Structural and Magnetic Properties of $$\hbox {Eu}^{3+}$$ Eu 3 + -Doped $$\hbox {CdNb}_{2}\hbox {O}_{6}$$ CdNb 2 O 6 Powders

Abstract

Europium-doped $$\hbox {CdNb}_{2}\hbox {O}_{6}$$ powders with the molar concentration of $$\hbox {Eu}^{3+}$$ (0.5, 3 and 6 mol%) were successfully prepared at $$900\,^{\circ }\hbox {C}$$ by using molten salt synthesis method. The effect of europium (Eu) molar concentration on the structural and temperature-dependent magnetic properties of $$\hbox {CdNb}_{2}\hbox {O}_{6}$$ powders has been investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), vibrating sample magnetometer (VSM) and ferromagnetic resonance (FMR) techniques in the temperature range of 10–300 K. XRD results confirm that all the powders have orthorhombic crystal structure. It has been confirmed from VSM and FMR measurements that $$\hbox {Eu}^{3+}$$ -doped $$\hbox {CdNb}_{2}\hbox {O}_{6}$$ powders have ferromagnetic behaviour for each $$\hbox {Eu}^{3+}$$ molar concentration between 10 and 300 K. XRD and EDX analyses indicate that there is no magnetic impurity in $$\hbox {Eu}^{3+}$$ -doped $$\mathrm{CdNb}_2\mathrm{O}_6$$ powders, supporting that the ferromagnetic behaviour of the powders arises from $$\hbox {Eu}^{3+}$$ ions. The observed ferromagnetism was elucidated with the intrinsic exchange interactions between the magnetic moments associated with the unpaired 4f electrons in $$\hbox {Eu}^{3+}$$ ions. The saturation magnetization decreases with increasing $$\hbox {Eu}^{3+}$$ molar concentration. The temperature-dependent magnetization behaviour was observed not to agree with Curie–Weiss law because europium obeys Van Vleck paramagnetism. Broad FMR spectra and a g-value higher than 2 were observed from FMR measurements, indicating the ferromagnetic behaviour of the powders. It was found that while the resonance field of FMR spectra decreases, the linewidth increases as a function of $$\hbox {Eu}^{3+}$$ molar concentration.