Ppm Sm Research Articles

Strategy for co-enhancement of corrosion resistance-strength of Cu-7Ni-3Al-1Fe-1Mn alloy: Rare earth Sm microalloying

Both high strength and superior corrosion resistance are necessary for Cu-Ni alloys when serving in marine engineering. We discover that the corrosion resistance and strength of Cu-7Ni-3Al-1Fe-1Mn alloy can be enhanced via rare earth Sm microalloying. When Sm content is 33 ppm, the alloy exhibits not only the lowest corrosion rate, which is 40% lower than the Sm-free alloy, but also the maximum tensile strength, which is 6% higher than the Sm-free alloy. After alloying 33 ppm Sm, the average grain size of Cu-7Ni-3Al-1Fe-1Mn alloy is reduced by 42%, from 205 μm to 118 μm. In addition, CuSm phase and (Sm2S3-Al2O3) composite phase appear in the alloy after alloying 33 ppm Sm. The improvement of corrosion resistance is primarily due to the formation of Cu-Sm precipitates, leading to a positive shift of the corrosion potential. Further analysis indicates that the increased strength can be mainly attributed to grain refinement and the formation of Sm-S precipitations. This work promotes a new method for enhancing the strength and corrosion resistance simultaneously of copper alloy.

Assessment of Heavy Metals in Guinea Sorrel (Hibiscus sabdariffa) Cultivated on Fadama Soils in Maiduguri, Nigeria

River Ngadda is one of the main sources of water used by the resident of Maiduguri Metropolis The proximity of the people to the river encourages a lot of irrigation farming along the river bank during the dry season especially vegetables therefore, concentration values of heavy metals namely Aluminum, Cobalt, Iron, Lanthanum, Manganese, Chromium, Rubidium, Scandium, Samarium, Thorium, Vanadium and Zinc were determined in Guinea Sorrel (Hibiscus sabdariffa) vegetable samples obtained at six different locations on different dry season farming (Fadama) sites along the bank of river Ngadda and Alau dam in Maiduguri, Nigeria. Instrumental neutron activation analysis (INAA) technique which is a sensitive method for determination of major, minor and trace element in a matrix was used to assessed the heavy metal accumulation levels in Guinea Sorrel with the aim to establish the food safety status from heavy metals concentration levels for guinea sorrel cultivated along the bank of river Ngadda and Alau dam and consumed on a daily basis as compared to WHO/FAO recommended maximum permissible limit (MPL) for edible vegetables. The result obtained showed that the concentration values of Al ranged from 932 ± 18 to 3369 ± 54 ppm, Co 0 .12 ± 0.03 to 40 ± 4 ppm, La 1.00 ± 0.03 ppm to 38 ± 4 ppm, Manganese 112 ± 0.4 to 176 ± 1 ppm, Rubidium 4 ± 0.5 to 21 ± 1ppm, Sc 0.10 ± 0.007 to 27 ± 1 ppm Sm 0.106 ± 0.004 to 17.2 ± 0.4 ppm, V 1.10 ± 0.3 to 4 ± 1 ppm and Zn 17 ± 3 to 63 ± 4 ppm, and Fe 379 ± 33 ppm to 2316 ± 65 ppm. This result indicates that the maximum concentrations of Fe, Cr, Mn and Co, in guinea sorrel from most of the sites were above the acceptable limits given by FAO/WHO for edible vegetables. Therefore, it is certain that there is the health risk associated with the continuous consumption of guinea sorrel vegetables cultivated from the study site and authors of this work hereby recommends that investigation of this kind should be carried out from time to time so as to know the buildup or otherwise of heavy metals in guinea sorrel cultivated in the study sites.

Synergistic corrosion inhibition effects of benzimidazole-samarium (III) molecules on the steel corrosion prevention in simulated seawater

Benzimidazole molecules and samarium nitrate were mixed together to synergistically reduce the steel corrosion rate in simulated seawater solution. Scanning electron microscopy analysis demonstrated that in the solution containing the mixture of inhibitive compounds (especially at 250 ppm Sm+750 ppm BI) a dense film without micro-crack uniformly deposited on the steel surface. The interaction (physical and/or chemical) between the samarium cations and benzimidazole molecules was confirmed by means of Fourier-transform infrared spectroscopy. By polarization and electrochemical impedance spectroscopy techniques, the corrosion inhibition activity of the deposited film on the steel surface was investigated. The electrochemical tests revealed the poor corrosion inhibition activity of each of inhibitors in NaCl solution, but 92% efficiency was attained in mixed form. The polarization test showed that the film of benzimidazole-samarium (III) could effectively retard the cathodic/anodic corrosion reactions on the steel surface in subjection to the chloride-containing electrolyte and decrease the corrosion current density from 8.5 to 0.7 μA/cm2.

Trace elements and REE enrichment at Seboah Hill, SW Egypt

Abstract Seboah Hill - a small body of peralkaline granite (< 0.1 km2) in south-western Egypt containing aegirine minerals ± magnesiohornblende ± riebeckite, cut by dikes of riebeckite-aegirine rhyolite, and exhibiting high radioactivity in veins of K-feldspar-aegirine-chalcedony-quartz ± trace hematite ± trace goethite was sampled and analyzed using inductively coupled plasma methods. Whole-rock chemical compositions of 5 granite, 3-rhyolitedike and 10 radioactive vein samples are presented. Of special significance is the enrichment of trace elements and rare earth elements (REE) in the radioactive veins. These include up to 6081 ppm Zr, 4252 ppm Ce, 1514 ppm Nd, 1433 ppm La, 1233 ppm Nb, 875 ppm Y, 388 ppm Pr, 350 ppm Th, 222 ppm Sm, 189 ppm Gd, 159 ppm Dy, 153 ppm Hf, 83 ppm Er, 76 ppm Yb and 58 ppm U. The chondrite-normalized patterns of REE in all samples show only limited variation and have negative europium (Eu) anomalies. These findings suggest that the sources of the REE are genetically related. Values of the Eu anomalies vary from 0.38-0.41 for the radioactive veins, 0.39-0.53 for the granite and 0.31-0.44 for the rhyolite dikes. Eu variations are consistent for different paragentic stages.

Standardless determination of Nd isotope ratios in glasses and minerals using laser-ablation multiple-collector inductively coupled plasma mass spectrometry with a low-oxide molecular yield interface setup

We investigated an appropriate instrumental setup for a laser-ablation multiple-collector inductively coupled plasma mass spectrometer (LA-MC-ICP-MS) and found that a reduced oxide setting allowed accurate and precise analysis of Nd isotope ratios in samples with or without concomitant interfering elements. We used an Aridus II solution–excimer laser dual-intake system. The ICP interface used a normal sample and skimmer cones with the torch shield switched off and an additional large interface rotary pump. The setting accomplished reduced oxide levels NdO+/Nd+ 0.01–0.05%, without significant sacrifice of the instrumental sensitivity (∼70%). Oxide molecular ions for the lighter elements were negligible and accurate internal mass bias corrections were achieved for both Sm and Nd using isotopic ratios derived from thermal ionization mass spectrometry measurements. This report reveals a novel setup that requires no external mass bias corrections (standardless analysis) for Sm and Nd isotope analyses by both solution- and LA-MC-ICP-MS methods. Solution analysis of La Jolla Nd standard gave a 143Nd/144Nd ratio of 0.511860 ± 0.000026, which is in excellent agreement with the reference value (relative deviation (RD) = +6 ppm). JMC Nd standard solution yielded a 143Nd/144Nd ratio of 0.512216 ± 0.000044 (RD = −14 ppm) while a Sm-doped JMC solution showed 0.512211 ± 0.000030 (RD = −23 ppm). For LA analyses, the observed ratios and RDs were 143Nd/144Nd = 0.511921 ± 0.000013 (RD = −12 ppm) for NIST SRM 610 glass standard (430 ppm Nd/453 ppm Sm); 0.512490 ± 0.000018 (RD = +14 ppm) for Durango apatite (1121 ppm Nd/147 ppm Sm); 0.512200 ± 0.000009 (RD = −26 ppm) for Fish Canyon Tuff sphene; 0.512232 ± 0.000003 (RD = +65 ppm) for EDR monazite and 0.512890 ± 0.000147 (RD = +34 ppm) for groundmass of a St. Helena lava (22.7 ppm Nd/∼5.01 ppm Sm). All measurements were in good agreement with the reference values. Examinations of Sm/Nd elemental fractionation have also been made and we confirmed that this originated from the ICP interface region rather than at the laser ablation site.

Characterization of multiple lithologies within the lunar feldspathic regolith breccia meteorite Northeast Africa 001

Abstract– Lunar meteorite Northeast Africa (NEA) 001 is a feldspathic regolith breccia. This study presents the results of electron microprobe and LA‐ICP‐MS analyses of a section of NEA 001. We identify a range of lunar lithologies including feldspathic impact melt, ferroan noritic anorthosite and magnesian feldspathic clasts, and several very‐low titanium (VLT) basalt clasts. The largest of these basalt clasts has a rare earth element (REE) pattern with light‐REE (LREE) depletion and a positive Euanomaly. This clast also exhibits low incompatible trace element (ITE) concentrations (e.g., <0.1 ppm Th, <0.5 ppm Sm), indicating that it has originated from a parent melt that did not assimilate KREEP material. Positive Eu‐anomalies and such low‐ITE concentrations are uncharacteristic of most basalts returned by the Apollo and Luna missions, and basaltic lunar meteorite samples. We suggest that these features are consistent with the VLT clasts crystallizing from a parent melt which was derived from early mantle cumulates that formed prior to the separation of plagioclase in the lunar magma ocean, as has previously been proposed for some other lunar VLT basalts. Feldspathic impact melts within the sample are found to be more mafic than estimations for the composition of the upper feldspathic lunar crust, suggesting that they may have melted and incorporated material from the lower lunar crust (possibly in large basin‐forming events). The generally feldspathic nature of the impact melt clasts, lack of a KREEP component, and the compositions of the basaltic clasts, leads us to suggest that the meteorite has been sourced from the Outer‐Feldspathic Highlands Terrane (FHT‐O), probably on the lunar farside and within about 1000 km of sources of both Low‐Ti and VLT basalts, the latter possibly existing as cryptomaria deposits.

Lunar meteorite regolith breccias: An in situ study of impact melt composition using LA-ICP-MS with implications for the composition of the lunar crust

Dar al Gani (DaG) 400, Meteorite Hills (MET) 01210, Pecora Escarpment (PCA) 02007, and MacAlpine Hills (MAC) 88104/88105 are lunar regolith breccia meteorites that provide sampling of the lunar surface from regions of the Moon that were not visited by the US Apollo or Soviet Luna sample return missions. They contain a heterogeneous clast population from a range of typical lunar lithologies. DaG 400, PCA 02007, and MAC 88104/88105 are primarily feldspathic in nature, and MET 01210 is composed of mare basalt material mixed with a lesser amount of feldspathic material. Here we present a compositional study of the impact melt and impact melt breccia clast population (i.e., clasts that were generated in impact cratering melting processes) within these meteorites using in situ electron microprobe and LA-ICP-MS techniques. Results show that all of the meteorites are dominated by impact lithologies that are relatively ferroan (Mg# 10), and have low incompatible trace element (ITE) concentrations (i.e., typically 10 ppm Sm), High Magnesium Suite (typically >70 Mg#) or High Alkali Suite (high ITEs, Sc/Sm ratios <2) target rocks. Instead the meteorite mafic melts are more ferroan, KREEP-poor and Sc-rich, and represent mixing between feldspathic lithologies and low-Ti or very low-Ti (VLT) basalts. As PCA 02007 and MAC 88104/05 were likely sourced from the Outer-Feldspathic Highlands Terrane our findings suggest that these predominantly feldspathic regions commonly contain a VLT to low-Ti basalt contribution.

Geochemical distinctions between “crustal” and mantle-derived peridotites/pyroxenites in high/ultrahigh pressure metamorphic complexes

Basic and ultrabasic rocks in high- and ultrahigh-pressure collision belts can provide important petrological information. Mantle-derived and “crustal” peridotites and pyroxenites are recognized among these rocks in Phanerozoic orogenic zones. The former were emplaced as mantle magma intrusions or tectonically transferred solid fragments of mantle material in the deeply subsided lithosphere, while the latter are shallow complexes of dikes and sills, which were altered and metamorphosed during subduction process. Both rock types were later exhumed at the Earth's surface. For geochemical comparison of these types, four groups of rocks were chosen: two sample sets of mantle-derived rocks and two sets of crustal rocks. The mantle-derived rocks include a set of spinel and garnet peridotites of alpine-type bodies from the Eastern and Western Alps and the Ronda massif in Spain as well as a set of pyroxenites from the Eastern Alps. The “crustal” rocks include a set of garnet and spinel peridotites from the Kokchetav massif, northern Kazakhstan, and garnet peridotites from the Western Gneiss Region, western Norway, together with a set of pyroxenites from the Kokchetav massif. Geochemical investigation has revealed that mantle-derived peridotites are characterized, as a rule, by high contents of MgO (35–46 wt.%), Cr (1750–12,770 ppm), and Ni (900–2500 ppm), low contents of FeO (5–10 wt.%), TiO 2 (0.01–0.3 wt.%), Zr (0.002–1.2 ppm), Nb (0.001–0.3 ppm), Sm (0.003–0.5 ppm), La (0.005–1 ppm), and Yb (0.006–0.54 ppm), and the total content of REE equal to 0.06–5.2 ppm. Mantle-derived pyroxenites contain 27–35 wt.% MgO, 2300–3300 ppm Cr, 5.5–9 wt.% FeO, 0.02–0.08 wt.% TiO 2, 0.2–1.4 ppm Zr, 0.007–0.06 ppm Nb, 0–0.13 ppm Sm, 0.007–0.23 ppm La, 0.02–0.2 ppm Yb, and 0.05–1.6 ppm total REE. “Crustal” peridotites are characterized by high contents of FeO (12–25 wt.%), TiO 2 (0.64–2.6 wt.%), Zr (33–179 ppm), Nb (3.4–13.8 ppm), Sm (0.7–4 ppm), La (1–8 ppm), Yb (0.8–3.3 ppm), and total REE (11.5–48 ppm) as well as by comparatively low contents of MgO (15–26 wt.%), Cr (79–244 ppm), and Ni (450–730 ppm). “Crustal” pyroxenites contain 6–21.5 wt.% MgO, 90–230 ppm Cr, 11–21 wt.% FeO, 0.7–1.3 wt.% TiO 2, 45–493 ppm Zr, 1–8 Nb, 1.6–4.3 ppm Sm, 4.7–14 ppm La, 1.3–7.4 ppm Yb, and 27–80 ppm total REE. These data permit us to develop D. Carswell's idea of distinctions between the mantle-derived and “crustal” peridotites and suggest some promising geochemical criteria. The criteria are based on distinctions between the contents of MgO, FeO, TiO 2, Cr, Ni, Zr, Nb, REE, etc. in peridotites and pyroxenites. Binary MgO–Cr, FeO–TiO 2, La–Yb, Lu–Nd, Eu–Gd, and Sm–ΣREE diagrams give an opportunity to discriminate the compositions in detail and are the most appropriate for practical use. The obtained information may be helpful in understanding the nature of protoliths when studying mafic/ultramafic granulites in high-grade metamorphic rocks.

Application of major- and trace-element geochemistry to refine U-Pb zircon, and Sm/Nd or Lu/Hf sampling targets for geochronology of HP and UHP eclogites, Western Gneiss Region, Norway

The geochemistry of kyanite and orthopyroxene eclogites (7 samples) indicate that they are gabbroic cumulates. Incompatible trace elements in these rocks occur at low concentrations compared to regionally associated eclogites that are compositionally similar to basaltic magmas (11 samples). Eclogites with cumulate protoliths commonly contain 100 ppm Zr, >4 ppm Sm, and >0.4 ppm Lu for basaltic eclogites. Because of low Zr concentrations, igneous and metamorphic zircons are rare or absent in these eclogites. Samarium and Lu concentrations are also low in the kyanite and orthopyroxene eclogites, but they have parent/daughter Sm/Nd ratios of 0.23–0.51 and Lu/Hf ratios of 0.22–0.60, higher than most associated basaltic eclogites at 0.22–0.38 and 0.11–0.18, respectively. These results suggest that kyanite and orthopyroxene eclogites are poor targets for zircon geochronologic work, but are good targets for Sm/Nd and Lu/Hf mineral/whole rock geochronology because of their high parent/daughter ratios.

Melting of the subcontinental lithospheric mantle by the Emeishan mantle plume; evidence from the basal alkaline basalts in Dongchuan, Yunnan, Southwestern China

The Emeishan continental flood basalt (ECFB) sequence in Dongchuan, SW China comprises a basal tephrite unit overlain by an upper tholeiitic basalt unit. The upper basalts have high TiO 2 contents (3.2–5.2 wt.%), relatively high rare-earth element (REE) concentrations (40 to 60 ppm La, 12.5 to 16.5 ppm Sm, and 3 to 4 ppm Yb), moderate Zr/Nb and Nb/La ratios (9.3–10.2 and 0.6–0.9, respectively) and relatively high ɛ Nd ( t ) values, ranging from − 0.94 to 2.3, and are comparable to the high-Ti ECFB elsewhere. The tephrites have relatively high P 2O 5 (1.3–2.0 wt.%), low REE concentrations (e.g., 17 to 23 ppm La, 4 to 5.3 ppm Sm, and 2 to 3 ppm Yb), high Nb/La (2.0–3.9) ratios, low Zr/Nb ratios (2.3–4.2), and extremely low ɛ Nd ( t ) values (mostly ranging from − 10.6 to − 11.1). The distinct compositional differences between the tephrites and the overlying tholeiitic basalts cannot be explained by either fractional crystallization or crustal contamination of a common parental magma. The tholeiitic basalts formed by partial melting of the Emeishan plume head at a depth where garnet was stable, perhaps > 80 km. We propose that the tephrites were derived from magmas formed when the base of the previously metasomatized, volatile-mineral bearing subcontinental lithospheric mantle was heated by the upwelling mantle plume.

Dating of the Giant Huize Zn‐Pb Ore Field of Yunnan Province, Southwest China: Constraints from the Sm‐Nd System in Hydrothermal Calcite

AbstractThe Huize ore field, which is the most famous high‐grade Mississippi Valley‐type Zn‐Pb ore field in China, consists of the Kuangshanchang and Qilinchang deposits. The Sm‐Nd isotopic compositions of gangue calcite were analyzed to constrain the timing of mineralization. Eight calcite samples from the No. 6 orebody in the Qilinchang deposit have Sm and Nd concentrations of 1.82–25.93 and 15.25–79.02 ppm, respectively, and yielded an age of 225 ± 9.9 Ma with epsilon Nd =−10.6 and MSWD = 0.13. Five calcites from the No. 1 orebody in the Kuangshanchang deposit contain 2.37–2.90 ppm Sm and 8.18–16.85 ppm Nd, and yielded an age of 228 ± 16 Ma, with epsilon Nd =−10.6 and MSWD = 0.28. These two ages are close to the age of the Emeishan flood basalt, which is ca 255 Ma, and agree with the reported 40Ar/39Ar plateau and isochron ages of the native copper mineralization related to the Emeishan flood basalt in this region, which are 226–228 Ma. Moreover, previous study shows that the magnitude of uplift resulting from the Emeishan flood basalts is &gt;1000 m. It indicates that the Kuangshanchang and the Qilinchang deposit formed during the same geological event and originated by fluid migration during uplift resulting from the Emeishan flood basalt.

Heat-producing elements in the lunar mantle: Insights from ion microprobe analyses of lunar pyroclastic glasses

We provide new estimates for the abundance of heat-producing elements in the lunar mantle by using SIMS techniques to measure the concentrations of thorium and samarium in lunar pyroclastic glasses. Lunar pyroclastic glasses are utilized in this study because they represent quenched products of near-primary melts from the lunar mantle and as such, they provide compositional information about the mantle itself. Thorium and samarium were measured because: (1) Th is not significantly fractionated from Sm during partial melting of the pyroclastic glass source regions, which are dominated by olivine and pyroxene. Therefore, the Th/Sm ratios that we measure in the pyroclastic glasses reflect the Th/Sm ratio of the pyroclastic glass source regions. (2) Strong correlations between Th, U, and K on the Moon allow us to use measured Th concentrations to estimate the concentrations of U and K in the pyroclastic glasses. (3) Th, Sm, U, and K are radioactive elements and as such, their concentrations can be used to investigate heat production in the lunar mantle. The results from this study show that the lunar mantle is heterogeneous with respect to heat-producing elements and that there is evidence for mixing of a KREEP component into the source regions of some of the pyroclastic glasses. Because the source regions for many of the glasses are deep (⩾400 km), we propose that a KREEP component was transported to the deep lunar mantle. KREEP enriched sources produce 138% more heat than sources that do not contain KREEP and therefore, could have provided a source of heat for extended periods of nearside basaltic magmatism. Data from this study, in conjunction with models for the fractional crystallization of a lunar magma ocean, are used to show that the average lunar mantle contains 0.15 ppm Th, 0.54 ppm Sm, 0.039 ppm U, and 212 ppm K. This is a greater enrichment in radiogenic elements than some earlier estimates, suggesting a more prolonged impact of radiogenic heat on nearside basaltic volcanism.

The thermal history of the Nares Strait, Kane Basin, and Smith Sound region in Canada and Greenland: constraints from apatite fission-track and (U–Th–Sm)/He dating

Apatite fission-track and (U–Th–Sm)/He data for samples with Proterozoic–Neogene lithologic ages from eastern Ellesmere, Devon, and Baffin islands in the Canadian Arctic Archipelago and northwest Greenland provide insights into the complex thermal history of this region. Most data reflect exhumational cooling of the region as a sediment source area for the developing Sverdrup Basin to the west during late Paleozoic – Mesozoic time. Samples proximal to the basin margin record late Paleozoic cooling consistent with erosion of uplifted rift flanks and widespread clastic sedimentation during early rifting and thermal subsidence. Data from distal samples are consistent with early Mesozoic epeirogenic denudational cooling during periods of high sediment supply from well-developed river systems. Around northern Baffin Bay, the data record erosional cooling of uplifted rift flanks in response to Late Cretaceous rifting. Rapid denudation rates are indicated for southeastern Devon Island, compatible with thick Upper Cretaceous strata offshore in Lancaster Sound. Slower denudation rates are indicated for northwest Greenland. Along Nares Strait, data reflect mafic volcanism or erosional exhumation associated with strike-slip and (or) thrust displacements during the Paleogene Eurekan orogeny and offer limited support for the existence of a Wegener fault. Fission-track ages older than those obtained in central Ellesmere Island, however, suggest that active tectonics occurred earlier near the strait, and strike-slip tectonism and deformation were likely partitioned across a relatively wide belt. Apatites obtained from Archean gneisses and Franklinian dykes have up to 500 ppm Sm, and up to 15% of the radiogenic He is Sm derived.

Partition coefficients for REE between garnets and liquids: implications of non-Henry's Law behaviour for models of basalt origin and evolution

Partition coefficients for the rare earth elements (REE) Ce, Sm and Tm between coexisting garnets and hydrous liquids have been determined at high pressure and temperatures (30 kbar and 1300 and 1500°C). Two synthetic systems were studied, Mg3Al2Si3O12-H2O and Ca3Al2Si3O12-H2O, in addition to a natural pyrope-bearing system.Deviations from Henry's Law behaviour occur at geologically relevant REE concentrations. At concentrations < 3 ppm Ce, < 12 ppm Sm, < 80 ppm Tm in pyrope and < 100 ppm Ce, < 250 ppm Sm, < 1000 ppm Tm in grossular (at 30 kbar and 1300°C), Dgarnet liquidREE increases as the REE concentration in the garnet decreases. At higher concentrations, DREE is constant. Dgrossular liquidREE also constant when the garnet contains less than about 2 ppm Sm or Tm. The REE concentration at which DREE becomes constant increases with increasing temperature, decreasing REE ionic radius and increasing Ca content of the garnet.Partitioning behaviour of Ce, Sm and Tm between a natural pyrope-rich garnet and hydrous liquid is analogous to that in the synthetic systems and substantiates the substitution model proposed by Harrison and Wood (1980).Values of DREEgarnet/liquid for which Henry's Law is obeyed are systematically higher for grossular than for pyrope (Dpyrope/liquid = 0.067(Ce), 0.108(Sm), 0.155(Tm) and Dgrossular/Liquid = 0.65(Ce), 0.75(Sm), 4.55(Tm).The implications of non-Henry's Law partitioning of REE for models of basalt petrogenesis involving garnet are far-ranging. Deviations from Henry's Law permit refinements to be made to calculated REE abundances once basic model parameters have been defined.

“Henry's law” behaviour of Sm in a natural plagioclase/melt system: Importance of experimental procedure

We report an experimental study of the partitioning of Sm in a natural plagioclase/melt system as a function of concentration of Sm at constant pressure, temperature and bulk composition. Both radioactive 151Sm and non-radioactive Sm 2O 3 were used. In experiments in which the sample was initially held at a temperature above the liquidus for only one hour, we find that the plagioclase/ melt partition coefficient for Sm increases with decreasing concentration of Sm. There is also evidence for isotopic heterogeneity in the initially molten charge. In experiments in which the sample was initially held at the same temperature above the liquidus for 24 hours, the partition coefficient was constant as a function of concentration and no evidence for isotopic heterogeneity was observed. These experiments indicate that partition coefficients obtained from experiments involving tracer isotopes are very sensitive to experimental procedure. Our experiments also indicate that the partition coefficient for Sm between plagioclase and melt is constant over the range 3 to 50,000 ppm Sm in the melt. That range encompasses most concentrations in natural systems.

Interference by neutron induced second order nuclear reaction in activation analysis of rare earths

In determining the trace impurities existing in high-purity rare earth samples by the neutron activation analysis, there are much interference due to nuclides induced from neutron induced second order nuclear reaction. This paper presents the degree of interference calculated over the ranges of irradiation time from 105 to 107 sec and of thermal-neutron flux from 1·1012 to 1·1015 n·cm−2·sec−1. According to the results of these calculations, degree of interference under the neutron irradiation condition for 288 hrs in the thermal-neutron flux of 3·1013n·cm−2·sec−1 is concluded to be 6.4·106 ppm Gd in Eu, 2.2·104 ppm Sm in Eu, 1.9·104 ppm Ho in Dy, 1.1·103 ppm Eu in Sm, 1.1·102 ppm Ce in La and 1.1·10 ppm Tb in Gd, respectively. Especially, the Gd determination in the Eu target is extremely affected by153Gd formed from the151Eu (n, γ) $${}^{1 5 1}Eu (n,\gamma ){}^{1 5 2}Eu\underrightarrow \beta {}^{1 5 2}Gd(n,\gamma ){}^{1 5 3}Gd$$ reaction. On the contrary, this reaction is effective in producing153Gd activity.

Partitioning of samarium and nickel between olivine, orthopyroxene, and liquid; preliminary data at 20 kbar and 1025°C

Olivine (ol) and aluminous enstatite (opx) coexist with a hydrous liquid (liq) of haplobasaltic composition in the system Fo An 50Ab 50 SiO 2 H 2O at 20 kbar and 1025°C. Concentrations of Ni and Sm in these three phases have been determined by mapping β tracks in nuclear emulsions using 63Ni and 151Sm as sources of β particles. Partition coefficients defined as K i α−β = C i α/C i β (concentrations in ppm of i =Ni or Sm in phases α and β) have been determined for total Sm content of the system (ΣSm) ranging from 1.27 to about 100 ppm and for total Ni content (ΣNi) ranging from 10 to 3000 ppm. The K Sm ol-liq ranges from 0.027 ± 0.002 at ΣSm = 1.27 ppm (∼0.8 ppm Sm in ol) to 0.024 ± 0.001 at ΣSm = 20 ppm. At higher samarium concentrations, K Sm ol-liq decreases to about 0.016 ± 0.001atΣSm ≥ 100 ppm. The K Sm opx-liq equals 0.056 ± 0.002 at ΣSm ≤ 20 ppm. The partition coefficient decreases rapid to less than 0.020 at higher samarium contents. The K Ni ol-liq equals about 19 at ΣNi ≤ 200 ppm (≲1000 ppm in olivine) and then decreases to less than 5 at higher nickel contents of the system. The K Ni opx-liq behaves similarly, equaling ∼1.3 in the low-Ni range and 0.6 in the high-Ni range. The data demonstrate that the concentration range over which the partition coefficient is constant is wider for nickel than for samarium. Furthermore, for nickel the range is wider for the ol-liq pair than for the opx-liq pair. With samarium as the trace element, the range of the constant partition coefficient is approximately the same for both the ol-liq and the opx-liq pairs.