Electrical and Dielectric Properties of Sr-Doped LaCuO₄ Perovskites: Structural Insights and Applications in High-Frequency Electronics and Energy Storage

In this study, La cations were replaced by Sr cations in La_(1−x)Sr_xCuO₄ perovskite structures where x = 0, 0.25, 0.5 at.%. The prepared samples were characterized using energy dispersive X-ray (EDAX), X-ray diffraction (XRD), electrical and magnetic measurements. EDAX plots showed the replacement of La by Sr, with the Sr peaks increasing while the La peaks decreasing, with increasing x. XRD patterns revealed changes in the crystallization peaks with the replacement of Sr by La. XRD analysis resulted in a phase transition from orthorhombic to tetragonal, indicating the formation of nanocrystals as well as an increase in lattice strain. Electrical measurements showed that strontium cations act as structural defects that trap charge carriers, reducing the electrical conductivity, especially at low frequencies. All samples exhibited thermally active conductivity, with lower activation energies at higher temperatures, reflecting semiconductor behavior. Increasing the strontium content resulted in lower power dissipation at higher frequencies, indicating that the prepared samples act as an efficient energy storage for high-frequency applications. The introduction of Sr increased both the activation energy and the characteristic relaxation time from 0.3 to 0.41 eV and from 3.08E−12 to 3.87E−11 s, respectively. The magnetic measurements, at RT, indicates that La_2−xSr_xCuO₄ perovskites exhibit paramagnetic behavior due to unpaired electrons in copper or lanthanide cations. Where the sample of Sr (0.25) showed the maximum saturation magnetization (Ms) and remanent magnetization (Mr). Compared to CoFeO₄, LaSrCuO₄ has low saturation magnetization but high remanence and coercivity, making it valuable in superconductivity and other applications. The balance between charge compensation, oxygen vacancies, and exchange interactions shapes the material’s magnetic behavior.