Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 4 de 4
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
RSC Adv ; 14(16): 11121, 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38590350

RESUMO

[This corrects the article DOI: 10.1039/D3RA90093B.][This corrects the article DOI: 10.1039/D1RA07059B.].

3.
RSC Adv ; 12(26): 16805-16822, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35754884

RESUMO

In the present research, polycrystalline samples of La0.5Sm0.2Sr0.3Mn1-x Cr x O3 are prepared using the self-combustion method. Then, we have studied their crystalline structure, and dielectric and electrical properties. The X-ray diffraction study shows that all the samples exhibit a single phase with orthorhombic structure (space group Pnma). The studied samples were also characterized by complex impedance spectroscopy in a wide range of temperatures and frequency. AC conductivity analyses are used to study the transport property of the investigated samples. These analyses indicate that the conduction mechanism is strongly dependent on temperature and frequency. It is also found that the conductivity decreases with Cr concentration. Complex impedance analysis confirms the contributions of grain and grain boundaries in the conduction mechanism. Finally, the impedance spectra, characterized by the appearance of semicircle arcs at different temperatures, were well modeled in terms of equivalent electrical circuits to explain the impedance results.

4.
RSC Adv ; 12(7): 3935-3947, 2022 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-35425461

RESUMO

We present a detailed study on the physical properties of La0.6Ba0.2Sr0.2Mn1-x Ni x O3 samples (x = 0.00, 0.05 and 0.1). The ceramics were fabricated using the sol-gel route. Structural refinement, employing the Rietveld method, disclosed a rhombohedral R3̄c phase. The magnetization vs. temperature plots show a paramagnetic-ferromagnetic (PM-FM) transition phase at the T C (Curie temperature), which decreases from 354 K to 301 K. From the Arrott diagrams M 2 vs. µ 0 H/M, we can conclude the phase transition is of the second order. Based on measurements of the isothermal magnetization around T C, the magnetocaloric effects (MCEs) have been calculated. The entropy maximum change (-ΔS M) values are 7.40 J kg-1 K-1, 5.6 J kg-1 K-1 and 4.48 J kg-1 K-1, whereas the relative cooling power (RCP) values are 232 J kg-1, 230 J kg-1 and 156 J kg-1 for x = 0.00, 0.05 and 0.10, respectively, under an external field (µ 0 H) of 5 T. Through these results, the La0.6Ba0.2Sr0.2Mn1-x Ni x O3 (0 ≤ x ≤ 0.1) samples can be suggested for use in magnetic refrigeration technology above room temperature. The electrical resistivity (ρ) vs. temperature plots exhibit a transition from metallic behavior to semiconductor behavior in the vicinity of T M-SC. The adiabatic small polaron hopping (ASPH) model is applied in the PM-semiconducting part (T > T MS). Throughout the temperature range, ρ is adjusted by the percolation model. This model is based on the phase segregation of FM-metal clusters and PM-insulating regions.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...