The solvent extraction of yttrium and neodymium from copper pregnant leach solutions (PLS) using Primene JM-T, a primary aliphatic amine, has been studied. Effect of contact time, pH, sulfate concentration, and extractant concentration were investigated using synthetic and actual PLS systems. Standard experimental conditions were 5 minute contact time, pH ~2.5, 10% v/v Primene JM-T concentration, and 1:1 O:A phase ratio. Distribution isotherms were constructed for the pure systems and for actual copper leach solutions. Synthetic solutions contained 100 ppm Y and ~75 ppm Nd. Copper PLS contained 2.1 ppm Nd and 14.9 ppm Y. Results showed that complete extraction of both yttrium and neodymium occurred within five minutes and at pH values greater than 1. It was also found that sulfate concentration does not inhibit extraction at any concentration. Additionally, the distribution isotherms created show that extraction for these metals can operationally take place in one stage from both synthetic solutions and copper leach solutions.

No description available.

The twenty approved members of the eudialyte group are complex zirconosilicates, primarily with general formula N15M(1)6M(2)3M(3)M(4)Z3[Si24O72]O4X2. An algorithm was created to address the inherent recalculation difficulties in the absence of single-crystal X-ray data and was an overall improvement over previous schemes. Eudialyte group minerals were analyzed from the East Hill Suite of the Mont Saint-Hilaire alkaline complex. Recalculations revealed previously undocumented eudialyte-group compositions and degrees of chemical zonation. These data suggest that late-stage melt heterogeneity in alkaline systems is far more pronounced than previously thought. All analyses exhibited a negative neodymium anomaly in chondrite-normalized data. This supports data from other investigators that point to a preintrusion fractionation event in the underlying mantle. Potassium content of the eudialyte group minerals from the East Hill Suite was restricted to a narrow range, as was that of analyses from numerous other localities, suggesting some internal control on potassium content in eudialyte group minerals.

Embora cristais boratos dopados com ions de terras raras sejam amplamente investigados, vidros boratos desses sistemas vêm sendo pouco estudados. O cristal NdAl3(BO3)4(NAB) cujas propriedades laser e de geração de segundo harmônico (GSH) são conhecidas e continuamente relatadas na literatura, vem sendo recentemente considerado como um forte candidato para dispositivo \"microchip laser\". Alem disso, cristais dopados com íons de neodímio têm demonstrado ser excelentes para o bombeio com laseres de diodo, devido ao intenso pico de absorção próximo a 800 nm. Entretanto, existe na literatura um número muito limitado de estudos relatando as propriedades de vidros do sistema Nd2O3-Al2-O3-B2O3. Partindo dessa premissa, o objetivo principal deste trabalho foi obter vidros neste sistema, para elevadas concentrações de Nd2O3 (5-20 mol%), por meio das técnicas de fusão/moldagem convencional e fusão a laser. Dentre os materiais preparados foram obtidos três vidros transparentes, um material com separação de fases e, onde ocorreu cristalização. Os vidros obtidos, NAB136, NAB152560 e NAB226 foram caracterizados através das técnicas de análise térmica diferencial (ATD), difratometria de raios X (DRX), absorção óptica (AO) e ICP-OES (análise de composição). De acordo como os resultados de ATD, os vidros não apresentaram uma variação significativa na temperatura de transição vítrea (Tg) com o aumento da concentração de Nd2O3. O vidro NAB136, obtido com composição próxima a do cristal NdAl3(BO3)4(NAB), foi submetido a um tratamento térmico de cristalização a uma temperatura de 820°C por 2 horas. Os resultados de DRY indicaram a presença das fases cristalinas majoritárias Al4B2O9 e NAB. Medidas de absorção Óptica (AO) dos vidros no intervalo espectral de 300-1000 nm indicaram intensa absorção nos comprimentos de onda 500 nm e 800 nm. As análises de ICP-OES indicaram alta pureza dos vidros e composições próximas das composições nominais / Although borate crystals doped with rare earth ions have already been extensively investigated, borate glasses of these systems were not widely studied. The NdAl3(BO3)4(NAB) crystal, which laser and second harmonic generation (SGH) properties are well know and continuously mentioned in literature, has been recently considered as a strong candidate for microchip laser devices. Moreover, neodymium doped crystals are known for their excellent performance when pumped with diode lasers due to its intense absorption peak near to 800 nm. However, a limited number of papers have been published referring to the properties of glasses in the system Nd2O3-Al2-O3-B2O3. Based on this premise, the main purpose of this work was to prepare glasses in this system for Nd2O3 elevate concentrations (5-20 mol%) by the conventional melting/molding and laser heated methods. Among the prepared materials it was obtained three clear glasses, a material with phase separation and another one, which has crystallized. The obtained glasses, NAB136, NAB152560 and NAB226, where characterized by differential thermal analysis (DTA), X-ray diffractometry (XRD), optical absorption (OA) and ICP-OES (compositional analysis). According to the DTA results, the glasses have not presenteá a rneaningfut change in the glass transition temperature (Tg) with the increase of Nd2O3 content. The NAB136 glass, with the closest composition to the crystal NdAl3(BO3)4(NAB), was submitted to a crystallization thermal treatment at 820°C for 2 hours. XRD results showed the existence of the main crystalline phases and NAB. Optical absorption (OA) measurements of the glasses in the spectral range 300-1000 nm indicated intense absorpâion in the 500 nm and 800 nm wavelengths. ICP-OES analysis showed that the glasses posses high purity stoichiometry, close to the nominal ones

The objectives of this thesis were to develop a methodology for the measurement of laser beam characteristics from a single cavity laser and to establish a preliminary guideline that would determine which crystals were acceptable for use in production of laser devices. These objectives were achieved by developing the experimental procedures and by statistical analysis of the data obtained. However, additional future work is needed to independently confirm the results of this thesis. Efficient and reliable operation of a lamp-pumped Nd:YAG laser is highly dependent on the crystal from which the beam is derived. However little attention is given to the quality of the laser beam produced by each crystal. Although many factors influence the output beam, the power dependent focal length is of particular importance. Unfortunately, direct measurement of the crystal focal length is not possible with a Nd:YAG laser beam. This is because the single cavity laser functions as both a resonator and amplifier simultaneously. Therefore, a method was developed that measured the caustic of the laser beam after it had emerged from the resonator and been focused by means of a focusing element. The caustic of the beam was analyzed utilizing a beam analyzer that calculated the beam focusability factor and the beam waist size. From this information, the waist diameter at the outcoupler mirror was calculated using Gaussian beam propagation principles. A resonator model was developed based on the self-repeating ABCD matrix that allowed for the determination of the induced thermal lens based on the input power. Several approaches to model the thermal lensing effect were taken, each with increasing complexity. As a result, three parameters were evaluated with the intention of using one or more as a means to classify good and bad crystals. They were the crystal sensitivity factor, the beam focusability factor, and the beam waist size at the measurement plane. Calculation of the crystal sensitivity factor, M^-1, was based on the developed resonator model and numerous approximations of the crystal behavior. Thus, after calculating the M-1 factor as a function of input power, no distinguishable pattern was seen. However, the beam focusability factor and the beam size, both showed distinct regions that separate good and bad crystals. Statistical analysis performed on the data supports a preliminary conclusion that these two parameters may be used as a quality control measure. These parameters are measured using existing internationally accepted procedures and are therefore the best currently available tools for determination of the quality of Nd:YAG crystals.

Neodymium (Nd) isotopes have been increasingly used to trace the modern and past ocean circulation. This assumes that seawater Nd isotope ratios (εNd) effectively fingerprint different water masses and approximate expected values from water mass mixing. However, the decoupling of Nd isotopes and Nd concentration (the “Nd paradox”) in the water column, and the lack of understanding of sources and sinks of Nd, restrain our understanding of the “quasi-conservative” behavior of εNd in seawater. Nd is one of the lanthanide rare earth elements (REEs) with similar chemical characteristics that undergo some degree of fractionation. The shale-normalized REE patterns and REE ratios can be used to investigate potential sources/sinks of REEs. Combining REEs with εNd will provide additional information to study REE cycling in the ocean. To better understand the reliability of εNd as a water mass tracer, 17 high-resolution seawater profiles were sampled meridionally in the Southwest Atlantic (GEOTRACES GA02 Leg 3; RRS James Cook 057) and measured for εNd. This region involves the major water masses in the Atlantic Meridional Overturning Circulation: southward flowing North Atlantic Deep Water (NADW), northward flowing Antarctic Intermediate Water (AAIW) and Antarctic Bottom Water (AABW). Along the cruise track, there are potential sources (eolian dusts, marginal sediments, oceanic volcanism, and nepheloid layer) that could add external Nd to seawater and disturb the “quasi-conservative” behavior of εNd. Our results show strikingly that the Southwest Atlantic transect confirms “quasi-conservative” behavior of εNd in intermediate and deep water. Our evaluations of Nd isotopic deviations (ΔεNd) from conservative behavior show that out of 198 intermediate and deep samples, 49% of ΔεNd-values are within ± 0.25 εNd units (< analytical error: ± 0.30 εNd units) and 84% of ΔεNd-values are within ± 0.75 εNd units. Potential sources that could add external Nd to seawater from oceanic volcanism and the nepheloid layer do not show impact on seawater εNd. Terrigenous sources of Nd (e.g. eolian dusts from Africa and Patagonia, marginal sediments from South America) show influence on surface/subsurface water εNd but this εNd signature is not transferred to intermediate and deep water. To better understand the conservative vs. non-conservative behavior of REEs in the ocean, the dissolved REE concentrations were analyzed for the 17 seawater profiles in the Southwest Meridional Atlantic Transect (GEOTRACES GA02 Leg 3). The shale-normalized REE patterns are consistent with typical seawater patterns. To investigate whether and how much REE concentrations deviate from conservative water mass mixing, the REE concentration deviations were calculated for the intermediate and deep water. It is shown that within the SAMT, the intermediate and deep water REEs generally reflect water mass mixing and nearly conservative behavior. Along this transect, the potential sources that could add external REEs to seawater are dissolution of REEs from eolian dust to the surface/subsurface water, REEs released from dissolution of Fe-Mn oxides in the oxygen depleted zone, REEs from sediments near the continental margin, and dissolution of REEs from deep sea sediments. REEs and Nd isotopes of most intermediate and deep water masses passing the volcanic Rio Grande Rise (RGR) and Vitória-Trindade Ridge (VTR) do not show influence from RGR and VTR. REEs and Nd isotopes of the bottom water Lower Circumpolar Deep Water (LCDW) and AABW passing the RGR are influenced by dissolved REEs from the deep sea sediments. LCDW and AABW passing the VTR are influenced by dissolved REEs from the deep sea sediments as well as the volcanic VTR. In order to better understand the oceanic Nd cycling in the North Pacific, its sources and sinks in seawater must be better characterized. The high εNd of North Pacific Deep Water (NPDW, ~ −4) has been difficult to reconcile with the eolian inputs as reflected in surface waters (e.g. Jones et al., 2008), which have much lower εNd (~ −10), indicating potential addition of a component from Pacific volcanism. In order to constrain the REE sources in the North Pacific, we measured εNd and REEs of seawater from five stations across the subarctic North Pacific sampled by the Innovative North Pacific Experiment (INOPEX) Cruise SO202 (2009). In the surface water (~10 m), the highest εNd is observed at the station closest to the Aleutian-Kamchatka volcanic margin (Northwest station SO202-5), suggesting higher contribution of external REEs from volcanic ashes compared to the other stations. In the shallow water (100-400 m, depending on location), remineralization of REEs from volcanic ashes prevails over Asian dusts at Northwest station SO202-5 and near Japan stations SO202-44, 41, and 39, whereas remineralization of REEs from Asian dusts prevails over volcanic ashes at the Northeast station SO202-32 in the open ocean of the Alaska Peninsula. From the depths of North Pacific Intermediate Water (NPIW) to NPDW, seawater εNd and REEs show conservative water mass mixing of NPIW-NPDW. They also show conservative behavior along the water mass transport paths of NPIW and NPDW. Below the depths of NPDW, addition of external REEs is observed in the vertical profiles of εNd and REEs as well as along the transport path of LCDW. The potential sources that add external REEs to the bottom water are (1) sediments on the Kuril-Kamchatka-Aleutian volcanic margin along the LCDW transport path, and (2) sediments on the seafloor, both of which could interact with seawater and modify the seawater εNd and REE signatures.

No description available.

Amostras de vidros aluminoboratos de bário contendo impureza de cromo, apresentando proporções de íons Cr POT. 3+, Cr POT 5+ e Cr POT. 6+, determinadas pelas condições oxidantes ou redutoras de fusão, foram preparadas e caracterizadas pelas técnicas de absorção óptica (AO), fluorescência e de ressonância paramagnética eletrônica (RPE). As condições redutoras necessárias para favorecer a obtenção de vidros contendo majoritariamente íons de Cr POT. 3+ foram satisfeitas com a adição de 0,6% em peso de Sb IND. 2 O IND. 3. Nos vidros contendo antimônio, a banda 4 ANTIPOT. T IND. 2 do Cr POT. 3+ aparece ligeiramente deslocada para comprimentos de onda maiores e mais alargada, em relação ao vidro contendo apenas cromo como impureza adicional. O parâmetro de Racah B e a intensidade de campo ligante Ll foram determinados, obtendo-se os valores B = 759 cm-1 e = 15800 cm-1 para o vidro com cromo e antimônio e B = 736 cm-1 e = 16150 cm-1 para o vidro contendo apenas a adição de cromo. Foram observadas antirressonâncias de Fano nos espectros de AO, mais definidas nas amostras sem antimônio. Os espectros de RPE indicam que os íons Cr POT. 3+ isolados estão preferencialmente localizados em sítios distorcidos de simetria octaédrica, apresentando uma linha de absorção em g = 5,15, notando-se também a presença de pares de Cr POT 3+ caracterizados por uma componente da linha em g = 2,0. Com a adição de neodímio, os espectros de AO e de RPE do Cr POT. 3- não sofreram alterações, mas o espectro de fluorescência, com o máximo localizado em 776 nm, foi bastante modificado, mostrando uma diminuição da intensidade em regiões do espectro características da absorção do Nd POT. 3+, indicando a ocorrência de um processo de transferência de energia dos íons Cr POT. 3+ para os íons Nd POT. 3+ nos vidros aluminoboratos de bário, à temperatura ambiente. Os espectros de fluorescência e excitação dos vidros duplamente dopados com cromo e neodímio mostraram o efeito de antiressonâncias de Fano, com o deslocamento de Lamb dos vales associados ao neodímio sobre do Cr POT. 3+. / Barium aluminoborate glass samples containing chromium impurities, presenting Cr3- , Cr5- e Cr6+ íon amounts determined by the oxidizing or reducing melting conditions, have been prepared and characterized by Optical Absorption (OA), fluorescence and Electron Paramagnetic Resonance (EPR) techniques. The reducing conditions necessary to obtain glasses having mainly Cr3+ íons were satisfied with the addition of 0.6 wt% of Sb2 O3 to the batch. In glasses containing antimony, the 4T2 band is wider and shifted towards the higher wavelengths in relation to glass containing only chromium as additional impurity. The Racah parameter B and the ligand field intensity L1 were determined, yielding B = 759 cm-1 and L1 = 15800 cm-1 for the chromium- and antimony-doped glass, and B = 736 cm-1 and L1 = 16150 cm-1 for glass containing only chromium impurity. Fano antiresonances were observed in the OA spectra, better defined in the samples without antimony. The RPE spectra show that the Cr3- ions are preferentially located at distorted octahedral sites. An absorption line was observed at g = 5. 15 and it has been noted also the presence of Cr3+ pairs characterized by a line component at g = 2.0. With the addition of neodymium, the OA and EPR spectra of Cr3+ did not change, but the fluorescence spectrum observed at 776 nm was considerably modified, indicating the occurrence of an energy transfer process from Cr3+ to Nd3- íons in barium aluminoborate glasses at room temperature. The fluorescence and excitation spectra of glasses doped with chromium and neodymium have shown the Fano antiresonance effect, with the Lamb shift of the valleys associated to neodymium over the emission bands ofCr3+.

Amostras de vidros aluminoboratos de bário contendo impureza de cromo, apresentando proporções de íons Cr POT. 3+, Cr POT 5+ e Cr POT. 6+, determinadas pelas condições oxidantes ou redutoras de fusão, foram preparadas e caracterizadas pelas técnicas de absorção óptica (AO), fluorescência e de ressonância paramagnética eletrônica (RPE). As condições redutoras necessárias para favorecer a obtenção de vidros contendo majoritariamente íons de Cr POT. 3+ foram satisfeitas com a adição de 0,6% em peso de Sb IND. 2 O IND. 3. Nos vidros contendo antimônio, a banda 4 ANTIPOT. T IND. 2 do Cr POT. 3+ aparece ligeiramente deslocada para comprimentos de onda maiores e mais alargada, em relação ao vidro contendo apenas cromo como impureza adicional. O parâmetro de Racah B e a intensidade de campo ligante Ll foram determinados, obtendo-se os valores B = 759 cm-1 e = 15800 cm-1 para o vidro com cromo e antimônio e B = 736 cm-1 e = 16150 cm-1 para o vidro contendo apenas a adição de cromo. Foram observadas antirressonâncias de Fano nos espectros de AO, mais definidas nas amostras sem antimônio. Os espectros de RPE indicam que os íons Cr POT. 3+ isolados estão preferencialmente localizados em sítios distorcidos de simetria octaédrica, apresentando uma linha de absorção em g = 5,15, notando-se também a presença de pares de Cr POT 3+ caracterizados por uma componente da linha em g = 2,0. Com a adição de neodímio, os espectros de AO e de RPE do Cr POT. 3- não sofreram alterações, mas o espectro de fluorescência, com o máximo localizado em 776 nm, foi bastante modificado, mostrando uma diminuição da intensidade em regiões do espectro características da absorção do Nd POT. 3+, indicando a ocorrência de um processo de transferência de energia dos íons Cr POT. 3+ para os íons Nd POT. 3+ nos vidros aluminoboratos de bário, à temperatura ambiente. Os espectros de fluorescência e excitação dos vidros duplamente dopados com cromo e neodímio mostraram o efeito de antiressonâncias de Fano, com o deslocamento de Lamb dos vales associados ao neodímio sobre do Cr POT. 3+. / Barium aluminoborate glass samples containing chromium impurities, presenting Cr3- , Cr5- e Cr6+ íon amounts determined by the oxidizing or reducing melting conditions, have been prepared and characterized by Optical Absorption (OA), fluorescence and Electron Paramagnetic Resonance (EPR) techniques. The reducing conditions necessary to obtain glasses having mainly Cr3+ íons were satisfied with the addition of 0.6 wt% of Sb2 O3 to the batch. In glasses containing antimony, the 4T2 band is wider and shifted towards the higher wavelengths in relation to glass containing only chromium as additional impurity. The Racah parameter B and the ligand field intensity L1 were determined, yielding B = 759 cm-1 and L1 = 15800 cm-1 for the chromium- and antimony-doped glass, and B = 736 cm-1 and L1 = 16150 cm-1 for glass containing only chromium impurity. Fano antiresonances were observed in the OA spectra, better defined in the samples without antimony. The RPE spectra show that the Cr3- ions are preferentially located at distorted octahedral sites. An absorption line was observed at g = 5. 15 and it has been noted also the presence of Cr3+ pairs characterized by a line component at g = 2.0. With the addition of neodymium, the OA and EPR spectra of Cr3+ did not change, but the fluorescence spectrum observed at 776 nm was considerably modified, indicating the occurrence of an energy transfer process from Cr3+ to Nd3- íons in barium aluminoborate glasses at room temperature. The fluorescence and excitation spectra of glasses doped with chromium and neodymium have shown the Fano antiresonance effect, with the Lamb shift of the valleys associated to neodymium over the emission bands ofCr3+.

Polybutadiene, the homopolymer of 1,3-butadiene, is a synthetic rubber especially important in the production of tires. Industrially, it is polymerized using multi-site catalysts that do not offer significant control over molecular weight distribution resulting in polymers with poor mechanical properties. Single-site polymerization of 1,3-butadiene results in narrow molecular weight distribution and thus increased impact resistance and durability. Complexes of chromium and neodymium bearing bis-phosphinimine pincer ligands have been synthesized and studied for their behavior in 1,3-butadiene polymerization in combination with methylaluminoxane. The complexes that were active produced highly cis-1,4-polybutadiene with high molecular weight and narrow polydispersities. The co-polymerization of acrylonitrile and 1,3-butadiene with the bis-phosphinimine chromium (III) complexes and methylaluminoxane to produce nitrile-butadiene rubber was also explored. The insertion of 1,3-butadiene into nickel-methyl and nickel-hydride complexes bearing the bis-phosphinimine pincer ligands was examined using nuclear magnetic resonance spectroscopy and will also be discussed.