New perovskite Ba0.7La0.3Ti0.55Fe0.45O3-δ prepared by citric sol-gel method: From structure to physical properties

Abstract

A new material Ba0.7La0.3Ti0.55Fe0.45O3-δ (BLTFO) has been prepared via the citric sol gel method. The correlation between structural, vibrational, and electric properties of BLTFO have been investigated using different technique. The XRD study showed that BLTFO perovskite was a single phase that crystallize in the cubic system with a space group Pm3̅m (a = 3.94 Å). The nanometric average crystallite size (D) was calculated from the XRD peaks using the two Scherrer and the Halder-Wagner methods. The particle sizes observed by SEM (70–140 nm) are several times larger than those calculated by XRD, indicating that each particle observed by SEM consists of several crystallites domains. The sphericity of each element present in this composition was studied by the Atomic Hirshfeld Surfaces (AHS) analysis in order to prove the obtained phase. Furthermore, this investigation proved that the BLFTO is stabilized by covalent, ionic and van Der Waals interactions. All stretching and bending vibrations were studied by IR and Raman. Moreover, the Mössbauer technique revealed the presence of Iron in the (+III) oxidation state. The electrical conductivity was measured in the frequency range from 20Hz to 2 MHz and temperatures between 520 and 700 K using impedance spectroscopy. The latter confirmed that an equivalent parallel Rg//C//CPE circuit can be connected. Besides, the analysis of Nyquist plots revealed the contribution of two electrically active regions The DSC analysis confirmed that this new material presented a phase transition at T = 600 K.