The effect of Ca-substitution in La-site on the magnetic properties of La2CoMnO6

Abstract

Double perovskite La2-xCaxCoMnO6 (x = 0, 0.1, 0.2, 0.5) ceramics samples were synthesized by the standard solid-state reaction method. The crystal structures have been confirmed to be monoclinic perovskite structure with space group of P21/n at room temperature by the powder x-ray diffraction (Cu-Kα). The grains of the samples are relatively dense and distribute in random directions from the scanning electron microscope patterns. Holes are doped into La2CoMnO6 with the substitution of the Ca2+ ions in La-site, and further lead to the valences of Mn ions and Co ions transforming from Mn4+ and Co2+ to Mn3+ and Co3+, respectively. Ferromagnetic coupling of Mn4+-O2–-Co2+ and antiferromagnetic coupling of Mn3+-O2–-Co3+ are coexistent in La2-xCaxCoMnO6 system, which correspond to two transitions existed in field-cooling magnetization versus temperature curves. Curie temperature of La2-xCaxCoMnO6 system decreases with the increasing of Ca-substitution amount. The coexistence of different magnetic phases leads to the exchange bias effect.

Tuning oxygen vacancy photoluminescence in monoclinic Y2WO6 by selectively occupying yttrium sites using lanthanum

“…This method has been extensively investigated in luminescent compounds, photo-catalysts, and magnetic materials. For example, La 3+ -doped ZnO has high photocatalytic activity19, and LaCoMnO 6 presents the coexistence of ferromagnetic and antiferromagnetic properties with increased Ca 2+ substitution amounts20. For tungstates, this approach mainly aims at enhancing luminescent intensity, changing optical activity, or broadening emission wavelength range212223.…”

Electrical transport properties and enhanced magnetoresistance effect in double perovskite La2–xCaxCoMnO6 (0 ≤ x ≤ 0.5)

“…The main diffraction peaks can be well indexed as a monoclinic perovskite structure with a space group of P2 1 /n . The peaks shift slightly to the right with increasing x value, due to the smaller radius ion Ca 2+ (0.99 Å) substituting La 3+ (1.06 Å) .…”

“…Samples of double perovskite La 2− x Ca x CoMnO 6 ( x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized by the standard solid‐state reaction method . The identification of the crystal structure was accomplished with the powder X‐ray diffraction (XRD), using Cu‐K α radiation.…”

“…We have studied the magnetic properties of La 2 CoMnO 6 with Ca 2+ ‐substitution . The Ca 2+ ‐substitution could lead to the transfer of the electrons between the Ca 2+ ions and the B‐site ions (Co and Mn ions), and further change the valences of Co and Mn ions.…”

The spontaneous exchange bias effect in La2-xCaxCoMnO6 series

“…The controversy occurs because the Co and Mn scattering factors are very similar for XRD performed with Cu-K α radiation. Different groups have reported such compounds as belonging to one of these space groups or even a mixture of both [18,24,25,26,27,28]. The Co-and Mn-based perovskites are known to be very sensitive to the synthesis route [6,29,30], and the La 2−x Ca x CoMnO 6 seems to be a clear manifestation of this.…”