This research introduces tellurium oxide (TeO2) glass doped with optically active erbium ions (Er3+) as an active oxide cladding material for silicon-on-insulator (SOI) waveguides for realization of a silicon-based erbium-doped waveguide amplifier (EDWA) for integrated optics. Optical amplification of this nature is enabled by energy transitions, such as stimulated absorption and emission, within the shielded 4f shell of the rare-earth atomic structure caused by excitation from photons incident on the system. Er3+ ions are doped into the TeO2 film during deposition onto the SOI waveguides using a reactive magnetron co-sputtering system operated by McMaster’s Centre for Emerging Device Technologies (CEDT). Prior to fabrication, the waveguides are designed using photonic CAD software packages, for optimization of the modal behaviour in the device, and Matlab, for characterization of the optical gain performance through numerical analysis of the rate and propagation equations of the Er3+-based energy system. Post fabrication, the waveguide loss and gain of the coated devices are experimentally measured. The fabricated waveguide amplifier produces a peak signal enhancement of 3.84 dB at 1533 nm wavelength for a 1.7 cm-long waveguide device. High measured waveguide losses (> 10 dB/cm) produce a negative internal net gain per unit length. However, the demonstration and implementation of an active rare-earth doped cladding material on a silicon waveguide is successful, which is a major step in developing integrated optical amplifiers for conventional silicon photonics platforms. / Thesis / Master of Applied Science (MASc)

Many literatures have been published recently regarding the recovery of REEs from coal-related materials, such as coal waste, acid mine drainage, and coal combustion ash. The recovery of REEs from coal waste has been investigated by the author in recent years, and it was found that after calcination at 600 ℃ for 2 h, a significant improvement in REE recovery can be achieved. In order to reveal the mechanisms of the enhanced REE recovery after calcination, coal waste samples from two different seams, i.e., Western Kentucky No. 13 and Fire Clay, were selected to investigate the modes of occurrence of REEs. Scanning electron microscopy- and transmission electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS and TEM-EDS) analyses were conducted to investigate the mineralogy of REEs in two coal waste samples. Totally, 49 and 50 REE-bearing particles were found from the SEM specimens of Western Kentucky No. 13 and Fire Clay coal waste samples, respectively. Based on the elemental composition analyses and TEM-EDS characterization, it was found that apatite, monazite, and crandallite-group minerals were the major light REE (LREE) carriers, while the heavy REEs (HREE) primarily occurred in zircon and xenotime in these two coal waste samples. Further analyzing the REE content and number of REE-bearing particles, it was confirmed that monazite, xenotime, and crandallite-group minerals were the dominant contributors to the total REE (TREE) contents in both materials. In addition to the mineralogy of REEs, the morphology of REE-bearing particles was also investigated. The SEM images suggested that the particle size of most REE-bearing particles was less than 5 μm. Moreover, not only completely liberated particles, but particles encapsulated by the host minerals present in the two coal waste samples. To identify the changes of mineralogy of REEs after recovery, the leaching solid residues of the raw and calcined coal waste samples were also characterized by SEM-EDS analysis. After REE recovery, the same REE mineralogical results were observed from the leaching residues of the raw coal waste samples. However, as for the calcined samples, the crandallite-group minerals disappeared. These results suggested that the crandallite-group minerals were decomposed into easy-to-leach forms after calcination at 600 ℃, thus leading to the improved REE recovery. Moreover, the number of REE-bearing particles (N) found from per area of the calcined leaching residue was confirmed to be larger compared to that of the raw ones. A combination analysis of these results indicated that two mechanisms of the enhanced REE recovery after calcination can be confirmed: (1) decomposing the crandallite-group minerals into more soluble species; and (2) promoting the liberation of the REE-bearing particles encapsulated in the host minerals. The thermal decomposition of crandallite-group minerals was mainly responsible for the enhanced REE recovery from coal waste. However, as a result of the complex isomorphic substitutions and association characteristics, it is difficult to collect a pure endmember of crandallite-group mineral for characterization. Therefore, florencite-(Ce) was synthesized in this study. X-ray diffraction (XRD), SEM-EDS, TEM, thermogravimetric and differential thermal analyses (TGA-DTA), and acid leaching tests were conducted on the synthesized product. The results showed that the variation in Ce leaching recovery corresponded to the phase transformation of florencite. The gradual transformation of florencite from a crystalline mineral into an amorphous phase resulted in the increases in the solubility of Ce. In addition, the thermal transformation of florencite was an independent reaction, which was not interfered by the host materials, such as kaolinite and coal waste. / Doctor of Philosophy / Coal waste has been identified as a promising alternative source of rare earth elements (REEs). This study showed that calcination can significantly improve the REE recovery from coal waste materials. Scanning electron microscopy- and transmission electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS and TEM-EDS) analyses were conducted to investigate the mineralogy of REEs in two coal waste samples. The results indicated that the REEs mainly present as apatite, zircon, monazite, xenotime, and crandallite-group minerals in the coal waste samples. However, after REE recovery, the crandallite-group minerals disappeared from the calcined coal waste samples. Therefore, it can be confirmed that the calcination treatment resulted in the solubility improvement of crandallite-group minerals in coal waste samples. In order to further investigate the crandallite-group minerals, florencite was synthesized and subjected to a series of characterizations. The results suggested that the thermal phase transformation of florencite from crystalline into amorphous state resulted in the solubility improvement.

Acid mine drainage (AMD) forms when sulfur bearing rocks such as pyrite, are exposed to air and water. The oxidation of these minerals leads to the generation of sulfuric acid, which in turn mobilizes metals such as iron, aluminum, manganese, and others. If left untreated, AMD can cause severe harm to the surrounding ecosystem. By law, mining companies are required to treat AMD, often by oxidizing the contaminated water, raising the pH with a chemical additive, and precipitating the metals out of solution. Recent studies at West Virginia University and Virginia Tech have shown that AMD and the treatment precipitates (AMDp) are enriched in rare earth elements (REEs). Given the importance of REEs to modern technology, as well as potential supply restrictions, subsequent research has attempted to identify promising methods to extract and recovery REEs from AMD and AMDp. Prior studies have shown that the physical characteristics of AMDp can vary considerably from site to site, and a robust processes scheme must account for any site-specific disparities. To better understand the inherent variability of AMDp, a scientific study was commissioned to investigate a standard method of characterizing AMDp for the optimization of rare earth extraction processes. The tests developed in this work define the total acid dose needed to dissolve AMDp at various target pH points. Through the course of the study, over 150 unique AMDp samples were evaluated, and comparative analyses were conducted on samples from different sites as well as replicate samples from the same sites. The resultant dataset was analyzed using an empirical model, and a statistical analysis was conducted to correlate the model parameters and other AMDp physical properties. Relationships between elemental assays, moisture, and fitting parameters of the empirical models were found. These results ultimately led to a recommendation for future treatment of AMD and prospective sites. / MS / Acid mine drainage (AMD) is a longstanding environmental issue that is caused when sulfur-bearing rocks are exposed to the environment during the mining process. By law, companies are required to treat AMD prior to discharging the water back into the environment. This treatment process creates a waste byproduct, AMD precipitate, that largely consists of metal hydroxides, including iron, aluminum, manganese, and others. Historically, AMD precipitate has been considered an undesirable waste that must be carefully disposed either in old mine workings or in permanent storage cells. However, recent research has shown that AMD precipitate contains elevated concentrations of rare earth elements (REEs). REEs are a group of chemically similar elements that are well known for their use in several modern technologies, including magnets, catalysts, glasses, light-weight metal alloys, and other high-tech uses. REEs are often sparsely concentrated in nature and rarely form ore deposits of a commercial grade. As a result, several private companies and government agencies have sought alternative sources of REEs. Prior research has shown that AMD precipitate may be a suitable alternative source; however, the chemical and physical nature of AMD varies considerably between different sites. This research seeks to utilize a standard characterization test to identify the characteristics of AMD precipitate that ultimately dictate process amenability. Throughout the course of the study, over 150 unique AMD precipitate samples were analyzed, and the cumulative results show which class of sites constitute the most promising prospecting targets.

Sediment is a major source of water quality impairment in streams, rivers and lakes in the US. However, sediment fate and transport in small streams is poorly understood. Previous attempts to characterize sediment transport often insufficiently represented the physical and chemical sediment properties and lacked spatial and/or temporal resolution. Therefore, there is a need to develop better sediment tracers, for which rare earth element (REE)-labeled sediment is examined as an alternative. The objectives of this study were to: 1) assess the adsorption of REEs to natural soils and ensure their reliability as a tracer in a fluvial environment; and 2) evaluate the efficacy of utilizing REE-labeled sediment to quantify fate and transport in a second-order stream during a series of storm events. Two natural stream bank soils from Stroubles Creek in Virginia were labeled with the REEs lanthanum and ytterbium. The REEs adsorbed equally to both soils and had minimal desorption after several washes with stream water. This suggests that REEs form a dependable natural sediment tracer and sufficiently label natural soils for use in a sediment tracing study. During two storm events, two unique REE tracers were injected into Stroubles Creek. These tracers were detected at varying discharges and sediment loads in bed and suspended sediment samples up to 875 m downstream. REE tracers proved to be an ideal tracer for detecting sediment fate and transport in a small stream during a series of storm events and hold great potential for evaluating best management practices and sediment transport models. / Master of Science

Rare Earth elements (REEs) are economically important due to their critical applications within multiple industries. This study investigates the Spruce Pine district of North Carolina, testing the economic feasibility of repurposing current mine waste tailings as a rare earth element resource. Spruce Pine is home to several active quartz and feldspar mining operations, with large waste tailing piles generated during the separation process for quartz and feldspar. The mineralogy, composition, and REE budget of the tailings was examined to assess the economic viability of rare earth element extraction. The local geology includes a series of muscovite class pegmatites of Devonian age (390 Ma), intruded into the primarily amphibolite-grade units of the Ashe and Alligator Back formations (Wood, 1996). The waste tailing piles of two on-going quartz mining operations were sampled to evaluate the potential economic feasibility of rare earth element extraction from key accessory phases, including apatite, remaining from the initial separation process. Sample characterization utilized laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), X-ray fluorescence (XRF), energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). The results of this investigation support the conclusion that, at the current recovery rate, price of rare earth elements, and cost of refinement, economic recovery of REE from the studied tailings is not viable. However, yttrium and dysprosium offer the highest potential for economic recovery. If some combination of improvements to the extraction process, reduction in refinement cost, or increases in price occur, yttrium and dysprosium are sufficiently abundant that extraction could become economically viable. / Master of Science / Rare Earth elements (REEs) are comprised of the Lanthanide series of elements as well as yttrium and scandium. REEs are economically important due to their critical applications within multiple industries. Current uses include electronics, magnets, lasers, electric motors, optical fibers, nuclear reactor control rods, visual displays, etc. Although the demand for REEs is high, the current sourcing of REEs is quite scarce. This study investigates the Spruce Pine district of North Carolina, testing the economic feasibility of repurposing current mine waste tailings as a rare earth element resource. Spruce Pine is home to several active quartz and feldspar mining operations, with large waste tailing piles generated during the separation process for quartz and feldspar. The mineralogy, composition and REE budget of the tailings was examined to assess the economic viability of rare earth element extraction. The waste tailing piles of two on-going quartz mining operations were sampled to evaluate the potential economic feasibility of rare earth element extraction from key accessory phases, including apatite, remaining from the initial separation process. The results of this investigation support the conclusion that, at the current recovery rate, price of rare earth elements, and cost of refinement, economic recovery of REE from the studied tailings is not viable. However, yttrium and dysprosium offer the highest potential for economic recovery. If some combination of improvements to the extraction process, reduction in cost of refinement, or increase in price were to occur, yttrium and dysprosium are sufficiently abundant that extraction could become economically viable.

The goal of this research was the fabrication of thin films with magneto-optic (MO) properties. Accomplishment of this task was achieved via sol-gel processing of rare-earth and aluminum substituted yttrium-iron garnet (RxY3-xAlyFe5-yO12, R,Al:YIG), where R= Bi, Gd, Er, Ho. Detailed are the processing conditions, parameters and results leading to R,Al:YIG films with MO response. Success was attained with a 0.25M Gd,Al:YIG solution spin coated for 120 seconds at 3500rpm onto a (111) gadolinium gallium garnet (GGG) substrate and calcinated at 900°C for 4 hours. Samples were characterized via x-ray diffraction (XRD), magneto-optical loop tracer, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), profilometry and optical microscopy. / Master of Science

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Neste trabalho apresentamos uma investigaÃÃo dos compostos RVO4 (onde R = Sm, Ho, Yb e Lu) e La1-xCexPO4 (onde x = 0,00, 0,04, 0,16, 0,22, 0,32 e 1,00) atravÃs da tÃcnica de espalhamento Raman. Medidas de espalhamento Raman polarizadas foram realizadas nos compostos RVO4 para obter uma descriÃÃo dos fÃnons a temperatura ambiente melhor do que aquelas publicadas anteriormente na literatura. Observamos que a freqÃÃncia da maioria dos fÃnons aumenta com o aumento do nÃmero atÃmico (Z) de R. Este comportamento resulta da contraÃÃo da rede quando R vai de La atà Lu. Por outro lado, devido Ãs dimensÃes e forma dos compostos La1-xCexPO4, medidas de espalhamento Raman nÃo-polarizadas foram usadas para obter seus espectros de fÃnons a temperatura ambiente. Nenhuma mudanÃa apreciÃvel foi observada, indicando que a rede do composto LaPO4 nÃo sofre modificaÃÃes considerÃveis por causa da dopagem de Ce. Contudo alguns fÃnons extras ou adicionais foram observados. A origem desses modos advÃm, provavelmente, da ativaÃÃo de modos infravermelho causadas por quebras de regras de simetria. / In this work we present a Raman investigation of RVO4 (where R = Sm, Ho, Yb and Lu) and La1-xCexPO4 (where x = 0,00, 0,04, 0,16, 0,22, 0,32 and 1,00) compounds. Polarized Raman scattering measurements were carried out in the RVO4 compounds to obtain a better description of the room temperature phonons than those previously reported in literature. We observe that the frequencies of most of phonons increase with increasing atomic number (Z) of R. This behavior results from the lattice contraction when R goes from La to Lu. On the other hand, due to their dimensions and shape, unpolarized Raman scattering was used to investigate the room temperature phonon spectra of La1-xCexPO4 compounds. No appreciable changes were observed, indicating that the LaPO4 lattice is not substantially modified by Ce doping. However, some extra or additional phonons were observed. The origin of these modes comes probably from the activation of infrared modes due to the breakdown of symmetry rules.

Master of Science / Department of Geology / Matthew Totten / Oil production in Kansas has a long history with plays being found on all sides of the state. The source of Kansas’s hydrocarbons has been traditionally thought to be outside the state due to low thermal maturity and the shallow burial of potential source rocks within Kansas. This research addresses the question regarding the source of the oil in Kansas, at least within a small geographic area of roughly 146mi[superscript]2. The Spivey-Grabs-Basil Field has been one of the more successful fields within the state of Kansas since the 1960’s. This field is compartmentalized and offers a natural laboratory in which to conduct the field’s first formal oil-source rock correlation since oils are locked into place. While the main focus of this research relies heavily on pyrolysis and GCMS for biomarker analysis, it also investigates the possibility of using rare earth element (REE) concentrations as a possible fingerprint of organic matter within a source bed. TOC values of the Chattanooga shale samples from the Spivey-Grabs-Basil filed range from 0.75 and 3.95 wt. %, well within productive capacity. Pyrograms show both the potential for additional production, and the likely previous expulsion of hydrocarbons. Biomarker concentration percentages between C[subscript]27, C[subscript]28, and C[subscript]29 steranes, as well as pentacyclic terpane ratios compared between crude oil from the Spivey-Grabs-Basil and the Chattanooga shale show a definite genetic relationship. REE values of the organic fraction of the Chattanooga inversely correlate with those of the crude oils, suggesting fractionation during oil generation. After comparison of results with the Woodford shale in Oklahoma, the conclusion of this study is that the Chattanooga shale which underlies the Spivey-Grabs-Basil oil field of southern Kansas is the probable source rock which generated the oil now being produced.

Master of Science / Geology / Matthew W. Totten / The most common practice of typing crude oils utilizes biomarkers to gain insight on the history of the oil. This practice only considers the organic chemistry of the oil, and does not consider the trace element concentrations within the oil. Rare earth element and other trace element concentrations in crude oil might provide further insight into the oil’s source and origin. This study analyzed REE and other trace metal concentrations of crude oil in the Spivey-Grabs field of south-central Kansas through analysis by ICP-MS and ICP-AES that, coupled with visual physical characteristics of oil and FT-IR analysis, could explain the reported “compartmentalization” of the field and provide insight on the origin of the oils. Analysis of physical characteristics of the crude oils suggested the presence of two types of oil, of differing viscosities, in the field. FT-IR confirmed the presence of these two oil types based on functional groups present in the oils. The existence of a high viscosity oil could potentially explain the compartmentalization behavior in the field. PAAS-normalized REE distribution patterns showed a general LREE enrichment, a positive cerium and negative europium anomaly, and a MREE and HREE depletion, but higher viscosity oils showed additional MREE and HREE enrichment. K/Rb values ranged from 2,864 to 44,118, with oils from mixed-viscosity wells having lower ratios overall. K/Rb values of Spivey-Grabs crude oils more closely resembled those of the Lansing-Kansas City formation than the K/Rb values of the Woodford shale and Mississippian formation of the Anadarko basin. Comparing the rare earth element distribution patterns and K/Rb values from this study to those of the Woodford shale suggests the Spivey-Grabs oil originated from a local source and not from the Woodford shale.

Call number: LD2668 .T4 1985 J365 / Master of Science