High Rare Earth Research Articles

Energy Efficient Strategies for Processing Rare Earth Permanent Magnets

Due to high magnetic fields causing strong interactions between permanent magnets and other ferromagnetic material, transport and handling of magnetized magnet bodies is challenging. To avoid undesired effects, such as influences on sensitive devices or difficult separation of the single magnets from stack, spacing and shielding of the magnet bodies is required leading to larger package sizes and thus in some cases higher energy demand during transport referred to the transported magnet mass. An optimization of the transport chain can be reached using the software tool presented in this paper. Further magnetizing high coercive rare earth magnets needs strong magnetic fields. To create the necessary field strength, copper coils are used requiring current strengths of several kA. Since the electrical resistance of copper differs from zero, this also means enormous thermal losses. Hence to reduce the losses and to avoid thermal damage of the coil, only short current pulses are applied generated by a pulse magnetizer. However, the efficiency of the process is very poor and lies in the lower per mil range. The presented paper explains the magnetization process in detail with focus on the losses within the magnetization device. Further different material parameters influencing the saturation field strength, such as conductivity, size and diameter to length ratio are presented and possibilities to improve the energy efficiency are shown.

Time-resolved interaction of seawater with gabbro: An experimental study of rare-earth element behavior up to 475 °C, 100 MPa

High metal and rare-earth element (REE) concentrations with unusual (‘atypical’) normalized REE patterns are documented in fluids from active hydrothermal vent fields on the Mid-Atlantic Ridge, 5°S and the East Scotia Ridge. Those fluids show relative enrichment of middle heavy REEs and almost no Eu anomalies in chondrite-normalized patterns. To understand the processes that produce such atypical REE patterns we ran a series of experiments, in which natural bottom seawater or aqueous solutions (NaCl, NaCl–MgCl2, or NaCl–CaCl2) were reacted with gabbro and gabbro mineral assemblages from 300 to 475°C and 40 and 100MPa. These P–T conditions are representative for water–rock interactions in hydrothermal root and discharge zones. Fluid flux variability and kinetics were addressed in the experiments by varying the water-to-rock mass ratio (w/r) from 0.5–10 and using different run durations from 3–720h.Only seawater and synthetic MgCl2-bearing fluid mobilized significant amounts of REEs, Si, Ca, Fe, and Mn from gabbro, from clinopyroxene, and from plagioclase. At 425°C and 40MPa, fluids were initially acidic with pH (25°C) of ∼2 increasing to values between ∼4 and 7 upon progressing reactions. Rare earth element and Fe contents peaked within 3–6h after interaction with gabbroic mineral grains (125–500μm) at w/r of 5 (REEs) and 2–5 (Fe) but decreased with continuing reaction without strong REE fractionation. Most of the REEs that were leached from primary minerals and dissolved in the fluids early became redeposited into solid reaction products after 720h.Contents of dissolved SiO2 were pressure-dependent, being about twofold higher at 100MPa than at 40MPa (425°C) and were below quartz saturation with gabbro and clinopyroxene as solid starting material and close to quartz saturation with plagioclase reactant. However, Si in fluids from the rock-dominated experiments at 100MPa with gabbro (w/r 0.5–1) dropped to very low contents. A concomitant decrease in chlorinity suggests that these changes may be due to the breakdown of olivine and the formation of serpentine and Fe-hydroxy chlorides.Regardless of the starting solid reactants, fluid REE patterns were dominantly controlled by w/r. Atypical fluid REE patterns and high fluid REE contents were obtained at high w/r (⩾5). Whereas typical REE patterns known from many mid-ocean ridge vent fluids, showing relative enrichments of light REEs and a positive Eu anomaly, were obtained at low w/r of 0.5–1. Our results hence clearly show that REE contents and patterns of vent fluids are sensitive to variations in the w/r.

MWCNT reinforced τ-Mn-Al nanocomposite magnets through spark plasma sintering

We herein exploit the inherent benefits of both multi-walled carbon nanotubes (MWCNTs) and spark plasma sintering (SPS) for augmenting the performance of rare-earth free Mn56Al44 permanent magnets through grain refinement and stabilization of τ-phase. A good combination of remanent magnetization, coercivity and energy product values: 42.5 emu/g, 3.22 kOe and 1.92 MGOe; and 45.6 emu/g, 3.64 kOe and 2.26 MGOe were achieved for the SPSed Mn-Al magnets with 1.5 and 2 wt % additions of MWCNTs, respectively. The observed coercivity enhancement in the SPSed Mn-Al/MWCNT nanocomposite magnets is hypothesized to originate from the domain-wall pinning, as a consequence of precipitation of MWCNTs in the form of broken nanotubes and amorphous carbonaceous material at the grain boundaries. Although, a more detailed study is essential to verify the above fact, the present strategy provides a new basis for producing high performance rare earth free Mn-Al permanent magnets in a simpler way using the SPS process.

Simultaneous recovery and separation of rare earth elements in ferromanganese nodules by using Shewanella putrefaciens

Rare earth elements (REEs) are used in various advanced materials including catalysts, alloys, magnets, optics, and lasers. REE resources are unevenly distributed around the world, which continues to cause geopolitical concerns. Thus, securing REE resources has become an important subject for the sustainable development of industry and society. In this study, we investigated ferromanganese (Fe-Mn) nodules and crusts as a REE resource because they contain high REE concentrations and are widely distributed on the seafloor in the Pacific Ocean. We examined recovery of REEs in Fe-Mn nodules by using Shewanella putrefaciens (Fe-reducing bacterium). In this method, Fe-Mn nodule decomposition and REE recovery were achieved simultaneously in a single solution system. Fe-Mn nodules were reductively decomposed in NaCl solution under anaerobic conditions with daily addition of sodium lactate as an electron donor. During the decomposition of Fe-Mn nodule, REEs released from the Fe-Mn nodule were adsorbed on bacterial cells. Light REEs had higher adsorption rates on bacterial cells than heavy REEs, which was possibly due to complexation with sodium lactate and carbonate produced by bacterial activity. Of the conditions studied here, the best REE adsorption rates were obtained with 0.5M NaCl solution at pH7 with daily addition of 1mmol sodium lactate. Most of the REEs adsorbed on the bacterial cells were recovered by leaching with 0.01M HCl. The reductive dissolution of Fe-Mn nodules using Fe-reducing bacteria is a promising environmentally friendly method for recovering REEs from Fe-Mn nodules and crusts.

Post-magmatic solid solutions of CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and REE-bearing epidote in miarolitic pegmatites of Permian Baveno granite (Verbania, central-southern alps, Italy)

CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and rare earth element (REE)-bearing epidote occur as globular aggregates and platy prismatic crystals in miarolitic cavities in a niobium, yttrium, fluorine (NYF) granitic pegmatite at Baveno, Verbania, Southern Alps, Italy. These samples were investigated by means of an electron probe micro-analyser (EPMA) and single-crystal X-ray diffraction. Our EPMA results show that the globular aggregates have the highest REE content in the core portion and decreases to REE-bearing epidote towards the rim whereas the prismatic crystals are characterized by marked oscillatory zoning that have the highest REE contents at the rim of the crystal. The unit-cell parameters of “allanites” have an intermediate unit-cell between CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and REE-free epidote, because reflect the strong chemical heterogeneity of the samples which form complete solid solutions. Hydrothermal fluids control the activity and precipitation of incompatible elements like high field strength elements (HFSE), Sc and REE by hydrous F-rich fluids below the critical temperature which allow to deposit accessory minerals in the cavities with decreasing temperature. The source of REE and Y are the sheet and REE-silicates like siderophyllite-annite, and gadolinite-(Y) which underwent partial to complete decomposition by the activity of aggressive F-rich hydrothermal fluids.

A new discrimination scheme for oceanic ferromanganese deposits using high field strength and rare earth elements

Ferromanganese (Fe-Mn) deposits constitute a ubiquitous mineral type in oceanic settings, with metal (Cu, Ni, Zn, Co, Pt) and rare earth element (REE) enrichments of potential economic interest. Routine analysis of trace elements by ICP-MS has advanced our understanding of the impact of hydrogenetic, diagenetic and hydrothermal processes on the mobility and interaction of high field strength elements (HFSE: Zr and Ti) and REE and yttrium (REY) with Fe-Mn oxyhydroxides. Recent discoveries in the French exclusive economic zone (EEZ) of Wallis and Futuna (southwest Pacific Ocean) have brought new insight into the formation of low temperature (LT) hydrothermal Mn deposits and lead us to reconsider the classification and discrimination diagrams for Fe-Mn deposits and ore-forming processes. Using a suite of LT hydrothermal Fe-Mn crusts from Wallis and Futuna, we investigate how contrasting genetic processes influence the distribution of metals (Mn, Fe, Cu, Ni, and Co), HFSE and REY in hydrogenetic, diagenetic, hydrothermal and mixed-type deposits from different environments in the global ocean. The interaction of the different metal oxide-forming processes indicates that: (i) enrichment of Co, HFSE and REY is favored by hydrogenetic precipitation, (ii) diagenetic processes produce higher Mn, Cu, and Ni concentrations with oxic remobilization in the sedimentary column, while suboxic conditions promote greater Mn and Fe remobilization that competes with the incorporation of Cu and Ni ions in nodules. HFSE and REY derived from seawater are usually low in diagenetic precipitates, which discriminate between hydrogenetic and diagenetic inputs within nodules, (iii) hydrothermal Fe-Mn deposits show strong depletion in HFSE and REY due to rapid formation and high contents of either Fe or Mn oxides. We present a new discrimination scheme for the genetic types of Fe-Mn deposits using a 10∗(Cu+Ni+Co)−100∗(Zr+Y+Ce)−(Fe+Mn)/4 ternary diagram. The use of HFSE and REY in the classification allows for a more robust discrimination of: (i) each ore-forming process with well-delimited fields, without overlap of metal-rich hydrothermal samples and hydrogenetic samples, (ii) oxic and suboxic diagenesis within nodules, (iii) trends between hydrogenetic and diagenetic end-members forming a continuum, and (iv) mixed genetic types such as the presence of hydrothermal particles within hydrogenetic crust layers. Alternatives are also explored to adapt our discriminative diagram to elements measurable by on-board instruments to aid in exploration at sea.

Hybrid electromagnetic shock absorber for energy harvesting in a vehicle suspension

Electromagnetic harvesters need to be designed with a mechanism to amplify the coil relative velocity to ensure compact size and lower weight. This paper discusses a novel technique to use fluid link for velocity amplification in an electromagnetic shock absorber. Incorporation of the fluid amplification significantly improves harvested power, without affecting the system dynamics. Numerical modelling and experimentation of a prototype shock absorber comprising of high energy rare earth magnets have been presented. Peak coil voltage of 0.60–24.2 V was recorded during experimentation on the prototype. Experimental and simulation results validate that incorporation of the fluid amplification link improves the harvested electric power by 9702%. Comprehensive design procedure for better harvesting efficiency and vibration isolation has been discussed. Lastly incorporation of the shock absorber in McPherson strut suspension is illustrated. The real size version will be able to harvest peak power of 18–227 W for the suspension velocities of 0.15–0.4 m/s.

Early Paleozoic subduction processes of the Paleo-Asian Ocean: Insights from geochronology and geochemistry of Paleozoic plutons in the Alxa Terrane

The Alxa Terrane is situated in a key area between the North China and Tarim cratons. Paleozoic magmatic records in this terrane place important constraints on the subduction processes of the southern Paleo-Asian Ocean. New data of zircon U-Pb ages and whole-rock elemental and isotopic data reveal two groups of intermediate to felsic plutons in the Alxa Terrane. One group consists of diorites and granitoids that were emplaced at ca. 460–440Ma and characterized by lower Al2O3/TiO2 ratios and higher TiO2 contents, implying high temperature–low pressure crystallization conditions and a shallow source region. The second group is dominated by granitoids aged at ca. 420–407Ma and displays high Sr and Ba, low Y and high rare earth elements, with very high Sr/Y ratios and mostly positive Eu anomalies. These characteristics imply low temperature–high pressure crystallization conditions and source regions at deep crustal levels where garnet is stable in the residual phase. Both of the two groups are mostly calc-alkaline to high-K calc-alkaline, depleted in Nb, Ta and Ti and enriched in Ba, K and Sr, indicative of an arc affinity most likely related to the southward subduction of the Paleo-Asian Ocean. Zircon εHf(t) and whole-rock εNd(t) values of these magmatic rocks decrease from 458Ma to 440Ma and increase from 417Ma to 407Ma, whereas whole-rock initial 87Sr/86Sr ratios display an opposite trend. Such an isotopic change suggests a tectonic switch from an advancing to a retreating subduction regime at ~407Ma. Synthesized data from this and previous studies suggest that the 460–400Ma magmatic arc in the Alxa Terrane represented the western extension of the Paleozoic arc belt on the northern margin of the North China Craton.

Resolution of rare earth element interferences in fossil energy by-product samples using sector-field ICP-MS

The supply and price of rare earth elements (REEs) have become a concern to many countries in the world, which has led to renewed interest in exploration and recovery of REEs from secondary or waste sources. Potential high REE waste sources that are of particular interest are coal mining, preparation, combustion, and other fossil energy by-products, including those from natural gas production. In this work, we have examined a set of five solid samples from the treatment of produced and flowback water containing elevated concentrations of barium. In order to confirm the correct concentrations of Eu, we studied these materials using sector field inductively coupled plasma mass spectrometry (SF-ICP-MS), which is capable of resolving species of nearly identical masses, including Eu and BaO. While the use of quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) for the REE analysis of most geological sample matrices should pose no problem, the presence of large amounts of Ba, as encountered in water treatment solids from natural gas produced and flowback samples may require SF-ICP-MS for accurate determination of all REEs.

Separation of Rare Earths by Solvent Extraction with an Undiluted Nitrate Ionic Liquid

A solvent extraction system based on the ionic liquid tricaprylmethylammonium nitrate, [A336][NO3], has been investigated for separation of mixtures of rare earth elements (REE) at high total REE concentrations (up to 2 M). The chelating agent EDTA was added to the aqueous nitrate feed solution to increase the separation factors (SFs). This improvement of the SFs is based on the fact that [A336][NO3] extracts the light REE (LREE) stronger than the heavy REE (HREE), whereas a chelating agent forms more stable complexes with the HREE than with the LREE. The combination of these two effects makes that the LREE are even more efficiently extracted than in the absence of a chelating agent. The most efficient separation of the LREE La–Nd from the other REE was obtained using a total initial REE concentration of 1 M, an EDTA concentration of 0.2 M, and a total nitrate concentration of 11 M. Stripping of the extracted REE from the ionic liquid phase could be done using water.

Mineral chemistry of melanite from calcitic ijolite, the Oka carbonatite complex, Canada: Implications for multi-pulse magma mixing

Ti-rich garnet is found within calcitic ijolite from the Oka carbonatite complex in Canada, which is characterized by 58%–73% andradite component (2.12 wt.%–4.18 wt.% TiO2) and classified as melanite. The garnet displays complex zoning and contains abundant high field strength elements (HFSEs) and rare earth elements (REEs). Three groups (I, II, III) have been identified based on their petrographic nature. Compared to groups II and III, Group I garnet cores contain higher TiO2, MgO, HFSE, and REE and lower SiO2 abundances. The distinct chemical and petrographic signatures of the investigated garnets cannot be attributed to simple closed system crystallization, but they are consistent with the multi-pulse magma mixing. Combined with previously reported U-Pb ages for apatite from the calcitic ijolite, at least three stages of magma evolution and subsequent mixing have been involved in the generation of calcitic ijolite at Oka. The early-formed melt that generated Group I garnet core was later mixed with at least two small-volume, more evolved melts. The intermediate stage melt formed the remaining garnet along with some pyroxene, calcite, nepheline, and apatite at 127±3.6 Ma. The youngest, most evolved melt generated the majority of pyroxene, calcite, nepheline, and apatite within the calcitic ijolite at 115±3.1 Ma.

Magma mixing in the Kalaqin core complex, northern North China Craton: Linking deep lithospheric destruction and shallow extension

The widespread Mesozoic magmatism in the North China Craton (NCC) has received considerable attention as a trigger for large scale lithospheric destruction. Here we investigate the Early Cretaceous Jiguanzi adamellite from the northern part of the NCC which is contemporaneous with shallow extensional deformation and deep lithospheric destruction. This intrusion emplaced at ca. 133Ma is located in the foot wall of the Kalaqin metamorphic core complex (MCC), and occurs as a synextensional ring complex with numerous magmatic equigranular (Group 1) and porphyritic (Group 2) enclaves. Hornblende and plagioclase from the host adamellite and xenocrysts of Group 2 enclaves show distinct inverse zoning with Mg- and Ca-rich mantle. The Group 2 enclaves are characterized by plagioclase xenocrysts hosting hornblende, biotite and apatite inclusions, quartz ocelli with fine-grained rim enriched in biotite and hornblende, and poikilitic biotite surrounded by hornblende. Geochemically, the host intrusion is calc-alkaline to alkaline and metaluminous with variable contents of SiO2 (60.70–72.20wt.%), Al2O3 (14.19–17.22wt.%), Na2O+K2O (6.16–9.42wt.%), and Mg# values (28.0–47.7), whereas the Group 2 enclaves exhibit low SiO2 (54.05–55.55wt.%), high Fe2O3 (8.18–8.64wt.%) and TiO2 (2.08–2.28wt.%), and moderate Mg# (44.0–44.1). Both the host intrusion and Group 2 enclaves are enriched in large-ion lithophile and light rare earth elements, and depleted in high field strength elements and heavy rare earth elements except that the latter has lower Ba and high Nb, Ta and Ti contents. The major and trace element contents of the Group 1 enclaves are broadly similar to those of the host intrusion. Analyses of Sr–Nd–Hf isotopes in the host intrusion, and in Group 1 and Group 2 enclaves show (87Sr/86Sr)ihost=0.70600–0.70618, εNd(t)host=−8.2 to −9.6, T2DM(Nd)host=1592–1706Ma, εHf(t)host=−9.2 to −12.0, (87Sr/86Sr)iGroup 1=0.70590–0.70635, εNd(t)Group 1=−9.6 to −10.4, T2DM(Nd)Group 1=1705–1775Ma, (87Sr/86Sr)iGroup 2=0.70586–0.70587, εNd(t)Group 2=−0.6 to −0.7, T2DM(Nd)Group 2=971–978Ma, and εHf(t)Group 2=−4.5 to −10.0. The mineralogical and geochemical features suggest that the host Jiguanzi adamellite and Group 2 enclaves were generated through synchronous mixing and fractional crystallization accompanied by mechanical and chemical exchanges. The Group 1 enclaves showing cogenetic affinity with their felsic host represent the mechanical concentrations of mafic minerals and accessory phases from evolved hybrid host magma. Magma sources of the host Jiguanzi adamellite and its Group 1 enclaves are dominated by lower crust (LCC) components, whereas those for the Group 2 enclaves are dominated by metasomatized lithospheric mantle. The magma genesis involved complex multi-stage crust–mantle interaction processes including: (1) lithospheric mantle modification induced by Triassic subduction of the Paleo-Asian Ocean slab and/or Triassic–Cretaceous asthenospheric melt underplating; and (2) melting of the ancient LCC and lithospheric mantle, and hybridization of mantle- and crust-derived melts. In conjunction with regional geological and geochemical data, we argue that the Late Jurassic–Early Cretaceous shallow extension events represented by the Kalaqin MCC triggered deep-seated multi-stage magmatism and lithospheric destruction, and the continuous generation of magma further strengthened the extension and result in more extensive lithospheric thinning.

High-Mg adakitic rocks and their complementary cumulates formed by crystal fractionation of hydrous mafic magmas in a continental crustal magma chamber

Understanding how adakitic magmas form is important for understanding the formation of the continental crust. Generating such high-Sr/Y rocks by crystal fractionation of basalts/basaltic andesites in magma chambers has been proposed in a wide range of tectonic settings. However, the complementary cumulates predicted by this scenario have rarely been observed. The late Triassic (~227Ma) Ningcheng complex from the North China Craton is composed of a websterite - (Ol−/Hbl-) pyroxenite - gabbro unit and a quartz-diorite unit. They are interpreted as the products (cumulates and derivative melts, respectively) of fractionation from hydrous mafic magmas at mid- to lower-crustal pressures (4.9~8.3kbar). The quartz diorites are high-Mg intermediate rocks with moderate SiO2 (57.0~62.9wt%), high Mg# (>49) and adakitic trace element signatures, such as high Sr (≥636ppm) and light rare earth elements (REEs), low Y (≤17ppm) and heavy REEs (Yb≤1.8ppm), lack of obvious Eu anomalies, and high Sr/Y (≥31) and La/Yb (≥24)). These adakitic signatures reflect differentiation of hydrous mantle-derived magmas in the deep crust, leaving behind a plagioclase-free residual solid assemblage in the early stages, which is represented by the coeval websterite-pyroxenite complex. This study therefore not only demonstrates that hydrous crystal fractionation is an important mechanism to form adakitic rocks, but also presents an example of a preserved fractionating system, i.e. high-Sr/Y rocks and their complementary cumulates. A geochemical comparison is made between representative adakitic rocks formed by fractionation of hydrous magmas and Archean TTGs. It is suggested that crystal fractionation is an efficient process for making Phanerozoic high Sr/Y rocks but was not responsible for the formation of Archean granitoids.

Influencing factors of micropores in the graptolite shale of Ordovician Pingliang Formation in Ordos Basin, NW China

Abstract Multiple tests were conducted on graptolite shale samples from Middle Ordovician Pingliang Formation in three typical areas in Ordos Basin to investigate the relationship between micro-nano pore structure, graptolite content, rock composition, TOC, maturity, main and trace elements and gas content. The graptolite of Pingliang Formation concentrates in the black shale at the lower section of this layer. Pores in the shale are diverse in types, including pores made by extracellular polymeric substance (EPS), in bio-graptolite body, as inter-granular void of clay minerals, intra-granular, interstitial space between mineral crystals, micro-fractures, and intra-granular dissolution structures etc. Tests show that graptolite affected the sedimentary environment and shale gas accumulation; graptolites content is positively correlated to TOC, in a certain range, specific surface area is positively correlated to TOC and maturity, etc., as overall a lithologic inorganic and organic ratios. The rare earth elements (REE) patterns of the three areas are similar, indicating the same provenance. REE, Fe, Al and Ti content are negatively correlated to TOC, indicating the high REE content is not caused by organic matter enrichment, but related to the absorption of minerals particles. Gas content is positively correlated to specific surface area, TOC and maturity. The above factors contribute to space and size distribution of micro-nano pores in shale.

Coloration of Natural Zircon

Abstract Selected literature data and new results from our own spectroscopic studies using optical absorption, paramagnetic resonance, and Raman spectroscopy are used to give an overview of recent understanding of the coloration of natural zircon. Pure ZrSiO 4 is colorless. Coloration is mainly related to point defects of the electron or hole type, although charge transfer mechanisms and crystal field-dependent internal electron transitions in f - and d -elements may sometimes also play a significant role. There is a common substitution of tetravalent zirconium by trivalent rare earth elements (REE) and yttrium which is frequently not compensated by phosphorus or other elements. As a result, hole defects are the dominant type of coloration centers in reddish and some rose natural zircon crystals. On the other hand, electron centers may be involved in coloration of common yellowish-brownish zircon which displays low REE and yttrium contents. These two coloration mechanisms are the most common in natural zircon. An unspecific absorption increasing steadily from the red to the blue part of the optical absorption spectrum may additionally affect zircon coloration. Color shades of grey, rose, and brown appearing with increasing intensity of this absorption feature may result. This optical characteristic, which is frequently observed in some zircons, is obviously related to the effects of radioactive irradiation and occurs in various types of zircon depending on their uranium and thorium contents. Sharp absorption lines caused by internal electron transitions of the f - f type related to U 4+ or, less typically, to Er 3+ and Nd 3+ substituting for Zr 4+ , occur frequently in the optical absorption spectra of zircon. As a rule, they have no significant influence on the visible color. However, very high U 4+ or Er 3+ contents combined with strong absorption in the blue part of the spectrum may cause greenish coloration. Rarely, green zircon coloration also occurs as a result of various broad absorption bands located in the red part of the spectrum. Very high REE contents in some zircons are the most likely cause for a strong, absorption edge-like feature in the blue part of the optical absorption spectrum, resulting in a rarely observed intense yellow coloration. Blue zircon coloration is mostly artificially induced by heating, but sometimes also occurs in nature. Besides the increase in unspecific absorption causing greyish to brownish colors, there are no simple relationships between zircon coloration, radioactivity, and structural order (or degree of metamictization) of the crystal grains.

Rare earth metals' influence on the heat generating capability of cobalt ferrite nanoparticles

The aim of this study is to synthesize and assess the potential applications of rare earth doped cobalt ferrite nanoparticles in cancer treatment through hyperthermia.The synthesis of CoFe2−xRExO4 (where RE=Yb, Dy, Gd and x=0.01–0.3) through the co-precipitation method is presented. The composition and properties of the nanoparticles where investigated and evaluated in correlation with their heat generating capability. The XRD and EDX analysis indicated phase separation for high rare earth content with the appearance of Gd2O3 and Dy2O3 secondary phases, which leads to unwanted changes in the nanoparticles' magnetic properties and consequently of the specific absorption rate. All the nanoparticles present functional group belonging to the surfactant as determined by FT-IR and Raman. Magnetic and specific adsorption rate measurement suggest increases in saturation magnetization and SAR value in doped ferrites, compared to CoFe2O4 with as much as 26% and 15% for Dy doped and Gd doped samples respectively.

Petrogenesis of Early–Middle Jurassic intrusive rocks in northern Liaoning and central Jilin provinces, northeast China: Implications for the extent of spatial–temporal overprinting of the Mongol–Okhotsk and Paleo-Pacific tectonic regimes

The Mesozoic tectonic evolution of NE China was controlled mainly by the Mongol–Okhotsk and Paleo-Pacific tectonic regimes. However, the extent of the spatial and temporal overprinting of these two regimes is poorly understood. Here, we report new zircon LA-ICP-MS U–Pb dating and geochemical analyses of Jurassic intrusive rocks in northern Liaoning and central Jilin provinces, northeast China, to discuss their petrogenesis and outline the extent of spatial and temporal overprinting of these two tectonic regimes. Dating results indicate that Jurassic magmatism occurred in two stages during the Early (ca. 175Ma) and Middle Jurassic (170–163Ma). These rocks represent two-stage typical bimodal igneous rock associations composed mainly of olivine gabbro, gabbro, and gneissic granitoids. The Early and Middle Jurassic gabbros have low rare earth element (REE) abundances, positive Eu anomalies, depletion in high field strength elements (HFSEs), and positive εHf(t) values (+4.0 to +10.3, except for one value of −17.8), suggesting that the primary magma was derived from partial melting of depleted lithospheric mantle metasomatized by subducted-slab-derived fluids. The Early Jurassic monzogranite exhibit high REE abundances (195–201ppm), weak negative Eu anomalies (δEu=0.63–0.64), and negative εHf(t) values (−11.9 to −8.2), suggesting a primary magma that was derived from partial melting of lower continental crust of the NCC. The Middle Jurassic granodiorites are enriched in light REEs (LREEs) and large ion lithophile elements (LILEs), and are depleted in heavy REEs (HREEs) and HFSEs, as well as high Sr/Y (29–132) and (La/Yb)N (15–44) ratios. In addition, the Middle Jurassic granitoids near or within the NCC exhibit negative εHf(t) values (−18.9 to +0.2), whereas those within the Xing'an–Mongolia Orogenic Belt (XMOB) have generally positive εHf(t) values (−0.6 to +6.4), suggesting their origin from partial melting of thickened ancient NCC and newly accreted continental crust of the XMOB, respectively.The above findings, combined with regional geologic data, suggest that the Early Jurassic bimodal igneous rocks formed in an extensional tectonic environment related to subduction of the Paleo-Pacific plate beneath the Eurasian continent. The Middle Jurassic bimodal igneous rocks possibly formed in an extensional environment related to the collapse of a thickened region of the lower crust after closure of the Mongol–Okhotsk Ocean.

Abnormal variation of magnetic properties with Ce content in (PrNdCe)2Fe14B sintered magnets prepared by dual alloy method**Project supported by the National Natural Science Foundation of China (Grant Nos. 51461033, 51571126, 51541105, and 11547032), the Natural Science Foundation of Inner Mongolia, China (Grant No. 2013MS0110), and the Inner Mongolia University of Science and Technology Innovation Fund, China.

Resource-saving (PrNdCe)2Fe14B sintered magnets with nominal composition (PrNd)15−xCexFe77B8 (x = 0−10) were prepared using a dual alloy method by mixing (PrNd)5Ce10Fe77B8 with (PrNd)15Fe77B8 powders. For Ce atomic percent of 1% and 2%, coercivity decreases dramatically. With further increase of Ce atomic percent, the coercivity increases, peaks at 6.38 kOe in (PrNd)11Ce4Fe77B8, and then declines gradually. The abnormal dependence of coercivity is likely related to the inhomogeneity of rare earth chemical composition in the intergranular phase, where PrNd concentration is strongly dependent on the additive amount of (PrNd)5Ce10Fe77B8 powders. In addition, for Ce atomic percent of 8%, 7%, and 6% the coercivity is higher than that of magnets prepared by the conventional method, which shows the advantage of the dual alloy method in preparing high abundant rare earth magnets.

Phase Concentration Determination of Fe16N2 Using State of the Art Neutron Scattering Techniques

Due to limitations on the availability of rare earth elements it is imperative that new high energy product rare earth free permanent magnet materials are developed for the next generation of energy systems. One promising low cost permanent magnet candidate for a high energy magnet is α″-Fe16N2, whose giant magnetic moment has been predicted to be well above any other from conventional first principles calculations. Despite its great promise, the α″ phase is metastable; making synthesis of the pure phase difficult, resulting in less than ideal magnetic characteristics. This instability gives way to a slew of possible secondary phases (i.e. α-Fe, Fe2O3, Fe8N, Fe4N, etc.) whose concentrations are difficult to detect by conventional x-ray diffraction. Here we show how high resolution neutron diffraction and polarized neutron reflectometry can be used to extract the phase concentration ratio of the giant magnetic phase from ultra-small powder sample sizes (~0.1 g) and thin films. These studies have led to the discovery of promising fabrication methods for both homogeneous thin films, and nanopowders containing the highest reported to date (>95%) phase concentrations of room temperature stable α″-Fe16N2.

Ordovician intrusive rocks from the eastern Central Asian Orogenic Belt in Northeast China: chronology and implications for bidirectional subduction of the early Palaeozoic Palaeo-Asian Ocean

ABSTRACTThe eastern segment of the Central Asian Orogenic Belt is traditionally called the Xing’an Mongolia Orogenic Belt (XMOB). Ordovician intrusive rocks exposed in the XMOB, from north to south, are the Abaga-East Ujimqin Qi-Duobaoshan belt, the Sonid Zuoqi-West Ujimqin Qi belt, and the Damaoqi-Baimaimiao-Tulinkai belt, respectively. Zircon U–Pb dating and geochemical data are presented for the intrusive rocks in East Ujimqin Qi and West Ujimqin Qi, Inner Mongolia. The intrusive rocks from East Ujimqin Qi consist of gabbro, diorite, and granodiorite. LA-MC-ICP-MS zircon U–Pb ages range 446 to 461 Ma. Geochemical data suggest that the gabbros and diorites from East Ujimqin are a tholeiitic series, both of arc-related and N-MORB (mid-ocean ridge basalt) signature, indicating a back-arc basin setting. The granodiorites have a shoshonitic series and arc-related signature. Rare earth element (REE) patterns and trace element characteristics suggest gabbros, diorites, and granodiorites are petrogenetically correlated. These intrusive rocks from East Ujimqin Qi have high light REE, Th, and U concentrations, suggesting the effect of middle–upper continental crustal contamination. Major oxides display positive or negative correlations, with increasing MgO or SiO2, indicating that fractional crystallization occurred during magma evolution. Geochemical data of diorite from West Ujimqin Qi indicate a tholeiitic series, arc-related signature. Zircon U–Pb dating yielded an age of 441.8 ± 1.5 Ma. Integrated with the regionally exposed Mid–Late Ordovician plutons and metasedimentary strata, we concluded that the northward subduction of the Palaeo-Asian Ocean (PAO) that occurred beneath the southern margin of the South Mongolian Micro-continent along the Sonid Zuoqi-Xilinhot gave rise to early Palaeozoic igneous rocks from the Abaga–East Ujimqin Qi–Duobaoshan and the Sonid Zuoqi–West Ujimqin Qi belts. Southward subduction beneath the North China Craton generated the Damaoqi–Baimaimiao–Tulinkai belt. The results support the bidirectional subduction model of the PAO in the early Palaeozoic.