Chitosan coated ZnSe:Mn (CS-ZnSe:Mn) nanocrystals were successfully synthesized in aqueous system through a gamma-radiation route at room temperature under ambient pressure. The structure and properties of nanocrystals were investigated with transmission electron microscope (TEM), fourier transform infrared spectrometer (FT-IR), ultraviolet-visible (UV-vis) spectrometer, photoluminescence emission (PL) spectra, X-ray Diffraction (XRD) and energy dispersion spectrum (EDS). Results showed that the diameter of these nanocrystals was about 4 nm with narrow size distribution. With the increase of doped Mn2+ concentration, strong emission peak at 610 nm was observed besides the weak emission peak at 425 nm since the non-radiative transition of 4T1(4G)-6A1(6S) level, resulting the transfer of fluorescence color from blue to orange. Moreover, analysis of SQUID magnetometer indicated that the nanocrystals were superparamagnetic with a saturation magnetization of 1.7 emu/g and a Curie-Weiss temperature of 14-15 K. Hep G2 cells were incubated in solution of nanocrystals and results showed that the synthesized nanocrystals could stain cytoplasm but could not enter into nucleus.
Solid‐solution ceramics show a potential in the field of electronic devices. In particular, it is necessary to investigate the photoluminescence and conductive properties of CaEuNbMoO8 (CENMO) solid solution ceramics. It is demonstrated that the sintered ceramics appear as CaMoO4 phase with scheelite structure. The results of X‐ray photoelectron spectroscopy show that the abnormal reduction of Eu3+→Eu2+ occurs in the ceramics, which is due to the formation of VCa′′$V_{Ca}^{^{\prime\prime}}$ vacancy caused by the substitution of Ca2+ by Eu3+, making it act as electron donors. The change of local symmetry of Eu3+ ions in ceramics results in a strong red fluorescence, and the charge transition between Eu, Nb, and Mo ions and O ions in the host lattice results in the near‐ultraviolet (near‐UV) excitation. As a result, CaEuNbMoO8 ceramic materials have promising applications in both near‐ultraviolet excited light‐emitting diodes and thermistors.
As new multifunctional semiconductor materials, solid‐solution ceramics demonstrate great potential in the field of electronic and optoelectronic devices. CaEuNbMoO8 ceramic is the solid solution of EuNbO4 and CaMoO4, but how to synergistically regulate its transmission of electricity and light still remains challenging. Herein, the structure modulations by adjusting the ratio of EuNbO4 and CaMoO4 and the changes in electrical transport and photoluminescence (PL) properties have been investigated. Meanwhile, the asymmetric ratio (5D0–7F2/5D0–7F1) further determines the symmetry variation of the local microstructure with the solid‐solution ratio of EuNbO4. The correspondence between the structure and phase transition of EuNbO4 ceramics at high temperature is investigated, and it is found that the point symmetry changes from C2h to C4h, and the activation energy changes significantly with increasing temperature. This work provides a solution for the synergistic optimization of PL and conductivity of solid‐solution ceramics by modulating the symmetry of the crystal structure.
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