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Sputter deposition of ScAlN using large size alloy target with high Sc content and reduction of Sc content in deposited films

This paper describes deposition of ScAlN thin films by the conventional radio frequency (RF) magnetron sputtering using large size Sc–Al alloy targets with high Sc content. Two 4-in. Sc–Al alloy targets with the Sc content of 43 and 32% were prepared by the sintering method instead of the conventional dissolution method, and deposited film qualities and uniformity were evaluated. In both cases, uniform ScAlN thin films were obtained throughout the three inch wafer. However, measured Sc content was significantly lower than that of the target. Influence of the N2 content in the sputtering gas was also investigated, and the result indicated that nitridation of the target surface is at least one of the major reasons causing the reduction of the Sc content in the deposited films. We also reports variation in film qualities observed with the accumulated sputtering time.

Main minerals of abnormally high-grade ores of the Tomtor deposit (Arctic Siberia)

The Tomtor massif of Paleozoic ultramafic alkaline rocks and carbonatites is located in the northern part of the Sakha Republic (Yakutia). The massif (its total area is ~250 km2) is ~20 km in diameter, with a rounded shape and a concentrically zoned structure. The core of the massif consists of carbonatites surrounded by a discontinuous ring of ultramafic rocks and foidolites. The outer part is composed of alkali and nepheline syenites. All rocks are weathered and covered with eluvium, which is the thickest after carbonatites enriched in phosphates and REE. The weathering profile consists of four layers, from the top: kaolinite-crandallite, siderite, goethite, and francolite. The highest-grade ores are observed in the bedded deposit which fills depressions in “sagging” eluvium. The ores are laminated and cryptogranular, with high Nb, Y, Sc, and REE contents (on average, 4.5% Nb2O5, 7-10% REE2O3, 0.75% Y2O3, and 0.06% Sc2O3). The highest-grade ores are natural Nb and REE concentrates. The total REE content in some layers is >10%. The morphologic features of the highest-grade phosphate ores from the northern part of the Burannyi site were studied. The ore-forming minerals belong to the pyrochlore group, crandallite group (goyazite), and monazite-Ce. The pyrochlore group minerals occur mainly as crystals that were completely replaced by barium-strontium pyrochlore and/or plumbopyrochlore but retained the original faces; also, they occur as numerous conchoidal fragments. The grains of the pyrochlore group minerals sometimes have a zonal structure, with an unaltered pyrochlore core and a reaction rim. Goyazite occurs predominantly as colloform grains. According to SEM and TEM data, monazite occurs in the ores as ~50 nm particles, which cover the outer part of halloysite tubes (800–3000 nm long and 300 nm in diameter) as a dense layer and make up peculiar biomorphic aggregates. The mineralogical data, the occurrence of biomorphic aggregates, and the close association of organic remains with ore minerals suggest that the high-grade ores of the Tomtor deposit, including the Burannyi site, resulted from a hydrothermal-sedimentary process with a presumably important role of bioaccumulation of REE phosphates.

Major, trace and REE characteristics of the high grade gold geochemical reference material from Middle Reef, Hutti gold mines, Karnataka

The geological, petrological, mineralogical and geochemical characteristics of the Hutti high-grade gold reference material representing the composite sample of sheared gold-sulphide bearing smoky-grey quartz vein hosted in felsic volcanics (Middle Reef) and hydrothermal altered wall rocks are investigated in the present work. Petrological studies on these rocks reveal the presence of deformed quartz ribbons, plagioclase, chlorite, biotite, stipnomelane, actinolite and abundant native gold, arsenopyrite, pyrite and minor scheelite, monazite and xenotime. The major, trace and REE geochemistry of the host barren rhyolites are interpreted as low Yb adakitic variety which show high Ba, Cr, V and Ni concentrations. REE patterns of the gold-sulphide bearing quartz reef is characterized by a pronounced positive Eu anomaly, LREE depletion and nearly flat HREE with a low total REE which indicate possible contribution from deep-seated fluids to the ore-forming process. These patterns also suggest a source which is enriched in Eu and depleted in LREE either due to crystal fractionation or the formation of scheelite. The associated hydrothermally altered wall rocks from proximal zone, exhibit flat REE patterns coupled with high concentrations of Cu, Zn, Cr, V, Sc and Ni indicating their derivation from secondary epigenetic fluids responsible for metasomatic alteration. The abundant barren schistose amphibolites from distal zone represent enriched type of island arc basalts (IAB). The trace, REE-HFSE data on the rhyolite (adakite) and IAB of Middle Reef in the Hutti schist belt substantiates the inference that Archaean subduction processes in an island arc/convergent margin setting are responsible for adakitic magmatism.

Electromechanical coupling and gigahertz elastic properties of ScAlN films near phase boundary

The electromechanical coupling, elastic properties, and temperature coefficient of elastic constant c33D of ScxAl(1−x)N films with high Sc concentration (x) of 0–0.70 were experimentally investigated. Near the phase boundary, a Sc0.41Al0.59N film exhibited a maximum thickness extensional mode electromechanical coupling coefficient kt2 of 12% (kt = 0.35), which is almost double the value of 6.4% for typical pure AlN films. In the region of 0 < x < 0.2, the electromechanical coupling was confirmed to increase without any detectable deterioration in the temperature stability of c33D (=−54.5 ppm/ °C). This region is favorable in terms of temperature stability and is suitable for wideband resonator filter applications.

Epiphytic lichens as indicators of air pollution in Tomsk Oblast (Russia)

This research presents the data on concentrations of 28 chemical elements in the ash of lichens growing in Tomsk Oblast where different industrial enterprises are located. In the sites of oil and gas exploration complex the lichens contain higher concentrations of Sc, Fe, Cr, Zn, As, Br, Rb, Ba, and Au in comparison with the background values. In the zone of Tomsk- Seversk industrial agglomeration the lichens accumulate Ca, Sr, Sb, Th, U, and lanthanides.

Petrology and geochemistry of the Wangjiazhuang banded iron formation and associated supracrustal rocks from the Wutai greenstone belt in the North China Craton: Implications for their origin and tectonic setting

The Wutai greenstone belt (WGB) is one of the most extensively studied greenstone belts in China. Together with the Hengshan and Fuping complexes, these three associations compose the central segment of the Trans-North China Orogen (TNCO) in the North China Craton (NCC). The Wangjiazhuang banded iron formation (BIF) is located in the bottom of the Jingangku Formation of the WGB. The associated supracrustal rocks consist of meta-basalts (amphibolites), meta-felsic volcanic rocks (leptynite) and metapelites (mica schist), which have experienced amphibolite-facies metamorphism. Amphibolites are commonly intercalated with the BIF. SIMS zircon U–Pb analyses on amphibolites suggest that the Wangjiazhuang BIF was formed at ca. 2543±4Ma. Combined with most Neoarchean Algoma-type BIFs in the NCC, these features indicate that a significant tectothermal event of the NCC have occurred at ∼2.5Ga. Mineral assemblages of the Wangjiazhuang BIF are composed of quartz, magnetite, amphibole, and minor garnet, pyrite and calcite. The precursor deposits of this BIF were likely ferric-oxyhydroxides, fine-grained carbonate oozes, silicate phases rich in Al–Ca–Mg–Fe and amorphous silica. The appearance of garnet and ferro-pargasite, high concentrations of Al2O3, HFSEs, Sc, and positive correlations among Al2O3, TiO2, HFSEs and REE indicate that there was a significant terrigenous input. Even so, the Wangjiazhuang BIF samples display distinctively seawater-like REE+Y profiles, characterized by positive La and Y anomalies and HREE enrichment relative to LREE in PAAS-normalized REE diagrams. Consistently positive Eu anomalies are also observed, which are typically from high-T hydrothermal fluids. In addition, the true negative Ce anomalies recorded in the Wangjiazhuang BIF might indicate the onset of bottom-water oxidation at the Archean-Proterozoic boundary, at least in restricted basins. Amphibolites have geochemical affinity with both MORB- and arc-like components, and the trace element characteristics of leptynites are also consistent with a subduction zone signature. These features suggest that the Wangjiazhuang BIF was deposited in a back-arc basin. Oceanic subduction, coupled with contemporary depleted mantle upwelling related to back-arc basin extension, can account for the typical interaction between these two components.

Post-supereruption Magmatic Reconstruction of Taupo Volcano (New Zealand), as Reflected in Zircon Ages and Trace Elements

New zircon U–Th model-age and trace element datasets are presented from Taupo volcano (New Zealand), which are used to investigate the timescales and broad-scale magmatic processes involving zircon crystallization after the caldera-forming 25·4 ka Oruanui supereruption. Detailed 14C-based chronologies and controls on vent locations allow the timing and location of post-caldera eruptions to be spatially and temporally constrained to an extent not possible for any other supervolcano. After ∼5 kyr of post-Oruanui quiescence, Taupo erupted three dacitic units, followed by another ∼5 kyr break, and then a sequence of rhyolitic units in three subgroups (SG1–SG3) from 12 ka onwards. Despite overlapping vent sites and crustal source domains between the Oruanui and post-Oruanui eruptions, U–Th zircon model ages in Taupo SG1 rhyolites (erupted from 12 to 10 ka) indicate only minor inheritance of crystals from the Oruanui magma source. Post-Oruanui model-age spectra are instead typically centred close to eruption ages with subordinate older pre-300 ka equiline grains in some units. U–Pb dating of these older grains shows that both 300–450 ka plutonic-derived and pre-100 Ma greywacke basement-derived zircons are present. The former largely coincide in age with zircons from the 350 ka Whakamaru eruption products, and are dominant over greywacke in young units that were vented within the outline of the Whakamaru caldera. Despite multiple ages and vent sites, trace element compositions are broadly similar in zircons, regardless of their ages. However, a small subset of zircons analysed from SG1 rhyolite (Units B and C) have notably high concentrations of U, Th, P, Y + (REE)3+ and Nb but with only minor variations in Hf and Ti. SG2 zircons typically have higher Sc contents, reflecting large-scale changes in melt chemistry and crystallizing mineral phases with time. The age spectra indicate that most Oruanui zircons were removed by thermally induced dissolution immediately following the supereruption. U–Th ages from single post-Oruanui eruptions show consistent inheritance of post-Oruanui grains with model ages that centre between the temporally separated but geographically overlapping eruption groups, generating model-age modes. Within the statistical limitations of the isotopic measurements, we interpret these repeated modes to be significant, resulting from incorporation of crystal populations from cyclic post-Oruanui periods of magmatic cooling and crystallization, acting within a crustal protolith chemically independent of that which was dominant in the Oruanui system. These periods of cooling and crystallization alternate with times of rejuvenation and eruption, sometimes demonstrably accompanying syn-eruptive regional rifting and mafic magma injection. Not only were the processes that developed the supersized Oruanui magma body rapid, but this huge magma system was effectively reset and rebuilt on a comparably short timescale.

Chemical characteristics of zircon from A-type granites and comparison to zircon of S-type granites

The trace element content in zircons from A-type granites and rhyolites was investigated by using back-scattered electron images and electron microprobe analyses. The studied Proterozoic (Wiborg batholith, Finland and Pará, Amazonas and Goiás states, Brazil) and Variscan (Krušné Hory/Erzgebirge, Czech Republic and Germany) plutons cover a wide range of rocks, from large rapakivi-textured geochemically primitive plutons to small intrusions of F-, Li-, Sn-, Nb-, Ta-, and U-enriched rare-metal granites. While zircon is one of the first crystallized minerals in less fractionated metaluminous and peraluminous granites, it is a late-crystallized phase in peralkaline granites and in evolved granites that may crystallize during the whole process of magma solidification. The early crystals are included in mica, quartz, and feldspar; the late grains are included in fluorite or cryolite or are interstitial. The zircon in hornblende–biotite and biotite granites from the non-mineralized plutons is poor in minor and trace elements; the zircon in moderately fractionated granite varieties is slightly enriched in Hf, Th, U, Y, and HREEs; whereas the zircon in highly fractionated ore-bearing granites may be strongly enriched in Hf (up to 10wt.% HfO2), Th (up to 10wt.% ThO2), U (up to 10wt.% UO2), Y (up to 12wt.% Y2O3), Sc (up to 3wt.% Sc2O3), Nb (up to 5wt.% Nb2O5), Ta (up to 1wt.% Ta2O5), W (up to 3wt.% WO3), F (up to 2.5wt.%F), P (up to 11wt.% P2O5), and As (up to 1wt.% As2O5). Metamictized zircons may also be enriched in Bi, Ca, Fe, and Al. The increase in the Hf content coupled with the decrease in the Zr/Hf value in zircon is one of the most reliable indicators of granitic magma evolution. In the zircon of A-type granites, the Zr/Hf value decreases from 41–67 (porphyritic granite) to 16–19 (equigranular granite) in the Kymi stock, Finland, and from 49–52 (biotite granite) to 18–36 (leucogranite) in the Pedra Branca pluton, Brazil. In the in situ strongly fractionated Cínovec cupola (Erzgebirge), the Zr/Hf value decreases from 33–51 in the protolithionite granite at a depth of 1255m to 7.5–25 in the zinnwaldite granite at a depth of 40m. At the scale of individual crystals, the Zr/Hf value decreases from 86 to 68 from the cores to the rims of the zircons from the Teplice rhyolite and from 64 to 33 in the zircons from the biotite granite at Krupka, Erzgebirge. The contents of Hf and U in zircon are dependent mainly on the degree of granite fractionation and the nature and volume of the volatile phases and are independent of the A- or S-character of the parental melt. The zircon Zr/Hf ratios 55 and 25 are proposed to approximately distinguish common, moderately evolved and highly evolved granites. Zircons from the moderately and highly evolved granites of A- and S-type can be discriminated on the basis of their HREE content and the U/Th ratios. Nb, Ta, and W are present in zircon from the highly evolved granites from all studied areas, while high As, Bi, and Sc contents are typical only for the Erzgebirge.

Nd isotopic and geochemical constraints on the provenance and tectonic setting of the low-grade meta-sedimentary rocks from the Trans-North China Orogen, North China Craton

In the Trans-North China Orogen (TNCO) of the North China Craton, low-grade supracrustal successions extensively occur in the Wutai, Lüliang, Zanhuang, Zhongtiao and Dengfeng Complexes from north to south. Meta-sedimentary samples from the Wutai and Zhongtiao Complexes were collected for geochemical and Nd isotopic studies and several samples from the Zanhuang and Dengfeng Complexes were also analyzed for Nd isotopic studies for comparative purpose. Most of the meta-siltstones and meta-sandstones from the Wutai and Zhongtiao Complexes are characterized by depletions in mobile elements like CaO, Sr and Na2O, high Chemical Index of Weathering (CIW) values and strong positive correlation between Al2O3 and TiO2, indicating intense weathering conditions. Significant post-depositional K-metasomatism is indicated in the A–CN–K diagrams for most of the analyzed samples and the relatively high pre-metasomatized Chemical Index of Alteration (CIA) values (43–87) also imply a high degree of source weathering. Depleted transitional trace elements (Ni, Cr, Co and Sc), fractionated light rare earth elements patterns, mild negative Eu anomalies in the majority of these meta-sedimentary samples point toward felsic source rocks, including the ∼2.5Ga granitics, TTG gneisses and the Paleoproterozoic granitics in the TNCO. Minor contribution from mafic rocks is evidenced from relative high contents of MgO, Fe2O3T, Sc and lower La/YbN ratios in some older sequence-set samples from the Zhongtiao Complex. Our geochemical and Nd isotopic data, combined with previous studies in the lithostratigraphic sequence, provenance and depositional age, suggest that the older and younger sequence-sets of the low-grade supracrustal successions in the TNCO were deposited in the different depositional environments. The older sequence-set was deposited in a back-arc basin between the “Andean-type” continental margin arc and the Eastern Block after ∼2.1Ga, whereas the younger sequence-set formed in a foreland basin between ∼1.88 and ∼1.80Ga, which is consistent with the model that the collision between the Eastern and Western Blocks to form the Trans-North China Orogen occurred at ∼1.85Ga.

Late Precambrian terrigenous rocks of the Anamakit–Muya zone of the Baikal–Muya belt: geochemistry and results of LA-ICP-MS dating of detrital zircons

A comparative geochemical characteristics of Late Precambrian sedimentary rocks (Ust’-Kelyana and Tuluya rock units) in the Anamakit–Muya zone of the Baikal–Muya belt is given, and the conditions of their sedimentation are considered. The first results of U–Pb (LA-ICP-MS) dating of detrital zircons and Sm–Nd isotope data on the Tuluya unit deposits are presented. Petrogeochemical study showed that the studied sediments are first-cycle rocks similar in composition to terrigenous island-arc sediments. The low contents of Th, Rb, Zr, Hf, and LREE and high contents of Co, Ni, Sc, V, Cr, and Fe2O3* in the sandstones of the Ust’-Kelyana unit evidence that these rocks are similar to oceanic-arc deposits. In contrast, the enrichment of the Tuluya unit rocks in Zr, LREE, Th, Rb, and Nb indicates their similarity to deposits of continental island arcs or active continental margin. Isotope-geochronological studies of the Tuluya rock unit showed the mixing of detrital material resulted from the erosion of Neoproterozoic island-arc igneous rock associations (625–700 Ma), like those in the Karalon–Mamakan zone (Yakor’ and Karalon Formations), and more ancient associations, like the Kelyana (812–824 Ma) and/or Dzhaltuk Groups. Judging from the minimum age of detrital zircon, the lower time bound of sedimentation corresponds to 0.6 Ga.

FIRST-PRINCIPLES CALCULATIONS FOR THE STRUCTURAL AND ELECTRONIC PROPERTIES OFScxAl1-xNALLOYS

The first-principles calculations based on Density Functional Theory (DFT) within generalized gradient approximation (GGA) of Engel–Vosko–Perdew–Wang and modified exact exchange potential of Becke–Johnson have been introduced for the structural and electronic properties of the ScxAl1-xN alloys, respectively. The present lattice constants calculated for the ScAlN alloys and the end compounds ( AlN and ScN ) are found to be in very good agreement with the available experimental and theoretical ones. The stable ground state structures of the ScxAl1-xN alloys are determined to be wurtzite for the Sc concentration less than ~0.403 and rock-salt for the higher Sc concentrations. The present electronic band structure calculations within Becke–Johnson scheme are found to be capable of providing energy band gaps of the AlN and ScN compounds very close to the ones of the available experiments and expensive calculations. According to the calculations of Becke–Johnson potential, the ScxAl1-xN alloys in the wurtzite and zinc-blende structures are direct band gap materials for the Sc concentrations in the ranges of (0.056 ≤ x ≤ 0.833) and (0.03125 ≤ x ≤ 0.0625, 0.375 ≤ x ≤ 0.96875), respectively. However, the ScAlN alloys in the rock-salt phase are determined to be direct band gap materials for total range of the Sc concentration considered in this work. While the energy gaps of the RS- AlScN alloys are found to be extending from near ultraviolet to near infrared with a large (negative) bowing, the ones of the WZ- AlScN and ZB- AlScN alloys are determined to be varying in a small energy range around near ultraviolet with a small (negative) bowing.

Age and geochemistry of Silurian gabbroic rocks in the Tongbai orogen, central China: Implications for the geodynamic evolution of the North Qinling arc–back-arc system

The tectonic properties of the Erlangping unit and the subduction polarity of oceanic basins in the North Qinling–Tongbai orogen have been the focus of debate for more than twenty years. The resolution of these controversies hinges on the refined constraints on the location and nature of subduction-related magmatism. In this contribution, we provide a combined study of zircon U–Pb ages, major and trace element geochemistry, and Sr–Nd–Hf isotope compositions of gabbroic rocks from the Erlangping unit in the Tongbai orogen. U–Pb dating of zircons from two gabbroic diorite samples yielded two weighted mean ages of 443±3 and 440±4Ma. The Erlangping gabbroic rocks are tholeiitic in composition with variable MgO (4.48–8.17%), and low K2O (0.25–1.01%) and TiO2 (0.60–1.79%) contents. They are characterized by enrichment of LILEs, depletion of HFSEs, and highly positive whole-rock εNd(t) (3.76–5.68) and zircon εHf(t) (12.0–12.1) values. The geochemical features indicate that the Erlangping gabbroic rocks were derived from a depleted lithospheric mantle that had been exposed to metasomatism by slab-derived fluid shortly before their generation. Their occurrence, coupled with coeval granitoids with highly positive εNd(t) values, manifest significant crustal growth in the North Qinling–Tongbai orogen during the late Ordovician–Silurian. In addition, the Erlangping gabbroic rocks have low Sr/Y (7.32–26.2) and (La/Yb)N (1.34–4.07) ratios, but high HREEs, Y and Sc contents. This implies that their mantle source had no residual garnet, and thus partial melting of the lithospheric mantle occurred under relatively low-pressure conditions. The generation of the Erlangping gabbroic rocks might result from incipient rifting of the Erlangping back-arc basin induced by the northward subduction of the Paleotethyan Shangdan Ocean. Taking into account the ca. 490Ma collision between the Erlangping arc and North Qinling microcontinent, we suggested that the evolution of the North Qinling belt from an arc to a back-arc realm involved a prolonged period of underplating of basaltic magma, granulite-facies metamorphism, and anatexis of precursor rocks. Consequently, the Qinling–Tongbai orogenic belt provides a key place for better understanding the Phanerozoic crustal growth and differentiation.

Distributions of Y + REE and Sc in tourmaline and their implications for the melt evolution; examples from NYF pegmatites of the Třebíč Pluton, Moldanubian Zone, Czech Republic

Tourmalines from NYF and mixed (NYF + LCT) pegmatites of the Trebic Pluton (Moldanubian Zone, Czech Republic) are generally characterized by variable and relatively high concentrations of Y + REE (4-457 ppm) and Sc (18-765 ppm). They show enrichment in LREE (Ce > La); the chondrite-normalized REE patterns decrease uniformly from La to Tb; Tb to Tm are mostly below the detection limits (<0.01-0.08 ppm) and are followed by an upturn to Yb and Lu. Our textural and paragenetic observations indicate that growth of magmatic tourmaline reflects Y + REE contents in the melt. Tourmaline is highly compatible with Sc and shows exceptionally high contents of Sc compared to the analyzed host pegmatite units (less than 1 ppm Sc). The contents of Sc positively correlate with Sigma Y + REE. Two distinct evolutionary trends of trace-elements in tourmaline were distinguished. (i) A conspicuous increase in Y + REE and Sc in tourmaline (dravite, Ca-rich dravite) from primitive euxenite-type pegmatites reflects their enrichment in the melt with the progressive crystallization and fractionation. It also was enhanced by low P (<0.02 wt. % P2O5) and Ca contents (<0.8 wt. % CaO) in host pegmatite unit preventing precipitation of Y + REE phosphates and allanite, respectively. (ii) Tourmaline (schorl, fluor-schorl, fluor-elbaite) from more evolved pegmatites (evolved euxenite-type and mixed (NYF + LCT) pegmatite) show a depletion in REE and Sc with progressive crystallization reflecting most likely the coeval precipitation of REE-rich minerals, especially monazite-(Ce), xenotime-(Y), samarskite- and aeschynite-group minerals. The Eu anomalies in tourmaline vary significantly from positive (up to Eu/Eu* similar to 16) to substantially negative ones and are related to the Eu contents in the melt and degree of its fractionation.

Health Inequalities, Level Differentials and Progress Assessment: Case of Measles Vaccination Coverage in India

This paper attempts to assess progress in measles vaccination coverage in India using a method that accounts both for health inequalities and leveldifferentials with the help of data from the National Family Health Surveys (NFHS) for 1992-1993 and 2005-2006. Methods such as rate-ratio, ratedifferentials, concentration index, group analogue of Gini coefficient and level-sensitive progress index have been adopted for this purpose. Results indicate that there are high income-related and group-related inequalities in measles vaccination coverage. The intersectional group of rural-female-SC ST, particularly from Bihar and Uttar Pradesh, are most disadvantaged. The progress is biased as richer and advantaged sections benefited disproportionately from expansion in coverage. Tamil Nadu, West Bengal and Kerala emerge as best performers. Supplementary immunization activities for measles can be effective in promoting health equity in a cost-effective manner. Rural areas and regions with high concentration of SC and ST communities should be explicitly targeted. Like Polio, global declaration for elimination of measles is important to generate political will for rapid progress.

The effect of Sc additions on the microstructure and age hardening behaviour of as cast Al–Sc alloys

The grain refinement effect and the ageing behaviour of Al–0.5wt.% Sc, Al–0.7wt.% Sc, and Al–1wt.% Sc alloys are studied on the basis of optic microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) observations and hardness measurements. In Al–Sc alloys the higher grain refinement is observed for Sc contents greater than 0.5wt.% accompanied by a notorious morphology modification, from coarse columnar grains to a fine perfect equiaxed structure. The as cast structures are characterised by a rich supersaturated solid solution in Sc, that promotes a great age hardening response at 250°C and 300°C. The age hardening curves also demonstrate a low overageing kinetics for all the alloys. Although the higher Sc content in solid solution for the alloys with 0.7 and 1wt.% Sc, the age hardening response of all the Al–Sc alloys remains similar. The direct age hardening response of the as cast Al–0.5wt.% Sc is shown to be greater than the solutionised and age hardened alloy.

Detecting Peritectic Garnet in the Peraluminous Cardigan Pluton, New Hampshire

The peraluminous Cardigan Pluton of New Hampshire contains restitic garnetites with abundant peritectic garnet that serves as a basis for comparison with garnet in the host-rock. The peritectic garnet is inclusion-rich and contains high concentrations of heavy rare earth elements (HREE), Sc, and Zr and low concentrations of Zn, P, and U. The high HREE, Zr, and Sc result from biotite and zircon melting, buffering liquid compositions. Because the HREE and Sc are compatible in garnet, the peritectic garnet is rich in these elements. Some garnet crystals in the host-rocks have cores with identical inclusions and trace element compositions to the peritectic garnet in the garnetites. We infer that these are also peritectic garnet grains dispersed in the host magma. These cores are mantled by inclusion-poor garnet. These mantles, along with other garnet crystals that are inclusion-poor throughout, show rimward trends of decreasing HREE, Sc, and Zr, and increasing Zn, P, U, and Eu/Eu*. We interpret the trace element variations as records of fractionation as the melt decreased in HREE, Zr, and Sc and was enriched Zn, P, and U. The rimward increase in Eu/Eu* records the effect of feldspar fractionation. Thus the peritectic garnet preserves evidence of crystallization from buffered melts whereas the phenocrystic garnet shows variable trace element abundances indicative of crystallizing from fractionating melts. These differences provide criteria for the recognition of peritectic garnet in the host pluton.

Effect of heat treatment on the hardness of micro deep drawn cups of Al‐2Sc

AbstractContinuous miniaturisation of products e. g. for the automotive or the microelectronic sector necessitates process chains, which allow the manufacturing of microscopically small components in high quantities. The development of required processes and technologies is the aim of the Collaborative Research Centre (CRC) 747 “Micro Cold Forming” of the German Research Foundation. Besides micro cold forming another necessary step in the manufacturing process chain is the heat treatment process that enables the adjustment of materials properties being suitable for cold forming. Finally the application properties also have to be adjusted e. g. by precipitation hardening of aluminium alloys to increase the strength above the strain hardened level. Within the CRC an advanced Al‐Sc alloy with 2 mass‐% Scandium was developed to achieve particular properties. According to the very high Sc content dissolved a greater number of fine and homogeneously distributed precipitates causing a significant strengthening effect will be formed during artificial ageing. To meet the requirements of a high production rate the ageing of the micro deep drawn cups (1 mm in diameter) was performed in very short time in a drop‐down tube furnace. Before and after ageing the cups were characterised by ultra micro hardness measurements.

Trace-element composition and zoning in clinopyroxene- and amphibole-group minerals: Implications for element partitioning and evolution of carbonatites

The present work is a first comprehensive study of the trace-element composition and zoning in clinopyroxene- and amphibole-group minerals from carbonatites, incorporating samples from 14 localities worldwide (Afrikanda, Aley, Alnö, Blue River, Eden Lake, Huayangchuan, Murun, Oka, Ozernaya Varaka, Ozernyi, Paint Lake, Pinghe, Prairie Lake, Turiy Mys). The new electron-microprobe data presented here significantly extend the known compositional range of clinopyroxenes and amphiboles from carbonatites. These data confirm that calcic and sodic clinopyroxenes from carbonatites are not separated by a compositional gap, instead forming an arcuate trend from nearly pure diopside through intermediate aegirine–augite compositions confined to a limited range of CaFeSi 2O 6 contents (15–45 mol%) to aegirine with < 25 mol% of CaMgSi 2O 6 and a negligible proportion of CaFeSi 2O 6. A large set of LA-ICPMS data shows that the clinopyroxenes of different composition are characterized by relatively low levels of Cr, Co and Ni (≤ 40 ppm) and manifold variations in the concentration of trivalent lithophile and some incompatible elements (1–150 ppm Sc, 26–6870 ppm V, 5–550 ppm Sr, 90–2360 ppm Zr, and nil to 150 ppm REE), recorded in some cases within a single crystal. The relative contribution of clinopyroxenes to the whole-rock Rb, Nb, Ta, Th and U budget is negligible. The major-element compositional range of amphiboles spans from alkali- and Al-poor members (tremolite) to Na–Al-rich Mg- or, less commonly, Fe-dominant members (magnesiohastingsite, hastingsite and pargasite), to calcic–sodic, sodic and potassic–sodic compositions intermediate between magnesio-ferrikatophorite, richterite, magnesioriebeckite, ferri-nyböite and (potassic-)magnesio-arfvedsonite. In comparison with the clinopyroxenes, the amphiboles contain similar levels of tetravalent high-field-strength elements (Ti, Zr and Hf) and compatible transition elements (Cr, Co and Ni), but are capable of incorporating much higher concentrations of Sc and incompatible elements (up to 500 ppm Sc, 43 ppm Rb, 1470 ppm Sr, 1230 ppm Ba, 80 ppm Pb, 1070 ppm REE, 140 ppm Y, and 180 ppm Nb). In some carbonatites, amphiboles contribute as much as 25% of the Zr + Hf, 15% of the Sr and 35% of the Rb + Ba whole-rock budget. Both clinopyroxenes and amphiboles may also host a significant share (~ 10%) of the bulk heavy-REE content. Our trace-element data show that the partitioning of REE between clinopyroxene (and, in some samples, amphibole) and the melt is clearly bimodal and requires a revision of the existing models assuming single-site REE partitioning. Clinopyroxenes and amphiboles from carbonatites exhibit a diversity of zoning patterns that cannot be explained exclusively on the basis of crystal chemistry and relative compatibility of different trace-element in these minerals. Paragenetic analysis indicates that in most cases, the observed zoning patterns develop in response to removal of selected trace elements by phases co-precipitating with clinopyroxene and amphibole (especially magnetite, fluorapatite, phlogopite and pyrochlore). With the exception of magnesiohastingsite–richterite sample from Afrikanda, the invariability of trace-element ratios in the majority of zoned clinopyroxene and amphibole crystals implies that fluids are not involved in the development of zoning in these minerals. The implications of the new trace-element data for mineral exploration targeting REE, Nb and other types of carbonatite-hosted rare-metal mineralization are discussed.

Growth and emission properties of Sc, Pr, and Ce co-doped Lu3Al5O12 epitaxial layers for scintillators

The effect of Sc, Pr, and Ce co-doping on the emission and scintillation properties of lutetium aluminum epitaxial garnet layers, Lu3Al5O12 (LuAG), was studied. The Sc and Pr co-doped garnets with optimized dopant content provide in many aspects better emission and scintillation response compared to those without Sc co-doping. Energy transfer from sensitizer Sc3+ to activator Pr3+ ions was observed for small Sc doping levels, which consequently resulted in increased radioluminescence intensity and photoelectron yield. At higher Sc content above 3at%, however, the Pr3+ emission was partly quenched. Considerable suppression of slow components and notable increase of fast components in the photoelectron yield was the most remarkable effect of the Sc co-doping in PrSc:LuAG.

Magnetic State of Y&lt;sub&gt;3&lt;/sub&gt;Fe&lt;sub&gt;5-X&lt;/sub&gt;Sc&lt;sub&gt;x&lt;/sub&gt;O&lt;sub&gt;12&lt;/sub&gt; Garnets

Ferrogarnets of the system {Y3}[Fe2-xScx](Fe3)O12 were investigated by neutron diffraction and magnetic methods. Parameters of crystal structure were refined. It was found that deviations from a collinear ferrimagnetic structure emerged at x ~ 0.7. At high concentrations of Sc a growth of the high-field magnetic susceptibility and an abnormal temperature dependences of dynamic susceptibility typical of local angular spin structures were revealed. The fracture temperatures for the local angular structures were determined.