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Journal ArticleDOI: 10.1021/JACS.0C13433

Rare-Earth Sulfide Nanocrystals from Wet Colloidal Synthesis: Tunable Compositions, Size-Dependent Light Absorption, and Sensitized Rare-Earth Luminescence.

02 Mar 2021-Journal of the American Chemical Society (American Chemical Society (ACS))-Vol. 143, Iss: 9, pp 3300-3305
Abstract: We report the synthesis of colloidal EuS, La2S3, and LaS2 nanocrystals between 150 and 255 °C using rare-earth iodides in oleylamine. The sulfur source dictates phase selection between La2S3 and LaS2, which are stabilized for the first time as colloidal nanocrystals. The indirect bandgap absorption of LaS2 shifts from 635 nm for nanoellipsoids to 365 nm for square-based nanoplates. Er3+ photoluminescence in La2S3:Er3+ (10%) is sensitized by the semiconducting host in the 390-450 nm range. The synthetic route yields tunable compositions of rare-earth sulfide nanocrystals. Interaction of light with these novel semiconducting nanostructures hosting rare-earth emitters should be attractive for applications that require broadband sensitization of RE emitters.

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Topics: Photoluminescence (52%), Oleylamine (52%), Sulfide (50%) ... show more

5 results found

Journal ArticleDOI: 10.1021/ACSAMI.1C07444
Yingnan Zhao1, Cailing Ou1, Jingkun Yu1, Yongqiang Zhang1  +5 moreInstitutions (2)
Abstract: Tunable emission carbonized polymer dots (CPDs) are highly desirable for the preparation of optoelectronic devices, especially white light-emitting diodes (WLEDs). In most available studies, polychromatic CPDs are synthesized using aromatic molecules as precursors. However, few studies report the successful synthesis of polychromatic CPDs using two or more unconjugated precursors. In this work, we prepare multicolor fluorescent CPDs from a single unconjugated precursor, glucose, via a hydrothermal reaction. By controlling the particle size and degree of graphitization of the synthesized CPDs, their emission wavelength can be tuned in the range 440-625 nm (i.e., almost the entire visible region). Furthermore, the CPDs can be used to construct LEDs of varying colors, including WLEDs (CIE coordinates: 0.34, 0.36) with the correlated color temperature and color rendering index of 4997 K and 92.69, respectively. In brief, the strategy proposed in this study successfully converts unconjugated glucose into high-performance LEDs with great application potential.

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3 Citations

Open accessJournal ArticleDOI: 10.1039/D1NA00566A
Yinping Wang1, Yinping Wang2, Yannick Coppel1, Christine Lepetit1  +3 moreInstitutions (2)
30 Aug 2021-
Abstract: Herein, we elucidate the key role of amine surfactants in the controlled anisotropic growth of ZnO nanoparticles that is achieved under mild conditions by organometallic hydrolysis. The structuring influence of alkyl substituents on the nitrogen atom of amines is jointly analyzed theoretically by DFT modeling, and experimentally by multinuclear NMR (1H, 13C and 17O) spectroscopy. We demonstrate that in initial steps leading to the growth of colloidal ZnO particles, the nature of molecular species that are involved in the solution strongly depends on the structure of the amine surfactant. By using tertiary, secondary or primary amines, no or weak adducts between the amine and zinc, or stable adducts, or adduct oligomers were identified, respectively. Afterwards, following the course of the reaction, the dynamic behavior of the amines on the grown ZnO nanocrystal surfaces is also strongly correlated with their structure. We identified that in the presence of tertiary, secondary or primary amines, no significant [Zn⋯N] adsorption, or surface adsorption with notable surface mobility, or a very strong adsorption is achieved, respectively. The last case, primary amines, significantly involves the structuring of a hydrogen bonding network. Therefore, such surface dynamic behavior has a predominant role in driving the nanocrystal growth, and orienting the ZnO material final morphology. By forming hydrogen bonds at the nanoparticle surface during the growth process, primary amines specifically lead to the formation of nanorods. Conversely, isotropic nanoparticles and aggregates are obtained when secondary and tertiary amines are used, respectively. These findings shed light on the role of weak surface interactions, herein H-bonding, that rule the growth of nano-objects and are as such crucial to identify, study, and control for achieving progress in nanoscience.

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Topics: Adsorption (53%), Nanocrystal (52%), Alkyl (52%) ... show more

Journal ArticleDOI: 10.1002/ANIE.202108993
18 Oct 2021-Angewandte Chemie
Abstract: In targeting reduced valent lanthanide chalcogenides, we report the first nanoparticle synthesis of the mixed-valent ferromagnets Eu3 S4 and EuSm2 S4 . Using divalent lanthanide halides with bis(trimethylsilyl)sulfide and oleylamine, we prepared nanoparticles of EuS, Eu3 S4 , EuSm2 S4 , SmS1.9 , and Sm3 S4 . All nanoparticle phases were identified using powder X-ray diffraction, transmission electron microscopy was used to confirm morphology and nanoparticle size, and magnetic susceptibility measurements for determining the ordering temperatures and valence. The UV/Vis, Raman and X-ray photoelectron spectroscopies for each phase were compared. Surprisingly, the phase is influenced by the halide and the reaction temperature, where EuCl2 formed EuS while EuI2 formed Eu3 S4 , highlighting the role of kinetics in phase stabilization. Interestingly, at lower temperatures EuI2 initially forms EuS, and converts over time to Eu3 S4 .

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Topics: Lanthanide (54%), Oleylamine (53%), Sulfide (52%) ... show more

Open accessJournal ArticleDOI: 10.1007/S40843-021-1801-8
Jiaojiao Wei1, Jiaojiao Wei2, Youyu Liu1, Youyu Liu2  +13 moreInstitutions (3)
Abstract: Lanthanide (Ln3+)-doped near infrared (NIR)-II luminescent nanoprobes have shown great promise in many technological fields, but are currently limited by the low absorption efficiency of Ln3+ due to the forbidden 4f→4f transition. Herein, we report a novel NIR-II luminescent nanoprobe based on efficient energy transfer from Ce3+ to Er3+ and Nd3+ in sub-10 nm SrS nanocrystals (NCs), which are excitable by using a commercial blue light-emitting diode (LED). Through sensitization by the allowed 4f→5d transition of Ce3+, the NCs exhibit strong NIR-II luminescence from Er3+ and Nd3+ with quantum yields of 2.9% and 2.3%, respectively. Furthermore, by utilizing the intense NIR-II luminescence of Er3+ from the thermally coupled Stark sublevels of 4I13/2, we demonstrate the application of SrS:Ce3+/Er3+ NCs as blue-LED-excitable NIR-II luminescent nanoprobes for ratiometric thermal sensing. These findings reveal the unique advantages of SrS:Ln3+ NCs in NIR-II luminescence, which may open up a new avenue for exploring novel and versatile luminescent nanoprobes based on Ln3+-doped sulphide NCs.

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64 results found

Journal ArticleDOI: 10.1103/PHYSREV.56.978
A. L. Patterson1Institutions (1)
15 Nov 1939-Physical Review
Abstract: An exact derivation of the Scherrer equation is given for particles of spherical shape, values of the constant for half-value breadth and for integral breadth being obtained. Various approximation methods which have been used are compared with the exact calculation. The tangent plane approximation of v. Laue is shown to be quite satisfactory, but some doubt is cast on the use of approximation functions. It is suggested that the calculation for the ellipsoidal particle based on the tangent plane approximation will provide a satisfactory basis for future work.

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Topics: Scherrer equation (62%)

5,803 Citations

Journal ArticleDOI: 10.1515/ZKRI-2014-1737
Abstract: Abstract JANA2006 is a freely available program for structure determination of standard, modulated and magnetic samples based on X-ray or neutron single crystal/ powder diffraction or on electron diffraction. The system has been developed for 30 years from specialized tool for refinement of modulated structures to a universal program covering standard as well as advanced crystallography. The aim of this article is to describe the basic features of JANA2006 and explain its scope and philosophy. It will also serve as a basis for future publications detailing tools and methods of JANA.

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2,743 Citations

Open accessJournal ArticleDOI: 10.1016/J.CCR.2015.02.015
Koen Binnemans1Institutions (1)
Abstract: The trivalent europium ion (Eu3+) is well known for its strong luminescence in the red spectral region, but this ion is also interesting from a theoretical point of view. Due to the even number of electrons in the 4f shell (4f6 configuration), the crystal-field perturbation by the crystalline host matrix lifts partly or completely the degeneracies of the 2S+1LJ levels. The Eu3+ ion has the great advantage over other lanthanide ions with an even number of 4f electrons that the starting levels of the transitions in both the absorption and the luminescence spectrum are non-degenerate (J = 0). Moreover, the interpretation of the spectra is facilitated by the small total angular momentum J of the end levels in the transitions. The number of lines observed for the 5D0 → 7FJ transitions in the luminescence spectrum or the 5DJ ← 7F0 transitions in the absorption spectrum allows determining the site symmetry of the Eu3+ ion. This review describes the spectroscopic properties of the trivalent europium ion, with emphasis on the energy level structure, the intensities of the f–f transitions (including the Judd–Ofelt theory), the decay times of the excited states and the use of the Eu3+ ion as a spectroscopic probe for site symmetry determination. It is illustrated how the maximum amount of information can be extracted from optical absorption and luminescence spectra of europium(III) compounds, and how pitfalls in the interpretation of these spectra can be avoided.

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Topics: Europium (61%), Ion (55%), Absorption spectroscopy (54%) ... show more

1,389 Citations

Open accessJournal ArticleDOI: 10.1021/AR9001069
Andrew M. Smith1, Shuming Nie1Institutions (1)
Abstract: Semiconductor nanocrystals are tiny light-emitting particles on the nanometer scale. Researchers have studied these particles intensely and have developed them for broad applications in solar energy conversion, optoelectronic devices, molecular and cellular imaging, and ultrasensitive detection. A major feature of semiconductor nanocrystals is the quantum confinement effect, which leads to spatial enclosure of the electronic charge carriers within the nanocrystal. Because of this effect, researchers can use the size and shape of these “artificial atoms” to widely and precisely tune the energy of discrete electronic energy states and optical transitions. As a result, researchers can tune the light emission from these particles throughout the ultraviolet, visible, near-infrared, and mid-infrared spectral ranges. These particles also span the transition between small molecules and bulk crystals, instilling novel optical properties such as carrier multiplication, single-particle blinking, and spectral diffusi...

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Topics: Multiple exciton generation (56%), Light emission (54%), Potential well (51%) ... show more

1,328 Citations