Nanostructure La1-x Sr x MnO3 (x = 0.15 ∼ 0.5) with Improved Metal-Insulator Performance

Abstract

Perovskite manganese oxide La1-x Sr x MnO3 (LSMO) is a metal-insulator ceramic compound for which the metal-insulator transition temperature (T MI) depends on the Sr doping value. Traditional LSMO fabrication processes achieve the metal-insulator behavior only over a limited doping level range of Sr (x = 0.175 to 0.25). To improve its metal-insulator performance, LSMO was synthesized with a wide range of x values (0.15 to 0.5) using the precisely controlled sol-gel Pechini method. XRD phase structure analysis, XPS composition and chemical state study, and SEM surface morphology investigation were employed to ensure high purity and quality of the synthesized compounds. Resistance was measured for all samples in the temperature range of 150 K to 380 K using the four probe technique. Investigations validated the improved metal-insulator characteristic of the fabricated nanostructured LSMOs, i.e., the temperature-resistivity curve of all the x values clearly behave like metals below T MI and like insulators above T MI .