Transitions Of Nd3 Research Articles

High-Pressure Behavior of NdF3: Structural and Photoluminescence Properties

Abstract This paper investigates the pressure-induced photoluminescence properties and structural phase transitions of functional material NdF3 at room temperature using diamond anvil cell (DAC), in-situ photoluminescence technology, and simulation calculations. Under hydrostatic experimental pressure and simulated pressure up to 20 GPa, the photoluminescence spectra, lattice parameters, and bond lengths of NdF3 were obtained, showing their variations with pressure. Experimental results show that a new emission line, corresponding to the 4F3/2→4I9/2 transition of Nd3+ ions, appears around 12 GPa and persists up to the highest pressure of the experiment. Upon decompression, the new emission line disappears, indicating a reversible phase transition. Notably, from 0 to 12 GPa, the emission intensity of NdF3 decreases significantly under pressure, which may be attributed to the increased energy of lattice phonons in the compressed crystal (shorter Nd-F bonds), leading to enhanced phonon-assisted non-radiative relaxation.

Spectroscopic analysis of CaGd2(WO4)4 phosphor doped with Nd3+ and Yb3+ for NIR applications

Considering the important applications of near infrared light sources, phosphors emitting in this region are always explored. New hosts are studied for this purpose. Keeping with this tradition we have investigated CaGd2(WO4)4 host by using SSR method. XRD pattern of the as prepared compound confirms the monoclinic crystal structure with I2/b space group. Well known lanthanide activators Nd3+ and Yb3+ led to the desired infrared emission. Nd3+ yielded emission by itself under f-f excitation while Yb3+ depended upon the energy transfer from Nd3+ and to yield near infrared light. The host also provided sensitization. However this is very weak compared to the intensities of the f-f transitions of Nd3+. PL and PLE spectra as well as the mechanism of energy transfer is explained on the basis of the known energy level diagrams. Prepared phosphor have potential application in the field of Solid State Laser and bio-imaging.

Temperature sensing by means of a near-infrared luminescent Ca8NaBi(PO4)6F2:Nd3+ fluorapatite phosphor

Microrods of calcium sodium bismuth fluorapatite doped with neodymium, denoted as Ca8NaBi1-xNdx(PO4)6F2 (with x ranging from 0 to 0.5), were synthetized using a modified Pechini sol–gel method. The crystalline structure of these phosphors was refined using the Rietveld method and exhibited hexagonal symmetry with space group P63/m—C26h, where the lattice parameters were a = 9.3855(5) Å and c = 6.8998(6) Å for x = 0.2. The particles morphology was analyzed through SEM, revealing an average length of approximately 1.5 µm. When excited at 808 nm, the Ca8NaBi(PO4)6F2:0.2Nd3+ microrods emitted strongly at 872, 957 and 1055 nm, falling within the near-infrared region. These emissions correspond to the 4F3/2 → 4I9/2 (P2), 4F5/2 → 4I11/2(P3), 4F3/2 → 4I11/2(P1) transitions of Nd3+ ions, respectively, and are situated within the first and second biological windows. The luminescence lifetime of the 4F3/2 state of Nd3+ was measured to be 294.4 µs for the sample with the lowest Nd3+ concentration of x = 0.05. In addition, the luminescence intensity ratios P2/P1 and P3/P1 were found to be temperature dependent, potentially making it suitable for luminescent ratiometric thermal sensing. These findings suggest that the synthesized Ca8NaBi(PO4)6F2:Nd3+ microrod thermometers exhibit favorable characteristics in terms of relative sensitivity, temperature uncertainty, and repeatability within the temperature range of 303–403 K.

Synthesis, optical and magnetic properties of Nd2O3/borate strontium fluoride glasses

The present work conducts the synthesis, thermal, optical, and magnetic characterization of (60-x)B2O3+20Li2O+20SrF2+ x Nd2O3 where x = 0, 0.5, 1, 1.5, 2 mol% glass samples. The samples were investigated via X-ray diffraction (XRD), Raman spectroscopy, differential scanning calorimetry (DSC), UV–Vis absorption spectroscopy, and vibrating sample magnetometry (VSM). XRD patterns for borate strontium fluoride glass samples doped with Nd2O3 showed broad humps around 30 and 43°, indicating their amorphous structure. Raman spectra of glass samples indicated that as Nd3+ ions were added to the host matrix, there was an increase in Raman intensity due to bond breakdown and the development of more non-bridging oxygen (NBO) species. The DSC data of the borate strontium fluoride glass samples doped with Nd2O3 demonstrated that the glass transition temperature (Tg) generally increased. UV–Vis absorption spectra showed transitions in Nd3+ ions doped borate glasses that are associated with the bands at different wavelengths, attributed to 4G5/2+2G7/2, 2H11/2, 4F9/2, 2H9/2 +4F5/2, and 4F3/2. The refractive index of borate strontium fluoride glass samples doped with Nd2O3 increased. The saturation magnetization values decreased from 0.9 to 0.29 upon increasing the Nd2O3 percentage (0–2 mol%). These low saturation magnetization glass samples can be used in spintronic devices to effectively reduce switching current density and lower the damping constant.

Development of Nd-doped CsI single crystal scintillators emitting near-infrared light

0.05, 0.1, 0.5, and 1% Nd-doped CsI single crystals were synthesized by the vertical Bridgman-Stockbarger method, and the photoluminescence and scintillation properties were evaluated. Under X-ray irradiation, two emission peaks were observed at 310 and 430 nm ascribed to on- and off-center configuration self-trapped excitons, respectively. In near-infrared regions, sharp peaks were observed at 900, 1080, and 1350 nm due to 4F3/2-4I9/2, 4F3/2-4I11/2, and 4F3/2-4I13/2 transitions of Nd3+, respectively. Dose rate response functions had good linearity in the range of 0.06–6 Gy/h in all the samples, and the 0.5% Nd-doped sample showed the highest intensity among all the samples.

Compact continuous-wave solid-state Raman lasers at 707 and 714 nm for laser trapping and cooling of atomic strontium and radium.

Two compact laser sources at 707 and 714 nm are realized efficiently by using a diode-pumped a-cut Nd:YVO4 laser with intracavity stimulated Raman scattering and sum-frequency generation (SFG). The fundamental wave at 1342 nm is generated by the 4F3/2 → 4I13/2 transition in Nd:YVO4 crystal. The Raman Stokes waves at 1496 and 1526 nm were obtained by placing the c-axis of the Nd:YVO4 crystal along the Ng and Nm axes of an Np-cut KGW crystal, respectively. LBO crystals with critical phase matching are used to perform the intracavity SFG of fundamental and Stokes waves. At a pump power of 36 W, the maximum output powers at 707 and 714 nm can reach 2.72 and 3.14 W, corresponding to light-to-light conversion efficiencies of 7.5% and 8.7%, respectively. The developed 707 and 714 nm laser sources are practically useful in laser trapping and cooling related to atomic strontium and radium.

One-dimensional LaF3:RE3+ (RE=Eu, Nd) nanostructured phosphors: Controllable synthesis and luminescence properties

A novel and universal method combining electrospinning with a twi-crucible fluorinating technology was utilized to fabricate one-dimensional LaF3:RE3+ (RE = Eu, Nd) nanostructured phosphors. A series of nanofibrous/nanoribbon-shaped LaF3:RE3+ (RE = Eu, Nd) phosphors were devised and facilely fabricated through the calcination of the relevant nanofibrous/nanoribbon-shaped La2O3:RE3+ (RE = Eu, Nd) precursors in air by applying a twi-crucible fluorinating method utilizing NH4HF2 as a fluorine source without additional usage of reducing gas and protective gas. Nanofibrous/nanoribbon-shaped La2O3:RE3+ (RE = Eu, Nd) precursors were synthesized by calcinating the electrospun nanofibrous/nanoribbon-shaped [RE(NO3)3+La(NO3)3]/polyvinyl pyrrolidone (PVP) composites. Nanofibrous/nanoribbon-shaped LaF3:RE3+ (RE = Eu, Nd) phosphors possess hexagonal structures with a space group of P63/mmc. Nanofibrous LaF3:RE3+ (RE = Eu, Nd) phosphors present excellent fibrous morphology with a uniform diameter of 131–143 nm. Nanoribbon-shaped LaF3:Eu3+ phosphors with 94.5 nm in thickness and 5.1 ± 0.4 μm in width were acquired. Nanoribbon-shaped LaF3:Nd3+ phosphors have a thickness of 179 nm and a width of 4.2 ± 0.4 μm. Upon excitation by ultraviolet light at 396 nm, nanofibrous/nanoribbon-shaped LaF3:Eu3+ phosphors emit the main emission band at approximately 591 nm, corresponding to the 5D0→7F1 magnetic dipole transition of Eu3+. With an increment of Eu3+ concentration, the fluorescent strength of nanofibrous LaF3:Eu3+ phosphors is improved greatly and achieves a maximum when the Eu3+ concentration is approximately 5 mol%. Moreover, the nanofiber/nanoribbon-shaped LaF3:Eu3+ phosphors emit a yellow color. For Nd3+-doped phosphors, nanofibrous/nanoribbon-shaped LaF3:Nd3+ phosphors possess near-infrared optical performances, and the main emission peak is at 854 nm, corresponding to the 4F3/2 → 4I9/2 transition of Nd3+. The luminescence intensity of LaF3:Nd3+ phosphors decreases significantly with increasing Nd3+ content and reaches a maximum at 5 mol% Nd3+. The corresponding formative mechanisms of nanofibrous/nanoribbon-shaped RE3+ (RE = Eu, Nd) phosphors are expounded, and the corresponding construction technique is established. The new findings in this work lay a foundation for wide applications of rare earth fluoride one-dimensional nanostructures.

Enhancing of 4F3/2 → 4I9/2 transition of Nd3+ doped BaO-Ga2O3– Al2O3–B2O3 glasses for near-infrared laser applications

Neodymium, Barium Gallium Aluminium Borate glasses having the composition of [35% B2O3 + 35% BaO + 15% Ga2O3 + (15-x)% Al2O3 + x% Nd2O3, (x = 0, 0.5, 1 and 2%)] were prepared using traditional melt quenching method. Physical properties such as refractive index (n), molar volume (VM), density (ρ), band-gap (Eg), and Urbach energy (ΔE) were measured and calculated. The results revealed that our glass has allowed indirect band-gap transitions and the addition of Nd3+ reduced the Eg energies from 3.24 to 3.01 eV. The Judd-Ofelt parameters were obtained using the least-square technique and they were used to compute the total radiative probability (At), radiative lifetime (τr), fluorescence branching ratio (Br), and quantum efficiency (η) for the meta-stable level 4F3/2. The glass system showed a high Spectroscopic factor (χ) ranging from 1.61 to 1.98. The Br showed that the 4F3/2 → 4I9/2 transition (883 nm) was enhanced at the expense of the 4F3/2 → 4I11/2 transition (1064 nm) and (4F3/2 → 4I13/2) transition (1342 nm). A relatively high quantum efficiency (η = 0.78) was noticed for our glass. Generally the spectroscopic properties and gain factor (γ) showed that the present glass system is a promising candidate for near-infrared laser applications (883 nm).

Spectral studies of Nd3+ doped different fluorophosphate glasses for their aptness in laser applications at 1060 nm

Neodymium doped fluorophosphate (FP:Nd3+) glasses with different chemical compositions (59NH4H2PO4+15ZnO +15BaF2+10X+1·0NdF3 (X=LiF, NaF, CaF2, SrF2, AlF3)) were prepared by melt quenching. Their structures and spectroscopic properties were studied using x-ray diffraction, FTIR, FT-Raman and 31P, 27Al MAS NMR techniques. Various structural groups were identified using FTIR and FT-Raman spectra. The depolymerisation of metaphosphate chains are described by the decrease of Q2 tetrahedral sites allowing the formation of pyrophosphate groups revealed by 31P MAS NMR spectroscopic studies. Optical properties were studied using absorption and photoluminescence spectroscopy. Judd–Ofelt intensity parameters Ωλ (λ=2, 4 and 6) were estimated from absorption spectra. Radiative parameters such as transition probabilities (A), radiative lifetimes (τR), integrated absorption cross-sections (Σ) and branching ratios (βR) were calculated. Two emission lines at 1060 and 1330 nm were observed for Nd3+ in all the fluorophosphate glasses. From the emission spectra, emission characteristics were studied via optical band gains (σe×τR) and gain bandwidths (σe×Δλeff). Fairly large numerical values for peak emission cross-sections (σe) and branching ratios (β) for 4F3/2Æ4I11/2 transition of Nd3+ ion doped calcium fluorophosphate glass were observed. These results are rosy for NIR laser application at 1060 nm.

Nd-doped NASICON-type nanophosphors for near-infrared excitation and emission

ABSTRACT Neodymium-doped phosphates, (Nd1-x Gd x )0.33Zr2(PO4)3 (0 ≤ x ≤ 1), were synthesized by co-precipitation. (Nd1-x Gd x )0.33Zr2(PO4)3 was obtained as a single-phase and was confirmed to be a NASICON-type structure consisting of a three-dimensional network of PO4 tetrahedra sharing corners with ZrO6 octahedra. The particle size of the (Nd1-x Gd x )0.33Zr2(PO4)3 samples was in the nanoscale, which is suitable for in vivo optical imaging. The (Nd1-x Gd x )0.33Zr2(PO4)3 samples showed characteristic luminescence corresponding to the f – f transitions of Nd3+. The highest emission intensity at 1072 nm with excitation at 824 nm was observed for (Nd0.75Gd0.25)0.33Zr2(PO4)3, which was 4.5 times higher than that of Nd0.33Zr2(PO4)3. The near-infrared (NIR) emission intensity of this nanophosphor was significantly higher than that of indocyanine green, which is actually used as an in vivo optical probe reagent.

NIR emissions from Nd3+-activated phosphate-based glass system for cost-effective, tunable, and miniaturised laser devices

This work represents a phosphate-based glass system of composition (40-x) P2O5 − 30 B2O3 − 30 ZnSO4 - x Nd2O3, ( × = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) to determine the optical absorption and emission spectral characteristics. Moreover, Judd-Ofelt (J-O) intensity and radiative parameters were computed. Samples were prepared using melt-quenching method and characterized using Archimedes measurement, Ultraviolet–Visible-Near Infrared Spectroscopy and Photoluminescence Spectroscopy. The density values of these samples were reduced as the Nd2O3 concentration increased. The absorption spectra revealed 11 peaks corresponded to Nd3+ transitions from the lowest electronic energy level (4I9/2) to various excited levels. The optical energy band gap was found to be reduced with Nd3+ doping. The refractive indices (n) increased as the Nd3+ increase. The improving tendency of n was clarified in terms of the enhancing trend of samples molar volume (obtained from density), indicating a structural-optical correlation in the proposed glass system. The obtained values of Urbach energy (Eu) have an increasing trend in the range of ∼ 0.318–0.711 eV. Tow significant NIR emission peaks were assigned to the 4F5/2 → 4I9/2 and 4F3/2 → 4I9/2 transitions of Nd3+. Values of J-O intensity parameters Ω2, Ω4 and Ω6 were found in the range of (1.63–2.25)× 10−19 cm2, (2.57–2.94)× 10−19 cm2 and (1.53–1.82)× 10−19 cm2, respectively. The obtained stimulated emission cross-section for the NIR transitions from Nd3+ ((23.83–26.64)× 10−20 cm2 for 4F5/2 → 4I9/2, and (10.93–17.91)× 10−20 cm2 for 4F3/2 → 4I9/2 obviously revealed the lasing effectiveness of the titled glass system.

Effect of Nd3+ Doping on Structural, Near-Infrared, and Cathodoluminescent Properties for Cadmium Tantalate Phosphors

Cd1-xTa2O6:xNd3+ (x=0.5, 1.5, 3, 5, 7, and 10 mol%) phosphor series were fabricated by conventional solid state method at 1100 °C for 17 hours. The samples of cadmium tantalate were investigated by structural (XRD, SEM) and spectroscopic (CL, PL) analyses. In XRD results, the symmetry of CdTa2O6 phase with orthorhombic columbite structure was confirmed between 0.5 and 10 mol% Nd3+ doping concentrations. SEM analysis of the grains revealed round and shapeless morphology while grain sizes ranged from submicron to several microns. The emission spectra of Cd1-xTa2O6:xNd3+ (x=0.5, 1.5, 3, 5, 7 and 10 mol%) phosphor series recorded with the transitions of 4F3/2→4I9/2 and 4F3/2→4I11/2. Among these transitions, the transition 4F3/2→4I9/2 (at 889 nm) has a high near-infrared emission intensity, which can be attributed to the laser potential of the phosphor. The NIR emission of the phosphor increased with increasing concentration of Nd3+ up to 5 mol% and then declined because of concentration quenching phenomenon. The CL emission peak at about 450 nm found in all samples is related to the intrinsic emission of the cadmium tantalate host. In addition, Nd3+ doped phosphors exhibited the 4F3/2→4I9/2 transition of Nd3+ and defect-related CL emissions at 670 nm. Decreasing crystallinity with increasing Nd3+ concentration caused a decrease in host emission intensity at 450 nm.

Stoichiometry, Orbital Configuration, and Metal-to-Insulator Transition in Nd0.8Sr0.2NiO3 Films

The discovery of superconductivity in the infinite-layer nickelate Nd0.8Sr0.2NiO2 has motivated tremendous efforts for its significance toward the understanding of high-temperature superconductivity. However, the synthesis of infinite-layer nickelates is instable and has become a hindrance to experimental progress. Optimizing the growth of precursor Nd0.8Sr0.2NiO3 by pulsed laser deposition is crucial for obtaining infinite-layer nickelates. By systematically investigating the growth of Nd0.8Sr0.2NiO3 with wide range of conditions, we found that the laser fluence plays a critical role in determining the stoichiometry, lattice structure, and electronic properties. A higher Ni deficiency and larger c-axis lattice constant appeared with the lower laser fluence. At 0.6 J/cm2, the Ni deficiency is as large as 25%. According to X-ray absorption spectra and X-ray linear dichroism, we further find that (i) there are no obvious changes of the Ni valence and (ii) the energy level of the dx2-y2 orbital gradually increases relative to the d3z2-r2 orbital with increasing Ni deficiency. What is more, the onset temperature and magnitude of the resistivity change at the metal-to-insulator transitions (MITs) also are found to decrease with increasing laser fluence during the growth.

Photoluminescence study of rare earth ions doped Sr2CeO4 phosphor prepared via conventional solid-state reaction method

The lanthanide ions either in their divalent or trivalent charge state form a very important class of luminescence activators in phosphors and single crystals. Doping these lanthanide ions in different host lattices are widely utilized in many areas for example the 5d-4f emission of Ce3+ used in scintillators for γ-ray detection, cathode ray tubes and electroluminescence phosphors. The photon cascade emission from 4f2 levels of Pr3+ used for developing high quantum efficiency phosphors excited by means of a Xe discharge in the vacuum-UV. The narrow line 4f3 transition in Nd3+ is used in laser crystals. The Sm3+ emission used as an electron trap and in information storage properties like optical memory applications, X-ray imaging phosphor applications. The famous 5D0-7Fj 4f6 redline emission of Eu3+ and the blue to red 5d-4f emission of Eu2+ are used in display and lighting phosphors. The 4f8 line emission of Tb3+ is used in tricolor tube lighting. The Dy3+ emission plays an important role in the persistent luminescence phosphors. Er3+, Tm3+ used to investigate for possible photon cascade emission phosphor applications. This is brief and still incomplete summary illustrates the diversity of applications involving the luminescence of lanthanide ions.

About spectroscopy of CeF3:Nd3+ crystal and the first laser experiments with diode pumping

The CeF3 crystal samples activated by neodymium ions were grown by the Bridgman method and studied under diode pumping. Spectroscopic studies were carried out for calculations of the lasing threshold, because some data for these calculations were not available in the literature or are not quite correct. As a result, the spectroscopic data on the CeF3:Nd3+ crystal available in the literature have been supplemented and corrected. It has been determined that concentration quenching occurs at concentrations not higher than 1.5%. Based on the obtained data, the threshold of oscillations at the 4F3/2 → 4I11/2 transition of Nd3+ ions was estimated to be about 2.3 mJ. In the first experiments with diode pumping, lasing was obtained at a wavelength of 1064 nm on the CeF3:Nd3+ crystal with a slope efficiency of 25%. The obtained experimental results agree with the theoretical estimate of the lasing threshold.

Enhancement of the NIR Emission of Cr3+-Yb3+ Co-doped La3GaGe5O16 Phosphors by Doping Nd3+ Ions via Efficient Energy Transfer for NIR Spectroscopy Regulation.

The efficient energy transfer in La3GaGe5O16:Cr3+, Yb3+/Nd3+ and La3GaGe5O16:Cr3+, Yb3+, Nd3+ was investigated in detail. In this phosphor, Cr3+ acts as the energy absorber (250-700 nm) to sensitize Yb3+/Nd3+ in La3GaGe5O16. Under excitation at 418 nm, La3GaGe5O16:Cr3+, Yb3+ phosphors exhibited a broad emission band in the near-infrared (NIR) region located at 976 nm (La3GaGe5O16:Cr3+, Nd3+ at 1056 nm), which was attributed to the 2F5/2-2F7/2 transition of the Yb3+ ions (2F3/2 → 4I11/2 transition of Nd3+). Moreover, a Nd3+ ion was introduced into La3GaGe5O16:Cr3+, Yb3+. The analysis of excitation spectra and decay time proves that Nd3+ acts as a bridging ion in the system. This can be used as a new strategy to enhance the energy transfer in Cr3+, Yb3+ co-doped phosphors, and these phosphors have potential applications in NIR spectroscopy regulation.

Tailoring synthesis conditions for [(Ba0.85Ca0.15)0.995Nd0.005](Ti0.9Hf0.1)O3 nanopowders by hydrothermal method and their luminescence properties

Synthesis conditions for preparing [(Ba0.85Ca0.15)0.995Nd0.005](Ti0.9Hf0.1)O3 (Nd-BCTH) nanopowders by hydrothermal method were tailored using orthogonal experiment method with three factors and three levels. X-ray diffraction measurement, field emission scanning electron microscopy, transmission electron microscopy, surface aperture adsorption analyzer, ultraviolet–visible spectra, and fluorescence spectrophotometer were used to characterized the synthesized nanopowders. Well dispersed Nd-BCTH nanopowders with excellent crystallization and luminescence properties are obtained at reaction temperature of 200 °C, 14 mol⋅L−1 alkali concentration, and 24 h reaction time without adding surfactant. The nanopowders present a pure pseudo-cubic perovskite structure with rhombohedral phase approaching the morphotropic phase boundary (MPB) at room temperature, which present nano-sized particles with slight conglomeration. Using 267 nm light exciting, strong photoluminescent emission peaks are excited at 364 nm, 422 nm and 440 nm in the Nd-BCTH nanopowders, which correlate with the transitions of Nd3+ from 4D3/2 → 4I9/2, 2D5/2 → 4I9/2 and 4G11/2 → 4I9/2 via two processes of non-radiative relaxation and fluorescent transition, respectively. The CIE1931 chromaticity calculation of the emission peaks and fluorescent photograph show that the Nd-BCTH nanopowders emit indigo blue fluorescent light.

Nd2Sn2O7/Bi2Sn2O7/Ag3PO4 double Z-type heterojunction for antibiotic photodegradation under visible light irradiation: Mechanism, optimization and pathways

A novel visible light response Nd2Sn2O7/Bi2Sn2O7/Ag3PO4 (NSO/BSO/APO) composite photocatalyst with double Z-type heterojunction was successfully synthesized by a one-pot hydrothermal-precipitation method. The addition ratios of Nd2Sn2O7(NSO) and Ag3PO4(APO) during composite photocatalyst preparation were optimized, and the photocatalytic reaction conditions included tetracycline hydrochloride (TC) concentration, catalyst dosage, and initial pH of the solution were screened. The maximum degradation rate of 15 mg/L TC (pH = 8) reached 97.10% exposed to visible light in 120 min by NSO/BSO/APO-30 photocatalyst (dosage: 0.4 g/L), its kinetic constant is about 9.78 times that pure Bi2Sn2O7 (BSO). The morphology, composition, and optical properties of the catalysts were characterized. The f-f transition of Nd3+ in NSO improves the absorption ability of the catalyst to visible light. In addition, h+, O2− and OH participated in the photodegradation of TC in NSO/BSO/APO-30 system. The fitting of the Mott-Schottky curve and Tauc-plot curves confirmed the rationality of the double Z-type electron transfer mechanism. The EIS and PL tests show that the NSO/BSO/APO-30 composite catalyst had the lowest charge transfer resistance and the lowest carrier recombination rate. In addition, three possible degradation pathways of TC during the photodegradation by NSO/BSO/APO-30 were analyzed by High-resolution mass spectrometry (APCI-MS).

High-sensitive temperature sensing based on thermal-enhanced emission and non-thermally coupled energy levels of white upconversion luminescence system

Na3Y(VO4)2:Nd3+,Yb3+,Ho3+,Tm3+ phosphors present significantly improved sensitivity of optical temperature sensing based on thermal-enhanced upconversion luminescence and non-thermally coupled energy levels. Under 808 nm excitation, white upconversion luminescence is successfully achieved in Nd3+-sensitized system. In addition, the emissions intensities originated from 4G5/2→4I9/2 transition of Nd3+ and 3F2,3→3H6 transition of Tm3+ gradually increase with elevating temperature owning to the thermal population effects, as opposed to the blue (1G4→3H6 transition of Tm3+), green (5S2,5F4→5I8 transition of Ho3+) and red (5F5→5I8 transition of Ho3+) emissions intensities show continuous decreasing trend. The temperature sensing behaviors are investigated by employing multiple non-thermally coupled energy levels. Based on non-thermally coupled energy levels of 4G5/2 (Nd3+)/1G4 (Tm3+), the absolute and relative sensitivities are obtained to be 0.433 K−1 and 2.81 % K−1. These results demonstrate that the Na3Y(VO4)2:Nd3+,Yb3+,Ho3+,Tm3+ phosphors with superior optical thermometry performance and white luminescence within a relatively wide temperature range can achieve optical applications in many fields.

Triple-Wavelength Lasing with a Stabilized β-LaBSiO5:Nd3+ Crystal.

Multi-wavelength lasers, especially the triple-wavelength laser around 1060 nm, could be produced by the 4F3/2 → 4I11/2 transition of Nd3+ and present numerous challenges and opportunities in the field of optoelectronics. The Nd3+-doped high-temperature phase of LaBSiO5 (β-LBSO) is an ideal crystal to produce triple-wavelength lasers; however, the crystal growth is challenging because of the phase transition from β-LBSO to low-temperature phase (α-LBSO) at 162 °C. This phase transition is successfully suppressed when the doping content of Nd3+ is larger than 6.3 at. %, and the Nd3+-doped β-LBSO is stable at room temperature. The local disorder of BO4 tetrahedra due to Nd3+ doping is essential to the stabilization of β-LBSO. For the first time, the β-LBSO:8%Nd3+ crystal with a dimension of 1.8 × 1.8 × 1.8 cm3 is obtained through the top-seeded solution method. The crystal shows strong optical absorption in the range of 785-815 nm, matching well with the commercial laser diode pumping source. The optical emission of 4F3/2 → 4I11/2 splits into four peaks with the highest optical emission cross section of 2.14 × 10-20 cm2 at 1068 nm. The continuous-wave triple-wavelength generation of coherent light at 1047, 1071, and 1092 nm is achieved with the highest output power of 235 mW and efficiency of 12.1%.