Tran Dang Thanh

The Halder–Wagner (H–W) method is widely used to separate crystallite size and microstrain contributions from X-ray diffraction (XRD) peak broadening. However, different forms of the H–W equation exist in the literature, including simplified expressions based on the full width at half maximum (FWHM). Here, we examine the dimensional consistency of a commonly used FWHM-based formulation. Our analysis shows that this form violates the requirement of dimensional homogeneity, potentially leading to physically questionable estimates of crystallite size (D) and microstrain (ε). Representative data from published studies are reanalyzed, revealing discrepancies between reported and recalculated values, with crystallite sizes differing by up to one order of magnitude in some cases. We then revisit the original H–W formulation, based on the integral breadth and a Voigt-type description of peak broadening, which preserves dimensional consistency. This approach provides a physically meaningful framework for size–strain analysis. This Comment highlights the importance of using dimensionally consistent formulations to improve the reliability and reproducibility of XRD-based microstructural characterization.

MFe ₂ O ₄ (M = Co and Mn) nanoparticles were synthesized from coconut coir extract using a microwave-assisted co-precipitation method, representing a green and sustainable approach for ferrite nanomaterial preparation.

Multiferroic composites of NiFe ₂ O ₄ /(0.5BaZr _0.2 Ti _0.8 O ₃ -0.5Ba _0.7 Ca _0.3 TiO ₃ ). Improvement the ferroelectric and ferromagnetic properties. Strong absorbing electromagnetic waves in the frequency range of 6–18 GHz.

Co _{n −1} TMO _{n −2} ⁺ ( n = 6–8), (TM = V, Cr, Mn, and Fe) clusters are investigated using density functional theory calculations.

In this study, we analyze the correlation between magnetization and magnetoresistance of perpendicularly anisotropic [Co/Pd] multilayered films with different thicknesses of Pd layers tPd = 0.6–2.0 nm in a wide range of temperatures, T = 4–300 K. We revealed that electron scattering by magnons makes a significant contribution to the magnetoresistance of the multilayers regardless of the layer thickness. Contrary to expectations, the effect of magnon magnetoresistance (MMR) increases with decreasing temperature below T = 50 K in the films with tPd = 0.8 and 1.0 nm. The revealed low-temperature MMR increase, which is most pronounced in the [Co0.5/Pd1.0] multilayers, is associated with the enhanced magnon excitation due to antiferromagnetic exchange coupling between the Co layers. The latter ensures an atypical shape of the magnetization curves of the [Co0.5/Pd1.0] multilayers at low temperatures in a perpendicular magnetic field, which combine a quadratic hysteresis loop of a perpendicularly anisotropic ferromagnet and an anomalous magnetization drop resulting from a violation of the ordering of magnetic moments and their amplified oscillations initiated by the interlayer exchange coupling.

Five samples of xNiFe2O4/(1 − x)Ba0.8Sr0.2TiO3 (where x = 0, 0.1, 0.2, 0.3, and 0.4) multiferroic nanocomposites have been successfully fabricated using ball milling combined with heat treatment in a short time. X-ray diffraction patterns indicated the coexistence of two phases, namely, NiFe2O4 (NFO) and Ba0.8Sr0.2TiO3 (BSTO). The average grain size obtained is about 50–100 nm, and NFO and BSTO phases are evenly distributed in the samples. With an increase in the content of NFO, the values characterizing the ferroelectric and ferromagnetic properties improve significantly. Furthermore, the bandgap energy (Eg) value was also strongly reduced. The results on the degradability of methylene orange show that the apparent first-order rate of composites containing NFO with x = 0.4 was found to be k = 0.0228 min−1, which is significantly higher than that of pure BSTO (k = 0.0166 min−1), suggesting that NFO/BSTO multiferroic nanocomposites could be considered as candidate photocatalysts for the degradation of pollutants.