Concentration Of Nd Research Articles

Spectroscopic properties and energy transfer study of Nd3+/Yb3+ co-doped in borosilicate glass for 1.0 μm emission

The Nd3+/Yb3+ co-doped borosilicate glasses are fabricated by using a conventional melt quenching technique in air atmosphere. The Spectroscopic properties of 1.0μm emission in Nd3+/Yb3+ co-doped borosilicate glasses are investigated under 808nm excitation. The luminescence decay curves show a nonexponential character, the energy transfer microscopic parameters and transfer efficiencies are calculated. Results indicate that the energy transfer takes place via nonradiative electric dipole–dipole processes and is enhanced with the concentration of Nd3+ donor ions. The glass co-doped with 0.5mol% Nd2O3 and 2mol% Yb2O3 has a large microscopic parameters 100×10−40cm6s−1, high transfer efficiencies 73.58% and long fluorescence lifetime 0.3ms at 1020nm, which is of great potential as a candidate material in the development of multiple-pump-channel Yb3+ fiber lasers.

Spectroscopic investigation of Nd3+ doped zinc phosphate glasses for NIR emission at 1.05 μm

Nd3+ doped lead free zinc phosphate glasses have been prepared by melt quenching technique. The functional groups have been assigned and clearly elucidated by FTIR spectra for all these glass samples. J-O parameters have been obtained from the spectral intensities of different absorption bands of Nd3+ ions. The radiative properties such as AR, τR, βR and Σ for different excited states are calculated by using J-O parameters. NIR luminescence spectra exhibit three emission bands for all the concentrations of Nd3+ ions. These glasses can be suggested as suitable host to produce efficient lasing action in NIR region at 1.05 μm.

Direct Imaging of the Distribution of Nd3+ Ions in Glasses Containing PbS Quantum Dots

The influence of Nd3+ ions was investigated on the precipitation and optical properties of PbS quantum dots (QDs) inside silicate glasses. The diameters of the PbS QDs decreased as the concentration of Nd3+ in the glass increased as evidenced by blue shifts in the absorption and photoluminescence spectra. Electron energy loss spectroscopy shows that Nd3+ ions exist preferentially inside the PbS nanocrystals rather than in the glass matrix. We postulate that Nd–O clusters are preserved during heat treatment and serve as nucleation sites for PbS crystals. No change in the local bonding scheme of the Nd3+ ions was observed following heat treatment.

Synthesis and spectral characterization of yttrium oxide nano-powders doped with Nd3+ ions with a large range of concentrations

The introduction of Nd3+ dopants in yttrium oxide nano-powders at concentrations as high as 10% has motivated the study of their emission as function of concentration. We have studied the luminescence of these systems as function of temperature, particle size, and concentration of Nd3+ and we report on the trends that we have been able to establish.

Fabrication of V2O5super long nanobelts: optical, in situ electrical and field emission properties

A low turn-on field of 1.4 V μm−1, carrier concentrations ofNd= 1.48 × 1018cm−3and electron mobility of 1.26 cm2V−1s−1were obtained for V2O5super long nanobelts.

Nd3+ dopant influence on the structural and spectroscopic properties of microcrystalline La2Mo2O9 molybdate

In this paper we report the detailed analysis of both structural characterization by XRD, DSC, Raman, SEM techniques and high resolution spectroscopic properties of microcrystalline Nd3+-doped La2Mo2O9 (LAMOX) dilanthanum dimolybdate obtained by the conventional solid state reaction. Basing on the analysis of a series of compounds with a wide range of Nd3+ ion concentration we discovered that the amount of Nd3+ dopant substituting La3+ ions affects significantly on structural and spectroscopic properties. Pure Nd3+-doped phases with monoclinic structure (α-form, the space group P21) were observed for the concentration of optically active ion up to 15%. When the concentration of Nd3+ ions is higher a cubic structure (β-form, the space group P213) starts to form. However, up to concentration of 50mol% of the Nd3+ ion a mixture of the monoclinic and cubic phases has been observed. Pure cubic phase was obtained when the Nd3+ contents had reached 50mol%. The spectroscopic analysis has shown that the Nd3+-doped monoclinic phase might be useful for application in the future as phosphors and ultra-short pulses (pico, femto) laser materials. The cubic phase could be useful to fabricate transparent ceramics and might be an important challenge for laser applications.

Spectroscopic studies of Nd3+ doped lead tungsten tellurite glasses for the NIR emission at 1062 nm

Lead Tungsten Tellurite (LTT) glasses doped with different concentrations of Nd3+ ions were prepared by using the melt quenching technique to study the absorption, emission and decay spectral profiles with an aim to understand the lasing potentialities of these glasses. From the absorption spectra, the Judd–Ofelt (J–O) parameters are evaluated and in turn used to calculate the transition probability (AR), total transition probability (AT), radiative lifetime (τR) and branching ratios (βR) for prominent emission levels of Nd3+. The emission spectra recorded for LTT glasses gives three emission transitions 4F3/2→4I9/2, 4F3/2→4I11/2 and 4F3/2→4I13/2 for which effective band widths (ΔλP) and stimulated emission cross-sections (σse) are evaluated. Branching ratios (βR) measured for all the LTT glasses show that 4F3/2→4I11/2 transition is quite suitable for lasingapplications. The intensity of emission spectra increases with increase in the concentrations of Nd3+ up to 1.0mol% and beyond concentration quenching is observed. Relatively higher emission cross-sections and branching ratios observed for the present LTT glasses over the reported glasses suggests the feasibility of using LTT glasses for infrared laser applications. From the absorption, emission and decay spectral measurements, it was found that 1.0mol% of Nd3+ ion concentration is aptly suitable for LTT glasses to give a strong NIR laser emission at 1062nm.

Coherent manipulation of dipolar coupled spins in an anisotropic environment

We study coherent dynamics in a system of dipolar coupled spin qubits diluted in solid and subjected to a driving microwave field. In the case of rare earth ions, anisotropic crystal background results in anisotropic g tensor and thus modifies the dipolar coupling. We develop a microscopic theory of spin relaxation in transient regime for the frequently encountered case of axially symmetric crystal field. The calculated decoherence rate is nonlinear in Rabi frequency. We show that the direction of static magnetic field that corresponds to the highest spin g-factor is preferable in order to obtain higher number of coherent qubit operations. The results of calculations are in excellent agreement with our experimental data on Rabi oscillations recorded for a series of CaWO4 crystals with different concentrations of Nd3+ ions.

Structural and Spectroscopic Characterization of Nd3+-Doped YVO4Yttrium Orthovanadate Nanocrystallites

Yttrium orthovanadate (YVO4) nanoparticles doped with Nd3+ ions (0.1–10 mol %), thermally treated at 700 to 1000 °C for 3 h were prepared using modified Pechini’s technique. The structure of products were studied using standard X-ray diffraction (XRD) technique and Rietveld method. The average particle size was found to be about 20 nm (both XRD and transmission electron microscopy) for samples annealed at 700 °C, and further rapid growth was noticed above 900 °C. The spectroscopic behavior of the Nd3+:YVO4 was studied in detailed based on the absorption, excitation, emission, and decay times measurements. The effect of the dopant concentration on progressive increase of reabsorption process and emission concentration quenching was observed. The size effect was manifested in the change of the relative intensities ratio for the resonant and laser transitions. In order to explain reverse behavior of the resonant line comparative studies with the Nd3+:YVO4 single crystal were conducted. An increase of synthetic parameters, concentration of Nd3+ cations and sintering temperature, leads to emission spectra comparable with the grinded single crystal.

Development of Nd3+-doped Monoclinic Dimolybdates La2Mo2O9 as Optical Materials

The work presented is mainly focused on synthesis and study of structural and optical properties of microcrystalline Nd3+-doped monoclinic dilanthanum dimolybdate at both room and cyrogenic temperatures (4K and 77 K). These compounds might be useful for application in the future as optical materials and also as transparent ceramics when the structure is cubic. The Nd3+-doped phases with monoclinic structure (α-form, space group P21, unit cell parameters a = 7:1426, b = 7:1544, c = 7:1618 Å and β = 89:538°) were observed for a concentration of the optically active ions equal to 5%. When the concentration of the Nd3+ ions is higher than 15%, a cubic structure is formed (β-form, space group P213, with the lattice parameter a = 7:155±0:005 Å). A series of Nd3+- doped La2Mo2O9 phases with different concentration of Nd3+ were prepared using conventional solid-state reactions. The formation of phase-pure Nd3+-doped La2Mo2O9 has been monitored by powder X-ray diffraction, DSC, SEM, Raman, and FT-IR absorption techniques. High-resolution absorption and emission spectra, as well as the dynamics of the Nd3+ excited states characterized by decay time measurements were recorded from room temperature to 4 K. At least two slightly different crystallographic sites are available for the Nd3+ ions. First results show that this new Nd3+-doped monoclinic La2Mo2O9 molybdate phosphor is promising for applications of ultra-short pulse lasers.

Absorption Spectra of Neodymium Doped Tellurite Glass

Modifying the optical and structural properties of tellurite glasses by controlling rare earth doping is an important issue. Neodymium doped magnesium-tellurite glasses of composition TeO2-MgO-Na2O with concentration from 0.5 to 2.5 mol% were synthesized by conventional melt-quenching technique. The amorphous natures of the glass were confirmed from x-ray diffraction (XRD) pattern. The absorption spectra (exhibits five bands) were recorded to determine the optical energy gap and Urbach energy. The values of the optical band gap are found to lie between 3.04-3.20 eV, while the Urbach energy values varies are between 0.21-0.12 eV. The optical energy gap for indirect forbidden transition has increased whereas the values of Urbach energy have decreased with the increasing of Nd2O3content. The structural and optical properties were found to be strongly affected by the varying concentration of Nd3+ions.

Cooperative absorption transitions in LiLa1−xNdxP4O12 nanocrystals

The absorption and excitation spectra of LiLa1−xNdxP4O12 nanocrystals were studied as a function of Nd3+concentration. The relative intensities of absorption transitions increase linearly with concentration of Nd3+ ions. It was found that the absorption from the first excited term 4I11/2 significantly contributes to the absorption band intensities both at room and liquid nitrogen temperatures. The mechanism of the effect is discussed in terms of cooperative absorption transitions.

Factors affecting afterglow properties of red-emitting phosphor MgSiO3:Mn2+,Nd3+ for luminescent fiber

With stable physical properties, the rare-earth silicate phosphor of MgSiO3:Mn2+,Nd3+ is one of the suitable luminescent materials used in preparing functional fibers. In order to promote the afterglow properties of red-emitting phosphors, we prepared it by means of solid-state reaction, and the effect of manufacturing elements including H3BO3 and environmental factor of calcining temperature, type of flux on its luminescence property were investigated through evaluating their afterglow properties. The results showed that with the concentration of Nd3+ increasing, the amounts of H3BO3 doping and calcining temperature, the afterglow time and initial brightness of the rare-earth silicate phosphor increased and then decreased gradually. The afterglow properties of different flux concentration were different from one to another as: H3BO3>Na+>K+>No flux.

Spectroscopic investigation of Nd3 + single doped and Eu3 +/Nd3 + co-doped phosphate glass for solar pumped lasers

We report on the fabrication and characterization of Nd3+ doped phosphate glass to be used as active laser medium for developing solar pumped fiber laser emitting at 1.06μm. Several Nd3+-doped phosphate glass samples were fabricated, with a host composition of (mol%) 65P2O5:17Li2O:3Al2O3:4B2O3:5BaO:6La2O3 and with a concentration of Nd3+ up to 10mol%. In order to exploit the unabsorbed solar energy by Nd3+ ions, Eu3+ co-doping of Nd3+-doped phosphate glasses was also investigated to asses a potential increase in the overall pump power conversion efficiency. Physical and thermal properties of single doped and co-doped samples were measured and their spectroscopic properties are discussed. The effect of Nd3+ doping concentration on emission spectra and lifetimes was investigated in single doped samples in order to study the concentration quenching effect on luminescence performance. The shape of the fluorescence spectrum did not change by increasing the Nd3+ doping level while the lifetime of the Nd3+:4F3/2 was found to decrease. The following characteristic value parameters were calculated: radiative lifetime τ0=367μs and quenching concentration N0=8.47 E+20ions/cm3.The Eu3+ co-doping was found to give a limited increase to the glass pump power absorption limited to the UV range. Although energy transfer from Eu3+ to Nd3+occured, a large Eu3+ concentration dependent quenching of Nd3+ fluorescence was observed. This latter process decreases the radiative quantum efficiency of Nd3+:4F3/2 emitting level and hence limits the attractiveness of Eu3+ sensitization for Nd3+ laser action.

Fluorescence quantum efficiency dependent on the concentration of Nd3+ doped phosphate glass

The thermal-lens (TL) method was applied to a new phosphate glass doped with Nd3+ to determine fluorescence quantum efficiency (η) and thermal properties such as: thermal diffusivity, thermal conductivity and the temperature coefficient of optical length change. Studies were performed as a function of Nd3+ concentration (0.5–3×1020ions/cm3). In addition, fluorescence quenching was studied by measuring the concentration dependence of fluorescence lifetime. The TL and fluorescence lifetime results are in good agreement and corroborate the theory for energy transfer involving a pair of ions in which cross-relaxation (CR) is the dominant process.

Investigation on 1.07 μm laser emission in Nd3+-doped sodium fluoroborate glasses

Spectroscopic and fluorescence properties of Nd3+ ions in sodium fluoroborate (SFB) glasses were prepared and characterized through optical absorption, emission and decay measurements. The energy level analysis was carried out using free-ion Hamiltonian model. Experimental oscillator strengths were determined by measuring the area encompassed by the absorption peaks recorded for 1.0 mol.% Nd3+- doped glasses. The Judd-Ofelt parameters (Ω2,4,6) were used to evaluate the laser characteristic parameters such as radiative transition probability (AR), radiative decay time (τR), fluorescence branching ratio (βR) and stimulated emission cross-section (σe) for the 4F3/2 metastable state. The fluorescence spectra for different concentrations of Nd3+ ions were recorded by exciting the samples at 514.5 nm Ar+ ion laser.

Splitting and broadening of the emission bands of Y2O3:Eu3+,Nd3+ and its dependence on Nd3+ concentration and annealing temperature

Although Eu3+ ion-doped Y2O3 has been extensively used as red phosphors, their color rendering needs to be improved for high-quality illumination and displaying. Here, we show that the emission spectra of Y2O3:Eu3+ red phosphors can be broadened by the doping of Nd3+ ion so that the color rendering capability of Y2O3:Eu3+ was remarkably enhanced. Y2O3:Eu3+ and Y2O3:Eu3+,Nd3+ colloidal spheres were synthesized by wet chemical procedure and high-temperature treatment. The fluorescence measurement under the 254 and 380 nm ultraviolet excitation indicates that the 612 nm red emission peak of Eu3+ can be splitted into two ones by the doping of Nd3+ ion, of which the full width at half maximum (FWHM) is broadened from 4.2 nm to 9.6 nm. By varying the concentration of Nd3+ ion, it was determined that the optimal doping concentration of Nd3+ ion is of 3 mol% for realizing the strongest emission intensity. The further increase of Nd3+ ion exceeding 3 mol% would lead to a concentration quenching phenomenon. The analysis based on XRD spectra and the simplified energy diagram suggested that the doped Nd3+ ion not only monitored the growth dynamics, but also took an efficient energy transfer and a cross relaxation process to generate intense emission from Eu3+ ion in both of C2 and S6 sites, instead of preferable one type of Eu3+ site (C2 or S6) in the Nd3+ undoped sample.

Fabrication and Luminescence Properties of Nd3+:Y2O3 Transparent Ceramics

Y2O3 nanoparticles doped with different concentrations of Nd3+ were prepared by the coprecipitation method, and the Nd3+:Y2O3 transparent ceramics were fabricated by vacuum sintering at 1700 degrees C, under 1 x 10(-3) Pa for 6 h. The structural, morphological, and luminescence properties of the samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and fluorescence analysis. The results show that the Nd3+:Y2O3 nanoparticles are homogeneous in size and nearly spherical, and the average diameter of the particles is in the range of 40-60 nm. There are no other phases except the Y2O3 cubic phase in the Nd3+:Y2O3 nanoparticles and transparent ceramics. Nd3+ dissolves completely in the Y2O3 cubic phase. The relative density of Nd3+:Y2O3 transparent ceramics is 99.7%, and the transmittance of the Nd3+:Y2O3 transparent ceramics exceeds 80% at the wavelength range.

Multicenter structure of the optical spectra and the charge-compensation mechanisms in Nd:SrWO4 laser crystals

An analysis of the high resolution optical spectra (10 and 300 K) of the self-stimulated Raman scattering active Nd:SrWO4 crystal was performed. Crystals doped only with low concentrations of Nd or codoped with Na+ or Nb5+ grown in N2 or air atmosphere were investigated. The single Nd-doped crystals show five main centers, whereas codoping with Na+ in the ratio Na/Nd=3/1 (in melt) simplifies considerably the spectra. Codoping with Nb5+ does not lead to a dominant center and introduces a new one. Growth in air revealed the role of the oxygen in the charge compensation and multicenter structure of the spectra. The spectral characteristics of the nonequivalent centers (levels, intensities, and polarization) function on concentration of Nd3+ and of codoping ions and growth conditions were analyzed. The polarization data show that only one center has ideal local symmetry S4. Based on the crystal structure, previous results, and the new spectral data, an attempt to connect various spectral nonequivalent centers to the charge compensators (Sr2+ vacancies, interstitial oxygen, Na+, and Nb5+) is made and structural models for various centers are proposed. The implications of these findings on the laser emission characteristics and on the selection of the pumping transitions are also discussed.

Photoluminescence and FTIR studies of pure and rare earth doped silica xerogels and aerogels

The luminescence properties of silica xerogels and aerogels have been studied using PL spectroscopy. Both silica xerogels and aerogels exhibit photoluminescence in the visible region when excited with UV radiation. The luminescence observed in xerogels and aerogels is attributed due to defect centers. Silica aerogels exhibit better photoluminescence than xerogels due to the increase in defect sites. The incorporation of rare earth ions (La3+, Nd3+and Sm3+) enhanced the luminescence of both silica xerogels and aerogels. La3+ shows least and Nd3+ shows maximum enhancement. Increase in the concentration of Nd3+ resulted in an increase in the luminescence intensity. The change in the environment of the defect centers due to the incorporation of rare earth ions and the superposition of 4f-f transitions of rare earths are considered as the reasons for the luminescence enhancement.