Study On Preparation And Properties Of Alkaline Earth Metal Sulfide Nanocrystals

As typical semiconductor nanomaterials, metal chalcogenides nanocrystals have received widely attention because of their electronic and optical properties. Various applications include photovoltaics, thermoelectric memory, electronic devices,biological tags, sensors, and others. It is necessary for spread application to Controll synthesis metal chalcogenides of various morphology, size, composition. So far, Both fundamental and applied research has been primarily carried out on nanocrystals of IIB- VI semiconductors, such as chalcogenides of Cd, Zn, and Hg, Much less attention has been given to chalcogenides of alkaline earth. because of the hard and soft acid and base theory(HSAB) have revealed a valid qualitative principle for understanding the synthesis of Semiconductor nanocrystals: nanocrystals such as IIB–VI semiconductors chalcogenide(Cd S, Zn S) are relatively easy to form, whereas the formation of nanocrystals of alkaline-earth compounds with only soft base S2- as anions remains a challenge in synthetic chemistry, due to a lack of affinity between the hard Lewis acid M2+ and the soft Lewis base S2-. As a good fluorescent matrix material, alkaline earth metal sulfide has great potential applications in biological fluorescent labels, optical information storage, white LED, etc., so it is necessary that we develop a method to prepare high quality alkaline earth metal sulfide nanocrystals.In this paper, two different synthetic methods for preparing monodisperse alkaline earth metal sulfide nanocrystals were reported. The as-prepared powders have been characterized by X- ray diffraction(XRD), transmission electron microscopy(TEM),fluorescence spectroscopy(PL), inductively coupled plasma atomic emission spectrometry(ICP-AES) and other analytical instruments, the detailed results are as follows:1.Herein, we report an chemoaffinity-mediated synthetic strategy toward MS nanocrystals, which originally have poor affinity between the cations(M2+)and the anions(S2-). By introducing impurity ions(A(acac), A=Li, Na, K), we have realized the synthesis of monodisperse and morphological tuning MS nanocrystals. the influence of alkali metal ion species and alkali metal ions amount on the Sr Snanocrystals’ morphology was discussed, the experimental results showed that spherical, concave cube and ellipsoid Sr S nanocrystalline was prepared by added different alkali metal ions(Li+, Na+, K+), Additionally, alkali metal ions played a significant role in the control of these NC morphologies and size. the Sr S:Li, Sr S:Na,Sr S:K nanocrystals shape changed from sphere to concave-cubic and then to ellipsoid.We also studied the luminescence spectra of different alkali metal-doped Sr S nanocrystals at a different Mn2+ion concentration. We used the same method to prepare different morphologies of Ca S nanocrystals, and explored the effect of alkali metal ions on Ca S:Mn fluorescence performance.2, Using alkali metal oleate as the metal source, dodecyl mercaptan as a sulfur source, all alkaline earth metal sulfide(Mg S, Ca S, Sr S, Ba S) were successfully prepared by Single-source precursor method. Meanwhile, we took Ca S and Sr S as example, the effect of dodecanethiol/amine ratio on dispersible of nanoparticles was discussed. the influence of Mn2+ and Cu+ on Ca S, Sr S nanocrystals luminescence properties was also studied.