Crystalline Precipitate Research Articles

INVESTIGATION OF ADSORPTION ABILITY OF DIAMINOMALEODINITRILE ON NICKEL SURFACE BY ELLIPSOMETRIC METHOD

The difficulty of the discharge of nickel ions due to the adsorption of the addition of diaminomeleodinitrile on the electrode surface contributes to the formation of a fine crystalline precipitate with high reflectivity. Therefore, in this work, we studied the adsorption capacity of diaminomeleodinitrile on the surface of nickel from borate buffer solution in the cathodic and anodic regions. The values of its free adsorption energy were determined, which were at a potential of -0.65 V - 39.7 kJ / mol, and at 0.2 V - 66.2 kJ / mol. It was determined that diaminomeleodinitrile has adsorbed on the surface of nickel from borate buffer solution at pH = 7.4 mainly due to the forces of chemical interaction. It has been established that on the oxidized nickel surface, the adsorption of diaminomeleodinitrile begins in the region of lower concentrations compared to the “clean” surface. On average, a monolayer has formed within 60-75 min, while changes in the phase angle of the reflected light are small, due to the small size of the adsorbed molecule. It was determined that on the oxidized surface these changes are more than on the “clean” one. By method of reflective ellipsometry, which allows to measure and analyze the differences in the polarization parameters of a plane polarized light flux incident at an angle on two homogeneous media with different optical properties, the thickness of the resulting monolayer was determined. On an oxidized surface, it was ~ 0.5 nm, and on a “clean” surface, ~ 0.2 nm. When comparing these thicknesses with the size of the diaminomeleodinitrile molecule, it can be assumed that at a potential of 0.2 V, the diaminomeleodinitrile molecules are drawn out at an angle to the nickel surface, and at a potential of -0.65 V they are adsorbed flat on the nickel surface.

Preparation of crystalline mixed rare earth carbonates by Mg(HCO3)2 precipitation method

In acid treatment technology of Baotou mixed rare earth ore, large quantities of ammonia-nitrogen wastewater are produced in the step of ammonium bicarbonate precipitation to transform rare earth sulfate. In this paper, we adopted a green precipitant magnesium bicarbonate (Mg(HCO3)2) to substitute ammonium bicarbonate to eliminate ammonia-nitrogen pollution. The effects of n(HCO3−):n(RE3+), aging temperature and aging time on the crystallization using Mg(HCO3)2 precipitation method were investigated. The results indicate that the rare earths could be completely recovered when n(HCO3−):n(RE3+) is higher than 3.15:1. The crystal water content of rare earth carbonates is affected by the aging temperature. The precipitate has a bad filterability when the aging temperature is over 40 °C. This can be attributed to the less crystallized water molecules of the hydrated rare earth carbonate precipitation. The mixed rare earth carbonates are prone to be crystalline, and have a good filterability at aging temperatures below 40 °C. Meanwhile, the evolution mechanism of crystalline mixed rare earth carbonates is reasonably deduced, the amorphous rare earth carbonates are first dissolute and then recrystallized. Under the optimized aging conditions, the purity of the crystalline precipitate meets the requirements of the fine product standard (GB/T 16479-2008). The filtrated could be used to produce Mg(HCO3)2, thus to realize the recycling of magnesium sulfate.

Infrared Glass–Ceramics with Multidispersion and Gradient Refractive Index Attributes

AbstractInfrared (IR) glass–ceramics (GCs) hold the potential to dramatically expand the range of optical material solutions available for use in bulk and planar optical systems in the IR. Current material solutions are limited to single‐ or polycrystalline materials and traditional IR‐transparent optical glasses. GCs that can be processed with spatial control and extent of induced crystallization present the opportunity to realize an effective refractive index variation, enabling arbitrary gradient refractive index elements with tailored optical function. This work discusses the role of the parent glass composition and morphology on nanocrystal phase formation in a multicomponent chalcogenide glass. Through a two‐step heat treatment protocol, a Ge–As–Pb–Se glass is converted to an optical nanocomposite where the type, volume fraction, and refractive index of the precipitated crystalline phase(s) define the resulting nanocomposite's optical properties. This modification results in a giant variation in infrared Abbe number, the magnitude of which can be tuned with control of crystal phase formation. The impact of these attributes on the GCs' refractive index, transmission, dispersion, and thermo‐optic coefficient is discussed. A systematic protocol for engineering homogeneous or gradient changes in optical function is presented and validated through experimental demonstration employing this understanding.

The structure and nanomechanical properties of amorphous welds made at reduced temperature

Presently, elements made of Fe-based amorphous materials are characterised by small dimensions. The use of the laser welding process will make it possible to increase diameters of parts along with the enhanced applicability of modern materials. To obtain exceptional post-weld properties of a given material, its structure in the heat affected zone (HAZ), the fusion zone (FZ) and in the parent material (PM) should be controlled.An important issue accompanying the welding of bulk metallic glasses (BMGs) is chemical composition of the amorphous phase. The crystallisation process is the most common phenomenon occurring in the HAZ during the welding of iron-based amorphous materials. The essence of the solution to the crystallisation issue consists in the use of laser welding as well as in the application of a cooling system enabling the reduction of temperature. The article presents the crystallisation process and a new solution to the problem.The primary objective of this research work involved the laser welding of specimens at a reduced (sub-zero) temperature and the presentation of the structure and nanomechanical properties of amorphous welds.Because of the metastable nature of welded BMGs and due to the small dimensions of the FZ, a high-resolution transmission electron microscope and a triboindenter equipped with a microscopic attachment were used in structural and properties-related tests. A decrease in temperature of the material subjected to welding was obtained using a specifically designed cooling system based on Peltier modules.The examination of the weld nanostructure revealed that the laser welding of the amorphous material cooled to a temperature of −17 °C enabled the joining of elements without the occurrence of crystalline precipitation. Detailed research revealed the presence of the amorphous phase in the PM, FZ and HAZ.

Optimization of Quenching and Tempering Parameters for the Precipitation of M7C3 and MC Secondary Carbides and the Removal of the Austenite Retained in Vanadis 10 Tool Steel

Vanadis 10 steel is a powder metallurgy processed tool steel. The aim of the present study is to analyze the microstructural variation in this steel that takes place when the process variables related to the heat treatments of quenching and tempering are modified. Specifically, the destabilization of austenite, the precipitation of secondary carbides and the amount of retained austenite were analyzed. The research methodology employed was a Design of Experiments (DoE). The percentage and types of precipitated crystalline phases were determined by XRD, while the microstructure was revealed by means of SEM-energy-dispersive X-ray spectroscopy (EDX). The destabilization of austenite was favored by tempering at 600 °C for at least 4 h. These same conditions stimulated the removal of the retained austenite and the precipitation of M7C3 secondary carbides. For the precipitation of MC secondary carbides, it was necessary to maintain the steel at a temperature of 1100 °C for at least 8 h. The highest hardness values were obtained when the tempering temperature was lower (500 °C). Tempering in air or oil did not have a significant influence on the hardness of the steel after double or triple tempering at 500 or 600 °C. These results allow the manufacturers of industrial tools and components that use this type of steel in the annealed state as a material to define the most suitable quenching and tempering heat treatment to optimize the in-service behavior of these steels.

Removal of iodide from water using silver nanoparticles-impregnated synthetic zeolites

Synthetic zeolite-based Ag-nanocomposites were synthesized, characterized and used to remove iodide from aqueous solutions. The results showed high removal efficiency (up to 94.85%) and the formation silver iodide which is stable into the material. The maximum achieved adsorption capacity of the nanocomposites was between 19.54 and 20.44mg/g. The removal mechanism was meticulously studied by taking into account both water chemistry and surface interactions backed by multiple characterization techniques, such as XRD, XRF, SEM/EDX, TEM and BET. The qualitative and quantitative examination of pre- and post-adsorption of nanocomposite samples proved that the anchored silver iodide was formed via oxidation of initial silver nanoparticles followed by reaction with iodide to form a stable crystalline precipitate on the surface of the materials. A diffusion-based adsorption model indicated that the controlling mechanism is a slow intraparticle surface diffusion with diffusion coefficients in the range of 0.37–1.72×10−13cm2/s. The investigation of competing and co-existing anions (Cl−, Br−, CO32−, and CrO42−) on the removal efficiency of iodide demonstrated a negligible effect showing a kinetically favorable precipitation reaction of iodide over other anions.

Direct aqueous carbonation of heat activated serpentine: Discovery of undesirable side reactions reducing process efficiency

This work discloses a possible explanation for the relatively low efficiency and yield observed in direct aqueous carbonation of heat activated serpentine which remained a critical unanswered question during three decades of ex-situ mineral carbonation research and development. The discovery of undesirable side reactions, occurring during direct aqueous carbonation of heat activated serpentine has been reported and investigated in detail. These reactions result in the reformation of crystalline serpentine and precipitation of amorphous magnesium silicate hydroxide phase/s on the surface of reacting feed particles. Reformation of serpentine occurs under relatively mild conditions (in terms of pressure and temperature) and after only a few minutes of reaction which is in stark contrast to the conditions and rates which occur during geological serpentinisation and other laboratory studies. Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy analyses showed precipitation of amorphous magnesium silicate hydroxide phase/s during carbonation process. Fourier Transform Infrared Spectroscopy and Thermogravimetric analyses identified and quantified free and hydrogen bonded hydroxyls of silanol groups in the structure of the reaction products when heat activated lizardite and antigorite were carbonated. The growth of a crystalline serpentine phase was confirmed and quantified by X-ray Diffraction and Thermogravimetric analyses in the reaction products when heat activated antigorite was used a feed.

Evaluation of rare‐earth element dopants (Sm and Er) on ablation resistance of ZrB2/SiC‐sintered billets

AbstractIn this paper, how rare‐earth element dopants (samarium and erbium) affect the scale development of sintered ZrB2/SiC (ZBS) samples during ablation testing was investigated. ZBS billets with five different Sm to Er ratios, with a nominal total amount of 3 mol% dopant incorporated, were prepared by sintering in vacuum to 2000°C and subjected to 60 and 300 seconds ablation cycles. Differences in surface temperatures between ZBS samples with different dopant ratios suggests differences in spectral absorptance/emittance between each of the five compositions investigated. ZBS billets co‐doped with Sm and Er form a beneficial c1‐(Sm/Er)0.2Zr0.8O1.9 oxide scale as the majority phase, with some glassy phase observed. The crystalline c1‐(Sm/Er)0.2Zr0.8O1.9 oxide scale is more thermally stable than the m‐ZrO2 oxide scale typically formed in oxidized ZBS systems, resulting in a more adherent oxide scale to the unreacted material. The crystalline oxide scale and the amorphous phase are formed by a convection cell mechanism where the c1‐(Sm/Er)0.2Zr0.8O1.9 crystalline islands precipitate, grow, and coalesce.

Crystallization of schoenite from saturated salt solutions

Influence of cooling and mixing rate on the process of schoenite crystallization from saturated salt solutions was investigated in laboratory conditions. It was established that as the system’s cooling rate and mixing speed increase, a significant decrease of the induction period of schoenite crystallization is observed. Fivefold increase of the cooling rate increases sizes of schoenite crystals by an average of 2.5–3.0. Mixing rate increase leads to the formation of a fine crystalline precipitate (crystal size 10−20 μ m).

Crustacean larval factor shares structural characteristics with the insect-specific follicle cell protein

Literature on the cuticle formation in larval stages of the diverse group of decapod crustaceans is lacking, as opposed to a wealth of knowledge in several insect groups. Here we provide the first glimpse of the cuticular organisation in larvae of the eastern spiny lobster Sagmariasus verreauxi. A bioinformatic approach applied to S. verreauxi transcriptome through metamorphosis identified for the first time a small secreted protein with multiple isoforms that is highly expressed in crustacean larvae. This protein, named crustacean larval factor (Clf) shares structural characteristics with insect follicle cell protein 3 (FCP3), an insect-specific, rapidly evolving protein, with spatial-temporal regulated expression that is restricted to follicular cells during the production of the vitellin coat. Furthermore, we identified the FCP3 domain in additional structural proteins in multiple arthropod groups. Recombinant Clf inhibited in vitro calcium carbonate crystalline precipitation, in keeping with the finding that the spiny lobster larval cuticle is mainly composed of amorphous calcium carbonate. In addition, the recombinant Clf was shown to bind chitosan. Taken together, this research identifies two novel structural domains with lineage-specific expansion across arthropods. In crustaceans, Clf is found predominantly in larvae and the spatial-temporal regulated FCP3 factor occurs as a domain identified in multiple structural proteins across arthropods. Given the shared ten cysteines backbone between the Clf and FCP domains, a shared evolution is suggested and should be further explored.

Optical, structural and luminescence properties of oxyfluoride phosphate glasses and glass-ceramics doped with Yb3+

The impact of Al2O3 and Y2O3 addition on the structure, Yb3+ luminescence and crystallization is investigated for glasses in the P2O5-SrO-Na2O system. Although the addition of Al2O3 and Y2O3 leads to a more connected phosphate network as evidenced using IR and Raman spectroscopies and increases the glass transition temperature, it does not affect strongly the site of the Yb3+. The addition of Al2O3 and Y2O3 slightly decreases the rate of the glass crystallization. Surface crystallization occurs upon heat treatment. Crystallization was confirmed by the presence of sharp peaks in the XRD patterns of the glasses. Independently of the glass composition, different crystalline phases precipitate in the glasses upon heat treatment. The precipitation of the Na1O7P2Yb1 crystal phase leads to an increase of the excited state 2F5/2 lifetime of Yb3+ and also of the bandwidth of the Yb3+ emission band centered at 1 μm.

Crystallization Products and Structural Characterization of CaO-SiO₂-Based Mold Fluxes with Varying Al₂O₃/SiO₂ Ratios.

During the casting of high aluminum steel, the dramatic increase in the Al2O3/SiO2 ratio is inevitable, resulting in significant changes of the crystallization behavior, which would result in heat transfer and lubrication problems. Crystallization products and structure characterization of glassy CaO-SiO2-based mold fluxes with different Al2O3/SiO2 ratios were experimentally investigated using a differential scanning calorimetry technique and Raman spectroscopy. With increasing Al2O3/SiO2 ratios, the following results were obtained. The crystallization temperature and the crystallization products are changed. With increasing Al2O3/SiO2 ratios from 0.088 to 0.151, the crystallization temperature first increases greatly from 1152 °C to 1354 °C, and then moderately increases. The crystallization ability of the mold flux is strengthened. The species of the precipitated crystalline phase change from two kinds, i.e., Ca4Si2O7F2 and Ca2SiO4, to four kinds, i.e., Ca4Si2O7F2, Ca2SiO4, 2CaO·Al2O3·SiO2 and Ca12Al14O32F2, the crystallization ability of Ca4Si2O7F2 is gradually attenuated, but other species show the opposite trend. The results of Raman spectroscopy indicate that Al3+ mainly acts as a network former by the information of [AlO4]-tetrahedral structural units, which can connect with [SiO4]-tetrahedral by the formation of new bridge oxygen of Al–O–Si linkage, but there is no formation of Al–O–Al linkage. The linkage of Al–O–Si increases and that of Si–O–Si decreases. The polymerization degree of the network and the average number of bridging oxygens decrease. Further, the relatively strong Si–O–Si linkage gradually decreases and the relatively weak Al–O–Si gradually increases. The change of the crystalline phase was interpreted from the phase diagram and structure.

Formation of Poorly Crystalline and Amorphous Precipitate, a Component of Infectious Urinary Stones: Role of Tetrasodium Pyrophosphate

The present study concerns an important topic regarding the search for new, improved, and effective methods of preventing the development of infectious urinary stones. In this article, the effect of tetrasodium pyrophosphate (TSPP) on the formation of a poorly crystalline and amorphous precipitate in artificial urine in the context of infectious urinary stone formation is studied. The spectrophotometric results suggest that TSPP presence shifts the formation of the poorly crystalline and amorphous precipitate (PCaAP) toward lower pH, which means that PCaAP is formed earlier. In other words, TSPP promotes the formation of PCaAP. Additionally, TSPP causes the formation of calcium pyrophosphate. These results are confirmed by X-ray diffraction and energy dispersive X-ray studies. The experimental results obtained are explained on the basis of theoretical chemical speciation analysis of chemical complexes formed in artificial urine.

Structural and optical properties of Gd+3 doped Bi2O3–GeO2 glasses and glass-ceramics

The gadolinium doped Bi2O3–GeO2 glasses and glass-ceramics have been synthesized by melt quenching and heat treatment. Structural and optical properties of prepared glasses and glass-ceramics have been examined by x-ray diffraction (XRD), Fourier transform infrared, absorption and emission measurements. XRD results have shown that the precipitated crystalline phases in glass-ceramics samples are Bi2GeO5, Bi2Ge3O9 and Bi4Ge3O12. [BiO3] and [GeO4] units are the main structural units present in Bi2O3–GeO2 glass and glass-ceramic network confirmed by IR spectra. Optical band gap values of prepared glass and glass-ceramic systems obtained from absorption spectra vary from 2.01 to 3.34 eV. The optical band gap values of glasses are larger than glass-ceramics. Bi2O3–GeO2 glass-ceramics have higher density values than glasses and densities present an increase with the elevated Gd3+ content. It is suggested that the luminescence under 366 nm excitation has been ascribed to different Bi-related emission centers. The CIE color coordinates and CCT values obtained under 366 nm excitation confirm that the Gd3+ doped bismuth germanate glasses and glass-ceramics exhibit white light emission. The most promising material for white light emitting applications within our research is found to be GC-2Gd with coordinates of (0.327, 0.314) and a CCT of 5753 K.

Barite formation in the ocean: Origin of amorphous and crystalline precipitates

Ocean export production is a key constituent in the global carbon cycle impacting climate. Past ocean export production is commonly estimated by means of barite and Barium proxies. However, the precise mechanisms underlying barite precipitation in the undersaturated marine water column are not fully understood. Here we present a detailed mineralogical and crystallographic analysis of barite from size-fractionated particulate material collected using multiple unit large volume in-situ filtration systems in the North Atlantic and the Southern Ocean. Our data suggest that marine barite forms from an initial amorphous phosphorus-rich phase that binds Ba, which evolves into barite crystals whereby phosphate groups are substituted by sulfate. Scanning electron microscopy observations also show the association of barite particles with organic matter aggregates and with extracellular polymeric substances (EPS). These results are consistent with experimental work showing that in bacterial biofilms Ba binds to phosphate groups in both cells and EPS, which promotes locally high concentrations of Ba leading to saturated microenvironments favoring barite precipitation. These results strongly suggest a similar precipitation mechanism in the ocean, which is consistent with the close link between bacterial production and abundance of Ba-rich particulates in the water column. We argue that EPS play a major role in mediating barite formation in the undersaturated oceanic water column; specifically, increased productivity and organic matter degradation in the mesopelagic zone would entail more extensive EPS production, thereby promoting Ba bioaccumulation and appropriate microenvironments for barite precipitation. This observation contributes toward better understanding of Ba proxies and their utility for reconstructing past ocean export productivity.This article is part of a special issue entitled: “Cycles of trace elements and isotopes in the ocean – GEOTRACES and beyond” - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González.

Impact of bacteria on aggregation of crystalline and amorphous components of infectious urinary stones

Infectious urinary stones consist of an agglomerate of bacteria, highly crystalline struvite, and poorly crystalline and amorphous precipitate (PCaAP). The paper describes an experimental study on the agglomeration of PCaAP in the presence and absence of bacteria of the Proteus mirabilis species, in which blind studies are done with bacterial macromolecules with and without lipopolysaccharide. The formation of struvite is avoided by using Mg-free artificial urine. Optical microscopy methods and zeta potential measurements both confirm that the bacterial lipopolysaccharides are the key factors promoting agglomeration, besides the bacterially induced pH change which leads to precipitation in the first place.

Hydroxycobalamin catalyzes the oxidation of diethyldithiocarbamate and increases its cytotoxicity independently of copper ions

It is known that some metals (Cu, Zn, Cd, Au) markedly increase the toxic effect of thiocarbamates. It was shown in the present study that hydroxycobalamin (a form of vitamin B12, HOCbl), which incorporates cobalt, significantly enhances the cytotoxicity of diethyldithiocarbamate (DDC), decreasing its IC50 value in tumor cells three to five times. The addition of HOCbl to aqueous DDC solutions accelerated the reduction of oxygen. No hydrogen peroxide accumulation was observed in DDC + HOCbl solutions; however, catalase slowed down the oxygen reduction rate. Catalase as well as the antioxidants N-acetylcysteine (NAC) and glutathione (GSH) partially inhibited the cytotoxic effect of DDC + HOCbl, whereas ascorbate, pyruvate, and tiron, a scavenger of superoxide anion, had no cytoprotective effect. The administration of HOCbl into DDC solutions (> 1 mM) resulted in the formation of a crystalline precipitate, which was inhibited in the presence of GSH. The data of UV and NMR spectroscopy and HPLC and Mass Spectrometry (LC/MS) indicated that the main products of the reaction of DDC with HOCbl are disulfiram (DSF) and its oxidized forms, sulfones and sulfoxides. The increase in the cytotoxicity of DDC combined with HOCbl occurred both in the presence of Cu2+ in culture medium and in nominally Cu-free solutions, as well as in growth medium containing the copper chelator bathocuproine disulfonate (BCS). The results indicate that HOCbl accelerates the oxidation of DDC with the formation of DSF and its oxidized forms. Presumably, the main cause of the synergistic increase in the toxic effect of DDC + HOCbl is the formation of sulfones and sulfoxides of DSF.

<i>In Situ</i> Hydration of Sulfoaluminate Cement Mixtures Monitored by Synchrotron X-Ray Diffraction

Mixtures of calcium sulfoaluminate and Portland clinkers with gypsum were hydrated with deionized water. The pastes were introduced in 0.7 mm borosilicate capillary tubes and kept at 40 oC while diffraction patterns were collected every 35 s for approximately 3 hours with a monochromatic radiation of 12 keV at the XRD1 beamline of the Laboratório Nacional de Luz Síncrotron (LNLS) in Campinas, SP - Brazil. The main crystalline phases (C2S, C3S, ettringite, ye’elemite and gypsum) involved in the hydration were quantified by Rietveld analysis. The most noticeable fact was the absence of portlandite as a crystalline precipitate, most likely due to the capture of calcium ions to form ettringite.

Impact of Drug Physicochemical Properties on Lipolysis-Triggered Drug Supersaturation and Precipitation from Lipid-Based Formulations.

In this study we investigated lipolysis-triggered supersaturation and precipitation of a set of model compounds formulated in lipid-based formulations (LBFs). The purpose was to explore the relationship between precipitated solid form and inherent physicochemical properties of the drug. Eight drugs were studied after formulation in three LBFs, representing lipid-rich (extensively digestible) to surfactant-rich (less digestible) formulations. In vitro lipolysis of drug-loaded LBFs were conducted, and the amount of dissolved and precipitated drug was quantified. Solid form of the precipitated drug was characterized with polarized light microscopy (PLM) and Raman spectroscopy. A significant solubility increase for the weak bases in the presence of digestion products was observed, in contrast to the neutral and acidic compounds for which the solubility decreased. The fold-increase in solubility was linked to the degree of ionization of the weak bases and thus their attraction to free fatty acids. A high level of supersaturation was needed to cause precipitation. For the weak bases, the dose number indicated that precipitation would not occur during lipolysis; hence, these compounds were not included in further studies. The solid state analysis proved that danazol and griseofulvin precipitated in a crystalline form, while niclosamide precipitated as a hydrate. Felodipine and indomethacin crystals were visible in the PLM, whereas the Raman spectra showed presence of amorphous drug, indicating amorphous precipitation that quickly crystallized. The solid state analysis was combined with literature data to allow analysis of the relationship between solid form and the physicochemical properties of the drug. It was found that low molecular weight and high melting temperature increases the probability of crystalline precipitation, whereas precipitation in an amorphous form was favored by high molecular weight, low melting temperature, and positive charge.

Impact of rare earth ion size on the phase evolution of MoO3-containing aluminoborosilicate glass-ceramics

Transition metal and rare earth (RE) elements are important fission products present in used nuclear fuel, which in high concentrations tend to precipitate crystalline phases in vitreous nuclear waste forms. Two phases of particular interest are powellite (CaMoO4) and oxyapatite (Ca2RE8(SiO4)6O2). The glass compositional dependencies controlling crystallization of these phases on cooling from the melt are poorly understood. In the present study, the effect of rare earth identity and modifier cation field strength on powellite and apatite crystallization were studied in a model MoO3-containing alkali/alkaline-earth aluminoborosilicate glass with focus on (1) influence of rare earth cation size (for RE3+: Ce, La, Nd, Sm, Er, Yb) and (2) influence of non-framework cations (RE3+, Mo6+, Na+, Ca2+). Quenched glasses and glass-ceramics (obtained by slow cooling) were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray absorption spectroscopy (XAS), and electron probe microanalysis (EPMA). All samples were X-ray amorphous upon quenching, except the Ce-containing composition which crystallized ceria (CeO2), and the sample devoid of any rare earth cations which crystallized powellite. On heat treatment, powellite and oxyapatite crystallized in the majority of the samples, with the former crystallizing in the volume and the latter on the surface. The EPMA results confirmed a small concentration of boron in the oxyapatite crystal structure. RE cations were incorporated in the glass, as well as in powellite, oxyapatite, and in the case of Yb3+, keiviite (Yb2Si2O7). Raman spectroscopy showed that the primary vibration band for molybdate MoO42− in the glasses was strongly affected by the ionic field strength of the modifying cations (alkali, alkaline earth, and RE), suggesting their proximity to the MoO42− ions in the glass, though the MoO bond length and coordination according to XAS suggested little local change.