Structural with Rietveld analysis and enhancement of magnetic, magnetocaloric study of Al substituted Ni-Cd bulk spinel ferrites

Ni0.65Cd0.35Fe2-xAlxO4 (0 <= x <= 0.060) disc shape bulk specimen fabricated from the sol-gel synthesized nanocrystalline powders. According to a structural analysis using XRD and Rietveld refinement, single-phase cubic spinel structure confirmed. Crystalline size (40-36) nm calculated using Scherer's formula. SEM images used to study surface morphology and grain size found decreasing trend from (1.4-1.0) mu m. The saturation magnetization (Ms) as well as magnetic moment increased for x = 0.45 and beyond that it decreased with Al content, which phenomenon is attributed due to the reduction of length between tetrahedral (A) sites and octahedral [B] sites of cations. The temperature-dependent magnetization graphs shown sharply declining value of the temperature (i.e., dM/dT maximum) dropping from 582.27 to 578.76 K at the Curie point with Al concentration. The maximum magnetic entropy change (- Delta SMmax\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta S_{M}<^>{\max }$$\end{document} ) derived from the Maxwell relation, is determined to be (0.54-0.72) JKg-1 K-1 as well as to relative cooling power of (43.18-56.97) Jkg-1 with an applied magnetic field of mu 0H = 3 T. UV-visible spectroscopy utilized to explore optical study and found enhancement of absorption properties with Al content.