Investigating the co-substitution impact of yttrium–nickel cations on lattice, morphological and magnetic parameters of SrM based ceramics

Abstract

This study details the impact of the co-substitution of Y3+-Ni3+ ions for the Fe3+ ions on the structural, morphological and, magnetic parameters of SrM based SrYxFe12-2xNixO19 (0.00 ≤ x ≥ 0.25) (SrYFeNiO) ceramic magnets synthesized by the ceramic route. Rietveld refinement of XRD confirmed the hexagonal (P63/mmc (194), z = 2) SrFe12O19 phase for all and an additional rhombohedral (R-3c (167), z = 6) hematite Fe2O3 phase for x = 0.2, x = 0.25 doping levels. The experimental and theoretical measurements abstracted the stretch of lattice parameters, i.e., the crystallographic axis and the lattice cell volume, and the dislocation of the crystallographic plane (1 1 4) for the hexagonal system, certified the heavy Y3+-Ni3+ ions substitution. To examine the morphological parameters, FESEM presented the regular hexagonal platelets of sizes ~ 1–2 μm, and EDX revealed the presence of constituent elements with their atomic and weight percentages in SrFeYNiO products. The extraction of vibrational frequencies of Fe–O bonds at tetrahedral and octahedral sites of iron through FT-IR spectroscopy authenticates the formation of the SrM phase. XPS correlated the doped elements, i.e., nickel in Ni+2 and Ni+3 and yttrium in Y+3, whereas parent element, i.e., iron in Fe+3 and Fe+2 chemical states, enlightened their impact on the magnetic parameters. Hysteresis loop analysis deduced a linear decline in magnetic parameters such as saturation magnetization (Ms) and remnant magnetization (Mr) due to non-magnetic Y3+ and less magnetic Ni3+ ions installment in 4f1 and 2b polyhedral sites of Fe3+ ions. However, high coercivity (Hc) up to 2.92 kOe ∈ x = 0.15 and extended magnetocrystalline anisotropy (MCA) up to 5.790× 106 Erg/g ∈ x = 0.15 of our obtained ceramic magnets affirmed their application in permanent magnetic industry. M(T) curves also demonstrated the decrease in Ms and displayed an SPM at TB, which is shifting towards lower temperatures with increasing Y3+-Ni3+ contents approved the expansion of lattice parameters.