Yb Concentration Research Articles

Synthesis, photoluminescence, and up-conversion luminescence properties of YTiTaO6:Er3+/Yb3+

The relationship between the factors (i.e. the concentrations of Yb3+ and Er3+ and heating temperature in air) and the properties of photoluminescence (PL) and up-conversion luminescence of YTiTaO6:Er3+/Yb3+ whose crystalline phase depended on heating temperature in air was examined using samples synthesized hydrothermally. The intense green emission (: 2H11/2,4S3/2→4I15/2 transitions of Er3+) was obtained by the excitation at 288 ​nm using the indirect energy transfer from the YTiTaO6 host crystal, which was about 1.8 times stronger than that obtained by the direct excitation at 380 ​nm via the f-f transition (: 4I15/2→4G11/2) of Er3+. Aeschynite phase exhibited intermediate luminescence property. The up-conversion emission intensity increased with increasing heating temperature and became the maximum at x ​= ​0.10 and y ​= ​0.20 with euxenite phase, although the co-presence of Yb3+ gave negative effect on the PL intensity of ErxYbyY1-x-yTiTaO6. As heating temperature rose to 1300–1400 ​°C the intensity of the red up-conversion emission (: 4F9/2→4I15/2 transition) became greater than that of the green emission (: 4S3/2→4I15/2 transition), accordingly the position of the color chromaticity coordinates shifted slightly from green to yellow.

Effect of Cr co-doping on the optical absorption and emission characteristics of Yb:YVO4 single crystals grown by OFZ technique

Cr co-doped Yb:YVO4 (Cr:Yb:YVO4) single crystals with concentrations of 1.0 and 1.5 at.% of Cr and 3.0 at.% of Yb were grown by the optical floating zone technique. X-ray diffraction analysis on the grown crystals revealed that the lattice parameters of Cr:Yb:YVO4 crystals do not depend on the Cr doping concentration. The dislocation etch pit density estimated from the etching study was found to be 103/cm2. The observed fringes of nearly uniform thickness and spacing in birefringence interferometry for [100] plate and conoscopy pattern for [001] plate indicate the compositional and optical homogeneity of the crystal. Further, the influence of the Cr doping concentration on the 2A1→2B2 transition (at ∼1100 nm) and 2A1→2E transition (at ∼640 nm) due to Cr5+ ion were analysed using two orthogonal polarized light with electric field perpendicular (π-polarization) and parallel (σ-polarization) to [001] axis. These absorption peaks of Cr ion were found to be sensitive to the polarization of incident light. The absorption transition 2A1→2B2 around 1100 nm are permitted for π-polarization and on the other hand, the absorption transition 2A1→2E at 640 nm are permitted only for σ-polarization. The characteristic broader absorption band around ∼1100 nm is of importance as it is useful for self-Q-switching in a laser gain medium. The absorption coefficient corresponding to Cr5+ ions at 1100 nm increases with the increase in Cr doping concentration. The band-gap for σ-polarized light is slightly higher than π-polarized light and decreases with Cr doping. The increase in the estimated Urbach energy (50–122 meV) with the increase in the Cr doping concentration confirms that the defect states close to the band edge increase thus decrease the band gap. Further the photoluminescence intensity is in-line with the absorption data and decreases with increase in the Cr concentration from 0 to 1.5 at.%.

Up-conversion luminescence performance of Tm3+/Yb3+ co-doped strontium cerate phosphors

Tm3+/Yb3+ co-doped Sr2CeO4 phosphors were fabricated via a high-energy ball milling technique. The structural, morphological, and luminescence characteristics were analyzed by XRD technique, field emission scanning electron microscopy, and up-conversion luminescence spectra, respectively. The structural X-ray diffraction patterns indicate their orthorhombic structure. Under excitation at 975 nm, the up-conversion luminescence spectra of Sr2CeO4:Tm3+/Yb3+ samples with various concentrations of Yb3+ were observed. The phosphor containing 10 mol% Yb3+ ions exhibited optimal up-conversion luminescence. All the samples show emission peaks at 478, 652, and 801 nm, which are assigned to the 1G4 → 3H6, 1G4 → 3F4, and 3H4 → 3H6 transitions of Tm3+. A detailed analysis of the up-conversion mechanisms is proposed based on simplified energy level diagram. The results show that the Sr2CeO4:Tm3+/Yb3+ phosphor has potential application prospects in wide-range and light emitting devices.

Cascaded energy transfer and enhanced near-infrared emission in visible-pumped Cr and Nd co-doped Yb:YAG

In this study, the energy transfer mechanism in Cr,Nd,Yb:YAG (yttrium aluminum garnet) materials was investigated. Based on the emission/excitation spectra and the temporal evolutions of the donor and acceptor ions in Cr,Nd:YAG, Nd,Yb:YAG, and Cr,Nd,Yb:YAG materials, the role of the cascaded Cr3+→Nd3+→Yb3+ energy transfer was elucidated in terms of Yb fluorescence enhancement. The quantum yield balance among Cr, Nd, and Yb fluorescences was determined by solving rate equations, which utilized parameters such as the lifetimes of Cr3+, Nd3+, and Yb3+ ions and the energy transfer parameters related to these materials. The quantum yield for Yb fluorescence was determined to be 35–81% at a Yb concentration of 1–7 at%.

Preparation and systematic spectra analysis of YPO4 crystal co-doped with Er3+ and Yb3+

The Er3+:YPO4 crystals co-doped with different concentrations of Yb3+ (7.5 at.% and 11.5 at.%) were successfully grown by high-temperature solution method with Pb2P2O7 as cosolvent. Crystal growth, structures and spectroscopic characterizations, including polarized absorption spectra, polarized fluorescence spectra and lifetime, were systematically explored and compared. The absorption FWHM at around 975 nm is 17.1 nm for σ-polarizations and 12.0 nm for π-polarizations, which makes Er3+/Yb3+:YPO4 crystal suitable for effective pumping by InGaAs laser diode. Based on J-O theory, the spectroscopic parameters, including J-O intensity, oscillator strength, line strength, fluorescence branching ratios, spontaneous transition rates and radiative lifetime were calculated systematically. Furthermore, four intense emission peaks at around 1505, 1537, 1561 and 1586 nm can be observed in the polarized fluorescence spectra. Theoretically, different frequencies interactions between these wavelengths may be used for the application of generating radiation in the range of 2.9–10.2 THz. The results show that Er3+/Yb3+:YPO4 crystal may be a potential laser material of 1.5–1.6 μm.

Temperature sensing properties of NaYTiO4: Yb/Tm phosphors based on near-infrared up-conversion luminescence

In this study, NaYTiO4: Yb/Tm phosphors with different concentrations of Yb3+ and Tm3+ ions were synthesized by conventional solid-state reaction. Upon a 980 nm laser excitation, the up-conversion luminescence properties in a wide temperature range (303–823 K) were investigated. By employing the fluorescence intensity ratio (FIR) techniques based on the robust near-infrared emissions of thermally coupled 3F2,3/3H4 energy levels and 3H4(1)/3H4(2) Stark energy levels, the calculated absolute sensitivity (Sa), relative sensitivity (Sr), and temperature uncertainty (δT) values demonstrated good temperature sensing properties. For the 3F2,3/3H4 energy levels, the maximum Sr and minimum δT values are 1.04% K−1 and 0.010 K at 463 K, respectively. Moreover, the maximum Sa is 0.32 × 10−3 K−1 at 823 K. In addition, the thermally coupled 3H4 Stark energy levels present the maximum Sa, Sr and the minimum δT are 0.88 × 10−3 K−1, 0.60% K−1 and 3.17 K at 303 K, respectively. Besides, due to the ratio of blue to red emission varying with elevated temperature, the NaYTiO4: Yb/Tm phosphors are expected to be applied as an intuitive high-temperature indicator.

Calculation of Thermal Expansion Coefficient of Rare Earth Zirconate System at High Temperature by First Principles

Compounds of rare earth zirconates with pyrochlore structure are candidates for the application of thermal barrier coatings of next generation. In order to modify the mechanic properties and maintain the low thermal conductivity, other trivalent rare-earth element substitution is commonly used. Presently, investigation on the evaluation of the property of thermal expansion is attracting more attention. In this paper, a feature parameter of thermal expansion coefficient at high temperature (α∞) was proposed by combining Grüneisen’s equation and the Debye heat capacity model. Using α∞ model, the thermal expansion property of different compounds can be easily figured out by first principles. Firstly, α∞ of ZrO2, HfO2, were calculated, and results are in good agreement with the experimental data from the literature. Moreover, α∞ of La2Zr2O7, Pr2Zr2O7, Gd2Zr2O7, and Dy2Zr2O7 were calculated, and results demonstrated that the model of α∞ is a useful tool to predict the thermal expansion coefficient at high temperature. Finally, Gd2Zr2O7 with 4 different Yb dopant concentrations (Gd1-xYbx)2Zr2O7 (x = 0, 0.125, 0.3125, 0.5) were calculated. Comparing with the experimental data from the literature, the calculation results showed the same tendency with the increasing of Yb concentration.

Over 100 mW Stable Low-Noise Single-Frequency Ring-Cavity Fiber Laser Based on a Saturable Absorber of Bi/Er/Yb Co-Doped Silica Fiber

Two kinds of Yb-doped fibers were fabricated, namely, Yb: YAG crystal-derived silica fibers (YCDSFs) with a gain coefficient of 6.0 dB&#x002F;cm, and Bi&#x002F;Er&#x002F;Yb co-doped silica fibers having a Yb concentration of 0.13 <inline-formula><tex-math notation="LaTeX">$ \times $</tex-math></inline-formula> 10²⁶ ions&#x002F;m³. Based on these fibers, a ring-cavity single-frequency fiber laser (SFFL) has been constructed, in which the YCDSF was used as a gain medium and the Bi&#x002F;Er&#x002F;Yb co-doped fiber acted as a saturable absorber. It has been demonstrated that the SFFL had an over 100 mW output at 1030 nm, a slope-efficiency of up to 18.3&#x0025;, and an optical signal-to-noise ratio of over 63 dB. The fluctuation of the output power of the laser was less than 0.65&#x0025; of 103.5 mW within 10 hrs and no mode-hopping was observed for 5 hrs. The SFFL had a linewidth &lt;7.5 kHz at the maximum output power, and the measured relative intensity noise was lower than &#x2212;142 dB&#x002F;Hz at the frequency above 1.0 MHz. The results indicate that the ring-cavity SFFL built could be used as a laser source for applications in high-power fiber laser and high-precision optical fiber sensing and detection.

Yb3+/Er3+ co-doped Gd2Te4O11 nanosheets with intrinsic polarity: One-step hydrothermal synthesis and upconverted optical temperature measuring ability

The digadolinium tellurite phosphors of Gd2Te4O11(GTO):Yb3+/Er3+ have been successfully synthesized as upconversion luminescence (UCL) materials via one-step hydrothermal method. The crystal structure, morphology, and upconversion luminescence property were systematically characterize by XRD, SEM, and spectroscopy techniques. The Rietveld refinements of crystal structure were carried out on the XRD patterns and the feature of crystal structure was analyzed. Under the 980 nm NIR excitation, these materials showed very bright upconverted emissions. The concentrations of Yb3+ and Er3+ were optimized and the strongest upconverted emissions were achieved in the GTO:15%Yb3+/1%Er3+. The possible energy transfer mechanism of UCL was proposed based upon the analysis of power-dependent UCL and fluorescence kinetics. Furthermore, the fluorescence intensity ratio (FIR) derive from the two thermally coupled energy levels (2H11/2 and 4S3/2) of Er3+ was employed as indicator for temperature measurement. The maximum absolute sensitivity can be achieved to be 7.34 × 10−3 K−1 at 501 K. This material exhibited good reliability and repeatability in optical temperature measurement, which could be a novel promising candidate for noncontact temperature sensors.

Structure- and excitation-dependent photoluminescence of As–S:Yb3+ films

In the article, we present and discuss the features of the structure and photoluminescence properties of Yb-doped As–S films synthesized by PECVD employing solid-state initial precursors. The doping was carried out during the deposition process. By controlling the temperature of the precursor sources and the composition of the low-temperature nonequilibrium plasma, we synthesized amorphous As–S:Yb films with Yb content ranging from 0.6 to 8.4 at. %. The change in the ratio of structural elements and surface morphology as a function of the elemental composition is shown. The increase of the Yb content leads to a redshift of the short-wavelength absorption edge. The dependence of the shape and intensity of 2F5/2 → 2F7/2 photoluminescence, observed in the range 930–1030 nm on the excitation wavelength (632.8 nm and 785 nm) and Yb concentration was evaluated. The relation between composition and atomic structure of the amorphous matrix of arsenic sulfide on the photoluminescent properties of Yb3+ ions is discussed.

Texture development and tensile properties of Mg–Yb binary alloys during hot extrusion and subsequent annealing

Ytterbium (Yb) containing magnesium alloys have aroused extensive interest due to their excellent mechanical properties after thermomechanical processing and heat treatment. Unfortunately, the sole effect of Yb addition on the microstructure and mechanical properties of pure Mg matrix remains uncertain to date. In this work, the effects of Yb concentration on the texture development and tensile properties of pure Mg matrix during hot extrusion and the subsequent annealing were systematically investigated. The results revealed that the constitutional supercooling induced by Yb addition refined the as-cast microstructure but exerted a negligible effect on the original columnar grain morphology. When extruded at 300 °C, the dynamic recrystallization (DRX) process was considerably retarded. The in-grain misorientation axes (IGMA) analysis combined with TEM observation indicated that non-basal slips operated with increasing Yb concentration. Specifically, the prismatic <a> slip should be robustly activated in Mg–1.0 Yb extrudate, promoting the formation of the texture with {10–10} plane normal to the extrusion direction (ED), while for the Mg–2.0 Yb counterpart, the increased activity of pyramidal < c + a > slip and the relaxation of basal/< c + a > dislocations generated an ED-tilted texture component. The preferential grain growth dominated the subsequent annealing texture development at 400 °C when a comparable grain size was achieved. An obvious ED-tilted texture intensity with the peak around <–12–13> was observed in Mg–2.0 Yb alloy, which was primarily caused by grains with the basal orientation vanished and with the non-basal orientations intensified due to a higher concentration of Yb solute. Favored by the grain refinement, the Mg–2.0 Yb extrudate exhibited a high tensile yield strength of 304 ± 3.5 MPa, while the subsequently annealed counterpart presented a favorable elongation to failure of 14.8 ± 1.2%, which mainly due to the homogeneous grain structure, weak ED-tilted texture, and dissolution of coarse phases after high-temperature annealing.

Effect of Li+ codoping on the mechanical strength of YB:ZnWO4 single crystals

ZnWO4 single crystals both undoped and doped with various concentrations of Yb3+ and Li+ ions have been grown. The actual concentrations of dopants had been measured by atomic emission spectroscopy with inductively coupled plasma, as well as by polarized optical absorption spectroscopy. The segregation coefficients of the dopants between the crystal and melt have been evaluated. Hardness and fracture toughness of the crystals were measured by indentation method. The dependencies of the measured values on the dopants concentrations were analyzed. The optimal dopants concentrations, providing the best mechanical strength of Yb,Li:ZnWO4 crystal have been found.

Luminescence and scintillation properties of Yb – Codoped GAGG:Ce single crystal

Co-doping is one of the important methods to optimize the performance of scintillation crystal. In this work, GAGG:1.0 at.%Ce,x at.%Yb(x = 0, 0.2, 0.5 and 1.0) crystals were grown by Czochralski method. Relationships between Yb concentration and optical, photoluminescence (PL), scintillation properties of GAGG:Ce,Yb are investigated, including absorption, light output, decay time. Moreover, PL decay curves were measured at various temperatures between 77 and 500 K to investigate the luminescence thermal quenching behavior. The results show that with the increase of Yb3+ concentration, the transmittance of GAGG crystal increases. Decay time is also significantly improved. 1.0 at.%Yb co-doped sample showed the fastest PL decay time of 36 ns among the Yb-co-doped samples. In addition, the impact of Yb on Vickers hardness was also studied.

Absorption properties of bromide photo-thermo-refractive glasses doped with Ytterbium

In this work bromide photo-thermo-refractive glasses with different Ytterbium concentration were explored. It is shown that UV irradiation and subsequent heat treatment of samples with Yb 2 mol.% causes significant red-shift absorption line from 410 nm with temperature lower than Tg to 517 nm with temperature Tg +60 °C. For small concentration of Yb (0,1 mol. %) maximum red-shift in plasmon resonance absorption band is shown as 485 nm and it is the same for heat treatment temperatures from Tg +20 °C to Tg +60 °C.

Effect of Yb concentration on the structural, magnetic and optoelectronic properties of Yb doped ZnO: first principles calculation

Density functional theory-based investigation of the electronic, magnetic, and optical characteristics in pure and ytterbium (Yb) doped ZnO has been carried out by the plane-wave pseudopotential technique with generalized gradient approximation. The calculated lattice parameters and band gap of pure ZnO are in good agreement with the experimental results. The energy band gap decreases with increasing Yb concentration. The Fermi level moves upward into the conduction band after doping with Yb, which shows the properties of an n-type semiconductor. New defects were created in the band-gap near the conduction band attributed to the Yb-4f states. The magnetic properties of ZnO were found to be affected by Yb doping; ferromagnetic property was observed for 4.17% Yb due to spin polarization of Yb-4f electrons. The calculated optical properties imply that Yb doped causes a blue shift of the absorption peaks, significantly enhances the absorption of the visible light, and the blue shift of the reflectivity spectrum was observed. Besides, a better transmittance of approximately 88% was observed for 4.17% Yb doped ZnO system. The refractive index and the extinction coefficient were observed to decrease as the Yb dopant concentration increased. As a result, we believe that our findings will be useful in understanding the doping impact in ZnO and will motivate further theoretical research.

Laser cooling of a Yb doped silica fiber by 18 Kelvin from room temperature.

An ytterbium doped silica optical fiber with a core diameter of 900µm has been cooled by 18.4 K below ambient temperature by pumping with 20 W of 1035 nm light in vacuum. In air, cooling by 3.6 K below ambient was observed with the same 20 W pump. The temperatures were measured with a thermal imaging camera and differential luminescence thermometry. The cooling efficiency is calculated to be 1.2±0.1%. The core of the fiber was codoped with Al3+ for an Al to Yb ratio of 6:1, to allow for a larger Yb concentration and enhanced laser cooling.

Effective sensitization of Yb3+ ions on Yb3+/Nd3+ co-doped fluoroborate glasses for NIR luminescence applications

Nd3+/Yb3+ co-doped fluoroborate glass samples were fabricated by melt quenching. The near infrared luminescence (NIR) spectral features of Nd3+/Yb3+ co-doped fluoroborate glasses were characterized by XRD, SEM, FT-IR, optical absorption, photoluminescence (PL) and PL decay spectral studies. An effective energy transfer process has been observed from Nd3+ to Yb3+ in the titled glasses under 808 nm excitation wavelength. Broad emission ranging from 850 to 1400 nm due to both Nd3+ (4F3/2→4I9/2, 4F3/2→4I11/2 and 4F3/2→ 4I13/2) and Yb3+ (2F5/2→2F7/2) transitions has been observed in all the glasses. The dependence of NIR emission, decay lifetime, and the energy transfer efficiency (ηETE) with the concentration of Yb3+ was studied in detailed. The PL spectra along with donor decay curves have been used to establish the energy transfer mechanism between Nd3+/Yb3+ ions. The results represent the possible sensitization of Yb3+ through 4f-4f transition of Nd3+ ions in titled glasses. The PL of the Nd3+ singly doped and Nd3+/Yb3+ co-doped titled glasses indicate their suitability as multiple pump channel sources for Yb3+ fiber laser systems. The results finally prove that the Nd3+/Yb3+ co-doped fluoroborate titled glasses are quite useful to fabricate infrared laser gain materials.

Nano Silica application for inducing rice resistance and the possibility for Ytterbium Rare Earth Elements green mining

There is a growing interest and recognition of Silicon (Si) in plants to increase growth, productivity, and plant resistance. This research examines the role of Nano Silica to increase yield and resistance. This study set out to assess the effect of hydrophilic fumed Nano Silica application with the frequency of 1×, 2×, 3×, and 4× applications respectively with three replications using RCBD as well as SEM-EDX and XRF analysis. Nano Silica frequencies showed a distinctive decrease of damage intensity at the 3× and 4× applications. The rice husk increases of metal-like surface appearance as more Nano Silica frequency was applied. It is proposed that Nano Si induced plant resistance through the modification of surface layer and stronger plant tolerance against environmental stress. The most unexpected observation to emerge was the Ytterbium (Yb) concentration known as a Rare Earth Elements at the 3× and 4× Nano Si applications. This indicates that Nano Silica application provides insights and opportunities to Nano Si application on Rice for the purpose of acquiring Ytterbium from farmland. Nano Silica can play an important role as a new method in addressing the Ytterbium green mining.

Compact Single-Frequency MOPA Using a Silica Fiber Highly Doped with Yb3+

We report on a single-frequency fiber master oscillator power amplifier utilizing a polarization-maintaining step-index fiber with an Al/Ce/F core-glass composition doped with a very high Yb concentration (0.25 at.%). This design made it possible to use a very short fiber (~1 m) and to coil it in a tight radius (4 cm in the amplifier, while 2 cm gave similarly negligible bending loss) so that the packaged system is one of the most compact reported to date (~0.6 L). The use of a short fiber increased the threshold for stimulated Brillouin scattering well above 100 W while maintaining near-ideal beam quality. The fiber was pumped with a diode-pumped solid-state laser and cooled passively by spooling it on a grooved aluminum mandrel. The amplifier produced a strongly linearly polarized output at 1064 nm in the fundamental mode (M2 ≤ 1.2) with a 150 kHz linewidth and a power of 81.5 W for 107 W of launched pump power. No deleterious effects from the elevated thermal load were observed. The residual photodarkening loss resulting from the high Yb concentration, found to be small (~0.7 dB/m inferred at 1064 nm) with accelerated aging, reduced the output power by only ~20% after 150 h of operation.

Down conversion studies in Ce3+ and Yb3+ doped Ca2SiO4 phosphors from agricultural waste: Si based solar cell applications

Ca2SiO4 phosphors activated with Ce3+/Yb3+ ions were prepared by the solid-state reaction method by extracting the raw materials from the agricultural waste of egg shells and rice husk. The XRD spectra reveal that the prepared phosphors have monoclinic structure. The introduction of Yb3+ ions led to decrease in intensities of Ce3+ ions at 381 nm. Conversely, the NIR emission intensity of Yb3+ ion at 980 nm is found to increased up to 0.5 mol % of Yb3+ ions and then decreases. The results indicate that there would be co-operative energy transfer between Ce3+ and Yb3+ ions. The lifetime is found to decrease from 12 to 6 μs when the concentration of Yb3+ is increased from 0.1 to 2.0 mol %. The results indicate that the Ce3+ and Yb3+ co-doped Ca2SiO4 phosphors could be useful for spectral down-conversion applications.