Rare-earth Solubility Research Articles

Distribution, and mobility of rare earth elements in surface sediment of Gomishan Wetland

Rare earth elements (REEs) are emerging environmental contaminants that pose a threat to ecosystem health. Their accumulation in sediments and potential release into the water column can raise concerns. Understanding the factors influencing REE mobility is crucial. Furthermore, our knowledge of the risk and occurrence of REEs in wetland ecosystems is inadequate. This study investigated REE release from sediments under varying redox conditions (Eh). The different redox potential values were adjusted using a photoanode (Ti/TiO2) and a cathode (graphite). Also, to recognize the relationship between REEs and other parameters, Pearson correlation (PC) was employed. Results showed that increasing Eh initially enhanced REE mobility (until around 300 mV), followed by a decrease at higher Eh values. Among the studied REEs, lanthanum (La), cerium (Ce), and gadolinium (Gd) exhibited the highest release potential into water, with measured concentrations reaching 199.4, 93.1, and 31.2 µg/L, respectively. Moreover, according to several eco-geochemical risk assessment indices, the sediment of the study area was classified as minimal contamination. Statistical analyses revealed that Eh indirectly affects REE mobility by influencing linked changes in pH, salinity, and iron-manganese (Fe-Mn) chemistry, which in turn impacts REE solubility and release from sediments.

Extension settings favour initial REE enrichment in the parent granites of ion-adsorption REE deposits: implication from Late-Permian to Triassic granites in South China

The mechanism of rare earth elements (REE) enrichment in granites is important to understand generation of ion-adsorption REE deposits. We investigated Late Permian to Triassic granites from South China to investigate these issues. The ore-related granites with high REE contents (192-467 ppm) intruded in Late Permian have high K 2 O and Zr+Ce+Nb+Y contents, high Ga/Al and K/Na ratios, and low CaO contents, which belong to aluminous A-type granite derived from melting of felsic igneous rocks at a high-temperature extensional setting. The ore-unrelated Triassic Pingtian granite with relatively low REE contents (81.7-127 ppm) is peraluminous with occurrence of muscovite, indicating a S-type affinity. Its high Rb/Sr and low CaO/Na 2 O ratios indicate magma origin from a metapelitic source related to the compressional setting due to the continental collision. In the extensional settings in South China, the high temperature condition promoting melting of REE-rich accessory minerals and F-rich conditions improving the solubility of REE in the melts could be the reasons for the initial REE enrichment in these granites. Given that parent rocks for ion-adsorption REE deposits are all generated in extensional settings, multiple tectonic stages and long-term extensional setting in South China contributed to generation of the specific ion-adsorption REE deposits in South China.

Effect of rare earth substitution on magnetic properties of strontium hexaferrite prepared by Pechini method

This study presents a comprehensive investigation into the impact of substituting rare earth elements on the magnetic properties of strontium hexaferrite. The samples, synthesized by the sol-gel Pechini method, followed the formula Sr1-xRexFe12O19 with Re = Gd, Sm, Nd, Pr, and La, for 0.025 ≤ x ≤ 0.100. The findings revealed that Re substitution promotes a considerable increment of the coercive field. However, the magnetic yield dropped with increasing the Re content. Therefore, the higher coercivity field, largest magnetization and maximum energy product (BHmax) were reached for samples with x = 0.025. This tendency was consistent across all rare earth-substituted samples although the hexaferrite substituted with samarium and praseodymium showed the strongest hard-magnetic properties. This behavior has been attributed to a reduction of the interaction field due to the emergence of a monodomain structure, and to the limited solubility of rare earth elements within the structure of strontium hexaferrite.

Synthesis, structure and properties of nanoparticles based on SrFe12-xRxO19 (R = Er, Tm) compounds

In this work a comprehensive analysis of the structure and properties of doped SrFe12-xRxO19 (R = Er, Tm) hexaferrites has been studied. The hexaferrtes were synthesized by two methods: mechanochemical and citrate approaches. The solubility of rare-earth elements (REE) has been studied by precision determination of the lattice spacings and cell volume of the samples, synthesized by mechanochemical method. It has been shown that the solubility of Er and Tm at a temperature of 1200 °C does not exceed × = 0.08 REE ions per formula unit. According to Mössbauer spectroscopy, REE atoms preferentially occupy 12k positions. Nanoparticles of SrFe12-xRxO19 (R = Er,Tm) compounds for MRI were obtained by high-energy ball milling of the citrate samples for 50 h in an octadecene solution with oleic acid. Stable hydrosols of nanoparticles were obtained after their coating with Pluronic F127 polymer. It has been shown that the obtained nanoparticles can be used for biomedical applications as contrast agents.

Selective recovery of rare earth elements and value-added chemicals from the Dicranopteris linearis bio-ore produced by agromining using green fractionation.

The increasing demand for Rare Earth Elements (REEs) and the depletion of mineral resources motivate sustainable strategies for REE recovery from alternative unconventional sources, such as REE hyperaccumulator. The greatest impediment to REE agromining is the difficulty in the separation of REEs and other elements from the harvested biomass (bio-ore). Here, we develop a sulfuric acid assisted ethanol fractionation method for processing D. linearis bio-ore to produce the pure REE compounds and value-added chemicals. The results show that 94.5% of REEs and 87.4% of Ca remained in the solid phase, and most of the impurities (Al, Fe, Mg, and Mn) transferred to the liquid phase. Density functional theory calculations show that the water-cation bonds of REEs and Ca cations were broken more easily than the bonds of the cations of key impurities, causing lower solubility of REEs and Ca compounds. Subsequent separation and purification led to a REE-oxide (REO) product with a purity of 97.1% and a final recovery of 88.9%. In addition, lignin and phenols were obtained during organosolv fractionation coupled with a fast pyrolysis process. This new approach opens up the possibility for simultaneous selective recovery of REEs and to produce value-added chemicals from REE bio-ore refining.

Luminescence and laser properties of RE-doped silica optical fibers: The role of composition, fabrication processing, and inter-ionic energy transfers

Silica glass doped with rare-earth ions remains one of the most frequently used materials for fiber lasers and amplifiers, owing to various advantages such as high thermal resistance, mechanical and chemical durability, high transparency up to 2.2 μm, and last but not least, a proven and relatively cheap technology. However, the performance of fiber lasers and amplifiers based on silica glass is limited by several drawbacks, including low solubility of rare earths, which causes a high rate of inter-ionic energy transfers processes, or high phonon energy of the silica lattice, which leads to non-radiative decay via multiphonon relaxation. Both obstacles can be countered by various strategies, with the most perspective being the addition of suitable co-dopants. The luminescence properties and laser characteristics of the final optical fiber are thus strongly dependent on the composition, as well as the fabrication processing of the material. In this review, we summarize the basic concepts and recent developments in the role of various co-dopants of rare earth ions, the fabrication processes used in the making of high-silica fibers and the inter-ionic energy-transfers, with respect to their influence on the luminescence and laser properties of the fibers.

(Invited) Rare-Earth-Doped Tellurium Oxide Light Emitting Nanophotonic Devices

Tellurium oxide is a promising material for passive, nonlinear and rare-earth-doped active photonic devices because of its high transparency, high refractive index, high nonlinearity and unique structure allowing for high rare-earth solubility. In this talk I present on our recent progress on tellurite glass on-chip light emitting nanophotonic devices. Low-loss passive devices including high-Q-factor microdisks and microring resonators will be discussed. In addition, rare-earth-doped active devices, including erbium-doped and thulium-doped waveguide amplifiers and microlasers will be presented. Using similar structures, we demonstrate nonlinear light emission via four-wave-mixing, supercontinuum generation and third harmonic generation. These tellurium oxide integrated nanophotonic devices are highly promising for compact and low-cost passive, active and nonlinear photonic integrated circuits for applications in communications, computing, and sensing.

Intrinsic defect-related thermoluminescence in Li1−xNaxMgPO4 (0 ≤x ≤ 0.20)

Solid solutions Li1−xNaxMgPO4 (0 ≤x ≤ 0.20) with olivine-type orthorhombic structure were synthesized by the conventional solid state reaction route and their optical properties and defect structure were examined by experimental and theoretical methods. A significant gain in the thermoluminescence of phosphate was found with an increase in sodium concentration up to 6%. The ab initio calculations and the study of the ESR spectra made it possible to attribute this effect to an increase in the number of defects, primarily oxygen vacancies. It was established that partial substitution of sodium for lithium can increase the solubility of rare earth elements in LiMgPO4, and this contributes to the development of materials with improved dosimetric characteristics.

Impact of rare earth (RE3+ = La3+, Sm3+) substitution in the A site perovskite on the structural, and electrical properties of Ba(Zr0.9Ti0.1)O3 ceramics.

Undoped Ba(Zr0.9Ti0.1)O3 and rare-earth-doped (Ba1−xRE2x/3)(Zr0.9Ti0.1)O3 (RE3+ = La3+, Sm3+) perovskite compounds were synthesized by the conventional solid-state reaction route. Both solubility of rare earth in Ba(Zr0.9Ti0.1)O3 and formation of perovskite structure with the Pm3̄m space group were verified by the Rietveld method using X-ray diffraction data. SEM micrographs of all ceramics revealed high densification, low porosity, and even homogeneous grain distribution of various dimensions over the total surface. The frequency-dependent electrical properties were analyzed by complex impedance spectroscopy. Different types of studies such as the Nyquist plot, real and imaginary part of impedance, conductivity, modulus formalism, and charge carriers activation energy were used to explain the microstructure–electrical property relationships.

Structural and spectroscopic properties of gadolinium-lead-lead dioxide glasses

The trivalent gadolinium, doped lead-lead dioxide glass, with the chemical composition xGd2O3•(100 − x) [4PbO2•Pb], where x= 10–50 mol% Gd2O3 have been successfully fabricated by conventional melt quenching technique, and investigated by X-ray diffraction, Fourier Transform Infrared, Electron paramagnetic resonance, Ultraviolet-Visible, and Photoluminescence spectroscopy for their structural, optical, and luminescence properties. The X-ray diffraction indicated high solubility of rare-earth. The high addition of Gd2O3 content generates changes of basic [PbOn] structural units. Electron paramagnetic resonance spectrum confirms the presences of the gadolinium as a Gd3+ in the lead host matrix. The formation of the non-bridging oxygens and chemical bonds is dependent upon the Gd2O3 content, Gd3+ ions environment, and its distribution in the glass. Under the 395 nm excitation, emissions corresponding to 6GJ → PJ and 6GJ → IJ transition of Gd3+ ions, were observed. The CIE color coordinates, suggested that Gd3+ activated lead-lead dioxide glasses is suitable for warm orange luminescence applications.

Quantitative prediction of the glass‐forming region and luminescence properties in Tm3+‐doped germanate laser glasses

AbstractGermanate laser glasses have received much attention as a promising host materials for mid‐infrared fiber lasers in recent years because of the outstanding infrared transparency, low phonon energy, and high rare earth solubility of such glasses. However, the development of high‐performance germanate laser glasses is usually based on intuition and a trial‐and‐error method, which can involve long experimental periods and high costs, and thus, this approach is highly inefficient. Recently, with proposals for materials genome engineering, the concept of the “glass genome” has grown of interest to us. Herein, the structures of Tm3+‐doped germanate laser glasses (BaO–GeO2 and BaO–La2O3–GeO2) were investigated by Fourier transform infrared spectra (FTIR) and Raman spectra analyses, which revealed that the resulting glass contains similar structural groups to the neighboring congruently melted glassy compounds (NCMGCs) in the composition diagram. What is more, the structure and properties of the resulting laser glasses largely depend on NCMGCs. Then, the glass‐forming region, physical properties, and luminescence properties were calculated via the use of NCMGCs in Tm3+‐doped BaO–GeO2 binary and BaO–La2O3–GeO2 ternary laser glass systems. The calculated results were in good agreement with the experimental results, thus demonstrating that our approach is practical for predicting the glass‐forming region, physical properties, and luminescence properties in Tm3+‐doped BaO–GeO2 binary and BaO–La2O3–GeO2 ternary laser glass systems. This work may provide an effective method to develop Tm3+‐doped germanate laser glasses rapidly and at low cost.

Intrinsic Magnetic and Ferroelectric Behaviour of Non-magnetic Al3+ Ion Substituted Dysprosium Iron Garnet Compounds

Synthetic garnets are a group of oxide materials that play a vital role in the development of solid state lasers, magnetic and optic-electronic devices. The analysis on the solubility of rare-earth elements in the well-crystallized system has led to the discovery of peculiar oxide materials with multifunctional properties. By following the above importance, Aluminium ion (Al3+) substituted Dysprosium Iron Garnet compounds with the chemical formula of Dy3Fe5−xAlxO12 (x = 0–0.5) have been synthesized by the solid state reaction method and the effect of substitution of non-magnetic ions into the magnetic sub-lattices have been analyzed. The Rietveld refinement of powder x-ray diffraction patterns confirms that the pure Dy3Fe5O12 compound crystallizes with cubic (Space group: Ia3d) superstructure whereas all the Al3+ substituted samples exhibit the coexistence of cubic (Ia3d) and trigonal Fe2O3 (R3c) phases. The energy gap values of the prepared compounds is found to be around 1.6 eV which reveals the semiconducting nature and the decreasing trend of band gap values may be due to the growth factor of crystallites, structural disorder and distortion introduced into the crystal lattice. From the Micro-Raman analysis, it is found that the substituted Al3+ ions starts filling into both tetrahedral and octahedral positions and the assignments of vibrational modes observed from Raman spectra confirm the incorporation of Al3+ ions into the Dy3Fe5O12 garnet structure. From the magnetization analysis, it is found that the response of super-exchange interaction between Fe3+ ions in the a and d sites of Dy3Fe5O12 compound leads to net magnetic moment and the substitution of Al3+ ions preferably replaces Fe3+ ions in d sites and suggests the decrease in net magnetization values. From the photoluminescence studies, it is noticed that the luminescence behavior of Al3+ ions substituted Dy3Fe5−xAlxO12 compounds are due to the superposition of a broad emission band and reveals the variation in concentration of Al3+ ions in the prepared compounds. An interesting point to note is that, a well saturated “soft” ferroelectric hysteresis loop is obtained in both pure and Al3+ substituted Dy3Fe5−xAlxO12 compounds, and the observed electric hysteresis loops are found to be influenced by the factors such as capacitance nature, resistivity effects and leakage current of the compounds. Hence, the study on effect of trivalent non-magnetic ion substitution in a hard magnetic Dy3Fe5O12 system leads to interesting intrinsic magnetic and ferroelectric properties and found suitability for the fabrication of energy storage and optoelectronic devices.

Electroluminescence from silicon-based light-emitting device with erbium-doped TiO<sub>2</sub> films: Enhancement effect of ytterbium codoping

In the past years, light-emitting devices (LEDs) based on erbium (Er)-doped insulators or wide-bandgap semiconductors have received intensive attention because the intra-4f transition (<sup>4</sup>I<sub>13/2</sub>→<sup>4</sup>I<sub>15/2</sub>) of Er<sup>3+</sup> ions at ～ 1540 nm has potential applications in the optical interconnection for silicon-based circuits. The LEDs with rare-earth (RE)-doped SiO<i><sub>x</sub></i> (<i>x</i> ≤ 2) or SiN<i><sub>x</sub></i> (<i>x</i> ≤ 4/3) films have been well investigated as the silicon-compatible emitters. However, they suffer difficulty in injecting current and easing fatigue. In this context, the LEDs with RE-doped oxide semiconductors have been extensively investigated out of research interest in recent years. Among the oxide semiconductors, TiO<sub>2</sub> is a desirable host for RE-doping because it is transparent for visible and infrared light, and cost-effective, and has considerably high RE solubility. In our previous work (Zhu C, Lü C Y, Gao Z F, Wang C X, Li D S, Ma X Y, Yang D R 2015 <i>Appl. Phys. Lett.</i> <b>107</b> 131103), we have realized erbium (Er)-related visible and near-infrared (～ 1540 nm) electroluminescence (EL) from the LED with a structure of ITO/TiO<sub>2</sub>:Er/SiO<sub>2</sub>/n<sup>+</sup>-Si, in which TiO<sub>2</sub>:Er refers to the Er-doped TiO<sub>2</sub> film as the light-emitting layer. In this work, we co-dope ytterbium (Yb) into the TiO<sub>2</sub>:Er film in the aforementioned LED to significantly enhance the Er-related visible and near-infrared EL. It is revealed that a certain amount of Yb co-doping enables the TiO<sub>2</sub>:Er film to transform its crystal phase from anatase to rutile. Such a phase transformation reduces the symmetry of crystal field surrounding the Er<sup>3+</sup> ions incorporated into the TiO<sub>2</sub> host. Moreover, the substitution of over-sized Yb<sup>3+</sup> ions for Ti<sup>4+</sup> ions in the TiO<sub>2</sub> host leads to the distortion of the crystal field around the Er<sup>3+</sup> ions. The aforementioned symmetry-reduction and distortion of the crystal field increase the probabilities of the intra-4f transitions of Er<sup>3+</sup> ions. Due to the aforementioned reason, the Yb co-doping into the TiO<sub>2</sub>:Er film remarkably enhances the EL from the corresponding LED. It is believed that the strategy of Yb-codoping can be adopted to enhance the EL from the LEDs with other RE-doped TiO<sub>2</sub> films.

Inputs of rare earth elements in Brazilian agricultural soils via P-containing fertilizers and soil correctives

The mineral exploration of rare earth elements (REEs) and their entry into the soil via fertilizers has generated concern about environmental impacts and human health risks. We evaluated 60 samples of limestone, gypsum and phosphate fertilizers marketed in Brazil in order to characterize their contents, signature and solubility of REEs. The fertilizers from igneous origin presented the largest accumulation of REEs. Accumulation of the light REEs Ce, La, Nd, Pr, Sm and Eu were larger than the heavy REEs (Y, Dy, Gd, Er, Yb, Ho, Tb and Lu). The solubility of fertilizers produced from sedimentary sources was greater than that of igneous sources. The mean annual REEs contribution of SSP and organo-mineral + phosphate rock (both of igneous origin) to soils was > 4000 t year−1, with highest additions for Ce, La, Nd and Y. Thus, phosphate fertilization and liming were considered to be significant sources of REEs and soils receiving continuously high doses of these inputs are likely to be enriched in REEs. Risk assessment studies are necessary to evaluate the impact of these REEs additions to soils on human health.

Precipitation-dissolution behaviors of rare earth ions in H3PO4[sbnd]Ca(H2PO4)2 solutions

In order to achieve deeper understanding of rare earth elements (REEs) behaviors during phosphate rock processing with H3PO4. The solubility of REEs in Ca(H2PO4)2H3PO4 solutions with various concentrations of Ca(H2PO4)2 at different temperatures were tested. The results demonstrate that REEs solubility decreases sharply with the increasing concentration of Ca(H2PO4)2. Equations between [REE3+] and [H+], [H+] and [Ca2+] in Ca(H2PO4)2H3PO4 solutions were built based on the precipitation-dissolution equilibrium of rare earth phosphates and the ionization equilibrium of H3PO4. According to the equations, the decreasing mechanism of REEs solubility caused by elevated concentration of Ca(H2PO4)2 was determined. The mechanism can be illustrated as that the elevated concentration of [H2PO4–] decreases the concentration of hydrogen ion by retarding the ionization process of H3PO4 and directly promotes the precipitation of rare earth phosphates. Furthermore, it can be easy deduced that similar effect would be caused by the other cation impurities (Fe3+, Al3+, etc.) on REEs solubility based on the mechanism. In addition, superimposed reduction effect on REEs solubility caused by the elevated concentration of Ca(H2PO4)2 and the elevated temperature is found. This superimposed effect leads to a super low solubility of REEs in Ca(H2PO4)2H3PO4 solution. On the basis of the experimental study, outlooks and suggestions for further development of REEs recovery method are given.

Dissolution behaviors of rare earth elements in phosphoric acid solutions

Abstract In order to provide practical fundamental data for rare-earth elements (REEs) recovery from phosphoric acid and to better understand REEs behavior during the phosphoric acid evaporation process, the solubilities of REEs in phosphoric acid with various concentrations of phosphorus at different temperatures were measured. A simple linear model between REEs solubility and phosphoric acid concentration is built and the experimental data are found to fit it very well (R2>0.94). Hydrogen-ion concentration is found to be the predominant factor controlling the solubility of REEs in phosphoric acid. In addition, the solubility of REEs in phosphoric acid is found to sharply decrease with increasing temperature, which can be attributed to the increase of the Gibbs energy of the REEPO4 dissolution reaction or the restraint of the disassociation of phosphoric acid molecules owing to the elevated temperature.

Mechanism for broadening and enhancing Nd3+ emission in zinc aluminophosphate laser glass by addition of Bi2O3

AbstractNd3+‐doped phosphate laser glasses have been attracting much attention and widespread investigation due to their high solubility of rare earth (RE) ions, excellent spectroscopic properties, and large damage threshold. However, the narrow NIR emission bandwidth (less than 30 nm) of these Nd3+‐doped phosphate glasses limits their further application toward ultrahigh power field and efficient fiber laser in new region. Here, we demonstrate the broadening and enhancing of Nd3+ NIR emission in laser glass of zinc aluminophosphate through tuning the glass structure and covalency of Nd‐O bond without limiting the radiative properties of Nd3+. The maximum bandwidth of 1.05 μm emission is broadened to 50 nm, which is comparable to that of Nd3+‐doped aluminate laser glasses. Simultaneously, the lifetime of 4F3/2 level is elongated nearly by two times. Structural and optical properties of prepared glasses were discussed systematically to reveal the mechanism. Detailed analysis on optical spectra and glass structure indicates that the bandwidth is affected by not only the covalency of Nd‐O but also the compactness of glass structure. Our results could enrich our understanding about the relationship between local glass structure and luminescence behaviors of active centers, and may be helpful in designing new RE‐doped laser glass systems.

Concentration dependent luminescence and cross-relaxation energy transfers in Tb3+ doped fluoroborate glasses

Recently, mixed-former glasses have attracted a large attention due to the appropriate combinations of the chemical, physical and optical properties of each glass former. In this scenario, the optical properties of fluoroborate glasses doped with rare earth ions is of importance due to their good transparency window from ultra-violet to near-infrared region, good rare-earth solubility, long excited state lifetime of such ions, and high mechanical strength. In this work, we had studied the optical properties of the Tb3+ doped fluoroborate glasses, focusing on the concentration dependent behavior of luminescence dynamics of 5D3 and 5D4 exited states of this ion. The blue-to-green intensity ratio, lifetime of the emitting levels under various excitation wavelengths, cross-relaxation rate, ion-ion critical distance and emission gain bandwidth are calculated.

Gain in polycrystalline Nd-doped alumina: leveraging length scales to create a new class of high-energy, short pulse, tunable laser materials

Traditionally accepted design paradigms dictate that only optically isotropic (cubic) crystal structures with high equilibrium solubilities of optically active ions are suitable for polycrystalline laser gain media. The restriction of symmetry is due to light scattering caused by randomly oriented anisotropic crystals, whereas the solubility problem arises from the need for sufficient active dopants in the media. These criteria limit material choices and exclude materials that have superior thermo-mechanical properties than state-of-the-art laser materials. Alumina (Al2O3) is an ideal example; it has a higher fracture strength and thermal conductivity than today’s gain materials, which could lead to revolutionary laser performance. However, alumina has uniaxial optical proprieties, and the solubility of rare earths (REs) is two-to-three orders of magnitude lower than the dopant concentrations in typical RE-based gain media. We present new strategies to overcome these obstacles and demonstrate gain in a RE-doped alumina (Nd:Al2O3) for the first time. The key insight relies on tailoring the crystallite size to other important length scales—the wavelength of light and interatomic dopant distances, which minimize optical losses and allow successful Nd doping. The result is a laser gain medium with a thermo-mechanical figure of merit of Rs~19,500 Wm−1 a 24-fold and 19,500-fold improvements over the high-energy-laser leaders Nd:YAG (Rs~800 Wm−1) and Nd:Glass (Rs~1 Wm−1), respectively. Moreover, the emission bandwidth of Nd:Al2O3 is broad: ~13 THz. The successful demonstration of gain and high bandwidth in a medium with superior Rs can lead to the development of lasers with previously unobtainable high-peak powers, short pulses, tunability, and high-duty cycles.

Nd3+:Ga-Ge-Sb-S glasses and fibers for luminescence in mid-IR: synthesis, structural characterization and rare earth spectroscopy

With high refractive indices, appropriate solubility of rare earth, low phonon energy and transparency from the visible to 10 µm, a Ga-Ge-Sb-S system allows emission from Nd3+ ions in the near- and mid-IR spectral ranges. The glass transition temperature, density, expansion coefficient, and near and mid-IR refractive indexes were measured on bulk samples. Their glass network structures were analyzed by Raman scattering spectrometry, NMR of 71Ga and extended X-ray absorption fine structure (EXAFS, K-edge of Ga, Ge, Sb, S and Nd). The absorption and emission spectra of neodymium doped sulfide glasses were recorded from the visible to the mid-IR. Excited state lifetimes were measured for several transitions. The lifetimes decrease with the concentration of Nd3+, especially for the 4I13/2 and 4I11/2 levels. The spectroscopic parameters were determined by the Judd-Ofelt method, allowing the calculation of cross-section emissions and the evaluation of quantum yields. Optical attenuation and emission measurements of fiber were also performed with a broad 4.7-5.7 µm emission band in the mid-IR.