Fuel Effect on the Structural, Morphological, and Electrical Properties of Perovskite-Type Mixed Oxide La0.7Ca0.3Mn1–xNixO3 (x = 0 and 0.07) Synthesized through Gel Combustion

The solution combustion synthesis method was used to prepare samples with stoichiometric La_0.7Ca_0.3Mn_1–xNi_xO₃ (x = 0 and 0.07) using glycine and tris(hydroxymethyl)aminomethane (TRIS) as fuels. X-ray diffraction showed that the samples crystallized into an orthorhombic structure of the Pnma space group with slight changes in the lattice parameters according to the type of fuel used, which can be attributed to their heat capacity. Likewise, using the transmission electron microscope technique, conglomerates of particles with relatively uniform morphology and crystallite sizes that varied in a range of 17–26 nm were observed. The electrical behavior exhibited a metal–semiconductor transition that displaced the temperature peak towards lower values, according to the Ni content. It was concluded that the properties of this type of complex inorganic oxide such as manganites can be varied with the use of different fuels in the synthesis process.