Diluted magnetic semiconductors Zn 1− Ni S with different consistency ratio ( = 0, 0.01, 0.03, 0.05, and 0.07) were successfully synthesized by hydrothermal method using ethylenediamine as a modifier. The influence of Ni doping concentration on the microstructure, morphology, and optical and magnetic properties of undoped and Ni doped ZnS nanocrystals was characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray energy dispersive spectrometry (XEDS), ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FT-IR), photoluminescence spectra (PL), and the vibrating sample magnetometer (VSM), respectively. The experiment results show the substitution of Ni 2+ on Zn 2+ sites without changing the hexagonal wurtzite structure of ZnS and generate single-phase Zn 1− Ni S with good crystallization. The lattice constant causes distortion and decreases with the increase of Ni 2+ doped concentration. The appearance of the samples is one-dimensional well-dispersed nanorods. UV-vis spectra reveal the band gap of all Zn 1− Ni S samples greater than that of bulk ZnS (3.67 eV), and blue shift phenomenon occurs. The photoluminescence spectra of undoped and doped samples possess the broad blue emission band in the range of 400-650 nm; the PL intensities of Zn 1− Ni S nanorods increase with the increase of Ni content comparing to pure ZnS and reach maximum for = 0.03. Magnetic measurements indicated that the undoped ZnS samples are superparamagnetic, whereas the doped samples exhibit ferromagnetism.
The superconducting properties of air-processed melt-textured growth Sm-Ba-Cu-O samples with addition of small amounts (0.004 wt%, 0.4 wt%, 4 wt%) of nano-sized Sm 2 BaCuO 5 particles (nm211) were studied. The microstructure observations show that the size distribution and morphology of the 211-particles of the nm211-doped samples are similar to that of the control (undoped) samples. However, except for the 4 wt% nm211-doped sample, both T c (critical temperature) and J c (H, T) (critical current density) are enhanced in nm211-doped samples, and the J c -H curves are different from those of control samples. The effect of nm211 particles on J c enhancement is larger at high magnetic fields (>1 T at 77 K) than at low magnetic fields (0∼1 T). The dominant pinning mechanism by analyzing the J c (H, T) data using the scaling theory indicate that the nm211-doped samples are originated from ⌬ pinning (i.e., T c variation); on the other hand, the control samples are originated from normal pinning (i.e., nonsuperconducting crystalline defects). It is proposed that nano-sized compositional fluctuations in the RE 1+x Ba 2−x Cu 3 O y matrix, which are products of nm211 particles and liquid peritectic reaction, act as the source of ⌬ pinning centers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.