Impact of Dy on the microstructural, electrical, and magnetic properties of topological FeBiYSe nanocrystals.

Nanoparticles of Dy-doped FeBiYSe ( = 0, 0.1, 0.2, 0.3) were synthesized using the sol-gel method. The effects of Dy doping on the microstructural, thermal, magnetic, and electrical properties of FeBiYSe nano-crystallites were investigated. X-ray diffraction (XRD) analysis confirmed higher crystallinity in undoped FeBiYSe. At higher Dy concentrations (: 0.1, 0.2, 0.3), a few peaks corresponding to the DyFeO phase appeared. Morphological analyses (SEM/TEM) and FTIR spectra revealed Dy-induced microstructural modifications, including an increase in particle size to 25-27 nm and alterations in Bi-O-Dy vibrations. Thermal analysis demonstrated dehydration-induced weight loss and excellent thermal stability up to 600 °C. Magnetic measurements indicated a transition from ferromagnetic to superparamagnetic with Dy doping, alongside superparamagnetic tendencies at higher Dy concentrations. Electrical measurements showed a transition from semiconducting to metallic behavior, with conductivity increasing at higher frequencies and temperatures, suggesting thermally activated conduction mechanisms. These findings confirm that Dy incorporation significantly influences the internal structure of BiFeSeY nanoceramics, enhancing their magnetoelectric properties. The improved structural, thermal, magnetic, and electrical characteristics make Dy-doped BiFeSeY nanoceramics promising candidates for applications in microelectronics, topological quantum devices, and spintronics.