Emission Of Nd Research Articles

Construction of multifunctional core-shell structure nanoprobe integrating NIR dual-mode optical thermometer and nuclear magnetic imaging

Precise temperature regulation and imaging are critical for in vivo photothermal treatment. The goal of this work is to realize non-contact temperature measurement and imaging in biological tissues by building a multifunctional nano-platform using optical temperature probes and imaging for biological diagnosis and therapy. Here, NIR dual-mode temperature probes of NaYF4: Nd/Yb/Gd@NaNdF4 were designed according to the LIR-I of 4F3/2 → 4I9/2/2F5/2 → 2F7/2 levels in 850 – 1025 nm and LIR-II of 2F5/2 → 2F7/2/4F3/2 → 4I11/2 in 950 – 1100 nm from the emissions of Nd3+/Yb3+. Transmission electron microscope (TEM) and X-ray diffraction (XRD) data of the sample demonstrate its superior dispersibility and accurate structure. The integrated intensity ratio centered around various luminescence intensity peaks is used as a temperature sensor since luminescence intensity is temperature-dependent. Additionally, the temperature sensing capabilities of two ratio temperature sensors were examined under 808 nm laser excitation, utilizing LIR (luminescence intensity ratio) technology. Furthermore, the MRI test indicated that the sample exhibited good imaging capacity when Gd3+ was added. These results assure the auspicious application prospects of the samples in temperature sensing, photothermal therapy, and biomedical imaging.

The effect of Al3+ ions on the self-reduction process of Yb3+ to Yb2+ ions and optical properties of Nd3+/Ybn+ (n = 3, 2) co-doped transparent silicate glass-ceramics containing Ba2LaF7 nanocrystals and Ag nanoparticles

The effect of Al3+ ions in the AlF3 compound on the reduction process of Yb3+ to Yb2+ ions in SiO2–AlF3–BaF2–TiO2–LaF3 (SABTL) transparent silicate glass-ceramics was investigated. The valence states of the elements in the raw materials mixture existing in the transparent silicate glass-ceramics were determined using X-ray photoelectron spectroscopy (XPS) spectrum analysis. The transparent silicate glass-ceramics SABTL containing Ba2LaF7 nanocrystals and Silver (Ag) nanoparticles (AgNPs) were identified through X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) image. With the increase of Al3+ ions molar concentration, the self-reduction process of Yb3+ to Yb2+ ions was enhanced and thus significantly affected the optical bandgaps and upconversion (UC)-, near-infrared (NIR)- emissions of Nd3+/Yb3+ co-doped in SABTL containing Ba2LaF7 nanocrystals and AgNPs under excitation of 980 nm laser diode (LD). The optimal molar concentration ratio between SiO2 and AlF3 compound was determined such that the NIR bandwidth flatness of Nd3+/Yb3+ co-doped in SABTL containing Ba2LaF7 nanocrystals in the wavelength range of 1000–1200 nm was the flattest. In addition, the CIE 1931 (x, y) color coordinates for UC- and visible (VIS)- emissions of Nd3+/Yb3+ co-doped SABTL-0.5Nd2Yb-xAg (x = 0, 2, 3, 4, and 5) glass-ceramics samples are also calculated and determined the color region for light-emitting diode (LED) application.

Energy transfer modulation of photoluminescence in glasses co-doped with Nd3+ and CsPbBr3 quantum dots

Nd3+ co-doped CsPbBr3 perovskite quantum dots (PQDs) glasses were prepared by conventional melt-quenching followed by a thermal treatment process. With the introduction of Nd2O3 to the parent glass, the optical properties of the CsPbBr3 PQDs are significantly improved. The energy transfer from CsPbBr3 PQDs to Nd3+ ions was investigated and confirmed by excitation and emission spectra. The results show that visible excitation band width for the near-infrared (NIR) emission of Nd3+ ions is significantly increased in the presence of PQDs. The strategy for modulation of the optical properties by the energy transfer between rare earth ions and PQDs in the glass matrix could be further utilized for spectral engineering of photonic glasses for optoelectronic applications.

Efficient near-infrared quantum cutting by cooperative energy transfer in Bi3TeBO9:Nd3+ phosphors

An efficient near-infrared quantum cutting process by cooperative down-conversion of active Bi3+ and Nd3+ ions was demonstrated in Bi3TeBO9:Nd3+ phosphors. In particular, the near-infrared emission of Nd3+ ions enhanced by Bi3+ ions of a series of novel Bi3TeBO9:Nd3+ microcrystalline powders doped with Nd3+ ions in various concentrations was investigated. In order to investigate the luminescent properties of BTBO:Nd3+ powders, the excitation and emission spectra and the fluorescence decay time were measured and analyzed. In particular, the emission of Bi3TeBO9:Nd3+ at 890 and 1064 nm was excited at 327 nm (via energy transfer from Bi3+ ions) and at 586.4 nm (directly by Nd3+ ions). The highest intensity emission bands in near-infrared were detected in the spectra of Bi3TeBO9:Nd3+ doped with 5.0 and 0.5 at.% of Nd3+ ions upon excitation in ultraviolet and visible spectral range, respectively. The fluorescence decay lifetime monitored at 1064 nm for Bi3TeBO9:Nd3+ powders shows the single- or double-exponential character depending on the concentrations of Nd3+ ions. The possible mechanisms of energy relaxation after excitation Bi3TeBO9:Nd3+ powders in ultraviolet or visible spectral range were discussed. The investigated Bi3TeBO9:Nd3+ phosphors efficiently concentrate the ultraviolet/visible radiation in the near-infrared spectral range and can be potentially used as effective spectral converters.Graphical abstract

High pressure effect in the near-infrared emission of Nd3+-doped alkali silicate glasses

ABSTRACT The effect of high pressure (7.7 GPa) densification on the absorption and near-infrared emission of Nd-doped lithium, sodium and potassium disilicate glasses was investigated. Judd-Ofelt parameters Ωλ (λ = 2, 4 and 6) were calculated from the absorption spectra, before and after densification of glasses, indicating that the irreversible structural changes induced by pressure increased the symmetry of the Nd-O bonding. Density and refractive index of the glasses also increased, probably related to the close packing of SiO4 tetrahedra during densification. The magnitude of the splitting due to the Stark effect was larger for potassium silicate, before and after densification. The radiative transition probabilities of the hypersensitive transition for sodium and potassium silicate increased after densification while the radiative lifetime decreased. For lithium silicate, the opposite behavior was observed. The experimental results corroborate the influence of alkali ion and densification on the luminescence properties of Nd-doped alkali silicate glasses.

Growth and optical properties of the Nd,Ce:YAG laser crystal

A high-quality 2-inch-diameter Nd3+, Ce3+ co-doped Y3Al5O12 (YAG) crystal was successfully grown by the Czochralski (CZ) method. During crystal growth, a modified temperature field was applied to prevent defects in the crystal. The spectrum of the sample showed strong absorption peaks corresponding to Nd3+ and Ce3+ ions. The effect of Ce3+ codoping on the photoluminescence of Nd3+ was investigated in detail. Strong 1066 nm emission of Nd3+4F3/2–4I11/2 was observed upon the 5d excitation of Ce3+. The energy transfer from Ce3+ to Nd3+ consists of nonradiative and radiative components. Compared to Nd:YAG, the double-doped Nd,Ce:YAG crystal realizes better utilization of the pump energy and higher laser energy output. Moreover, the laser threshold value is also significantly reduced. These results imply that Ce3+ doped into the YAG crystal acts as a good sensitizing ion for Nd3+. Hence, this double-doped Nd,Ce:YAG crystal is expected to be of industrial significance for manufacturing high-energy, low-volume solid-state lasers.

Rational Design of a Nd3+‐Mn4+ Co‐doped Luminescent Thermometer: Towards High‐Sensitivity Temperature Sensing

AbstractHigh temperature sensitivity is an important development direction for luminescent thermometers, especially in the physiological temperature range. Herein, neodymium(III) and manganese(IV) ions were co‐doped into a yttrium gallium garnet host (YGG) and the relevant dopant concentrations were optimized in detail. The temperature‐dependent spectral survey indicates that when the temperature was above 240 K, the 2Eg→4A2g transition of Mn4+ and the 4F5/2→4I9/2 emission of Nd3+ show strong fluorescence quenching and gradual fluorescence enhancement, respectively. Such an apparent contrast mainly originates from the nonradiative cross‐relaxation between 2Eg (or 4T2g) and 4A2g states of Mn4+ and thermal coupling between the 4F5/2 and 4F3/2 levels of Nd3+, respectively. The obvious difference in fluorescence between the two luminescent ions leads to an excellent temperature sensing performance. The obtained relative sensitivity shows a maximum value at 280 K (7.90 % K−1) and maintains a magnitude above 5.00 % K−1 over the whole physiological temperature range. Moreover, the related temperature uncertainties are below 0.1 K from 298 K to 323 K, and the repeatability capability is larger than 98 %. The findings in this study offer a feasible approach to promote the sensing capability of temperature sensors by rationally designing co‐doping systems.

Effects of La3+ on the enhancement NIR quantum cutting and UC emissions in Nd3+–Yb3+ co-doped transparent silicate glass-ceramics for solar cells

Near-infrared (NIR) quantum cutting (QC) and upconversion (UC) emission of Nd3+–Yb3+ co-doped in Si–Al–Ba–La transparent silicate glass-ceramics (SGC) were prepared. Influence of La3+ on the enhancement NIR QC and UC emission intensity of the co-doped Nd3+–Yb3+ in SGC were investigated. Thereby, NIR QC and UC emission intensity of the co-doped Nd3+–Yb3+ were increased strongly with increasing concentration of LaF3 from 5 up to 25 mol. %. The value of NIR QC emission intensity of the co-doped Nd3+–Yb3+ band centered at ~890, 947, 1071, 1339 and 1430 nm is maximized when the concentration of LaF3 reaches 25 mol. %. At the same time, with the increasing concentration of Yb3+, NIR QC emission intensity of the co-doped Nd3+–Yb3+ bands centered at ~890, 1071, 1339 and 1430 nm of Nd3+ and 947 nm of Yb3+ were gradually increased and reaches its maximum at 2.5 mol. % Yb3+, then decreased owing to the self-quenching effect. In addition, NIR QC mechanism and energy transfer (ET) processes between 2F5/2 → 2F7/2 transition of Yb3+ and transitions of Nd3+ are discussed.

Optical studies of Y3(Al,Ga)5O12:Ce3+,Cr3+,Nd3+ nano-phosphors obtained by the Pechini method

The Y3(Al,Ga)5O12:Ce3+,Cr3+,Nd3+ (YAGG) nano-phosphors with homogeneous particle-size distribution, low aggregation and average crystalline size of about 65 nm were obtained using a modified Pechini method. Only slight aggregation of the crystallites occurs after post-annealing at 1100 °C. The intense Ce3+ bands in the excitation spectra of the Ce3+,Cr3+,Nd3+ co-doped materials monitoring the Cr3+ emission at 690 nm indicate energy transfer from Ce3+ to Cr3+. Weak Nd3+ lines are observed, as well. In addition, the emission of Nd3+ at 1060 nm with excitation of Ce3+ and Cr3+ confirms the Ce3+/Cr3+ to Nd3+ energy transfer. The short average luminescence decay times for the Ce3+ emission indicate the Ce3+/Cr3+ to Nd3+ energy transfer. Eventually, the Y3(Al,Ga)5O12:Ce3+,Cr3+,Nd3+ nano-phosphors exhibit persistent luminescence originating from the 4f3 → 4f3 transitions of Nd3+ which matches well to the first biological window to be used in bioimaging applications.

Sensitization of NIR Photoluminescence of Lanthanides in [LnCl3(tppe)2(thz)2] by trans‐1‐(2‐pyridyl)‐2‐(pyridyl)ethylene

In order to evaluate the structural and spectroscopic influence of further pyridyl ligands, e.g. as sensitizers for Ln3+‐based photoluminescence, the ligand trans‐1‐(2‐pyridyl)‐2‐(pyridyl)ethylene (tppe) was selected. In reactions with trivalent chlorides of the lanthanides and thiazole (thz), complexes of the formula [LnCl3(tppe)2(thz)2] were obtained for Ln = Nd, Tb, Ho, Er. They are isotypic along the series of the lanthanides and provide ligand sensitizer functions for the Ln‐luminescence emission of Nd3+ and Er3+ in the near infrared region. Alike 1,2‐bis(4‐pyridyl)ethylene, no sensitization is observed for the 4f‐based emission of Tb3+ in the visible.

Blue and green upconversion emissions of Zr:Nd:LiNbO3 single crystals

Zr:Nd:LiNbO3 crystals codoped with 0.1 mol% of Nd2 O3 and three concentrations of ZrO2 (0, 2 and 4 mol%) were grown by the Czochralski method from the congruent melt. The X-ray diffraction (XRD) patterns, UV–visible absorption and infrared (IR) spectra were measured to analyze the crystal composition and defect structure. The blue and green upconversion emissions of Nd3+ ions under 598 nm excitation were observed. The intensity of upconversion emissions was increased by the introduction of 2 mol% zirconium ion (Zr4+) and decreased by the introduction of 4 mol% Zr4+ ions. The luminescence decay measurement indicated that the 4G7/2 state of Nd3+ ion was mainly populated by excited state absorption process. It was proposed that Nd:LiNbO3 crystals doped with approximately 2 mol% Zr4+ ions could be applied as laser materials at 522/535 nm.

Novel Plasmonic Nanometal - Rare-Earth Ions co-doped Antimony Glasses for Nanophotonic Applications

ABSTRACTGlasses are recognized as the ideal hosts to incorporate plasmonic metal nanoparticles (NPs), semiconductor NPs, and luminescent rare-earth (RE3+) ions. This is due to their unique optical properties, stability, absence of high energy bond vibrations and inertness towards the incorporated NPs. However, conventional methods of metal-glass nanocomposite fabrication involve ion-implantation or sputtering and subsequent heat-treatment under H2, UV-light/X-ray/γ- or laser irradiation. They are (i) multi-step, (ii) require expensive set-up, (iii) bear risk of sample damage and (iv) the formation of NPs occurs only in surface layers. Here we develop two novel glass-systems K2O-B2O3-Sb2O3 and K2O-B2O3-Sb2O3-ZnO. Using the selective reducing property of the main component Sb2O3 in these hosts, here we demonstrate for the first time the strategy for single-step in-situ fabrication of metal (M0) NPs and RE3+ ions co-embedded within bulk glasses. This new series of novel composites co-embedding metal NPs (elliptical Au, elongated Ag NPs and Aucore-AuAgshell NPs) and RE3+ ions exhibit enhanced upconversion for solar panels, advanced displays and other nanophotonic applications. Metal NPs exhibit surface plasmons resonance results in concentration and enhancement of the local electromagnetic field (LFE) around them. The luminescent RE3+ ion in the vicinity experiences the local field effect. We observe that the LFE effect is stronger on electric dipole transitions of the RE3+ than the magnetic dipole ones. LFE induced by nano Au enhance the (i) 4G7/2 → 4I9/2 540 nm green and 4G7/2 → 4I15/2 650 nm red upconversion emissions of Nd3+ by 9 and 11 fold, (ii) electric dipole 4G5/2 → 6H9/2 636 nm red upconversion of Sm3+ by about 7 fold and (ii) 4S3/2 → 4I15/2 536 nm green and 4F9/2 →4I15/2 645 nm red emissions of Er3+ by 2 and 5 fold respectively. LFE induced by nano Ag enhance both the green and red upconversion emission of Er3+ by 8 fold. The Aucore-AuAgshell NPs enhance the red upconversion of Sm3+ only by 2 fold due to smaller LFE effect of bimetallic NPs. All the Au-doped antimony glasses are dichroic. They transmit the blue light and reflect the brown light, which make them very interesting material comparable to the historic Lycurgus Cup.

Multifunctional visible/near-infrared luminescent core–shell magnetic silica structured nanocomposites

In this paper, we report the fabrication and characterization of magnetic silica nanospheres covalently bonded with near-infrared (NIR) and ultraviolet-visible (UV-vis) luminescent lanthanide complexes [denoted as Fe3O4@SiO2@Ln–PABI/SiO2 (Ln = Nd, Eu)]. Fe3O4@SiO2@Ln–PABI/SiO2 (Ln = Nd, Eu) nanospheres with an average size of 150–200 nm were synthesized via incorporation of the chelate ligand PABI (N-(4-benzoic acid-yl)-N′-(propyltriethoxysilyl) urea) with Ln (Nd, Eu) into a framework of magnetic silica (denoted as Fe3O4@SiO2), followed by a modified Stober method and a layer-by-layer assembly technique. The morphological, structural, textural, magnetic, NIR luminescence and UV luminescence properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometry, and photoluminescence spectroscopy. These multifunctional nanocomposites exhibit superparamagnetic behavior, and the characteristic NIR emission and UV emission of Nd3+ and Eu3+, respectively. Such materials with superparamagnetic and lanthanide-based near-infrared and UV luminescence properties have several advantages for potential applications in optical imaging or as biological luminescent labels.

Factors affecting the Nd3+ (REE3+) luminescence of minerals

In this paper, possibilities and limits of the application of REE3+ luminescence (especially the Nd3+ 4F3/2 → 4I9/2 emission) as structural probe are evaluated. Important factors controlling the Nd3+ luminescence signal are discussed, including effects of the crystal-field, crystal orientation, structural state, and temperature. Particular attention was paid to the study of the accessory minerals zircon (ZrSiO4), xenotime–(Y) (YPO4), monazite–(Ce) (CePO4) and their synthetic analogues. Based on these examples we review in short that (1) REE3+ luminescence can be used as non-destructive phase identification method, (2) the intensities of certain luminescence bands are strongly influenced by crystal orientation effects, and (3) increased widths of REE3+-related emission bands are a strong indicator for structural disorder. We discuss the potential of luminescence spectroscopy, complementary to Raman spectroscopy, for the quantitative estimation of chemical (and potentially also radiation-induced) disorder. For the latter, emissions of Nd3+-related centres are found to be promising candidates.

Photoluminescence of EuGa<sub>2</sub>Se<sub>4</sub>:Nd<sup>3+</sup>

The photoluminescence (PL) in temperature interval 77 - 300 K is investigated in Eu Ga2Se4:Nd polycrystals. It is established that broad band PL with maximum at 561nm is caused by intracentral transitions 4f65d - 4f7(8S7/2) of Eu2+ ions. The intracentral emission of Nd3+, corresponding to both transitions from 4F3/2 level and higher situated levels, is observed at interband excitation. The essential intensity of transitions from 2H11/2 and 4F9/2 levels is the interested peculiarity of luminescence spectra of Nd3+ in these crystals.

Optical Properties of Nd<SUP>3+</SUP> Doped Ionic Liquid Immobilized on Mesoporous Silica Support

The synthesis of a new material based on Nd3+ ions doped into an imidazolium-type ionic liquid with further immobilization on a mesoporous silica support is reported. The material was investigated by DR-UV/VIS, FT-IR, thermogravimetric analysis, N2 adsorption measurements and time-resolved photoluminescence spectroscopy. The intensity of the near-infrared emission of Nd3+ was weak and the lifetime measured at about 910 nm was 7 micros.

Spectroscopic and stimulated emission characteristics of Nd3+ in transparent glass ceramic embedding β-YF3 nanocrystals

A transparent SiO2–Al2O3–LiF–YF3 glass ceramic doped with Nd3+ was fabricated by melt quenching and subsequent heating. X-ray diffraction and transmission electron microscope results demonstrated that orthorhombic β-YF3 nanocrystals with a mean size of 23nm were homogeneously precipitated among the glass matrix. Confirmed by the energy dispersive x-ray spectroscopy measurements, the crystal-like absorption and emission of Nd3+ indicated the partition of Nd3+ into YF3 nanocrystals in the glass ceramic. Detailed characterizations of the Stark components of the I9∕24, I11∕24, and I13∕24 manifolds were performed using the low temperature fluorescence spectra for F3∕24→I9∕24, F3∕24→I11∕24, and F3∕24→I13∕24 transitions of Nd3+ in the glass ceramic. The stimulated emission cross sections of the F3∕24→I11∕24 intermanifold transition and the F3∕24(R1)→I11∕24(Y1) inter-Stark transition were determined to be 7.24×10−20 and 11.55×10−20cm2, respectively, being preferable to those of Nd3+-doped laser glasses and glass ceramic embedding (Pb,Cd)F2 nanocrystals.

Spectral characterizations of Nd3+: KLa(WO4)2 crystal

The absorption and emission of Nd3+: KLa (WO4)2 crystal were investigated. The uniaxial crystal Nd3+: KLa(WO4)2 shows strong polarization dependence. The intensity of the absorption bands in E//c is about four times than that in E//a. The absorption cross section σa is 22.6 × 10−20 cm2 for E//c. The emission cross section at 1.069 μm is 2.09 × 10−19 cm2. The fluorescence lifetime is 157 μs at 300 K. The relationship of Nd3+ concentrations with fluorescence intensity and lifetime was discussed. The results show the ca 3 at % Nd3+ concentration in Nd3+: KLa(WO4)2 crystal is appropriate.

Spectral characterizations of Nd3+:KLa(WO4)2 crystal

The absorption and emission of Nd3+:KLa(WO4)2 crystal were investigated. The uniaxial crystal Nd3+:KLa(WO4)2 shows strong polarization dependence. The intensity of the absorption bands in E//c is about four times than that in E//a. The absorption cross section σa is 22.6 × 10–20 cm2 for E//c. The emission cross section at 1.069 μm is 2.09 × 10–19 cm2. The fluorescence lifetime is 157 μs at 300 K. The relationship of Nd3+ concentrations with fluorescence intensity and lifetime was discussed. The results show the ca 3 at % Nd3+ concentration in Nd3+:KLa(WO4)2 crystal is appropriate.

Room temperature visible/infrared emission and energy transfer in Nd3+-based organic/inorganic hybrids

The photoluminescence features and the energy transfer processes of Nd3+-based siloxane-poly(oxyethylene) hybrids are reported. The host matrix of these materials, classed as di-ureasils, is formed by a siloxane backbone covalently bonded to polyether chains of two molecular weights by means of urea cross-links. The room-temperature photoluminescence spectra of these xerogels show a wide broad purple-blue-green band (350–570 nm), associated with the emitting centres of the di-ureasil host, and the typical near infrared emission of Nd3+ (700–1400 nm), assigned to the 4F3/2 → 4I9/2,11/2,13/2 transitions. Self-absorptions in the visible range, resonant with intra-4f3 transitions, indicate the existence of an energy conversion mechanism of visible di-ureasil emission into near infrared Nd3+ luminescence. The existence of energy transfer between the di-ureasil's emitting centres and the Nd3+ ions is demonstrated calculating the lifetimes of these emitting centres. The efficiency of that energy transfer changes both with the polymer molecular weight and the Nd3+ concentration.