Cr3+ substitution influence on structural, magnetic and electrical properties of the Ni0.3Zn0.5Co0.2Fe2-xCrxO4 (0.00 ≤ x ≤ 0.20) nanosized spinel ferrites

•The sol-gel auto combustion method prepared the Cr3+ substitution in Ni0.3Zn0.5Co0.2Fe2-xCrxO4 (0.00 ≤ x ≤ 0.20) ferrite nanoparticles.•The measured lattice constant and crystallite size from XRD data show a single-phase cubic spinel.•FESEM images indicate the particles are of small size are confirmed.•There were two absorption peaks around 577.43 cm−1 and around 392.46 cm−1 in the FTIR spectra supporting their spinel structure, as is indicated by the XRD pattern.•The magnetic saturation decreased from 110.87 to 70.28 emu/g with the Cr3+ ions substitution.•The BB interaction is prominent over the AB interaction, and the DC electricity measurement shows their highly resistive nature.