe-Cu, where Fe atoms are gradually substituted for Cu atoms, an initial ScFe2 compound belongs to the Laves phases. It has hexagonal C36 structure (hP24, space group P63/mmc) an...
Systems of the (T1−xT’ x)Fe2-type (where T = Y, Nb, Ti and T’ = Sc, Zr) have been extensively inv... more Systems of the (T1−xT’ x)Fe2-type (where T = Y, Nb, Ti and T’ = Sc, Zr) have been extensively investigated. In many such pseudobinary systems interesting magnetic and structural properties were observed [6, 8, 11]. In the cubic C15 YFe2 phase (MgCu2-type, space group Fd3m) Fe atoms (16d positions) create a sublattice of corner sharing regular tetrahedrons (see Fig. 1a). Six Fe atoms and six Y (8a positions) atoms surround each Fe atom composing its nearest neighbourhood. The Y atoms create a sublattice of the diamond type. These two sublattices penetrate each other. In the hexagonal C14 TiFe2 phase (MgZn2-type, space group P63/mmc) Fe atoms create a sublattice of regular tetrahedrons linked alternately by apexes (2a positions) or by their bases (6h positions). In this structure the population ratio of 6h and 2a sites is 3:1. The Ti atoms create a sublattice of the wurcite type. The compound YFe2 is a ferrimagnet (TC = 542 K) with a saturation magnetization of 2.9μB per formula unit ...
Measurements of X-ray diffraction and Mössbauer effect were made on a series of Y1-xScxFe2 polycr... more Measurements of X-ray diffraction and Mössbauer effect were made on a series of Y1-xScxFe2 polycrystalline samples (x = 0.0, 0.2, 0.5, 0.7, 0.8, 1.0). It was found that the system has the cubic MgCu2 structure except for x = 1.0 where hexagonal MgZn2 structure type is stable. The lattice constant decreases with increasing x. The results of Mössbauer effect study at room temperature show that the easy axes of magnetization remain in the <111> direction for the cubic samples and <100> for the hexagonal one. Curie temperatures TC were determined from temperature dependence of the hyperfine magnetic fields. The concentration dependence of the hyperfine fields and TC show similar trends, exhibiting a maximum at x = 0.8. The magnetic and structural behaviour show that, in spite of being isoelectronic, the substitution of Y by Sc induces clear changes in the structural and magnetic properties of the compounds under investigation.
Uploads