Mn2+, Pb2+共掺杂ZnS纳米材料制备及光致发光

采用聚乙烯基吡咯烷酮(PVP)为表面包覆剂,在室温大气条件下的水溶液中制备了ZnS:Mn,Pb纳米晶。讨论了Mn²⁺和Pb²⁺掺杂量对ZnS纳米发光材料光致发光强度的影响,确定了Mn²⁺和Pb²⁺掺杂量相对于Zn²⁺的最佳的量的比,并对其发光机理进行了初步的探讨。

Preparation and Photoluminescence Properties of ZnS Nanocrystals Co-doped with Mn2+ and Pb2+

Nanocrystals doped with optically active luminescence centers create new opportunities for luminescent study and application of nanoscale materials.ZnS is the most typical and important crystalline phosphor in both applications and basic science,and doping might change its properties,especially,the transition metallic ions co-activated ZnS nanoparticles form a new class of luminescent materials.The arrested chemical precipitation method is the most popular technique that is used in industrial applications because of its cheap raw materials,easy handing and large-scale production,many doped ZnS nano-particles were prepared by this method.In order to volume-produce homodisperse free-standing,with good surface,and high luminescent doped ZnS nanoparticles,polymer PVP was used as surfactant.Preparation produce was as follows:6.0 g PVP was dissolved in 70~80 mL ultrapure water(R≈18 MΩ),while the solution was stirred,10 mL of 1 mol·L^-1 Zn(CH₃COO)₂·2H₂O,and 1~7 mL of 0.1 mol·L^-1 Mn(CH₃COO)₂·4H₂O,0.1~2 mL of 0.1 mol·L^-1 Pb(CH₃COO)₂·3H₂O were then added.After stirring for 15 min,10 mL of 1 mol·L^-1 Na₂S·9H₂O was injected,a suspension occurred immediately.After centrifuging and washing the particles twice with distilled water and once with ethanol.The nano-particles were dried in vacuum.All agents used are analytical pure and without further treatment.Nanocrystalline ZnS:Mn²⁺,Pb²⁺ have been prepared via the precipitation method at room temperature and under ambient conditions.X-ray diffraction analysis shows that the average crystalline particles size of samples is about 2~4 nm.TEM image shows the nanoparticles are homodisperse.By measurement of the fluorescence spectra,the excitation(λ_exc≈410 nm) and emission(λ_em≈510~560 nm) wavelength are both in visible-light range.A novel luminescent property has been observed in the photoluminescence(PL) spectra of the ZnS:Mn²⁺,Pb²⁺ nanocrystals.These nanocrystals can be doped with Mn²⁺ and Pb²⁺ during the synthesis without altering the X-ray diffraction pattern,however,the PL intensities of the co-doped samples vary with changing of the impurity mole ratios in the Mn²⁺ and Pb²⁺ co-doped samples,but the emission wavelength is not changed with the changing of the impurity mole ratios.The PL properties of the co-doped samples are dramatically different from those of Mn²⁺ and Pb²⁺ single doped ZnS nanorystals,and a probable explanation is presented also.All the results strongly reveal that co-doped ZnS nanocrystals form a new class of luminescent materials.