Nitrided Sm2Fe17-based materials possess excellent intrinsic magnetic properties, and in this stu... more Nitrided Sm2Fe17-based materials possess excellent intrinsic magnetic properties, and in this study we have investigated two compositions: Sm13.8Fe82.2 Ta4.0 and Sm13.7Fe86.3. The stoichiometry of each phase was determined and the SmFeTa material was found to include Ta3Fe7, in addition to the Sm2Fe17, SmFe2 and SmFe3 phases observed in the SmFe alloy, but without the αFe dendrites which are characteristic of the binary material. Hydrogen absorption-desorption studies carried out on both materials using thermopiezic and gas-flow analyses demonstrated the different hydrogenation disproportionation desorption recombination (HDDR) behavior of the SmFeTa alloy. Scanning and transmission electron microscopy studies revealed that in the cast structure some 2.0 at.% Ta is initially dissolved in the Sm2(FeTa)17 phase, however, a single HDDR cycle causes the formation of Ta-based precipitates leaving the Sm2(FeTa)17 phase with much less dissolved Ta.
In order to access the damaging mechanismsof DNA and its bases on themolecular level by T Hz radi... more In order to access the damaging mechanismsof DNA and its bases on themolecular level by T Hz radiation, it isnecessary to create a database of assessingdamage at different spectral regions.Possible damage by T Hz radiation will beassessed by comparison. Furthermore, theexpose of the cytosine to radiation at157 nm, suggest that photochemical bondbreaking is the only damaging mechanism inthe vacuum ultraviolet region of thespectrum, (157-170) nm where one photonbreaks one chemical bond.
The adhesion strength of magnetic films of intermetallic alloys on different substrates specifies... more The adhesion strength of magnetic films of intermetallic alloys on different substrates specifies their long‐term magnetic functionality, among other physicochemical characteristics of the films. Nanospheroids of Sm/FeTaN intermetallic alloys were grown from the Sm13.8 Fe82.2 Ta4.0 target by pulse laser deposition at 157 nm. The high‐temperature, liquefied nanodroplets were formed in the plume. They eventually solidified on the surface of a Ta substrate covered with a thin Ta/O layer in the form of biphasic nanospheroids, consisting of a crystalline nucleus surrounded by an amorphous mantle. Such nanostructures exhibit a ferromagnetic response because the oxidization of the inner crystalloid nucleus, which specifies the magnetic properties, is prevented by the amorphous spheroid mantle. The strength of adhesion of the nanodroplets on the Ta substrate was inversely proportional to the Sm/Fe concentration. The nanodroplets with high Sm/Fe concentration were bound on the Ta substrate...
Equiatomic Fe–Pd thin films with thicknesses of 200 nm were deposited from a single electrolyte o... more Equiatomic Fe–Pd thin films with thicknesses of 200 nm were deposited from a single electrolyte onto glass-based, Au-coated substrates using the electrodeposition method. The as-deposited films were annealed at temperatures from 400 to 600 °C for 1 h in Ar+7% H2. The phase formation, microstructure and the magnetic properties were analyzed. The L10 ordering was found to coincide with the grain growth and the interdiffusion reaction between the substrate and the thin film when temperatures above 500 °C were used, which resulted in lower coercivities. The highest coercivity of 870 Oe was achieved when modest temperatures (400 °C) were used.
ABSTRACT Gd5Si2Ge2 is known for its giant magnetocaloric effect (GMCE), but also for its associat... more ABSTRACT Gd5Si2Ge2 is known for its giant magnetocaloric effect (GMCE), but also for its associated large hysteretic losses. These losses result in a significant reduction in the net cooling capacity of this material when it is used for magnetic cooling. Attempts have been made to reduce these losses by adding other elements, like iron. Individual Ge and Si substitutions have been reported, but in this paper we focus on the system where both elements were substituted simultaneously with different amounts of Fe, with an additional interest in the new Gd5(Si, Ge)3 phase that appears after the substitution. We found that when substituting iron in small quantities the MCE and the hysteresis losses remain high, with a small decrease in the Curie temperature, and the low-temperature XRD revealed that the structural transformation is still present. However, with an increasing amount of Fe the MCE was drastically reduced because of the newly formed Gd5(Si, Ge)3 phase. The magnetic transition temperature of this newly formed phase was investigated in all three substituted systems: Si, Ge and Si and Ge. This transition temperature was strongly affected by the type and the amount of substitution; however, the changes could not be directly related to the composition of the phases.
Hierarchical micro/nano self–assembled 2D structures on thin films of block copolymers/Fe hybrid ... more Hierarchical micro/nano self–assembled 2D structures on thin films of block copolymers/Fe hybrid materials were induced on Si/Ta substrates, either by wet chemistry or by laser vacuum ultraviolet (VUV) light at 157 nm. Formation of either lamellas or micelle depends on the symmetric diblock copolymer composition and the volume fraction of the solutions. Honey comb-like nano-self-assembled cylindrical structures were formed for one of the diblock copolymer hybrid material. The honey comb-like structures have a different chemical composition than the rest areas of the film and they are rich in iron concentration. VUV irradiation is altering the surface morphology, and under certain illumination conditions semi regular micro ordering on the film surface was induced. Inside the micro-structured domains nano-structured aggregations were formed rich in iron concentration.
ABSTRACTChemical surface modification can be used as a method for corrosion protection of sensiti... more ABSTRACTChemical surface modification can be used as a method for corrosion protection of sensitive powders based on intermetallic alloys between rare earth and transition metals. Surface coating is used for preventing fine powders, based on Nd-Fe-B, or Sm2Fe17−xTaxN3−δ prepared by HDDR processing and mechanically alloying, from hydrolysis. Powders coated by chemisorbed organic substance, after exposing to a humid atmosphere, do not show any chemical or physical change.Different coating agents were used and the sufficient amount of various materials was optimised with the emphasis on minimising their quantity. Simple experiment shows that the surfactant is successfully chemisorbed on the powder surface and that the coated powders are hydrophobic indefinitely. Magnetic properties were measured on samples after they were exposed to the same corrosion tests. Measurements on coated and bonded samples were compared with the measurements of non-coated and bonded samples. By using Auger el...
Sm-Fe-Ta-N-O nanospheres were synthesized by pulsed-laser deposition from a Sm(13.8)Fe(82.2)Ta(4.... more Sm-Fe-Ta-N-O nanospheres were synthesized by pulsed-laser deposition from a Sm(13.8)Fe(82.2)Ta(4.0) target in a nitrogen atmosphere. Three structurally and compositionally distinct types were identified: amorphous, core-shell and hollow nanospheres. Amorphous spheres were compositionally homogeneous and completely oxidized. The core-shell spheres were composed of an iron-rich crystalline core with up to 10 at.% interstitially incorporated nitrogen, surrounded by an amorphous and oxidized shell. The hollow spheres were characterized by voids filled with N(2) gas. It was found that the formation of either amorphous or complex nanospheres is defined by an initial Fe/Sm ratio within the molten droplet. The formation of hollow spheres is believed to be related to the general affinity of liquid metals for gas intake. During rapid solidification the dissolved gas in the melt is trapped within the surrounding solid rim, preventing the outwards diffusion of gas. As long as the amount of gas atoms in the melt is kept below its solubility limits it can be completely interstitially incorporated into the solid, thus forming crystalline Fe(N)-rich cores. If the melt contains more than an equilibrium amount of nitrogen it is possible that the gas recombines to form N(2) molecules, which are condensed inside the spheres.
Nitrided Sm2Fe17-based materials possess excellent intrinsic magnetic properties, and in this stu... more Nitrided Sm2Fe17-based materials possess excellent intrinsic magnetic properties, and in this study we have investigated two compositions: Sm13.8Fe82.2 Ta4.0 and Sm13.7Fe86.3. The stoichiometry of each phase was determined and the SmFeTa material was found to include Ta3Fe7, in addition to the Sm2Fe17, SmFe2 and SmFe3 phases observed in the SmFe alloy, but without the αFe dendrites which are characteristic of the binary material. Hydrogen absorption-desorption studies carried out on both materials using thermopiezic and gas-flow analyses demonstrated the different hydrogenation disproportionation desorption recombination (HDDR) behavior of the SmFeTa alloy. Scanning and transmission electron microscopy studies revealed that in the cast structure some 2.0 at.% Ta is initially dissolved in the Sm2(FeTa)17 phase, however, a single HDDR cycle causes the formation of Ta-based precipitates leaving the Sm2(FeTa)17 phase with much less dissolved Ta.
In order to access the damaging mechanismsof DNA and its bases on themolecular level by T Hz radi... more In order to access the damaging mechanismsof DNA and its bases on themolecular level by T Hz radiation, it isnecessary to create a database of assessingdamage at different spectral regions.Possible damage by T Hz radiation will beassessed by comparison. Furthermore, theexpose of the cytosine to radiation at157 nm, suggest that photochemical bondbreaking is the only damaging mechanism inthe vacuum ultraviolet region of thespectrum, (157-170) nm where one photonbreaks one chemical bond.
The adhesion strength of magnetic films of intermetallic alloys on different substrates specifies... more The adhesion strength of magnetic films of intermetallic alloys on different substrates specifies their long‐term magnetic functionality, among other physicochemical characteristics of the films. Nanospheroids of Sm/FeTaN intermetallic alloys were grown from the Sm13.8 Fe82.2 Ta4.0 target by pulse laser deposition at 157 nm. The high‐temperature, liquefied nanodroplets were formed in the plume. They eventually solidified on the surface of a Ta substrate covered with a thin Ta/O layer in the form of biphasic nanospheroids, consisting of a crystalline nucleus surrounded by an amorphous mantle. Such nanostructures exhibit a ferromagnetic response because the oxidization of the inner crystalloid nucleus, which specifies the magnetic properties, is prevented by the amorphous spheroid mantle. The strength of adhesion of the nanodroplets on the Ta substrate was inversely proportional to the Sm/Fe concentration. The nanodroplets with high Sm/Fe concentration were bound on the Ta substrate...
Equiatomic Fe–Pd thin films with thicknesses of 200 nm were deposited from a single electrolyte o... more Equiatomic Fe–Pd thin films with thicknesses of 200 nm were deposited from a single electrolyte onto glass-based, Au-coated substrates using the electrodeposition method. The as-deposited films were annealed at temperatures from 400 to 600 °C for 1 h in Ar+7% H2. The phase formation, microstructure and the magnetic properties were analyzed. The L10 ordering was found to coincide with the grain growth and the interdiffusion reaction between the substrate and the thin film when temperatures above 500 °C were used, which resulted in lower coercivities. The highest coercivity of 870 Oe was achieved when modest temperatures (400 °C) were used.
ABSTRACT Gd5Si2Ge2 is known for its giant magnetocaloric effect (GMCE), but also for its associat... more ABSTRACT Gd5Si2Ge2 is known for its giant magnetocaloric effect (GMCE), but also for its associated large hysteretic losses. These losses result in a significant reduction in the net cooling capacity of this material when it is used for magnetic cooling. Attempts have been made to reduce these losses by adding other elements, like iron. Individual Ge and Si substitutions have been reported, but in this paper we focus on the system where both elements were substituted simultaneously with different amounts of Fe, with an additional interest in the new Gd5(Si, Ge)3 phase that appears after the substitution. We found that when substituting iron in small quantities the MCE and the hysteresis losses remain high, with a small decrease in the Curie temperature, and the low-temperature XRD revealed that the structural transformation is still present. However, with an increasing amount of Fe the MCE was drastically reduced because of the newly formed Gd5(Si, Ge)3 phase. The magnetic transition temperature of this newly formed phase was investigated in all three substituted systems: Si, Ge and Si and Ge. This transition temperature was strongly affected by the type and the amount of substitution; however, the changes could not be directly related to the composition of the phases.
Hierarchical micro/nano self–assembled 2D structures on thin films of block copolymers/Fe hybrid ... more Hierarchical micro/nano self–assembled 2D structures on thin films of block copolymers/Fe hybrid materials were induced on Si/Ta substrates, either by wet chemistry or by laser vacuum ultraviolet (VUV) light at 157 nm. Formation of either lamellas or micelle depends on the symmetric diblock copolymer composition and the volume fraction of the solutions. Honey comb-like nano-self-assembled cylindrical structures were formed for one of the diblock copolymer hybrid material. The honey comb-like structures have a different chemical composition than the rest areas of the film and they are rich in iron concentration. VUV irradiation is altering the surface morphology, and under certain illumination conditions semi regular micro ordering on the film surface was induced. Inside the micro-structured domains nano-structured aggregations were formed rich in iron concentration.
ABSTRACTChemical surface modification can be used as a method for corrosion protection of sensiti... more ABSTRACTChemical surface modification can be used as a method for corrosion protection of sensitive powders based on intermetallic alloys between rare earth and transition metals. Surface coating is used for preventing fine powders, based on Nd-Fe-B, or Sm2Fe17−xTaxN3−δ prepared by HDDR processing and mechanically alloying, from hydrolysis. Powders coated by chemisorbed organic substance, after exposing to a humid atmosphere, do not show any chemical or physical change.Different coating agents were used and the sufficient amount of various materials was optimised with the emphasis on minimising their quantity. Simple experiment shows that the surfactant is successfully chemisorbed on the powder surface and that the coated powders are hydrophobic indefinitely. Magnetic properties were measured on samples after they were exposed to the same corrosion tests. Measurements on coated and bonded samples were compared with the measurements of non-coated and bonded samples. By using Auger el...
Sm-Fe-Ta-N-O nanospheres were synthesized by pulsed-laser deposition from a Sm(13.8)Fe(82.2)Ta(4.... more Sm-Fe-Ta-N-O nanospheres were synthesized by pulsed-laser deposition from a Sm(13.8)Fe(82.2)Ta(4.0) target in a nitrogen atmosphere. Three structurally and compositionally distinct types were identified: amorphous, core-shell and hollow nanospheres. Amorphous spheres were compositionally homogeneous and completely oxidized. The core-shell spheres were composed of an iron-rich crystalline core with up to 10 at.% interstitially incorporated nitrogen, surrounded by an amorphous and oxidized shell. The hollow spheres were characterized by voids filled with N(2) gas. It was found that the formation of either amorphous or complex nanospheres is defined by an initial Fe/Sm ratio within the molten droplet. The formation of hollow spheres is believed to be related to the general affinity of liquid metals for gas intake. During rapid solidification the dissolved gas in the melt is trapped within the surrounding solid rim, preventing the outwards diffusion of gas. As long as the amount of gas atoms in the melt is kept below its solubility limits it can be completely interstitially incorporated into the solid, thus forming crystalline Fe(N)-rich cores. If the melt contains more than an equilibrium amount of nitrogen it is possible that the gas recombines to form N(2) molecules, which are condensed inside the spheres.
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