Compositional dependency of morphology, elastic parameters and radiation shielding features in Co–Zn–Cr-nanoferrite materials

In this study, we investigate the impacts of chromium additions on the properties of the Co_0.8-xZn_0.2Cr_xFe₂O₄ nanoferrite system, where x takes values of 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10. Our analysis involved field emission scanning electron microscope (FESEM), ultrasonic measurements, and radiation shielding assessments. Our findings reveal that the morphology, longitudinal modulus, shear modulus, Young's modulus, bulk modulus, effective atomic number, mass attenuation coefficient and half-value layer of Co–Zn–Cr-nanoferrites are highly sensitive to variations in Cr concentration. Notably, the nanoferrite Co_0.74Zn_0.2Cr_0.06Fe₂O₄ exhibits the highest shear modulus of 1.29 GPa and Young's modulus of 3.41 GPa. Conversely, the nanoferrite Co_0.72Zn_0.2Cr_0.08Fe₂O₄ showed the lowest longitudinal modulus of 4.12 GPa and bulk modulus of 2.53 GPa. These results can be explained by differences in nanoparticle size and the sample porosity. Moreover, the nanoferrite Co_0.70Zn_0.2Cr_0.1Fe₂O₄ demonstrates the highest longitudinal modulus of 5.24 GPa. This increase in modulus is attributed to the smaller ionic radius of Cr³⁺ (0.615 Å) compared to Co²⁺ (0.645 Å in octahedral sites), leading to a decrease in interionic distance and an increase in bond strength as Cr³⁺ content rises. Hence, both the longitudinal and Young's moduli increase with higher Cr concentrations. However, it was observed that excessive Cr additions lead to a reduction in the density of the nanoferrite system, decreasing from 4.612 to 3.814 g/cm³. This increase in Cr content also causes a decline in the effective atomic number, which, inturn, results in lower linear and mass attenuation coefficients. Additionally, we compared the half-value layers of the nanoferrite materials with standard shielding materials to assess their radiation shielding efficiency. Despite the slight reduction in radiation shielding efficiency with higher Cr content, all nanoferrite samples exhibit a lower half-value layer (indicating higher radiation shielding efficiency) compared to the standard shielding materials included in the study.