Structural and morphological characterization of cuprate superconductor La _2-x Sr _x CuO ₄ (x=0 and x=0.07) synthesized by sol-gel method

The La _2-x Sr _x CuO ₄ materials with x=0 and x=0.07 were prepared by sol-gel method. These materials are the family of cuprate superconductor. These samples were heated three times by drying at 120°C for 2 hours, calcining at 500°C for 5 hours, and sintering at 700°C for 15 hours. The powder sample was pressed and compacted to be a bulk samples. These materials were characterized by X-Ray Diffraction (XRD) to study the structure of materials and Scanning Electron Microscopy - Electron Dispersive Spectroscopy (SEM-EDS) to study morphology and confirm the composition of materials. The results of XRD and High-Score application showed that the structure of both samples is orthorhombic (Cmca/64 space group). The substitution of Sr ²⁺ ion with x = 0.07 to the La site did not change the crystal structure of material but it showed the variation of lattice parameter and unit cell volume. The variation indicated a decreasing of unit cell volume by substituting Sr ²⁺ ion to La site. SEM-EDS characterization showed that both samples have homogeneity and confirmed that Sr ²⁺ ion has successfully substituted to La site for La _1.93 Sr _0.07 CuO ₄ material. It also revealed that composition of both samples is similar to the stoichiometry calculation.