Effect of Ag addition on the microstructure and electrical properties of Ni0.6CoMn1.4O4/Ag composite ceramics

In this work, novel Ni0.6CoMn1.4O4: x wt%Ag (NCMO: Ag-x, x = 0, 5, 7.5, 10, 12.5, and 15) composite ceramics were successfully fabricated by combining chemical reduction with solid-state coordination reaction method. The phase composition, microstructure, element distribution, and electrical properties are systematically investigated. The introduced Ag nanoparticles formed heterogeneous interfaces with the NCMO particles and were uniformly distributed in the samples. Due to the introduction of Ag, the Co2+ content increases from 33.2% to 50.0%. The average valence state of Mn ions increases from 2.91 to 3.17, then it decreases to 2.89. The Ag addition does facilitate the remarkable reduction of room temperature resistivity from 250.38 to 7.61 Omega cm and makes the resistivity drift below 2.57%, while B value decreases from 3145 to 1909 K, which are caused by the decreases of grain resistance and grain boundary resistance. Moreover, space electronic transmission mechanism is also proposed to further explain the positive effect of Ag introduction on electrical properties of the NCMO/Ag composite ceramics. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Novel Ni0.6CoMn1.4O4: x wt%Ag (NCMO: Ag-x) composite ceramics were successfully fabricated and their properties were investigated. The introduction of Ag nanoparticles improved the conductivity of the material and reduced the resistivity by decreasing grain boundary resistance and grain resistance.