Rongfang Wang

Synthesis and luminescence properties of Eu2+-doped CdSe nanocrystals

CdSe host nanocrystals (NCs) doped with Eu2+ ions are synthesized in an aqueous solution using thioglycollic acid as a stabilizer. The structures, elements, shape, and spectral properties of these nanocrystals are investigated. The obtained CdSe:Eu2+ nanocrystals are consistent with the zinc blende crystal structure, with an approximately spherical shape of about 5 nm in diameter. CdSe:Eu2+ nanocrystals display a broadband emission peak at 505 nm attributed to the parity and spin-allowed 4f–5d transition of the Eu2+ ion, and the energy from the absorbed photons can be effectively transferred to the Eu2+ impurity ions on the nanocrystal surface. The obtained CdSe:Eu2+ nanocrystals not only maintain the intrinsic properties of being monodisperse and homogeneous, but also exhibit the characteristic luminescence of Eu2+ ions.

Luminescent properties of MMgP2O7:Eu3+ (M=Ca, Sr, Ba) phosphor

A series of red phosphors Eu3+-doped MMgP2O7 (M=Ca, Sr, Ba) were synthesized by solid-state reaction method. X-ray powder diffraction (XRD) analysis confirmed the formation of pure CaMgP2O7, SrMgP2O7 and BaMgP2O7 phase. Photoluminescence spectra of MMgP2O7 (M=Ca, Sr, Ba):Eu3+ phosphors showed a strong excitation peak at around 400 nm, which was coupled with the characteristic emission (350-400 nm) from UV light-emitting diode. The CaMgP2O7:Eu3+, SrMgP2O7:Eu3+ and BaMgP2O7:Eu3+ phosphors showed strong emission bands peaking at 612, 593 and 587 nm, respectively. Due to the difference of the ion sizes between Ba2+ (0.142 nm), Sr2+ (0.126 nm), Ca2+ (0.112 nm), Mg2+ (0.072 nm) and Eu3+ (0.107 nm), Eu3+ ions were expected to substitute for different sites in CaMgP2O7, SrMgP2O7 and BaMgP2O7 lattice.

Synthesis of Color-Tunable CdSe Nanocrystals via a Green Synthetic Method

In this letter, ascorbic acid was used as a novel and environmental friendly reducing agent in the synthesis of high-quality L-cysteine-capped CdSe nanocrystals. The X-ray diffraction and high-resolution transmission electron microscope results show that the as-prepared CdSe quantum dots (QDs) had a cubic crystal structure with an average size of 5 nm. The synthetic conditions were optimized by adjusting the n(L-Cys)/n(Cd2+), pH, and Cd/Se molar ratios. Under optimum conditions, the quantum yield of CdSe QDs reached 22%.