The effect of partial substitution of Pd in LaMnO3 polycrystalline materials synthesized by sol–gel technique on the electrical performance
- 18 Downloads
This work reports the change in the structural and electrical behavior of partial substitution of manganese by palladium in LaMnO3 perovskite materials synthesized through sol–gel method. X-ray diffraction analysis reveals that all the obtained materials crystallize in the orthorhombic perovskite structure (Pnma space group). Morphological investigations show the presence of fine nanometric particles of similar shape and high tendency to agglomerate, and the elemental analysis highlights the presence of palladium. Detailed study of complex impedance measurements in the frequency range 20 Hz–2 MHz and different temperatures between (30 and 120) °C indicate the presence of electrical relaxation in materials; the activation energy of relaxation decreases from 0.207 eV (0.05% Pd–LMO–Pd1) to 0.102 eV (0.15% Pd–LMO–Pd3) when the x concentration of Pd increases from 0.05 to 0.15. The electrical conductivity analyses indicate that the conduction mechanisms in the low-frequency range (f < 100 kHz) are activated thermally and were explained using the Mott’s variable-range-hopping (VRH) model. In the high-frequency range (f > 100 kHz), the conduction mechanism is due to the charge carriers hopping between the nearest neighboring states, in agreement with the CBH model (correlated barrier hopping). Based on this model, the bandgap energy, Wm was determined. The results show that by increasing the Pd concentration, the value of Wm of the sample increases, from 0.229 eV (LMO–Pd1) to 0.298 eV (LMO–Pd3), in agreement with the decreasing of electrical conductivity of samples.
Partial substitution of Mn by palladium in LaMnO3 perovskite materials.
Heat treatment was performed at low temperature.
Detailed studies of impedance and electric conductivity have been performed.
KeywordsSol–gel Perovskite Palladium Electrical properties
Financial support for this work was provided by the Experimental Demonstrative Project 48PED/2017 and Nucleu National Project PN 19220201, Ctr. 40 N/2019. The authors thank D. Ursu for help during the materials characterization.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- 2.Rao CNR and Raychaudhuri AK (1998) Colossal magnetoresistance, charge ordering and other novel properties of manganates and related materials. Colossal Magnetoresistance, Charge Ordering and Related Properties of Manganese Oxides. https://doi.org/10.1142/9789812816795_0001
- 8.Giannakas AE, Vaimakis TC, Ladavos AK, Trikalitis PN, Pomonis PJ (2003) Variation of surface properties and textural features of spinel ZnAl2O4 and perovskite LaMnO3 nanoparticles prepared via CTAB–butanol–octane–nitrate salt microemulsions in the reverse and bicontinuous states. J Colloid Interface Sci 259:244–253CrossRefGoogle Scholar
- 20.Sfirloaga P, Malaescu I, Poienar M, Nicolae MC, Malaescu D, Vlazan P (2016) Synthesis, structural and electrical properties of NaTaO3:Cu. J Mater Sci: Mater Electron 27:11640–11645Google Scholar
- 25.Debye P (1929) PolarMolecules. The Chemical Catalog Company. Inc., New York, NY, p 89–95.Google Scholar
- 26.Moulson AJ, Herbert JM, Electroceramics: Materials, Properties, Applications. Minden, NV, USA. 1992Google Scholar
- 27.Jonscher AK (1996) Universal relaxation law: a sequel to Dielectric relaxation in solids, Chelsea Dielectrics Press 198–200Google Scholar
- 28.Mott NF, Davis EA (1979) Electronic Processes in Noncrystalline Materials, 2nd ed. Clarendon, OxfordGoogle Scholar