Jing Wang

Bio: Jing Wang is an academic researcher from Pukyong National University. The author has contributed to research in topics: Luminescence & Phosphor. The author has an hindex of 10, co-authored 21 publications receiving 537 citations. Previous affiliations of Jing Wang include Weifang University & Nanjing University of Posts and Telecommunications.

Optical Thermometry Based on Vibration Sidebands in Y2MgTiO6:Mn4+ Double Perovskite

Abstract: Mn4+-doped Y2MgTiO6 phosphors are synthesized by the traditional solid-state method. Powder X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectrometer are employed to...

Influence of Doping and Excitation Powers on Optical Thermometry in Yb 3+ -Er 3+ doped CaWO 4

Abstract: Optical thermometry has been widely studied to achieve an inaccessible temperature measurement in submicron scale and it has been reported that the temperature sensitivity depends mainly on host types. In this work, we propose a new method to improve the optical temperature sensitivity of Yb3+-Er3+ co-doped CaWO4 phosphors by doping with Li+, Sr2+, and Mg2+ ions and by controlling excitation powers of 980 nm laser. It is found that the thermometric parameters such as upconversion emission intensity, intensity ratio of green-to-red emission, fluorescence color, emission intensity ratios of thermally coupled levels (2H11/2/4S3/2), and relative and absolute temperature sensitivity can be effectively controlled by doping with Li+, Sr2+, and Mg2+ ions in the Yb3+-Er3+ co-doped CaWO4 system. Moreover, the relative sensitivity SR and the absolute sensitivity SA are proved to be dependent on the pump power of 980 nm laser. The sensitivities of SR and SA in Yb3+-Er3+ co-doped CaWO4 increase about 31.5% and 12%, respectively, by doping with 1 mol% Sr2+.

Excitation powder dependent optical temperature behavior of Er 3+ doped transparent Sr 0.69 La 0.31 F 2.31 glass ceramics.

Abstract: The knowledge of the pump power for which the population of thermally coupled energy levels (TCL) changes with power increase is of valuable importance for optical temperature sensors. In this paper, novel Er3+ doped transparent Sr0.69La0.31F2.31 glass ceramics was fabricated successfully, and its structure is studied by XRD, TEM and HRTEM analyses. The 2H11/2/4S3/2, 4F9/2(1)/4F9/2(2), and 4I9/2(1)/4I9/2(2) levels of Er3+ are proved as TCL by analyzing the temperature dependent fluorescence intensity ratios. The spectrum split, thermal quenching ratio, population stability, and temperature sensitivity from three TCL are observed to be dependent on the pump power. A new fitting method has been developed to establish the relation between fluorescence intensity ratios and temperature. It is found that the combined use of 2H11/2/4S3/2 and 4F9/2(1)/4F9/2(2) as thermally coupled energy levels will get a more precise temperature reading from 62.7 K to 800 K with the help of low excitation power at 66.8 mW/mm2.

Luminescence, energy transfer and optical thermometry of a novel narrow red emitting phosphor: Cs2WO2F4:Mn4+

Abstract: A novel red emitting Cs2WO2F4:Mn4+ phosphor was successfully synthesized by a two-step wet chemical method. The crystal structure, morphology, and elemental composition were confirmed by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The luminescence properties were investigated from emission, excitation and luminescence decay curves in the temperature region of 10-500 K. The application of non-contact optical thermometry of Cs2WO2F4:Mn4+ based on the fluorescence intensity ratio (FIR) of the two coupled anti-Stokes and Stokes sidebands is discussed. The as-prepared Cs2WO2F4:Mn4+ phosphor shows a bright narrow red emission at 632 nm under excitation by a blue lamp at 470 nm and it also presents a broad and yellow-white intrinsic tungstate emission (∼520 nm) under UV excitation. The mechanism of energy transfer from [WO2F4]2- (the sensitizer) to Mn4+ (the activator) is discussed.

Mn2+ and Mn4+ red phosphors: synthesis, luminescence and applications in WLEDs. A review

Abstract: Transition-metal activated phosphors are an important family of luminescent materials that can produce white light with an outstanding color rendering index and correlated color temperature for use in light-emitting diodes. In recent years, work in this quite “hot” research field has focused on the development of Mn2+ and Mn4+ activated red phosphors. In this review article, we provide an overview of recent studies on Mn2+ and Mn4+ doped phosphors, including detailed synthesis routes (solid-state reaction and wet-chemical synthesis) and description of luminescence mechanisms and phosphors’ behaviors; discuss their promising applications in white light-emitting diodes; and present an extensive list of references to representative works in this field.

On the absorption spectra of complex ions. II

Abstract: The secular determinants obtained in the previous paper are solved for the energy levels which are important in the absorption spectra of the normal complex ions, leaving the crystalline field strength as a parameter. The values of B and C (Racah's parameters) there needed are determined from the observed spectra of free ions or in some cases by extrapolation. The f -values of the transitions which connect the energy levels calculated are estimated and compared with the observed intensities. The difference of the spectral width among absorption bands and lines is also considered using the energy diagram obtained. Following the assignments determined by the above considerations, the calculated positions of lines and bands are rather in good agreement with the experimental data in divalent ions [MX 6 ] 2+ (M=Cr, Mn, Fe, Co, Ni), when we adjust the crystalline field parameter D q suitably. In trivalent ions [MX 6 ] 3+ (M=Ti, V, Cr, Mn, Fe), it is necessary besides the adjustment of D q to use smaller values ...

Luminescent perovskites: recent advances in theory and experiments

Abstract: Perovskites form an important and enormous class of inorganic compounds. Recently, perovskite materials have attracted extensive research interest owing to their excellent optoelectronic properties. Deep insights into the relationships between the crystal structure, electronic structure and properties play an important role in the development of new functional materials and high-performance devices. In this review, after a brief introduction, we first discuss the crystal structure and crystal chemistry of perovskites according to their three classes: standard perovskites, low-dimensional perovskites and perovskite-like halides. Next, the electronic structure and luminescence from different physical origins are presented. Then, we present a survey on the design, synthesis and luminescence properties of different perovskites, including halide perovskites, oxide perovskites, and lanthanide- or transition metal-doped perovskites, also including dimension-different perovskites (3D, 2D, 1D and quantum dots). We also summarize the strategies for improving the photoluminescence quantum yield (PLQY) and chemical stability, including by surface passivation, encapsulation and doping. Finally, we review their applications and give a brief outlook.