Structural, magnetic and electronic properties on the Li-doped manganites

Journal of Magnetism and Magnetic Materials

et al. 2018

Self Cite

The magnetocaloric effect (MCE) and electric-dielectric properties of the Nd-cobaltate perovskites Nd 0.6 Sr 0.4 Co 1Àx Mn x O 3 (x = 0, 0.3, 0.7 and 1) were investigated for possible use in magnetic cooling applications. Upon Mn substitution, the magnetic exchange interaction is affected by the (Mn 4+ /Mn 3+) ratio, which in turn impacts several physical properties. The XRD patterns of the synthesized composites revealed a single phase with an orthorhombic structure with space group Pbnm (62). The orthorhombic lattice distortion increases linearly with the Mn content, reaching a maximum value (D = 7.377 Â 10 À3) for Nd 0.6 Sr 0.4 MnO 3. The temperature and frequency dependence of the dielectric permittivity was studied and analyzed using Maxwell-Wagner interfacial polarization and Koops phenomenological theory. The rapid increase in magnetic susceptibility around the paramagnetic (PM)-ferromagnetic (FM) transition temperature T C is greatly affected by Mn substitution. The decrease in susceptibility with increasing temperature can be attributed to a charge ordering effect. The PM-FM transition occurs in the temperature range of 150-200 K. Moreover, the presence of spontaneous magnetization with second-order phase transitions is observed from Arrott plot isotherms. The MCE was also investigated by determining DS M and the relative cooling power (RCP), and the maximum value is found for Nd 0.6 Sr 0.4 Co 0.3 Mn 0.7 O 3. These results compare favorably with those reported for similar materials, indicating our materials as a possible candidate for use in magnetocaloric refrigerators.

Section: Susceptibility Measurementssupporting

confidence: 85%

Magnetocaloric effect, electric, and dielectric properties of Nd0.6Sr0.4MnxCo1−xO3 composites

Abdel-Latif

Journal of Magnetism and Magnetic Materials

et al. 2018

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“…(Nd 0.6 Sr 0.4 MnO 3 ) 1-x /(CrO 3 ) x composites with x = 0, 0.005, 0.010, 0.015, 0.020, 0.025&0.030 wt% were prepared by the conventional solid-state reaction method as reported in [7]. Thermoelectric power measurements were carried out in previous reports [10,11]. The magnetic measurements were carried out using aDynacool/Quantum Design Physical Properties Measuring System (PPMS).…”

Section: Methodsmentioning

confidence: 99%

Thermopower and magnetocaloric properties in NdSrMnO/CrO3 composites

Journal of Magnetism and Magnetic Materials

Paixão

et al. 2018

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The thermoelectric power (TEP) and magnetocaloric effect (MCE) for (Nd 0.6 Sr 0.4 MnO 3 ) 1-x /(CrO 3 ) x composites have been measured. The TEP measurements show a negative sign value of the Seebeck coefficient (S), in microvolts. TEP data construe in the low range of temperature by the magnon and phonon drag model, whereas at high temperature by small polaron conduction mechanism. Magnetic measurements exhibit that all composites show a paramagnetic-ferromagnetic transition with decreasing temperature. The Arrott plots of composites reveal the occurrence of a second order phase transition. The maximum value of magnetic entropy change (DS) is 2.37 J kg À1 K À1 , achieved fore the composite with x = 0.015. Moreover, the maximum value of relative cooling power (RCP) is 122.1 J kg À1 , achieved for the composite with x = 0.020. These composites may be appropriate for magnetic application near room temperature.

Enhancement of Optical, Electrical, Magnetic, and Thermopower Properties of LaMnO₃ by Potassium‐Doping

Physica Status Solidi (b)

et al. 2023

Optical, magnetoresistance, and thermoelectric properties of La1−xKxMnO3 (x = 0.05, 0.15, and 0.25) compounds have been investigated. The crystallography demonstrates that the samples x = 0.05 and 0.15 are a single‐phase rhombohedral () structure, while x = 0.25 is near to a single rhombohedral phase with a minor amount of Mn3O4 (with a ratio of ≈2%). The optical properties manifest that the reflectivity decreases slightly with increasing x‐doping, where the sample of x = 0.05 has the lowest reflection value, making it a promising material for photovoltaic applications. Electrical resistivity measurements show that the samples have a metal–semiconductor transition, and the transition temperature Tms decreases with the K content. The thermoelectric data show a remarkable coincidence behavior of the ρ–T relationship, which has a peak at a transition temperature (TS). Magnetic susceptibility data show that the samples undergo ferro‐paramagnetic transition at a certain temperature (Curie temperature).