Comprehensive Improvement of Various Features of Cu–Cd Ferrites (Cu0.5Cd0.5Fe2–xCexO4) by Cerium (Ce3+) Ion Substitution

Cerium (Ce3+) substitution in Cu–Cd spinel nanoferrites with the compositional formula Cu0.5Cd0.5Fe2–xCexO4 (x = 0.0, 0.0125, 0.0250, 0.0375, 0.050) was performed by the hydrothermal route. The structural, morphological, optical, electrical, and dielectric properties of Ce-substituted Cu–Cd ferrites were explored. X-ray diffraction revealed the single-phase cubic structure of all nanoferrites. The average crystallite size (72.42–11.61 nm) and lattice constant (8.419–8.449 Å) were observed for the synthesized ferrites. The surface shapes of particles were determined by scanning electron microscopy. The substitution was also verified by Fourier transform infrared spectroscopy and ultraviolet–visible spectrophotometry. The semiconducting behavior of ferrites was determined from their electrical properties, such as direct current (DC) electrical resistivity. The Curie temperature was observed at 523 K temperature for all nanoferrites. The dielectric constant and dielectric loss significantly indicated the reducing behavior with an increase in the cerium concentration. The sample Cu0.5Cd0.5Fe1.975Ce0.025O4 resulted in the lowest optical bandgap energy, DC resistivity, and dielectric losses. The nature of the electrical resistivity and dielectric constants indicate that the designed materials are highly appropriate for the design of microwave gadgets

Non-magnetic impurity doping effect on the magnetic state of p-type Al-doped delafossite oxide CuCrO2

International audienceWe investigated the substitution effects of Al3+ for Cr3+ on the structure and magnetic, properties of delafossite oxide CuCrO2, which possesses a quasi-2D Heisenberg triangular antiferromagnetic (AFM) lattice. The lattice parameters was found to vary according to the Vegard's rule. We also found that the large local lattice distortion, caused by the nonmagnetic dopant with different radii between magnetic and nonmagnetic ions, affects the samples significantly. Magnetization and specific heat measurements indicated that AFM ordering is diluted by the substitution of nonmagnetic Al3+ for Cr3+ (S = 3/2)

Al-doping effect on the structural and physical properties of delafossite-type oxide CuCrO2

International audienceThe structure, Raman spectroscopy, magnetization, and dielectric properties of delafossite-type oxide CuCr1 ﰄ xAlxO2 have been characterized. It was found that Al substitution generates an anisotropic effect on the structure, besides magnetic dilution. The temperature dependence of all samples exhibits paramagnetic behavior at high temperature. Above x 1⁄4 0.2 the ferromagnetic transition at 120 K disappears. It is argued that Al substitution destabilizes the antiferromagnetic order of Cr3 þ ions and modulates the spin configuration, leading to a weak ferromagnetism. The coupling between the magnetic order and ferroelectric order is also characterized

Synthesis, structural and magnetic studies of the CuCr1ﰄxRhxO2 delafossite solid solution with 0 ﰉ x ﰉ 0.2

International audienceThe CuCr1ﰄxRhxO2 series is investigated by X-ray diffraction, magnetization measurements and Raman spectroscopy on ceramic samples. It is found that a delafossite solid solution is maintained up to x = 0.2 in CuCr1ﰄxRhxO2. The small observed variation in cell parameters is consistent with the small difference between the ionic radii of Cr3+ and Rh3+. A significant broadening of X-ray reflections is observed and when analyzed using the Williamson-Hall relationship showed that the strain generated by Rh substitution is strongly anisotropic, affecting mainly (Cr,Rh)-O bonds in the ab plane. Room temperature Raman spectra displayed three main Raman active modes. All modes shift to lower frequency and undergo significant changes in intensity with increasing Rh content, showing the effect of Rh atoms on the M3+-O bond strength. The magnetic behavior of CuCr1ﰄxRhxO2 samples was investigated as a function of temperature and applied field. At high temperature paramagnetic behavior, and at low temperature, evidence for weak ferromagnetism, reinforced by a hysteresis loop at 4 K is observed. The magnetic behavior of CuCr1ﰄxRhxO2 is attributed to the disorder of Cr and Rh in octahedral sites resulting in short-range Cr-O-Cr and Cr-O-Rh interactions, which give rise to short-range weak ferromagnetism

Metal transition doping effect on the structural and physical properties of delafossite-type oxide CuCrO2

International audienceIn this paper we reported on the non magnetic substitution effects on the structural, spectroscopic, and magnetic properties of the CuCrO2 delafossite. The incorporation of M3+ generates very anisotropic microstrains in the structure beside a magnetic dilution. The temperature dependence of all samples exhibits paramagnetic behavior at high temperature. It is argued that non magnetic-substitution destabilizes the antiferromagnetic order of Cr3+ ions and modulates the spin configuration leading to a weak ferromagnetism. The coupling between the magnetic order and ferroelectric order is also characterized

Cationic doping effect on the structural, magnetic and spectroscopic properties of delafossite oxides CuCr1−x(Sc,Mg)xO2

International audienceThis article reports the effect of Sc and (Sc + Mg) substitution on the structural and physical properties of delafossite-type CuCrO2 oxide. X-ray diffraction and Raman spectroscopy show that the structure is maintained for 10% Sc and (10% Sc + 4% Mg) substitutions for chromium. The incorporation of these elements generates very anisotropic microstrains in the structure. Strain also increases with oxygen intercalation, probably because a non-uniform distribution of intercaled oxygen. Thermal stability in oxygen was found to decrease with increasing the M3+ cation size. The evolution of relative intensities of Raman bands points towards an increase in lattice distortion with substitution, in agreement with ionic radii considerations. Comparing the substitution effect of Mg2+ to those of the nonmagnetic Sc3+, magnetization around the AF transition does not seem to correlate with randomness and lattice parameter but with itinerancy of the doped hole

Studies on Cobalt(II) Complexes with Benzenesulfonate: Synthesis, Crystal Structure, and Spectroscopic and Magnetic Properties

International audienc

Iron(III) and Cobalt(III) Complexes with Oxalate and Phenanthroline: Synthesis, Crystal Structure, Spectroscopy Properties and Magnetic Properties

International audienc