Influence of copper substitution on structural, electrical and dielectric properties of Ni(1−x)CuxMn2O4 (0 ≤ x ≤ 1) ceramics

Copper substituted polycrystalline nickel manganite viz. Ni(1−x)CuxMn2O4 (0 ≤ x ≤ 1) ceramics were prepared by oxalate process. The replacement of nickel by copper plays an important role in changing the lattice parameter, X-ray density, sintered density, porosity, grain size, DC resistivity at different temperatures, drift mobility and dielectric properties at different frequencies. The lattice parameter and crystallite size decreases with increase in copper content. The addition of copper promotes grain growth, decrease in porosity and increase in sintered density. The room temperature DC electrical resistivity decreases from 43.50 to 32.92 MΩ cm and dielectric constant increases from ∼2 × 103 to 3 × 105 at low frequency (20 Hz) as copper concentration increases.

Research highlightsOn the basis of the experimental results the substitution of copper in Ni(1−x)CuxMn2O4 ceramics produce appreciable changes in the structural and electrical properties. Grain size and sintered density increased linearly with copper content and porosity decreased. The resistivity decreased linearly with copper and low activation energy obtained. The good value of thermistor constant (B), make these compounds promising for high temperature NTC type thermistor applications, with tunable range of sensitivity. The results obtained in this work strongly suggests that Ni(1−x)CuxMn2O4 (0 ≤ x ≤ 1) ceramics can be a good candidate for applications where high dielectric constant with low loss in radio-frequency range are required. Copper content has significant influence on the electromagnetic properties, such as initial permittivity, quality factor, DC resistivity, dielectric constant and dielectric loss tangent as well as their frequency dispersion for Ni–Cu manganite and it can be applicable in temperature-compensating dielectrics at room temperature.