Lanthanum hexaboride nanoparticles,with high emission electrons in cathode materials and peculiar blocking near infrared wavelengths,were applied for many aspects.Based on the quasi-static approximation of Mie theory,the size dependent optical properties of LaB6nanoparticles were researched,such as refractive index n(ω),extinction coefficient k(ω),reflectivity R(ω),absorption coefficientα(ω),and electron energy loss L(ω).Due to the localized surface plasmon resonance(LSPR),the extinction coefficient k(ω)and absorption coefficientα(ω)depended on the size,and the LSPR peaks red-shifted with sizes increased,which was different from that of bulk materials.In addition,electron energy-loss spectrum L(ω)showed electrons oscillation reinforced,since electrons absorbed the photon energy and generated resonance.Further,reflectivity R(ω)and refractive index n(ω)indicated that the light in near infrared region could not be propagated on the surface of LaB6materials,which exhibited metallic behaviors.So the resonance peak of LaB6nanoparticle was located in near-infrared region,making use of this property for solar control glazing and heat-shielding application.
Si4+-doped BaZr(BO3)2:Eu3+ phosphors are prepared by a conventional solid-state reaction.The influence of Si4+ addition on the charge transfer state of Eu3+-O2- and photoluminescence(PL) properties of BaZr(BO3)2:Eu3+ are discussed.Room temperature PL spectra indicated that efficient emission is obtained by Si doping.Increased values for the peak-peak ratio(PPR) of BaZr(BO3)2:Eu3+ at higher Si doping concentrations implied that the Eu3+ ion is located in a more asymmetric environment in BaZr0.8Si0.2(BO3)2:Eu3+ than in the undoped samples.The Judd-Ofelt parameters Ωλ(λ=2,4) were calculated from the PL data,giving results that were consistent with those from the PPR.The maximum radiative quantum efficiency was achieved at a Si doping concentration of 20 mol%.
ZHANG ZhongPengLI GuangMinZHANG XiaoSongXU ShengYanJI TingLI Lan
ZnO quantum dots (QDs)with the sizes of 3.0-5.6 nm are synthesized by solution-phase method at different temperatures. We find that temperature has great influence on the size of ZnO QDs. The growth process is the most sensitive to temperature, and the process is well explained by Lifshitz-Slyozov-Wagner (LSW) model. By photoluminescence (PL) spectra of the quantum dots at different temperatures and reactive time, we come to a conclusion that ultraviolet emission is mainly due to surface defects, and the origination of green visible emission comes from the transition between the bottom of the conduction band and the level of Oi.
A series of Zn–Cu–In–S nanocrystals(ZCIS NCs) are prepared and the optical properties of the ZCIS NCs are tuned by adjusting the reaction time. It is interesting to observe that the temperature-dependent photoluminescence(PL) spectra of the ZCIS NCs show a redshift with decreasing intensity at low temperature(50–280 K) and a blueshift at high temperature(318–403 K). The blueshift can be explained by the thermally active phonon-assisted tunneling from the excited states of the low-energy emission band to the excited states of the high-energy emission band.
