Improvements in electrical and dielectric properties of substituted multiferroic LaMnO3 based nanostructures synthesized by co-precipitation method

A series of La1−xGdxMn1−yCryO3 nanoparticles (where x, y = 0, 0.25, 0.50, 0.75 and 1.0) has been synthesized by the chemical co-precipitation method, involving double ion substitution philosophy. The nanoparticles were characterized by thermo gravimetric analysis (TGA), X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometer (VSM), DC electrical resistivity and dielectric measurements. The XRD and FTIR analysis confirmed the single orthorhombic phase and the crystallite size were found in the range of 16–34 nm. DC resistivity exhibited very interesting behavior which increased from 1.41 × 108 to 16.35 ± 0.2 × 108 Ω cm upon complete double ions replacement of La and Mn with Gd and Cr, respectively. This very high resistivity variation upon substitution definitely would open new avenues for applications of these materials in microwave devices and other related areas. The dielectric properties of these nanoparticles were also studied at room temperature in the range of 6 kHz to 5 MHz and the maximum dielectric behavior (ɛ′ = 2.86 × 103, tan δ = 5.41, ɛ″ = 15.5 × 103) was exhibited by La0.75Gd0.25Mn0.75Cr0.25O3 at 6 kHz. Hysteresis loops measurements showed that the synthesized nanomaterials are paramagnetic in nature at room temperature.