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The sol-gel process was used to produce ferrite Ni_0.3Zn_0.7Cr_2−xFe_xO₄ compounds with x = 0, 0.4, and 1.6, which were then subsequently calcined at several temperatures up to 1448 K for 48 h in an air atmosphere. X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and ⁵⁷Fe Mössbauer spectrometry were used to examine the structure and magnetic characteristics of the produced nanoparticles. A single-phase pure Ni_0.3Zn_0.7Cr_2−xFe_xO₄ nanoparticle had formed. The cubic <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>F</mi><mi>d</mi><mover accent="false"><mrow><mn>3</mn></mrow><mo>¯</mo></mover><mi>m</mi></mrow></semantics></math></inline-formula> spinel structure contained indexes for all diffraction peaks. The crystallite size is a perfect fit for a value of 165 ± 8 nm. Based on the Rietveld analysis and the VSM measurements, the low magnetization Ms of Ni_0.3Zn_0.7Cr_2−xFe_xO₄ samples was explained by the absence of ferromagnetic Ni²⁺ ions and the occupancy of Zn²⁺ ions with no magnetic moments in all tetrahedral locations. Moreover, because of the weak interactions between Fe³⁺ ions in the octahedral locations, the magnetization of the current nanocrystals is low or nonexistent. According to Mössbauer analyses, the complicated hyperfine structures are consistent with a number of different chemical atomic neighbors, such as Ni²⁺, Zn²⁺, Cr³⁺, and Fe³⁺ species that have various magnetic moments. A Fe-rich neighbor is known to have the highest values of the hyperfine field at Fe sites, while Ni- and Cr-rich neighbors are responsible for the intermediate values and Zn-rich neighbors are responsible for the quadrupolar component.