The present study comprehensively scrutinizes the complex magnetism and hyperthermia efficiency of greenly synthesized Zn_0.25Ca_0.25Fe_2.5O₄ nanoparticles (ZNCF NPs). ∼23 nm sized ZNCF NPs in single phase fcc-spinel symmetry were successfully produced through sugarcane juice-mediated self-combustion tactics. Biocompatibility examination against BEAS-2B cell lines indicated a safer limit of ZNCF NPs as 1 mg. Exhaustive field (upto ±70 kOe) and temperature-dependent (10 K to 300 K) dc-magnetization measurements showed that ZNCF NPs are in the ferrimagnetic (FiM) phase at low temperatures and superparamagnetic (SPM) along with minute magnetically hard FiM component at 300 K. ⁵⁷Fe-Mössbauer analysis validated SPM (43%) and FiM (57%) at 293 K and FiM state at low temperatures. Observed isomer shift revealed that the majority of Fe ions are in a high spin Fe³⁺ state along with Fe²⁺ ions in ZNCF NPs. Shifting in the real part of ac—susceptibility data toward the higher temperature side upon increasing frequency and obeying Vogel–Fulcher law affirmed collective freezing of superspins below freezing temperature (T _f = 200 K). Dynamic scaling fit yielded relaxation time of ∼10⁻¹² s, Mydosh parameter (=0.021) and critical exponent (8.9) ascertaining superspin glass (SSG) state in ZNCF NPs below glass temperature (T _g = 220 K). Furthermore, SSG phase at low temperatures is approved by archetypal experimental signatures like ageing, memory and rejuvenation. The induction heating characteristics of ZNCF NPs probed via infrared thermography yielded intrinsic loss parameter in the 0.26 nHm² kg⁻¹–5.10 nHm² kg⁻¹ range. Linear response theory provided non-zero power dissipation for ZNCF (suspension in de-ionized water) functioning range of 6–8 nm with an optimum particle size of ∼7 nm. A prudent analysis asserted that only 18% of NPs contribute to a non-zero SAR value. Overall, this research is an exhaustive investigation of the complex magnetism and hyperthermia efficiency suitable for mild hyperthermia applications.

We discuss the atomic structure of amorphous ferromagnetic FeCoB alloys, which are used widely in spintronics applications. Specifically, we obtain the pair-distribution functions for various atomic pairs based on high-energy x-ray diffraction data taken from an amorphous Co ₂₀ Fe ₆₁ B ₁₉ specimen. We start our reverse Monte Carlo cycles to determine the disordered structure with a two-phase model in which a small amount of cobalt is mixed with Fe ₂₃ B ₆ as a second phase. The structure of the alloy is found to be heterogeneous, where the boron atoms drive disorder through the random occupation of the atomic network. Our analysis also indicates the presence of small cobalt clusters that are embedded in the iron matrix and percolating the latter throughout the structure. This morphology can explain the enhanced spin polarization observed in amorphous magnetic materials.

An amorphous alloy Co₉₀Sc₁₀ has been prepared by rapid quenching from the melt. The results of magnetization measurements show that this alloy has the highest Curie temperature reported for any amorphous transition metal based alloys. Furthermore, for a Co based amorphous alloy, the magnetic moment is remarkably high. Moreover, the alloy exhibits soft magnetic properties. Based on the findings, amorphous Co₉₀Sc₁₀ appears to be an attractive candidate for applications as a soft magnetic material. The temperature dependence of the reduced magnetization can be described by the Bloch power law. The results show that the B coefficient of the amorphous Co₉₀Sc₁₀ alloy, which is a measure of the rigidity of spin waves, exhibits the lowest value observed until now for any amorphous alloy and is comparable to crystalline alloys. It is found that the Sc atoms in the Co₉₀Sc₁₀ alloy lead to an increase of the itinerant spin moment of Co atoms, and, in contrast to this behaviour, to a decrease of the local 3d-electrons of Co.

High-energy x-ray diffraction (HE-XRD) experiments combined with an analysis based on atomic-pair-distribution functions can be an effective tool for probing low-dimensional materials. Here, we show how such an analysis can be used to gain insight into structural properties of PbTe nanoparticles (NPs). We interpret our HE-XRD data using an orthorhombic Pnma phase of PbTe, which is an orthorhombic distortion of the rocksalt phase. Although local crystal geometry can vary substantially with particle size at scales below 10 nm, and for very small NPs the particle size itself influences x-ray diffraction patterns, our study shows that HE-XRD can provide a unique nano-characterization tool for unraveling structural properties of nanoscale systems.

We discuss the ground state electronic structure and magnetization properties of a series of NiFe _{2− x} Al _x O ₄ solid solutions ( x = 0.0, 0.4, 0.8, 1.2, 1.6, and 2.0) using magnetic Compton scattering measurements, together with parallel first-principles computations. In this way, we systematically extract the complicated cation distributions in this ferrite system as a function of x . The relationship between the electronic ground state, magnetism, and cation distributions is explained in terms of a model, validated by our first-principles computations, wherein the magnetic properties of the three cation distributions are assumed to be different. A good accord is found between the computed and measured magnetic Compton profiles.

Spinel crystallization is known to be detrimental to the operation of Joule heated ceramic melters during the vitrification of iron‐rich high‐level nuclear wastes (HLW) into borosilicate glasses. The literature on this subject focuses on tackling the problem by developing empirical constraints to design compositions, which limit the fraction of spinels formed in the melter or by developing empirical models to predict the settling behavior of spinels in the melter as a function of the glass composition. While these empirical models can predict the behavior of most of the compositions, they are not failsafe as there are always some compositions, whose behavior is beyond the predictive ability of these models. This can lead to undesirable situations during the vitrification of the nuclear waste, and therefore an in‐depth investigation of the chemo‐structural descriptors controlling the crystallization behavior in these glasses is warranted. Accordingly, the present study aims to understand the impact of non‐framework cation mixing (i.e., Li ⁺ /Na ⁺ and Ca ²⁺ /Na ⁺ ) on the structure (through Raman spectroscopy and Mössbauer spectroscopy) and crystallization behavior (through XRD, SEM‐EDS, and vibrating sample magnetometry) of iron‐rich model HLW glasses in the system: (mol.%) x M _y O–(25− x ) Na ₂ O–9.12 B ₂ O ₃ –6.4 Al ₂ O ₃ –51.25 SiO ₂ –7.22 Fe ₂ O ₃ –0.38 MnO–0.08 Cr ₂ O ₃ –0.55NiO (M _y O = Li ₂ O or CaO).