We synthesize Tm3+/Tb3+/Eu3+triply-doped ZrF4–BaF2–LaF3–AlF3–NaF(ZBLAN) transparent glass by using a melt-quenching method. Under excitation of 365 nm, the white emission with Commission internationale deL'Eclairage(CIE) coordinates of(0.33, 0.33) is achieved at the Eu3+concentration of 1.1 mol%. The mechanisms for white emission and the energy transfer process of Tb3+→ Eu3+are discussed in terms of the photoluminescence, photoluminescence excitation spectra, and the light emission decay curves. The nature for the Tb3+→ Eu3+energy transfer is described with the aid of an energy level diagram.
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.
KBr:Pr with a submicron rod structure is successfully synthesized by a solid-state reaction using absolute alcohol as the abrasive.X-ray diffraction,scanning electron microscopy,photoluminescence spectra and fluorescence decay curves are used to characterize the resulting materials.The influences of Pr^(3+)dopant concentration on the luminescence and lifetime are discussed.Furthermore,luminescent measurements show that KBr:Pr has a high emission intensity compared with other Pr-doped matrixes,which is related to the low phonon energy of KBr.The results suggest that the phonon energy of the host is important in determining the luminescent efficiency.
Er3+-doped 25BaO-(25-x)SiO2-xAl2O3-25B2O3 transparent glasses are prepared with x = 0,12.5 and 25 by a solid-state reaction.The Er-related NIR luminescence intensity,which corresponds to the transition of 4I15/2-4I13/2,is obviously altered with different silicon/aluminum ratios.The Judd-Ofelt parameters of the Er3+ ions are adopted to explain the intensity change in the NIR fluorescence,and the Raman scattering intensity versus the amount of Al and/or Si components are discussed.The spectra of the three samples are quite similar in the peak positions,but different in intensity.The maximal phonon density of state for the samples is calculated from the Raman spectra and is correlated to the NIR luminescence efficiency.
本文通过化学浴沉积法获得了直径约为50 nm,长度约为250 nm的ZnO纳米棒阵列,引入纳米ZnS对ZnO纳米棒进行表面修饰,分别制备得到了具有ITO(indium tin oxides)/ZnO/Poly-(3-hexylthiophene)(P3HT)/Au和ITO/ZnO@ZnS/P3HT/Au结构的多层器件.通过I-V曲线对比讨论了两种结构器件的开启电压,串联电阻,反向漏电流及整流比等参数,认为包含ZnS修饰层器件的开启电压、串联电阻、反向漏电流明显降低,整流比显著增强,展现出更优异的电子传输性能.光致发光光谱分析结果证实由于ZnS使ZnO纳米棒的表面缺陷产生的非辐射复合被明显抑制,弱化了电场激发下的载流子陷获,改善了器件的导电特性.
A series of Al3+-doped 3.5MgO·0.5MgF2·GeO2:Mn4+red-emitting phosphors is synthesized by high temperature solid-state reaction. The broad excitation band at 300 nm–380 nm, resulting from the4A2→4T1transition of Mn4+,exhibits a blue shift with the increase of Al2O3 content. The observation of the decreased Mn4+–O2-distance is explained by the crystal field theory. The temperature-dependent photoluminescence spectra with various amounts of Al2O3 content are comparatively measured and the calculation shows that the activation energy increases up to 0.41 eV at the Al2O3 content of 0.1 mol. The maximum phonon densities of state for these samples are calculated from Raman spectra and they are correlated with the thermal properties.
