LaF3 Nanoparticles Research Articles

Structure-Activity Optimization of Luminescent Tb-doped LaF3 Nanoparticles.

A series of Tb-doped LaF3 nanoparticles (NPs) was prepared by systematically varying the Tb doping rate from 0 to 100%. The elemental composition was confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis, and the size, morphology, and crystal structure were determined in the solid state by transmission electron microscopy and X-ray diffractometry, while the size and ζ-potential of the NPs in solution were studied by dynamic light scattering, Taylor dispersion analysis, and laser Doppler electrophoresis. While the crystal structure appears to be hexagonal for a doping rate of up to 70%, an admixture of hexagonal and orthorhombic phases is observed for 80 and 90% Tb contents with a pure orthorhombic phase being obtained for TbF3. The spectroscopic properties of the NPs were studied for bare NPs and in the presence of dipicolinic acid as a surface-capping antenna ligand in solution. The coverage of the NPs by the ligand resulted in an increase in the luminescence lifetime of the emitting Tb centers, as a consequence of a better protection toward luminescence quenching from water molecules, as well as a large improvement in the brightness of the NPs. Taking into account the various parameters, a doping rate of 40% Tb was shown to be the best compromise for the development of such NPs for bioanalytical applications.

Effect of the temperature on the luminescence profile of photonic materials for biological applications

Temperature has a significant impact on the luminescence profile of photonic materials for biological applications. This paper presents the effect of temperature on the luminescence profile of three different photonic materials in the range of the second biological window. The effect of temperature on luminescence properties is shown on glass, glass-ceramics, and phosphors co-doped with Eu3+/Nd3+/Yb3+ under UV laser diode excitation. Each sample has been analyzed for temperature effects on optical parameters in biological window ranges. Moreover the effect of temperature on mechanisms of energy transfer Eu3+ → Nd3+ → Yb3+ in all fabricated photonic materials was analyzed. Full Text: PDF References J. Zhou, J.L. Leano Jr., Z. Liu, D. Jin, K.-L. Wong et al., "Impact of Lanthanide Nanomaterials on Photonic Devices and Smart Applications", Small 14, 1801882 (2018). CrossRef Z. Li, Y. Zhang, G. Han, "Lanthanide-Doped Upconversion Nanoparticles for Imaging-Guided Drug Delivery and Therapy", Springer Series in Biomaterials Science and Engineering 6, 139 (2016). CrossRef A. Zhang, Z. Sun, M.Jia, et al., "Simultaneous luminescence in Ⅰ, Ⅱ and III biological windows realized by using the energy transfer of Yb3+→Er3+/Ho3+→Cr3+", Chemical Engineering Journal 365, 400 (2019). CrossRef M.-F. Tsai, S.-H.G. Chang, F.-Y. Cheng, V. Shanmugam, Y. Cheng et al., "Au Nanorod Design as Light-Absorber in the First and Second Biological Near-Infrared Windows for in Vivo Photothermal Therapy", ACS Nano 7, 5330 (2013). CrossRef S. Ding, L. Lu, Y. Fan, F. Zhang, "Recent progress in NIR-II emitting lanthanide-based nanoparticles and their biological applications", J. Rare Earth. 38, 451 (2020). CrossRef U. Rocha, K.U. Kumar, C. Jacinto, I. Villa, F. Sanz-Rodriguez et al., "Neodymium-Doped LaF3 Nanoparticles for Fluorescence Bioimaging in the Second Biological Window", Small 10, 1141 (2014). CrossRef M. Jia, Z. Sun, H. Xu, X. Jin, Z. Lv et al. "An ultrasensitive luminescent nanothermometer in the first biological window based on phonon-assisted thermal enhancing and thermal quenching", J. Mater. Chem. C 8, 15603 (2020). CrossRef H. Lin, T. Hu, Y. Cheng, M. Chen, Y. Wang, "Glass Ceramic Phosphors: Towards Long-Lifetime High-Power White Light-Emitting-Diode Applications–A Review", Laser Photonic Rev. 12, 1700344 (2018). CrossRef H. Su, Y. Nie, H. Yang, D. Tang, K. Chen, T. Zhang, "Improving the thermal stability of phosphor in a white light-emitting diode (LED) by glass-ceramics: Effect of Al2O3 dopant", J. Eur. Ceram. Soc. 38, 2005 (2018). CrossRef Kenry, Y.Duan, B. Liu, "Recent Advances of Optical Imaging in the Second Near-Infrared Window", Adv. Mater. 30, 1802394 (2018). CrossRef M.L. Debasu, H. Oliveira, J. Rocha, L.D. Carlos, "Colloidal (Gd0.98Nd0.02)2O3 nanothermometers operating in a cell culture medium within the first and second biological windows", J. Rare Earth. 38, 483-491 (2020). CrossRef L. Pavasaryte, A. Katelnikovas, V. Klimavicius, V. Balevicius, A. Krajnc et al., "Eu3+-Doped Y3−xNdxAl3O12 garnet: synthesis and structural investigation", Phys. Chem. Chem. Phys. 19, 3729 (2017). CrossRef K. Sadowska, P. Awramiuk, I Zgłobicka, K Rećko, J. Żmojda, "Quantum efficiency of europium doped LaPO4 phosphors for UV sensing applications", Photonics Lett. Poland 14, 28 (2022). CrossRef P. Lei, J. Feng, H. Zhang, "Emerging biomaterials: Taking full advantage of the intrinsic properties of rare earth elements", Nano Today 35, 100952 (2020). CrossRef K. Sadowska, T. Ragiń, M. Kochanowicz, P. Miluski, J. Dorosz, et al., "Analysis of Excitation Energy Transfer in LaPO4 Nanophosphors Co-Doped with Eu3+/Nd3+ and Eu3+/Nd3+/Yb3+ Ions", Materials 16, 1588 (2023). CrossRef

Pr3+-doped YF3, LaF3, and GdF3 nanoparticles: comparative crystallographic, Raman, optical, and photoluminescence properties

Pr3+-doped YF3, LaF3, and GdF3 nanoparticles: comparative crystallographic, Raman, optical, and photoluminescence properties

Dual-Mode Nanoprobes Based on Lanthanide Doped Fluoride Nanoparticles Functionalized by Aryl Diazonium Salts for Fluorescence and SERS Bioimaging.

The design of dual-mode fluorescence and Raman tags stimulates a growing interest in biomedical imaging and sensing applications as they offer the possibility to synergistically combine the versatility and velocity of fluorescence imaging with the specificity of Raman spectroscopy. Although lanthanide-doped fluoride nanoparticles (NPs) are among the most studied fluorescent nanoprobes, their use for the development of bimodal fluorescent-Raman probes has never been reported yet, to the best of the authors knowledge, probably due to the difficulty to functionalize them with Raman reporter groups. This gap is filled herein by proposing a fast and straightforward approach based on aryl diazonium salt chemistry to functionalize Eu3+ or Tb3+ doped CaF2 and LaF3 NPs by Raman scatters. The resulting surface-enhanced Raman spectroscopy (SERS)-encoded lanthanide-doped fluoride NPs retain their fluorescence labeling capacity and display efficient SERS activity for cell bioimaging. The potential of this new generation of bimodal nanoprobes is assessed through cell viability assays and intracellular fluorescence and Raman imaging, opening up unprecedented opportunities for biomedical applications.

Optical and Electron Microscopy of Clusters of Nd3+:LaF3 Nanoparticles Synthesized by the HTMW Method

Optical and Electron Microscopy of Clusters of Nd3+:LaF3 Nanoparticles Synthesized by the HTMW Method

Eu3+-ion doped LnF3 NPs: Comparative study of the crystallographic, and photophysical properties

The thermal co-precipitation approach was employed for the synthesis of the Eu3+-ion doped YF3, LaF3, and GdF3 nanoparticles (NPs) and compared their photophysical properties. Ammonium fluorite was used as a fluorine source for the synthesis of metal fluorides at lower temperatures. Luminescent lanthanide fluoride (LnF3) NPs were characterized by different techniques containing X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), FT-Raman, UV/Visible absorption spectra, and photoluminescence spectroscopic procedures to investigate the crystal structural, thermal, Raman effect, surface, optical, and luminescent properties. XRD study shows two types of crystal phase orthorhombic in YF3:Eu & GdF3:Eu and hexagonal in LaF3:Eu NPs. TGA, FTIR, and absorption spectra studies show the exterior adsorbed –OH molecules, which assist in the development of colloidal solution in aqueous media. Raman vibrations were strongly affected which were correlated with the XRD reflection planes. In comparative photo-physical properties, the excitation and emission spectra exhibited remarkable intensities of the Eu3+-ion transitions. Similarly, the emission spectra of all three samples exhibited the highest emission efficiency of the magnetically-dipole(5D0→7F2) transition in comparison to the electric-dipole 5D0→7F1 transition, which reflected the transformation of the crystal symmetry. Comparative analysis was presented to investigate the role of the host lattice on crystallinity, thermal stability, and luminescent properties. These findings are highly fruitful in designing photonic-based applications including optical biosensors, fingermark detection, security systems, etc.

Magnetic properties of LaF3 nanoparticles doped with Pr3+ ions

The magnetic properties of LaF3:1%Pr3+ fluoride nanoparticles were studied in comparison with bulk LaF3:1%Pr3+ crystal and microcrystalline powder using EPR and magnetization measurements complemented by XRD and TEM methods. LaF3:1%Pr3+ fluoride nanoparticles were synthesized by co-precipitation method and had two morphotypes: nanospheres and nanoplates. Microcrystalline powder was obtained by grinding a bulk LaF3:Pr3+ crystal using a pestle and a mortar. We have found the room temperature ferromagnetic-like response in magnetization measurements for nano- and microcrystalline powders whereas no such response was observed for the bulk crystal. We supposed that surface defects play a key role in the observed magnetization dependences on the magnetic field.

The Influence of Medium on Fluorescence Quenching of Colloidal Solutions of the Nd3+: LaF3 Nanoparticles Prepared with HTMW Treatment.

An original method was proposed to reduce the quenching of the NIR fluorescence of colloidal solutions of 0.1 at. % Nd3+: LaF3 nanoparticles (NPs) synthesized by aqueous co-precipitation method followed by hydrothermal microwave treatment. For this, an aqueous colloidal solution of NPs was precipitated by centrifugation and dissolved in the same volume of DMSO. The kinetics of static fluorescence quenching of Nd3+ donors of doped NPs dispersed in two solvents was analyzed to determine and to compare the concentrations of OH- quenching acceptors uniformly distributed throughout the volume of the NPs. The dependences of the relative fluorescence quantum yield φ of colloidal solutions on the concentration of OH- groups in the NPs were calculated and were also used to determine concentration of acceptors in the volume of NPs in different solvents. It was found that the concentration of OH- groups in NPs dispersed in DMSO is almost two times lower than in NPs dispersed in water. This gives an almost two-fold increase in the relative fluorescence quantum yield φ for the former. The sizes of synthesized NPs were monitored by common TEM and by applying a rapid procedure based on optical visualization of the trajectories of the Brownian motion of NPs in solution using a laser ultramicroscope. The use of two different methods made it possible to obtain more detailed information about the studied NPs.

Highlighting of LaF3 Reactivity with SiO2 and GeO2 at High Temperature

LaF3 is commonly added to oxide glass, in particular to silica, to form oxyfluoride glass. After appropriate thermal treatment at a temperature lower than 800 °C, usually, glass ceramics are obtained. Recently, LaF3 nanoparticles have been used as precursors to obtain amorphous nanoparticles of undefined composition in optical fiber. However, fiber fabrication necessitates temperature much higher (typically up to 2000 °C) than the one required for bulk glass. In this article, we report on the reactivity of fluoride ions in LaF3 with SiO2 and GeO2 (a common dopant used to dope optical fiber) powders at high temperature. TGA, EDX-SEM, XRD and Raman analyses were performed. Above 1000 °C, LaF3 starts to react, preferentially with SiO2, to form SiF4 gaseous species. The remaining lanthanum ions form La2Si2O7 and La2Ge2O7 phases. These results could contribute to improve material development for the fiber optics community.

Influence of Different Synthetic Methods on Morphology and Luminescent Properties of LaF3:Eu3+ Nanoparticles

Fluorescent europium ion doped lanthanum fluoride (LaF3:Eu3+) nanoparticles were synthesized using various methods which includes hydrothermal, co-precipitation and sonochemical method. A series of experiments were performed to obtain variations in the morphology, structure and optical behaviour of fabricated products. The optical and structural properties of the fabricated nanoparticles (NPs) were characterized through scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectrometry, and particle size by dynamic light scattering (DLS). In LaF3 nanoparticles, the existence of europium as dopant ions was confirmed through energy dispersive X-ray spectroscopy (EDS). The optical properties of the synthesized nanoparticles were investigated by conducting photoluminescence (PL) studies.

Synthesis and NMR cryoporometry of LaF3 nanoparticles with closed pores filled by D2O

Synthesis and NMR cryoporometry of LaF3 nanoparticles with closed pores filled by D2O

Influence of oleic acid-treated LaF3 nanoparticles as an additive on extreme pressure properties of various grades of polyalphaolefins

The present work focused on the extreme pressure characteristics of different grades of polyalphaolefins (i.e., PAO 4, PAO 6, PAO 40, and PAO 100) with LaF3 nanoparticles as an additive. The LaF3 nanoparticles were synthesized by the sol-gel method and modified with oleic acid. The synthesized nanoparticles were characterized with various analytical tools viz. X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The varying dose (0.025-0.15 wt.%) of synthesized nanoparticles were blended in all PAOs to prepare nanolubricants. The extreme pressure (EP) properties of nanolubricants were measured using a four-ball tester as per ASTM D2783 to find the last non-seizure load (LNSL), initial seizure load (ISL), just before weld (JBWL), weld load (WL), and load wear index (LWI). The results revealed that the incorporation of LaF3 nanoparticles efficiently enhanced the EP properties of all PAOs. However, 0.15 wt.% of additive was the optimum dose in all PAOs, demonstrating the best EP behavior, i.e., the highest LWI and lowest wear scar diameter (WSD) at ISL and JBWL. Numerous characterization techniques such as scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and scan probe microscope (SPM) were adopted to investigate the probabilistic rationale for the improvement in EP properties.

Stable Aqueous Colloidal Solutions of Nd3+: LaF3 Nanoparticles, Promising for Luminescent Bioimaging in the Near-Infrared Spectral Range.

Two series of stable aqueous colloidal solutions of Nd3+: LaF3 single-phase well-crystallized nanoparticles (NPs), possessing a fluorcerite structure with different activator concentrations in each series, were synthesized. A hydrothermal method involving microwave-assisted heating (HTMW) in two Berghof speedwave devices equipped with one magnetron (type I) or two magnetrons (type II) was used. The average sizes of NPs are 15.4 ± 6 nm (type I) and 21 ± 7 nm (type II). Both types of NPs have a size distribution that is well described by a double Gaussian function. The fluorescence kinetics of the 4F3/2 level of the Nd3+ ion for NPs of both types, in contrast to a similar bulk crystal, demonstrates a luminescence quenching associated not only with Nd–Nd self-quenching, but also with an additional Nd–OH quenching. A method has been developed for determining the spontaneous radiative lifetime of the excited state of a dopant ion, with the significant contribution of the luminescence quenching caused by the presence of the impurity OH– acceptors located in the bulk of NPs. The relative quantum yield of fluorescence and the fluorescence brightness of an aqueous colloidal solution of type II NPs with an optimal concentration of Nd3+ are only 2.5 times lower than those of analogous Nd3+: LaF3 single crystals.

Chemiluminescence enhanced by cerium-doped LaF3 nanoparticles through electron-hole annihilation

In this paper, cerium-doped LaF3 nanoparticles (LaF3:Ce NPs) were synthesized and applied in enhancing chemiluminescence (CL) process of NaIO4–H2O2 system. The CL intensity was enhanced 42 times compared to that of NaIO4–H2O2 system without LaF3:Ce NPs. The CL mechanism was systematically investigated and accounted by the annihilation between electron-injected and hole-injected LaF3:Ce NPs. Experimental conditions were optimized to obtain the optimum CL. This work introduced a new pathway for enhancing traditional luminescent process through developing advanced nanomaterials.

Transmission electron microscopy and flow cytometry study of cellular uptake of unmodified Pr3+:LaF3 nanoparticles in dynamic

Transmission electron microscopy and flow cytometry study of cellular uptake of unmodified Pr3+:LaF3 nanoparticles in dynamic

Ultra-Weak Chemiluminescence Enhanced by Cerium-Doped LaF3 Nanoparticles: A Potential Nitrite Analysis Method.

In this work, cerium-doped LaF3 nanoparticles (LaF3:Ce NPs) were successfully synthesized and characterized. Its chemiluminescence (CL) property was studied, and it was amazingly found that it intensely enhanced the ultra-weak CL of the NaNO2-H2O2 system. The CL mechanism was systematically investigated and suggested to be the recombination of electron-injected and hole-injected LaF3:Ce NPs. The new CL system was developed to be a facile, original, and direct method for nitrite analysis. Experimental conditions were optimized and then a satisfactory linear relationship between CL intensity and nitrite concentration was obtained. This work introduced a new pathway for the research and application of traditional fluoride NPs doped with RE3+.

Role of heat treatment on the structural and luminescence properties of Yb3+/Ln3+ (Ln = Tm, Ho and Er) co-doped LaF3 nanoparticles.

Hexagonal LaF3:Yb3+/Ln3+ and tetragonal LaOF:Yb3+/Ln3+ (Ln = Ho, Tm, Er) have been successfully prepared via a two-step reaction, which includes a facile aqueous ligand free solution method and the following heat treatment of the as-prepared LaF3 precursor. The phase formation evolution from LaF3 to LaOF with different phase structures was characterized by X-ray diffraction (XRD), scanning electron microscopy, Fourier transform infrared, and Raman spectroscopy. At an annealing temperature of 500 °C pure hexagonal LaF3:Yb3+/Ln3+ (Ln = Ho, Tm, Er) nanoparticles with an average size of 32 nm were obtained and they showed a strong visible upconversion and a modest infrared emission upon 976 nm laser excitation. Further, using an annealing temperature of 900 °C, tetragonal LaOF:Yb3+/Ln3+ (Ln = Ho, Tm, Er) nanoparticles with a size of around 44 nm were obtained (obtained from XRD) and an expressive enhancement in the emission of the VIS and near-infrared regions was observed. These results envision applications that require efficient emissions such as fluorescent and thermal images, and LaF3 nanocrystals have recently been widely explored for applications in biological systems.

The comparison of Pr3+:LaF3 and Pr3+:LiYF4 luminescent nano- and microthermometer performances

In the present work, we make a comparison of Pr3+:LaF3 and Pr3+:LiYF4 luminescent nano- and microthermometer performances. We studied Pr3+:LaF3 nanoparticles, synthesized via co-precipitation method (further Pr3+:LaF3 (co-precipitation)), Pr3+:LaF3 nanoparticles, synthesized via hydrothermal method (further Pr3+:LaF3 (hydrothermal)), and Pr3+:LaF3 microparticles as well as Pr3+:LiYF4 nanoparticles, synthesized via hydrothermal method (further Pr3+:LiYF4 nanoparticles) and Pr3+:LaF3 microparticles. According to the X-ray diffraction, Pr3+:LaF3 (co-precipitation) and Pr3+:LaF3 (hydrothermal) nanoparticles are hexagonal-structured nanocrystals. Pr3+:LiYF4 nanoparticles are tetragonal-structured nanocrystals. The average diameters of Pr3+:LaF3 (co-precipitation), Pr3+:LaF3 (hydrothermal), and Pr3+:LiYF4 nanoparticles are 13.9, 19.4, and 33.3 nm, respectively. The Pr3+:LaF3 (co-precipitation) and Pr3+:LaF3 (hydrothermal) nanoparticles demonstrate broadband luminescence caused by crystal lattice defects (luminescence background). This luminescence background notably decreases the temperature sensitivity of these samples. The luminescent background removing procedure significantly complicates the signal processing procedure. Pr3+:LaF3 microparticles, Pr3+:LiYF4 nanoparticles, and Pr3+:LaF3 microparticles do not demonstrate this undesirable phenomenon. The absolute temperature sensitivity Sa of Pr3+:LiYF4 nanoparticles, Pr3+:LiYF4 microparticles, and Pr3+:LaF3 microparticles at 300 K are 0.0117 ± 0.0010, 0.0106 ± 0.0010, and 0.0102 ± 0.0012 K−1, respectively. Although the values of Sa are very close for these samples, the nanosized dimensionality of Pr3+:LiYF4 nanoparticles allows achieving high spatial resolution and expanding the fields of application of Pr3+:LiYF4 nanoparticles.

The effects of ultrasonication on the microstructure, gelling and tribological properties of 12-HSA soft-nanocomposite with LaF3 nanoparticles

During the preparation of soft-nanocomposites, ultrasonic treatment is widely utilized to improve the dispersion of nanomaterial in the gel system. However, both the nanomaterials and the low molecular weight organic gelators (LMWGs) could interact with the ultrasonic energy. In this paper, the influence of ultrasonication in the microstructure and the properties of 12-hydroxystearic acid (12-HSA) soft-nanocomposites with LaF3 nanoparticles were investigated. It was found that despite ultrasonication could improve the dispersion of LaF3 nanoparticles, the viscoelastic properties of the gel system were greatly changed. Via characterizing the xerogel, the ultrasonic-induced fining effect in gelator fibers was confirmed, which accounted for the changed gel properties. Tribological evaluations show that the 12-HSA gel with coarse fibers shows better performance under low load, while the one with fine fibers exhibits better performance under higher load. With the aid of LaF3 nanoparticles, the adaptability of soft-nanocomposites for severe conditions could be further improved due to the cooperative effects between 12-HSA and LaF3 nanoparticles in constructing the boundary lubricating films. Although the nanomaterials are effective to improve the functionality of LMWG gels, the microstructure of gelator assembly and gel properties could be also significantly changed during the dispersion process of nanomaterials via sonication.

Cellular uptake and cytotoxicity of unmodified Pr3+:LaF3 nanoparticles

Pr3+:LaF3 (CPr = 1%) nanoparticles were characterized by means of transmission electron microscopy (TEM), X-ray diffraction, energy-dispersive spectroscopy, and optical spectroscopy. The obtained 14 nm Pr3+:LaF3 (CPr = 1%) crystalline hexagonal-structured nanoparticles contain Pr, La, and F only. The luminescent spectra emission bands corresponded to the emission bands of Pr3+ions. The Pr3+:LaF3 (CPr = 1%) nanoparticles effectively interact with A 549, LEС, and MDCK cells. By means of TEM, it was revealed that after 2 h of the nanoparticle exposure, A 549, MDCK, and LEС cells internalized the nanoparticles and 20–300 nm agglomerates of the nanoparticles packed into 200–500 nm vesicles were found into the cytoplasm. It seems that the internalization occurs via macropinocytosis. In A 549 cells, some vesicles were disrupted and the nanoparticles escaped the vesicles floating freely in the cytoplasm. Flow cytometry showed that all the cells effectively interact with nanoparticles. This interaction leads to cell granularity change. Specifically, A 549, MDCK, and LEС, and cells treated by nanoparticles have the values of size scattered signal 16 ± 2, 20 ± 3, and 39 ± 3%, respectively, comparing with the untreated cells. The Pr3+:LaF3 (CPr = 1%) nanoparticles were not found into the cellular organelles. The cytotoxicity of the Pr3+:LaF3 (CPr = 1%) nanoparticles is not significant at concentrations of 0.05, 0.1, 0.25, and 0.5 g/L.