Structural, Magnetic, and Giant Dielectric Properties of Gd Substituted CuFeO 2 Composites

To study the effects of structural modulation by doping rare earth element on the magnetic and dielectric properties, CuFe 1- x Gd x O 2 (0 ≤ x ≤ 0.2) samples are synthesized using the solid-state reaction method. The XRD and SEM results show that a small amount of Gd 3+ ions ( x ≤ 0.07) effectively occupies the Fe 3+ site and promotes the grain growth of the CuFeO 2 system. Judging from the magnetic property measurements, the samples ( x = 0, 0.01) undergo two successive magnetic transitions. Further increase of x , the magnetic transition of the samples ( x ≥ 0.07) has not been detected in the testing temperature range. The magnetization hysteresis loops show that all of the samples have weak ferromagnetic properties, and the saturation magnetization is obviously enhanced with increasing x . Most interestingly, the dielectric measurements suggests that CuFeO 2 samples exhibit a giant dielectric constant ( ε γ ~10 4 ), and ε γ is obviously improved (~ 4.0 × 10 4 ) using the proper Gd content. The dielectric properties are explained using the internal barrier layer capacitance model (IBLC).