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In this work, we were interested in the Ca2−xNdxMnO4 compounds when (0.1 ≤ x ≤ 0.4). These oxides are synthesized through the solid-state method. In this study, we investigated the evolution of the structure, the magnetic properties and the Mn3+/Mn4+ ratio with the Nd content. The morphological study shows a decrease in the size of the grain in relation to x. The X-ray diffraction reveals a transition from the tetragonal phase to the orthorhombic phase when x = 0.4. Magnetic measurements have been taken for all the compounds in the temperature range between 2 and 300 K. The temperature-dependent magnetic susceptibility shows the presence of three transitions TN, TC and TCO. A dramatic difference in magnetic susceptibility between ZFC and FC was observed below the Neel temperatures for Ca2-xNdxMnO4, which shows the onset of a ferromagnetic moment below these temperatures. This moment is caused by the Dzyaloshinskii–Moriya interaction. [ABSTRACT FROM AUTHOR]

In this work we investigate the effect of Ag+ doping at Sr2+ site in La0.57Nd0.1Sr0.33−xAgxMnO3 (LNSAMOx, x = 0.00 and 0.15) system on the magnetic and magneto-electrical properties. The variation of the magnetization M versus temperature T, at 0.05 T, reveals a ferromagnetic–paramagnetic transition for all samples. All samples undergo a sharp metal–semiconductor transition at a temperature Tρ, accompanying the ferromagnetic–paramagnetic transition. The maximum values of resistivity temperature coefficient (TCR) and magneto-resistance were 2.5% K−1 and 63% at room temperature of 290 K and 305 K, respectively. The TCR value is considered as an important factor in determining the sensitivity of uncooled infrared bolometers. Most interesting is that the adjustment of the low-temperature range ρ–T revealed the presence of low-temperature peaks in the resistivity curves, attributed to the diffusion effects of grain boundaries, electron–electrons, electron–magnon, electron–phonons and the interactions between them. Overall, LNSAMOx polycrystalline ceramics appear promising for uncooled infrared detectors, magnetic memories or magnetic storage devices. [ABSTRACT FROM AUTHOR]

In this research paper, our central focus is upon structural, optic, magnetic, magnetocaloric, and critical phenomena of La0.57Nd0.1Sr0.18Ag0.15MnO3 (LNSMAO) compound. This compound is crystallized in the rhombohedric system, with a R 3 - c space group. The band gap energy of this powder was 2.5 eV. Therefore, the LNSAMO sample proved to be not only a photocatalysis material but also a photovoltaic application. The FTIR spectra confirmed the formation of the structure of orthorhombic perovskite. The second-order transition of the magnetic phase in the LNSMAO sample was also reported by the positive slopes of the Arrott plot. Beneath 5 T, the values of magnetic entropy change and relative cooling power, respectively, amounted to about 5.08 J kg−1 K−1 and 146.7 J/Kg. In perspective, this sample stands for an agreeable candidate for magnetic refrigeration. By analyzing the dependence on the field of the magnetic entropy change (ΔSM) data as well as the relative cooling power (RCP), it was possible to assess the values of the critical exponents. Moreover, the critical exponents of LNSMAO compound were estimated based on multiple techniques like Kouvel-Fisher (KF), modified Arrott plot (MAP) method, and critical isotherm analysis (CIA). The reliability of these critical behaviors was verified by the Widom scaling relation and the universal scaling hypothesis. Our results demonstrate an excellent correlation between magnetocaloric effect (MCE) properties in manganese systems and critical behavior. [ABSTRACT FROM AUTHOR]

The Nd0.6Sr0.4MnO3 sample has been synthesized by the solid-state reaction. In this research paper, structural, morphological, magnetic and magnetocaloric properties are reported. The refinement by Fullprof has revealed the coexistence of both Pnma orthorhombic and R-3c rhombohedral phases. The obtained magnetic results show a paramagnetic–ferromagnetic transition at TC = 245 K. The magnetocaloric effect was estimated from the magnetic isotherms. We can estimate that the magnetic entropy change (ΔS) values by the Hamad theory are very close to those obtained using the classical Maxwell relation. Under an applied field 5 T, the maximum of the magnetic entropy change (ΔS) max and the relative cooling power is found to be 3.68 J/kg K and 216.03 J/kg, respectively. The obtained values are compared with those of some other reported manganite and show that our compound could be a promising candidate for magnetic refrigeration. Finally, the construction of the universal curve of the magnetic entropy change confirmed the studied manganite undergoes a second-order magnetic phase transition. [ABSTRACT FROM AUTHOR]

In this paper, we present the effect of lanthanum (La) and sodium (Na) vacancies in site A on the morphological, structural, magnetic, and electrical properties of La0,8-x□xNa0,2-x□xMnO3 compounds with x = 0.00, x = 0.05, and x = 0.075 prepared with the sol–gel method. The results of the X-ray powder diffraction diagrams show that these samples crystallize in a rhombohedral structure deformed with the space group R 3 ¯ c, while electron microscopy was carried out for the surface morphology. From the magnetic measurements, the transition from a ferromagnetic (FM) state to a paramagnetic (PM) state in the vicinity of Curie temperature TC is detailed. Moreover, in the electrical part, we study the gap effect on the transition temperature TMI; thus, the nature of the charge transport for the resistance behavior in the different regions (low temperature, metallic, and insulating) has been explained by different models. This work is completed by explaining the two types of magnetoresistance (MR) observed as a function of temperature and applied magnetic field: low-temperature extrinsic magnetoresistance (EMR) and high-temperature intrinsic magnetoresistance (IMR) have been found to be conserved (≈ 30 ℅) with decreasing precursor percentage at room temperature. [ABSTRACT FROM AUTHOR]

In this paper, we have investigated the influence of substitution of Nd by Sr on the structural, magnetic, and magnetocaloric properties of Nd1 − xSrxMnO3 (x = 0.3 and x = 0.4). These compounds were prepared using the solid state method. The structural, morphological, and magnetic properties of our system were characterized by XRD, MEB techniques, and a magnetometer for magnetic characterization. The Rietveld refinement has revealed the coexistence of both Pnma orthorhombic and R-3c rhombohedral phases. The magnetic data indicate that the compounds exhibit a continuous paramagnetic (PM) to ferromagnetic (FM) phase transition. In addition, the critical behavior in both compounds associated with the magnetic phase transition has been studied by the magnetization isotherms. The critical exponents are deduced using various techniques such as the modified Arrott plot, Kouvel–Fisher plot, and critical isotherm technique. Finally, the results obtained of the magnetocaloric effect are in agreement with the reported values of previous researches. These results show that our samples can be used as a magnet refrigerant at room temperature. [ABSTRACT FROM AUTHOR]

The magnetic properties and the critical behavior in SrNdMnO have been investigated by magnetization measurements. The magnetic data indicate that the compound exhibits a second-order phase transition. The estimated critical exponents derived from the magnetic data using various techniques such as modified Arrott plot, Kouvel-Fisher method, and critical magnetization isotherms M ( T, H). The critical exponent values for this compound was found to match well with those predicted for the mean-field model ( δ = 2.212 ± 0.124, γ = 0.975 ± 0.018, and β = 0.502 ± 0.012) at T = 228.59 ± 0.17. The critical exponent γ is slightly inferior than predicted from the mean-field model. Such a difference may be due, within the context of the quenched disorder and essentially the presence of the Griffiths phase. The temperature variation in the effective exponent ( γ) is similar to those for disordered ferromagnets. [ABSTRACT FROM AUTHOR]

Synthesis, crystal structure, vibrational study and magnetic properties of the compound (CHN) CuCl are reported. The latter crystallizes in the monoclinic system (space group P2, Z = 4) with the following unit cell dimensions: a = 7.569(5) Å b = 14.174(5) Å, c = 13.193(2) Å and β = 105.53(3). Besides, its structure was solved using 5754 independent reflections down to R = 0.0475. The atomic arrangement can be described by alternating organic and inorganic layers stacked in the [ $\bar {1}$01] direction, made up of tetrahedral of tetrachlorocuprate CuCl $_{4}^{2-}$ sandwiched between two organic layers. In crystal structure, the inorganic layer, built up by independent monomeric [CuCl], is connected to the organic ones through hydrogen bonding in order to build a three-dimensional network. The magnetic behavior of (CHN) CuCl samples was investigated as a function of temperature and applied field. At hightemperature paramagnetic behavior, and at low temperature, evidence for weak ferromagnetism, reinforced by a hysteresis loop at 2 K is observed. The magnetic behavior of (CHN) CuCl is attributed to Cu (II) due to the presence of an active Jahn-Teller effect in the d electronic system, which give rise to short-range weak ferromagnetism. [ABSTRACT FROM AUTHOR]

1-(2Aminoethyl) pyrrolidinium tetrachlorocobaltat (CHN) CoCl has been prepared and analyzed by X-ray diffraction. The compound crystallizes in the orthorhombic system with space group P222. The unit cell dimensions are a= 7.3279(13), b= 13.051(2) and c= 13.831(2) Å with Z= 4. The crystal structure of this salt was solved by Patterson methods and refined by full-matrix least squares on F to the final values of R= 0.0486 and wR = 0.1347. The structure consists of diprotonated 1-(2aminoethyl) pyrrolidinium cations and monomeric CoCl $_{4}^{2-}$ These entities are interconnected by means of hydrogen bonding contacts forming a threedimensional network. Magnetization was used to investigate the magnetic properties. This compound exhibits an antiferromagnetic (AFM) to paramagnetic (PM) phase transition at a temperature ( T) lower than 2 K. The values of paramagnetic Curie-Weiss temperature ( 휃) and the exchange parameter ( J/ K) emphasize the existence of an antiferromagnetic interaction between the neighboring cobaltions. [ABSTRACT FROM AUTHOR]

The crystal structure of [1-(2-aminoethyl) piperazinium] choride trachloridocobaltate (II): [CHN] ClCoCl has been synthesized and analyzed by X-ray diffraction. Magnetization was used to investigate the magnetic properties. The salt crystallizes at room temperature in the monoclinic system with space group P2, the unit cell dimensions are: a=7.2113 Å, b=12.4844 Å, c=8.0554 Å, β=97.274 with Z = 2. The crystal structure of this salt was solved by Patterson methods and refined by full-matrix least squares on F to final values of R=0.0361 and wR=0.0701. The structure consists of monomeric triprotonated [1-(2-aminoethyl) piperazinium] cations, monomeric $\mathrm{CoCl}_{4}^{2-}$ and Cl anions. These entities are interconnected by means of hydrogen bonding contacts forming a three-dimensional network. The magnetic measurements experimentally show a deviation from the Curie-Weiss law at low temperatures, which reveals the occurrence of weak ferromagnetism at low temperature. The measurements of isothermal magnetics at low temperature show a weak hysteresis, which was confirmed by the small coercive field found at low temperature. In addition, self-consistent ab initio calculations, based on FLAPW method (Wien2k code), are performed to investigate magnetic, electronic properties and crystal structure, of [1-(2-aminoethyl) piperazinium] choride trachloridocobaltate(II). Spins polarized within the framework of the Coherent Potential Approximation (CPA) are considered. [ABSTRACT FROM AUTHOR]

The [(CHN)CuCl] compound crystallizes in the monoclinic system with P21/n space group. The copper (II) ion is five-coordinated by two nitrogen atoms form the bidentate 1-(2-aminoethyl) piperazinium cation and three chloride ions in a distorted square-pyramidal environment. Magnetic susceptibility and hysteresis-loop measurements are reported. The magnetic susceptibility shows a maximum around 4 K and decreases gradually. Below this temperature, the system is antiferromagnetic with a weak moment. The electronic structure calculation based on the Full potential Linearized Augmented Plane Wave (FLAPW) method is also performed to shed light on magnetic and electronic structures. The experimental results are in agreement with theoretical studies. [ABSTRACT FROM AUTHOR]

The CaSmMnO ( x=0-0.4) compounds were synthesized by a solid-solid method and characterized by XRD at room temperature. The XRD profiles were indexed with a tetragonal structure ( I/4mmm space group) for x≤0.3 and orthorhombic one ( Pnma space group) for x=0.4. The magnetic measurements were studied as a function of temperature ( T=2-300 K) and applied field ( μ H=0-10 T). When the temperature decreases, each compound has shown first a ferromagnetic-paramagnetic (FM-PM) transition and then an antiferromagnetic-ferromagnetic (AFM-FM) one. The transition temperatures are found to be Sm-doping dependent. For all compounds, a spin-glass phenomenon is evidenced by FC/ZFC magnetization curves. [ABSTRACT FROM AUTHOR]