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The spinel ferrites with the compositional formula Ni0.8Zn0.2Fe2−xDyxO4 (x = 0, 0.004, 0.008, 0.012, 0.016) have been prepared using the sol–gel method. The X‐ray diffraction measurements confirm the cubic spinel structure of the sample with a space group of Fd‐3m. Morphological analysis of scanning electron microscope images reveals that the particles are spherical in shape. Energy dispersive X‐ray spectroscopy (EDX) confirms the elemental composition. Thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC) analysis of synthesized dysprosium (Dy) doped Ni–Zn ferrites are carried out from 25 to 700 °C. Fourier‐transform infrared (FTIR) spectroscopy studies reveal the stretching and bending vibrations of the various bonds presented in the compounds. The UV–vis absorption spectrum indicates the energy gap values which small decrease with the Dy concentration increase. Raman spectroscopy reveals the crystal distortion and phases of the samples. The room temperature magnetic measurements (M–H loops) are carried out to study the effect of Dy doping on magnetic properties.

Holmium (Ho)‐doped DyMnO3 multiferroic compound is prepared using conventional solid‐state reaction route, and X‐ray powder diffraction analysis is conducted to confirm the single‐phase structure. Coexistence of magnetic and electric behavior in case of multiferroics is analyzed by heat capacity measurements from low temperature (2 K) to room temperature (300 K) under different magnetic fields. Herein, the existence antiferromagnetic and ferroelectric phase transitions in this compound at <10, 18, and 40 K, respectively, is revealed, which are attributed to the structural ordering or alignment of Mn3+ ions and R3+ ions. The magnetocaloric effect of this sample is also studied from heat capacity measurements. A maximum magnetic entropy change (ΔS)M of ≈6.3 J kg−1 K−1 and adiabatic temperature change (ΔT)ad of 3–4 K is achieved in 0.1Ho‐doped compound for a magnetic field change of 5 T and useful for low‐temperature magnetic refrigeration applications.

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Single-phase spinel ferrites with formula of Ni1-xCoxFe2O4 where x values vary from 0 to 1 with 0.25 steps were synthesized by sol-gel technique. Microstructure, cation distribution, valence state of iron, and dielectric properties are discussed. From the deconvoluted Raman spectra the positions of five Raman modes and intensity variation was calculated. Cationic arrangement in A and B sites was estimated from deconvoluted Raman peaks. The characteristic magnetic patterns of ferrites were given by room-temperature Mossbauer spectra. Parameters like isomer shift, hyperfine magnetic field, quadrupole shift were estimated for all ferrites after fitting Mossbauer spectra. From X-ray photoelectron spectroscopy analysis +3 ionic state for iron was found. Dielectric parameters were also studied for ferrites at room temperature. NiFe2O4 and Ni0.75Co0.25Fe2O4 had high values of dielectric permittivity, AC conductivity and loss tangent. The ferrite Ni0.5Co0.5Fe2O4 showed very less dielectric constant and conductivity values and dielectric loss resonance peak was around 1 kHz.