Search results

1

The low temperature magnetic properties of potassium holmium double tungstate

100%

Borowiec M., Khatsko E., Dyakonov V., Rykova A., Majchrowski A., Zayarnyuk T., Barański M., Żmija J., Szymczak H.

Open Physics

|

2011

|

vol. 9

|

issue 1

260-262

EN

The magnetic investigations of potassium holmium double tungstate KHo(WO4)2 have been performed. The results of measurements of magnetic susceptibility and magnetization as a function of both temperature (T = 0.5–100 K) and magnetic field (up to 2 T) are presented.

2

Evaluation of Differences between Fe₃O₄ Micro- and Nanoparticles Properties

100%

Duriagina Z., Tepla T., Kulyk V.

Acta Physica Polonica A

|

2018

|

vol. 133

|

issue 4

869-872

EN

Small sizes of nanoparticles lead to the appearance of new unique functional properties. Under transition to nanosizes in metals and their compounds new specific characteristics appears. In this work, the microstructural and magnetic properties of Fe₃O₄ nanoparticles (Fe₃O₄-NP) have been compared with those of commercially available Fe₃O₄ microparticles (Fe₃O₄-MP) and detailed analysis of differences has been carried out. The synthesis of Fe₃O₄-NP was carried out by means of colloidal method performed without the use of surfactants. Commercial and synthesized particles were characterized using NTEGRA Prima (NT-MDT) atomic force microscope. For magnetic properties investigations we used the method of vibrating sample magnetometer.

3

Structure and some magnetic properties of (BiFeO3) x -(BaTiO3) 1− x solid solutions prepared by solid-state sintering

100%

Kowal K., Kowalczyk M., Czekaj D., Jartych E.

|

issue 1

81-85

EN

This paper presents the results of the study on structure and magnetic properties of the perovskite-type (BiFeO3)x-(BaTiO3)1−x solid solutions. The samples differing in the chemical composition (x = 0.9, 0.8, and 0.7) were produced according to the conventional solid-state sintering method from the mixture of powders. Moreover, three different variants of the fabrication process differing in the temperatures and soaking time were applied. The results of X-ray diffraction (XRD), Mössbauer spectroscopy (MS), and vibrating sample magnetometry (VSM) were collected and compared for the set of the investigated materials. The structural transformation from rhombohedral to cubic symmetry was observed for the samples with x = 0.7. With increasing of BaTiO3 concentration Mössbauer spectra become broadened reflecting various configurations of atoms around 57Fe probes. Moreover, gradual decreasing of the average hyperfine magnetic field and macroscopic magnetization were observed with x decreasing.

4

Magnetic properties of the mixed spin-5/2 and spin-3/2 Blume-Capel Ising system on the two-fold Cayley tree

88%

Yessoufou R., Amoussa S., Hontinfinde F.

Open Physics

|

2009

|

vol. 7

|

issue 3

555-567

EN

We use exact recursion relations to study the magnetic properties of the half-integer mixed spin-5/2 and spin-3/2 Blume-Capel Ising ferromagnetic system on the two-fold Cayley tree that consists of two sublattices A and B. Two positive crystal-field interactions Δ1 and Δ2 are considered for the sublattice with spin-5/2 and spin-3/2 respectively. For different coordination numbers q of the Cayley tree sites, the phase diagrams of the model are presented with a special emphasis on the case q = 3, since other values of q reproduce similar results. First, the T = 0 phase diagram is illustrated in the (D A = Δ1/J,D B = Δ2/J) plane of reduced crystal-field interactions. This diagram shows triple points and coexistence lines between thermodynamically stable phases. Secondly, the thermal variation of the magnetization belonging to each sublattice for some coordination numbers q are investigated as well as the Helmoltz free energy of the system. First-order and second-order phase transitions are found. The second-order phase transitions become sharper and sharper when D A or D B increases. The first-order transitions only exist for some appropriate non-zero values of D A and/or D B. The corresponding transition lines never connect to the second-order transition lines. Thus, the non-existence of tricritical points remains one of the key features of the present model. The magnetic exponent β 0 of the model is estimated and found to be ¼ at small values of D A = D B = D and β 0 = ½ at large values of D. At intermediate values of D, there is a crossover region where the magnetic exponent displays interesting behaviours.

5

Magnetic Properties of Steel Ball Samples, Investigated before and after Nitriding

88%

Fuks H., Kaczmarek S. M., Leniec G., Michalski J., Kucharska B., Wach P.

Archives of Metallurgy and Materials

|

2018

|

vol. 63

|

issue 3

6

Square Ising Nanowire on the Bethe Lattice

88%

Albayrak E.

Acta Physica Polonica A

|

2017

|

vol. 131

|

issue 6

1470-1473

EN

The square-type nanowire is simulated on the Bethe lattice by using the core-shell structure consisting of the Ising spins. A nanoparticle is formed by placing a spin to the center and four others to the corners of a square. Then, each nanoparticle is combined with two neighboring ones with a perfect alignment of the squares to form the nanowire. Only nearest-neighbor spin interactions, either ferromagnetic or antiferromagnetic type, are allowed. The phase diagrams are calculated by studying the thermal variations of magnetizations for various values of bilinear interactions. It is found that the model gives both second- and first-order phase transitions in addition to the tricritical points and compensation temperatures.

7

Effects of low-level La doping and ageing on TlPb-1223 high T c superconductors

88%

Cigáň A., Plesch G., Škrátek M., Kopčok M., Maňka J., Jurdák P., Koňakovský A.

Open Physics

|

2011

|

vol. 9

|

issue 1

213-221

EN

Bulk samples of the nominal composition of (Tl0.6Pb0.5)(Sr0.8Ba0.2)2Ca2Cu3O8+δ−xLaO1.5 (x = 0–0.1) were prepared by using two-step process and their microstructure, T c values, and magnetization were studied. The samples consist of the Tl-1223 dominant phase with small Tl-1212 admixture, which increases with a rise of La content. Five years ageing and following oxygen annealing at 450°C and subsequently at 750°C have only a modest effect on T c values of the studied samples. Low-level La doping (x = 0:04) leads to an increase of T c values by about 2 K in comparison with undoped samples. Oxygen annealing at 750°C results in an increase in the volume magnetization hysteresis in low applied magnetic fields and rise of critical current density at zero magnetic field and 77 K. This effect is most pronounced for the low La doped sample with x = 0.04. Changes of the induced voltage, U originating in the Meissner effect and of its harmonics in dependence on temperature were measured and used for characterization of the temperature distribution of inter-grain junctions.

Refine search results

The low temperature magnetic properties of potassium holmium double tungstate

Evaluation of Differences between Fe₃O₄ Micro- and Nanoparticles Properties

Structure and some magnetic properties of (BiFeO3) x -(BaTiO3) 1− x solid solutions prepared by solid-state sintering

Magnetic properties of the mixed spin-5/2 and spin-3/2 Blume-Capel Ising system on the two-fold Cayley tree

Magnetic Properties of Steel Ball Samples, Investigated before and after Nitriding

Square Ising Nanowire on the Bethe Lattice

Effects of low-level La doping and ageing on TlPb-1223 high T c superconductors