Three distinct alloys: Fe
Zr
Nb
Cu
, Fe
Zr
Nb
Cu
, and Fe
Pt
Zr
Nb
Cu
were characterized both magnetically and structurally. The samples, obtained with spinning roller method as a ribbons 3 mm in ...width and 20 μm thick, were investigated as-quenched and after each step of a multi steps heating treatment procedure. Each sample was annealed at four steps, fifteen minutes at every temperature, starting from 573K+600K up to +700K depending on type of alloy. Mössbauer spectroscopy data and transmission electron microscope (HRE M) pictures confirmed that the as-quenched samples are fully amorphous. This is not changed after the first stages of treatment heating leads to a reduction of free volumes. The heating treatment has a great influence on the magnetic susceptibilities. The treatment up to 600K improves soft magnetic properties: an χ increase was observed, from about 400 to almost 1000 for the samples of alloys without Pt, and from about 200 to 450 at maximum, for the Fe
Pt
Zr
Nb
Cu
. Further heating, at more elevated temperatures, leads to magnetic hardening of the samples. Curie temperatures, established from the location of Hopkinson’s maxima on the χ(T) curve are in very good agreement with those obtained from the data of specific magnetization, σ(T), measured in a field of 0.75T. As a critical parameter β was chosen to be equal 0.36 for these calculations, it confirmed that the alloys may be considered as ferromagnetic of Heisenberg type. Heating treatment resulted in decreasing of TC. These changes are within a range of several K.
Microstructure, revealed by X-ray diffraction, transmission electron microscopy and Mössbauer spectroscopy, and magnetic properties such as magnetic susceptibility, its disaccommodation, core losses ...and approach to magnetic saturation in bulk amorphous (Fe0.61Co0.10Zr0.025Hf0.025Ti0.02W0.02B0.20)100−xYx (x=0, 2, 3 or 4) alloys in the as-cast state and after the annealing in vacuum at 720K for 15min. are studied. The investigated alloys are ferromagnetic at room temperature. The average hyperfine field induction decreases with Y concentration. Due to annealing out of free volumes its value increases after the heat treatment of the samples. The magnetic susceptibility and core losses point out that the best thermal stability by the amorphous (Fe0.61Co0.10Zr0.025Hf0.025Ti0.02W0.02B0.20)97Y3 alloy is exhibited. Moreover, from Mössbauer spectroscopy investigations it is shown that the mentioned above alloy is the most homogeneous. The atom packing density increases with Y concentration, which is proved by the magnetic susceptibility disaccommodation and approach to magnetic saturation studies.
▶ Microstructure and magnetic properties of amorphous. ▶ Fe0.61Co0.10Zr0.025Hf0.025Ti0.02W0.02B0.20)100−xYx (x=0, 2, 3 or 4) rods in the as-cast state. ▶ After the annealing at 720K for 15min are studied. ▶ The best thermal stability exhibits the alloy with x=3. ▶ The atom packing density increases with yttrium concentration.
Li2O-Nb2O5-ZrO2-SiO2 glasses were synthesised and subsequently crystallised with different CuO contents (0-0.3 mol% in steps of 0.05) as nucleating agents and characterised using XRD, SEM and DSC. ...The optical and dielectric properties were investigated to explore the influence of copper valence states and their coordination with oxygen on the structural and optoelectronic properties of the samples. Results indicated that there was a possibility for the copper ions to exist in Cu+ and Cu3+ states (in addition to Cu2+ state) in these glass-ceramics and participate in glass formation. Photoinduced second harmonic generation studies were undertaken with a 10 ns Er:glass laser to examine the suitability of these materials for optically operated devices. Analysis of the results of non-linear optical studies showed that 0.2 mol% of CuO was the optimal concentration to obtain the highest values of second order susceptibility coefficients.
ZnF2–PbO–TeO2 glasses doped with different concentrations of TiO2 were synthesized and subsequently crystallized. The prepared samples were characterized by XRD, SEM and DSC. IR, ESR and optical ...absorption were studied to explore the influence of titanium valance states and their coordination with oxygen on structural and optoelectronic aspects of the samples. These studies have indicated that there is a possibility for the titanium ions to exist in Ti3+ and Ti4+ states in these glass ceramics and participate in the glass network forming. Finally, we have undertaken second harmonic generation (after the samples were dc field treated at elevated temperatures) with 10ns Er3+: glass laser (of wavelength 1540nm with power densities up to 1.5GW/cm2) and birefringence studies (in the wavelength range 420–750nm) to examine the suitability of these materials for optically operated devices. The results of non linear optical studies were discussed in the light of nature of different micro/nano crystallites ingrained in the glass ceramic samples.
After annealing alloys below crystallization temperatures, the decrease of the average hyperfine field due to the invar effect is observed. At early stages of crystallization, the iron content in the ...amorphous matrix is the same as in the as-quenched state. The amorphous samples show broad disaccommodation spectra with activation energies from 0.6 to 0.9eV. The highest initial magnetic susceptibility was obtained for the nanocrystalline Fe85.4Zr5.8Nb1B6.8Cu1 alloy. However, the best thermal stability of the susceptibility is observed for the Fe85.4Zr6.8B6.8Cu1 alloy.
We stated that crystalline grains in the nanocrystalline alloys obtained by a proper annealing consist of the ordered α-FeCo phase. However, in the partially crystallized alloys during a rapid ...solidification α-FeCo phase is completely disordered. In both, the amorphous and nanocrystalline samples broad disaccommodation spectra are observed. The activation energies of relaxation processes range from 1.00 to 1.34eV and from 1.47 to 1.82eV for the amorphous and nanocrystalline samples, respectively.
The phase composition, magnetic properties i.e. coercivity and the magnetic polarization at room temperature for the bulk Fe67Co5Nd3Y6B19 and Fe64Co5Nd6Y6B19 alloys were studied. The bulk amorphous ...Fe67CosNd3Y6B19 alloy, inhomogeneous in the as-quenched state, crystallized after annealing at 948 K for 0.5 h and consisted of Nd2Fe14B-type, Fe2B and paramagnetic phases. The rapidly solidified Fe64Co5Nd6Y6B19 alloy contained the Nd2Fel4B-type and paramagnetic phases. The annealing of the bulk Fe67CosNd3Y6B19 alloy at 948 K for 0.5 h led to hard magnetic properties. However, the bulk Fe64Co5Nd6Y6B19 alloy exhibited good hard magnetic properties directly after preparation.
Good quality single crystals of a complex between urea and resorcinol (UR–C
6H
5O
2
−:(NH
2)CO(NH
3)
+) in the ratio (1:1) have been grown by low temperature solution growth technique using acetone ...and a mixture of acetone and water (1:1). The solubility studies have been carried out in both the solvents at various temperatures. The X-ray diffraction studies show that the complex crystallized in orthorhombic space group P2
12
12
1. The linear electro optical, piezooptical and second harmonic generation measurements were performed. The results obtained in these studies were discussed in detail. The optical transparency window observed in the visible and near IR regions recommends the crystal for nonlinear optical applications. Dependence of the effective second order optical susceptibility on time of simultaneously applied dc-electric field and UV-treatment were performed and discussed.
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