Structure, oxygen vacancy regulation and electromagnetic wave absorption of cobalt-doped La1.875Sr0.125NiO4±δ

Abstract

Electronic devices, especially those with sensitive components and communication systems, are highly susceptible to electromagnetic interference (EMI). As a result, there is an increasing demand for materials capable of efficiently attenuating or shielding against microwave radiation. In this work, we have successfully demonstrated that co-doping of Sr and Co in the La₂NiO₄ with electron-rich Cobalt atoms in smaller concentrations, balancing the electrical neutrality. Here, we present an improved electromagnetic wave (EMW) absorption in La_1.875Sr_0.125Ni_1−xCo_xO_4±δ (x = 0.05, 0.1, 0.15, 0.20). A phase transition from tetragonal to orthorhombic was observed with an increase in x, which is due to non-stochiometric oxygen content, exhibiting long-range charge and spin ordering with antiferromagnetic arrangement. Electron paramagnetic resonance spectroscopy results showed that oxygen vacancies decreased with an increase in x which influenced the dielectric and magnetic properties, thereby enhancing EMW absorption. All the samples exhibited antiferromagnetic-like behavior. The sample with x = 0.1 showed ~ 97% of EMW absorption in the X-band, indicating potential for EMI shielding applications.