Effect of Sintering Temperature and Cu Substitution on the Structure of La_0.7Ba_0.291Ca_0.009Mn_1-xCu_xO₃ (x = 0 and 0.10) Manganite

Series of Cu substituted manganese La_0.7Ba_0.291Ca_0.009Mn_1-xCu_xO₃ (x = 0 and 0.10) has been studied and it has affect in the structure. The powder sample was elaborated using sol-gel method. Samples were sintered at two different temperatures, 1173 K and 1473 K. Structures of all samples were investigated by X-ray diffraction (XRD). The Rietveld analysis of the powder X-ray diffraction shows that the samples crystallize in rhombohedral structure with R3c space group symmetry without any impurity phase. The values of tolerance factor (t_G) shows that the sample without Cu substitution (t_G = 0.98486) and with Cu substitution (t_G = 0.980703) are still in perovskite structure. Substitution by Cu does not change the structure but it decreases unit cell volume, lattice parameters and Mn-O-Mn bond angle and increases Mn-O bond length. The result of experiments confirms that the Cu substitution at Mn-site interrupt the Mn³⁺-O^2--Mn ⁴⁺ bridges and weaken the double exchange (DE) interaction between Mn³⁺ and Mn⁴⁺ ions. This phenomenon is indicated by a decrease in the bandwidth value.