In this work, CdS nanocrystals (NCs) doped with Mn were synthesized in a glass matrix by fusion. The as-grown ${\text{Cd}}_{1-x}{\text{Mn}}_x\text{S}$ NCs were investigated by optical absorption, atomic force microscopy, and electron paramagnetic resonance (EPR). The incorporation of ${\text{Mn}}^{2+}$ ions in CdS NCs was confirmed by an absorption transition blueshift with increasing Mn concentration $x$ . EPR spectra demonstrated the existence of two distinct ${\text{Mn}}^{2+}$ ion locations: one incorporated in the core and the other near the surface of the ${\text{Cd}}_{1-x}{\text{Mn}}_x\text{S}$ NCs. The hyperfine interaction constants used to simulate the EPR spectra were $A=7.6$ and 8.2 mT, respectively. The synthesis of high quality ${\text{Cd}}_{1-x}{\text{Mn}}_x\text{S}$ NCs may allow the control of optical and magnetic properties.

Mn-doped PbS nanocrystals (NCs) in an oxide glass matrix have been synthesized by the fusion method. Two kinds of ${\mathrm{Mn}}^{2+}$ sites, located inside and on the surface of NCs, are observed by electron paramagnetic resonance (EPR) spectroscopy in the $X$ band and at room temperature. The proportion of their contribution to the hyperfine structure in the EPR spectrum depends strongly on thermal annealing time. The authors illustrate how thermal annealing process manifests itself in engineering the magnetic properties of NCs.

Iron-doped bismuth sulphide (Bi_2−xFe_xS₃) nanocrystals have been successfully synthesized in a glass matrix using the fusion method. Transmission electron microscopy images and energy dispersive spectroscopy data clearly show that nanocrystals are formed with an average diameter of 7–9 nm, depending on the thermic treatment time, and contain Fe in their chemical composition. Magnetic force microscopy measurements show magnetic phase contrast patterns, providing further evidence of Fe incorporation in the nanocrystal structure. The electron paramagnetic resonance spectra displayed Fe³⁺ typical characteristics, with spin of 5/2 in the 3d⁵ electronic state, thereby confirming the expected trivalent state of Fe ions in the Bi₂S₃ host structure. Results from the spin polarized density functional theory simulations, for the bulk Fe-doped Bi₂S₃ counterpart, corroborate the experimental fact that the volume of the unit cell decreases with Fe substitutionally doping at Bi1 and Bi2 sites. The Bader charge analysis indicated a pseudo valency charge of 1.322|e| on Fe_Bi1 and 1.306|e| on Fe_Bi2 ions, and a spin contribution for the magnetic moment of 5.0 µ_B per unit cell containing one Fe atom. Electronic band structures showed that the (indirect) band gap changes from 1.17 eV for Bi₂S₃ bulk to 0.71 eV (0.74 eV) for Bi₂S₃:Fe_Bi1 (Bi₂S₃:Fe_Bi2). These results are compatible with the 3d⁵ high-spin state of Fe³⁺, and are in agreement with the experimental results, within the density functional theory accuracy.

Samples of ${\text{Pb}}_{1-x}{\text{Mn}}_x\text{Se}$ nanocrystals were synthesized by fusion method and characterized by optical absorption, atomic force microscopy, x-ray diffraction, and electron paramagnetic resonance (EPR) techniques. Effects of $\text{Mn}{2}^{+}$ ion incorporation into PbSe nanocrystals are manifested by well resolved optical spectra for different concentrations of Mn. The EPR spectra of as grown and thermal annealed ${\text{Pb}}_{1-x}{\text{Mn}}_x\text{Se}$ samples show that the magnetic properties of these Mn-doped nanocrystals can be tuned by thermal processes using different annealing times.