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1.
Currently, the efficient detection of fingerprints is essential for the crime investigations. Revealing fingerprints is commonly achieved with fluorescent organic compounds but they are not efficient for fingerprint detection on porous or reflective surfaces. In order to solve the problem of collecting fingerprints on porous/reflective surfaces, inorganic phosphors have been employed, since they have characteristics of variable color emission, afterglow, high chemical stability and nano-size, which allow the fingerprint detection on any porous or non-porous surfaces. Due to these last properties, this review presents a summary about the use of phosphorescent and fluorescent phosphors for the detection of latent fingerprints. First, we discussed the main physical and chemical characteristics of the fingerprints which permit their detection and collection from any surface. After this, we presented the main morphological, structural and luminescent properties of the phosphorescent and fluorescent phosphors that allow their use for fingerprint detection. Later, we demonstrated with pictures of fingerprints (with and without light emission from the phosphors deposited on them) that both, phosphorescent and fluorescent phosphors can be used to visualize fingerprints with high resolution and high contrast without interference of the background surface, which is ideal for its collection and registration in the Automated Fingerprint Identification System (AFIS). We believe that this review could be useful to understand how to select an appropriate phosphorescent or fluorescent material for fingerprint detection depending on the type of surface (porous or non-porous, reflective or not reflective) where the fingerprint is deposited. 相似文献
2.
Yumi Fukuda Ariane Keiko Albessard Iwao Mitsuishi 《Journal of the American Ceramic Society》2019,102(7):4161-4169
The luminescence properties of yellow-emitting Ce3+-doped Sr-containing sialon phosphor Sr(Al,Si)5(O,N)7:Ce3+ were notably improved by the Ce raw material selection. By changing the Ce raw material from oxides to nitrides or chlorides, the emission wavelength shifted to above 560 nm, which is beneficial for higher color rendering index white light-emitting diodes. This result from an increase in the covalency of the host crystal being associated with a decrease in the oxygen content. When Ce chloride was used, both the absorption and internal quantum efficiency increased, resulting in an increase in the external quantum efficiency up to 65%–72%. Inductively coupled plasma mass spectrometry, X-ray diffraction, and electron spin resonance measurements showed that the reason for the absorption increase is an increase in Ce3+ content and suppression of the generation of the second phase, and the reason for the increase in the internal quantum efficiency is a decrease in the host crystal absorption via suppression of anion vacancy generation. It was found that Ce chloride not only suppresses oxygen impurities but also acts as a flux that results in improved crystallinity. 相似文献
3.
The synthesis of BaMgAl10O17∶ Eu2 (BAM) phosphors using the sol-gel method and their luminescence properties were reported. The blue-light emitting BAM was synthesized using citric acid and ethylene glycol as chelating materials. Emission of blue-light was obtained from these phosphors. The luminescent intensity increases as the temperature of heat treatment is increased. This study investigated the effects of the molar ratio of ethylene glycol to citric acid (Φ value), with respect to the phase formation and luminescence properties of BAM. The variation of the Φ value resulted in the change of the sol-gel reaction mechanism and the microstructures of the resultant powders. An increase in Φ value leads to an increase in the rate of BAM phase formation. The photoluminescent intensity of the prepared phosphors increases with heating temperatures because of enhanced crystallization. 相似文献
4.
发光体MAl2O4:Eu2+,RE3+的长余辉形成机理 总被引:7,自引:0,他引:7
提出了Eu^2 激活的MAl2O4:Eu^2 ,RE^3 (M=Ca,Sr,Ba;RE=Dy,Nd,Ho,Er,Pr,Tb等稀土元素)系列铝酸盐发光体的长余辉发光机理。认为O^2-空位Vo是一种电子俘获陷际,是形成余辉的根本原因,RE^3 的引入使陷阱深度适宜而使余辉时间延长。缺陷在晶格中成簇分布,Vo和碱土金属离子空位VM在高温下可相互缔合。利用电子陷阱模型解释了实验中的一些普遍现象并提出了固相反应法合成此类发光体的工艺改进措施。 相似文献
5.
Zhiyong Fang Xiaohui Lai Jian Zhang Rui Zhang 《International Journal of Applied Ceramic Technology》2021,18(4):1106-1113
K2TiF6:Mn4+ is an attractive narrow-band red-emitting phosphor for warm white light-emitting diodes (LEDs). Nevertheless, the hexafluoride phosphor is liable to deliquesce in moist environments, which leads to a sharp deterioration performance of luminescence. Surface modification of K2TiF6:Mn4+ phosphor with SrF2 coating has been introduced, with the aid of KHF2 transition layer to moderate the lattice mismatch. The reaction mechanism is discussed in detail, as so as the influence of SrF2 coating on the luminescence intensity. The SrF2 coating is able to prevent the hydrolysis of internal [MnF6]2− group; thereby, the luminescence intensity retains over 90% of initial value after being immersed in distilled water for 2 h. The LED devices fabricated with commercial Y3Al5O12:Ce3+ and as-modified K2TiF6:Mn4+ phosphors exhibit bright white light with tunable chromaticity coordinate, correlated color temperature, and color rendering index. It enlightens a convenient method to enhance the moisture resistance of Mn4+ doped fluoride phosphors for commercial application in the field of white LEDs. 相似文献
6.
Mn^2+在铝酸盐中的发光 总被引:1,自引:0,他引:1
用金属硝酸盐、稀土氧化物和乙酸锰为原料,用燃烧法合成了Ce^3 、Tb^3 、Mn^2 共激活的铝酸盐绿色荧光粉,在Ce^3 和Tb^3 共激活的铝酸盐体系中掺入Mn^2 后,发射峰中出现锰的特征峰。通过对其结构的分析,对Mn^2 发光和最佳掺杂量给出了合理的解释.同时研究了不同碱金属和碱土金属离子代替Mg^2 时,对Mn^2 发光的影响. 相似文献
7.
Noor Zamin Khan Sayed Ali Khan Muhammad Sohail M. A. Majeed Khan Jahangeer Ahmed Li Zhan Feihong Wang Muhammad Tahir Abbas Xin Xu 《Journal of the American Ceramic Society》2021,104(9):4911-4922
The trivalent rare-earth (RE3+) doped phosphors show tremendous achievement in narrow band multicolor line emission for various applications. However, the 4f–4f absorption transition of these ions is forbidden in UV and blue light excitation. Usually, a sensitizer having spin allowed transition was used as a co-dopant to excite these ions via the energy transfer phenomenon. Another approach promisingly using to excite these ions by efficient energy transfer from the intrinsic emission of the Ca2LuTaO6 double perovskite phosphors host lattice. Phosphors of Ca2LuTaO6 with double perovskite structure were synthesized by using a high-temperature solid-state reaction method. The produced Ca2LuTaO6 double perovskite phosphors show an intrinsic broad band emission centered at 424 nm under the excitation of 313 nm UV light. The origin of this broad band blue emission was deeply investigated by using computation and experimental approaches. The trivalent activator Dy3+ and Eu3+ were doped is a single and co-dopant in the produced Ca2LuTaO6 phosphors to check their excitation in UV and near-UV spectral region. X-ray diffraction and scanning electron microscopy were used to investigate the structure and phase analysis. Various characterizations such as photoluminescence excitation, emission, and CIE chromaticity coordinates were measured which illustrate the potential of Dy3+ and Eu3+ activated Ca2LuTaO6 double perovskite phosphors for narrow band multicolor line emission for various applications. 相似文献
8.
Robert Withnall Jack Silver Paul G. Harris Terry G. Ireland Paul J. Marsh 《Journal of the Society for Information Display》2011,19(11):798-810
Abstract— The current status of AC powder electroluminescent (ACPEL) displays is reviewed with particular emphasis given to color and lifetime. The printing of the displays in forward and reverse architectures is also discussed, in addition to the fabrication of ACPEL displays with interdigitated electrodes, and different types of ACPEL phosphors and materials for back electrodes, transparent conducting electrodes, binders, and dielectrics are considered. Furthermore, shape conformable and highly flexible ACPEL displays are surveyed. 相似文献
9.
Haijme Yamamoto Shinji Okamoto Satoe Mitsumine 《Journal of the Society for Information Display》2000,8(3):241-245
Abstract— A red‐emitting phosphor, SrTiO3:Pr3+, for low‐voltage‐type FEDs and VFDs was developed by Futaba Corporation in 1996. The addition of Al or Ga is essential in the preparation of this phosphor because it improves the luminescence efficiency dramatically. For this impurity effect, Futaba Corporation proposed a charge‐compensation mechanism, which was supported by a recent observation of emission lines due to Al3+‐Pr3+ pairs. In addition, it was found that Al also works as a scavenger of planar defects, presumably SrO thin layers interleaved in the SrTiO3 lattice, by forming strontium aluminates. The latter mechanism suggests the possibility that a similar impurity effect can be found in materials with crystal structures, including alkaline‐earth oxide layers (Ruddlesden‐Popper phases). 相似文献
10.
Polycrystal of GdPO4:RE3+ (RE=Tb, Tm) phosphors were prepared by solid-state method. Vacuum ultraviolet excitation and emission spectrum and the energy
transfer mechanism between the host and dopants of Tb3+ and Tm3+ were investigated respectively. The emission of Gd3+ at 313 nm was enhanced by the strong absorption of CTS of Tm3+ at 180 nm in GdPO4: Tm. It has also been concluded that the excitation of Gd3+ is transferred to Tb3+ and then emission peaks of 5DJ→7FJ of Tb3+ were observed. 相似文献