Zeitschriftenartikel: „U-Zr-Fe-O“

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Tsurikov, D. F., V. N. Zagryazkin, V. Yu Vishnevskii, E. K. Diakov, A. Yu Kotov und V. M. Repnikov. „U–Zr–Fe–O Melt density“. Atomic Energy 107, Nr. 4 (Oktober 2009): 247–54. http://dx.doi.org/10.1007/s10512-010-9222-2.

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Asmolov, V. G., V. N. Zagryazkin und D. F. Tsurikov. „The thermodynamics of U-Zr-Fe-O melts“. High Temperature 45, Nr. 3 (Juni 2007): 305–12. http://dx.doi.org/10.1134/s0018151x07030042.

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Asmolov, V. G., V. N. Zagryazkin und D. F. Tsurikov. „Estimation of the density of U-Zr-Fe-O melts“. High Temperature 46, Nr. 4 (30.07.2008): 579–82. http://dx.doi.org/10.1134/s0018151x08040202.

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Ohgi, Hiroshi, Yuji Nagae und Masaki Kurata. „THERMODYNAMIC EVALUATION ON SOLIDIFICATION PATH FOR U-ZR-FE-O CORIUM“. Proceedings of the International Topical Workshop on Fukushima Decommissioning Research 2022 (2022): 1066. http://dx.doi.org/10.1299/jsmefdr.2022.0_1066.

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Bottomley, Paul David W., Mairead Murray-Farthing, Dario Manara, Thierry Wiss, Bert Cremer, Cos Boshoven, Patrick Lajarge und Vincenzo Rondinella. „Investigations of the melting behaviour of the U–Zr–Fe–O system“. Journal of Nuclear Science and Technology 52, Nr. 10 (10.04.2015): 1217–25. http://dx.doi.org/10.1080/00223131.2015.1023381.

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FUKASAWA, Masanori, Shigeyuki TAMURA und Mitsuhiro HASEBE. „Development of Thermodynamic Database for U—Zr—Fe—O—B—C—FPs System“. Journal of Nuclear Science and Technology 42, Nr. 8 (August 2005): 706–16. http://dx.doi.org/10.1080/18811248.2004.9726440.

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Pöml, Philipp, und Boris Burakov. „Study of the redistribution of U, Zr, Nb, Tc, Mo, Ru, Fe, Cr, and Ni between oxide and metallic phases in the matrix of a multiphase Chernobyl hot-particle extracted from a soil sample of the Western Plume“. Radiochimica Acta 106, Nr. 12 (27.11.2018): 985–90. http://dx.doi.org/10.1515/ract-2018-2957.

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Abstract A “hot particle” found 6 km west of the Chernobyl nuclear power plant 4 years after the Chernobyl severe nuclear accident was analysed by scanning electron microscopy and electron probe micro-analysis. The matrix of the particle consists of relics of partly molten UO2 nuclear fuel and two different phases of solidified U–Zr–O melt (U0.77Zr0.23O2 and U0.67Zr0.33O2). The particle also contains a unique metallic inclusion of a size of 30×22 μm. The inclusion is non-homogeneous and in some parts shows a dendrite-like structure. It consists of about 38 wt.% Fe, about 10 wt.% U, Mo, and Nb, about 5 wt.% Ru, Zr, Ni, and Cr, and small amounts of Tc (2 wt.%) and Si (0.4 wt.%). The presence of partly molten nuclear fuel suggests a local temperature exceeding 2850 °C. The metallic inclusion most likely formed when steel, fuel, and cladding reacted together and molten steel incorporated U, Zr, Nb, Tc, Mo, and Ru from molten fuel and cladding during a very fast high-temperature process. Fast quenching of the metallic and the oxide melt left no time for Tc and Mo to evaporate. Molten Zr was partly oxidised and acted as a buffer for O which caused the reduction of a fraction of the U. The data of this study support the previously reported supercritical nature of the Chernobyl explosion.

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SUDO, Ayako, Fumiki MIZUSAKO, Kuniyoshi HOSHINO, Takumi SATO, Yuji NAGAE und Masaki KURATA. „Fundamental Study on Segregation Behavior in U–Zr–Fe–O System during Solidification Process“. Transactions of the Atomic Energy Society of Japan 18, Nr. 3 (2019): 111–18. http://dx.doi.org/10.3327/taesj.j18.029.

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Nandan, Shambhavi, Florian Fichot und Bruno Piar. „A simplified model for the quaternary U-Zr-Fe-O system in the miscibility gap“. Nuclear Engineering and Design 364 (August 2020): 110608. http://dx.doi.org/10.1016/j.nucengdes.2020.110608.

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Khabensky, V. B., V. I. Almjashev, E. B. Shuvaeva, E. V. Krushinov, S. A. Vitol, A. A. Sulatsky, S. Yu Kotova und V. V. Gusarov. „Experimental determination of spatial inversion pointof coexisting molten phases in the U-Zr-Fe-O system“. Nuclear Propulsion Reactor Plants. Life Cycle Management Technologies., Nr. 3 (2021): 63–81. http://dx.doi.org/10.52069/2414-5726_2021_3_25_63.

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FUKASAWA, Masanori, und Shigeyuki TAMURA. „Thermodynamic Analysis for Molten Corium Stratification Test MASCA with Ionic Liquid U-Zr-Fe-O-B-C-FPs Database“. Journal of Nuclear Science and Technology 44, Nr. 9 (September 2007): 1210–19. http://dx.doi.org/10.1080/18811248.2007.9711364.

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RIBEIRO, Maria Manuela Malhado Simões, Malva Andrea MANCUSO, Celeste Rosa Ramalho JORGE, Jorge Luís MARTINEZ, João Ferro PELICA, Maria Fernanda PESSOA und Fernando Henrique REBOREDO. „ACUMULAÇÃO DE METAIS PESADOS E ALTERAÇÃO DAS PROPRIEDADES FÍSICAS E QUÍMICAS DE AREIAS DE DUNAS LITORÂNEAS“. Geosciences = Geociências 37, Nr. 3 (27.09.2018): 543–53. http://dx.doi.org/10.5016/geociencias.v37i3.11106.

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Nos dois últimos séculos, na orla costeira de Portugal, generalizou-se a prática agrícola em areias de duna com a aplicação de agroquímicos, sem controlo técnico, de onde resultaram alterações da composição físico-química e acumulação de metais pesados nas areias. Com o objetivo de avaliar os efeitos do manejo agrícola foram coletadas e caracterizadas, do ponto de vista físico e químico, amostras das dunas, entre os 0,0 cm e os 20 cm de profundidade, com e sem prática agrícola. Foi determinada, por ensaio de peneiramento, a fração fina (partículas com diâmetro inferior a 0,074 mm) e pelo método MAB – Peróxido a composição em matéria orgânica. Foi estimada a umidade das amostras e determinado, pelo método eletroquímico, o pH, a condutividade elétrica e o potencial de oxirredução. A composição química foi analisada por fluorescência de raios-x. Verificou-se que o manejo agrícola das dunas resultou no aumento da fração fina, da matéria orgânica, da umidade, da condutividade elétrica e do potencial de oxirredução das areias. O pH diminuiu, de básico para valores próximos de neutro, aumentando o risco de acumulação e mobilização de Fe, Mn, Cu, Zn, Pb, As, Zr, Th, Rb, Cr, V, Ni, Hg, Co e U.

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Mira, Hamed Ibrahim, Hussein Kamal Hussein, Sameh Zakaria Tawfik und Neveen Salah Abed. „Stream Sediments Geochemical Exploration in Wadi El Reddah area, Northeastern Desert, Egypt“. Mediterranean Journal of Chemistry 10, Nr. 8 (02.11.2020): 809. http://dx.doi.org/10.13171/mjc10802011021539st.

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Wadi El Reddah representing a semi-closed basin, extends in the N-S direction. It has only one outlet at the northern tip while the wadi collects floodwater from internal tributaries along wall rocks. The present study discusses the relationship between geology and geochemistry data to detect anomalous radioactive locations. The geochemical maps show the mineralization areas with abnormal rare metal contents. This led to two uranium occurrences (GXXIII and GXXIV) at Gabal Gattar in the perthitic leucogranite. At Wadi El Reddah, high contents of pathfinder elements (REE, Y, Zn, Nb and As) were discovered at the southern and eastern boundaries. This may be attributed to the presence of alkali feldspar granite at Gabal Gattar at the upstream of Wadi El Reddah and also to the sharp contact between Gabal Gattar and Hammamat Sedimentary rocks. A strong positive correlation coefficient between Fe2Ot and or Al2O3 with Zr, Hf, Nb, Ta, REE, U, Rb, and Th reflects their association with thematization processes.

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FUKASAWA, Masanori, Shigeyuki TAMURA und Masaki SAITO. „Analysis of B4C Influences on Thermodynamic Properties and Phase Separation of Molten Corium with Ionic Liquid U-Zr-Fe-O-B-C-FPs Database“. Journal of Nuclear Science and Technology 46, Nr. 7 (Juli 2009): 724–36. http://dx.doi.org/10.1080/18811248.2007.9711579.

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Villanova, S., G. Piotto, A. F. Marino, A. P. Milone, A. Bellini, L. R. Bedin, Y. Momany und A. Renzini. „The multipopulation phenomenon in Galactic globular clusters: M4 and M22“. Proceedings of the International Astronomical Union 5, S266 (August 2009): 326–32. http://dx.doi.org/10.1017/s1743921309991219.

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AbstractWe present an abundance analysis based on high-resolution spectra of red-giant-branch (RGB) stars in the Galactic globular clusters NGC 6121 (M4) and NGC 6656 (M22). Our aim was to study their stellar population in the context of the multipopulation phenomenon recently discovered to affect some globular clusters. Analysis was performed for the following elements: O, Na, Mg, Al, Ca, Fe, Y, and Ba. Spectroscopic data were completed by high-precision wide-field U BV IC ground-based photometry and HST/ACS observations. For M4, we find a well-defined Na–O anticorrelation composed of two distinct groups of stars with significantly different Na and O content. The two groups of Na-rich and Na-poor stars populate two different regions along the RGB. As regards M22, Na and O follow the well-known anticorrelation found in many other GCs. However, at odds with M4, it appears to be continuous without any hint of clumpiness. On the other hand, we identified two clearly separated groups of stars with significantly different abundances of the s-process elements Y, Zr and Ba. The relative numbers of the members of both groups are very similar to the ratio of the stars in the two subgiant branches of M22 recently found by Piotto (2009). The s-element-rich stars are also richer in iron and have higher Ca abundances. This makes M22 the second cluster after ω Centauri where an intrinsic spread in Fe was found. Both spectroscopic and photometric results imply the presence of two stellar populations in M4 and M22, even if both clusters have completely different characteristics.

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Mamo, Dilbetigle Assefa, Ashok Kumar Chaubey, Awoke Taddesse Hailu und Asres Yihunie Hibstie. „Analysis of Atmospheric Air Pollutants using Lichens as a Bio-monitor by Calibration Free-Laser Induced Breakdown Spectroscopy Technique“. European Journal of Applied Physics 5, Nr. 6 (08.12.2023): 52–61. http://dx.doi.org/10.24018/ejphysics.2023.5.6.286.

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Biomonitoring provides information on the quality of the environment or its modification and has been used as an alternative to monitoring chemical pollutants. The lichen bio-monitoring technique and calibration Free-Laser induced Breakdown spectroscopy (CF-LIBS) were used to study trace element atmospheric deposition in five areas of Addis Ababa city. The emission of air pollutants, mainly from anthropogenic sources, has led to the degradation of air quality. The element contents of the transplanted Epiphytic lichen were determined in the vicinity of different heavy traffic and small industry places. We identified twenty-one elements (Fe, Ti, U, V, Ni, Eu, Zr, Sr, Ba, Hf, Na, K, Sc, Si, Al, Mg, Ca, C, N, O, and H). Calibration Free-Laser induced breakdown spectroscopy and semi-quantitative methods were used to calculate the concentration of pollutants to point out the most polluted areas for the chemical analysis. Dried samples of the lichen containing heavy pollutants elements like Fe, Ti, Sr, Sc, Ba, Ni, Eu, and Zn are found, and their concentration is determined. Comparison of the elemental concentration in lichen samples transplanted in 4-kilo and science faculty compound with those the Bola airport, central bus station, and Laghar train station reveals that the science faculty compound and 4-kilo areas show a considerably higher concentration of most elements in the lichen than observed in the other areas of the city where lichen samples have been transplanted. Advanced MATLAB algorithm have been used for data analysis.

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Suzuki, Masanori, Ken Kurosaki, Shinsuke Yamanaka, Toshihiro Tanaka, Masayoshi Uno, Yukihiro Murakami, Tatjana Jantzen, Stephan Petersen und Klaus Hack. „Development of thermodynamic databases in the system U–Zr–Ce–Cs–Fe–B–C–I–O–H for application to simulating phase equilibria in severe nuclear accidents“. Journal of Nuclear Science and Technology 55, Nr. 8 (31.03.2018): 885–99. http://dx.doi.org/10.1080/00223131.2018.1449679.

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Deshmukh, S. B., A. M. Pophare, Y. A. Murkute und G. G. Wadpalliwar. „Geochemical Characteristics of Mafic Dykes from Wairagarh Area, Western Bastar Craton, Central India“. Journal of Geosciences Research 8, Nr. 2 (01.07.2023): 133–41. http://dx.doi.org/10.56153/g19088-022-0132-31.

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The NW-SE trending mafic dykes intrude the Amgaon gneisses and Dongargarh granite in Wairagarh area of the Western Bastar Craton (WBC). These dykes consist of mainly the clinopyroxene, plagioclase feldspar and minor amphiboles and titano-magnetite. These are metamorphosed to green schist facies. The mafic dykes show tholeiitic trend on multivariate geochemical plots and moderate range of variation in SiO2 (50.15 to 52.84 wt.%), MgO (5.13 to 7.64 wt.%), Fe O (12.97 to 15.08 wt.%), Al O (12.74 to 14.48 wt.%) and the Mg# value ranges from 37.74 to 51.21. Strong positive correlation of Sr, Th, Hf, U, Ga, Ta, Pb, Cs, Rb and HREEs negate the effect of post magmatic alteration. Negative Nb, Ta and Ti with positive Zr and Hf anomalies suggest the effect of assimilation and crustal contamination, which is also supported by Ce/Nb (0.23-0.33) equivalent to the crustal value. Negative ΔNb value suggests depleted mantle source for the mafic dykes of the WBC. Restricted range of (Gd/Yb)N (1.05-1.67), (Dy/Yb)N (0.94-1.25) and (Sm/Yb)N (1.22-2.26) advocate that these mafic dykes were derived from spinel lherzolite source. About 5-15% degrees of partial melting of depleted mantle source is envisaged for the generation of the mafic dykes. The field and geochemical evidences suggest that the mafic dykes of Wairagarh area, WBC were emplaced within continental rift environment. Keywords: Mafic dykes, Geochemistry, Wairagarh, Bastar Craton, Central India

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Kowalska, Sylwia. „Analiza chemostratygraficzna różnowiekowych osadów budujących górotwór karpacki“. Nafta-Gaz 79, Nr. 10 (Oktober 2023): 623–39. http://dx.doi.org/10.18668/ng.2023.10.01.

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"Artykuł prezentuje próbę przeprowadzenia analizy chemostratygraficznej dla różnowiekowych skał budujących górotwór karpacki. W pierwszej kolejności zdecydowano się stworzyć syntetyczny profil geologiczny dla osadów występujących we wschodniej części polskich Karpat. Wykorzystane próbki, w większości piaskowce, pochodziły z głównych poziomów stratygraficznych w obrębie jednostek skolskiej i śląskiej, gdzie zidentyfikowano skały od dolnej kredy po paleocen. Ze względu na dostępność materiału badawczego do badań wytypowano próbki o udokumentowanej stratygrafii z dwóch otworów, D-1 i H-1, zwracając głównie uwagę na ich klasyfikację stratygraficzną. Następnie dla porównania wykonano profil chemostratygraficzny dla otworu Kuźmina-1. Stwierdzono obecność bardzo dużego zróżnicowania składu chemicznego pomiędzy głównymi poziomami stratygraficznymi wyróżnianymi na podstawie badań paleontologicznych w badanych otworach, co pozwoliło wyznaczać zdecydowane granice pomiędzy poszczególnymi poziomami stratygraficznymi. Możliwość stworzenia unikalnych modeli chemostratygraficznych dla czterech analizowanych poziomów stratygraficznych: kredy górnej – senonu (warstwy inoceramowe), kredy górnej / paleocenu (warstwy istebniańskie), eocenu (warstwy pstre) oraz oligocenu (warstwy krośnieńskie) potwierdziło również wykonanie diagramu klasyfikacyjnego Herrona. Największe zróżnicowanie cech chemostratygraficznych uzyskano w przypadku utworów kredowych. Wstępnie badania wykonano w laboratorium akredytowanym Actlabs, tak aby móc później przeprowadzić ewaluację wyników uzyskanych za pomocą przenośnych spektrometrów (pXRF Titan, o zakresie pomiarowym od Mg do U, oraz pXRF Tracer, który umożliwia również pomiar zawartości Na, oba aparaty firmy Bruker). Potwierdzono, że wyraźne zróżnicowanie zawartości poszczególnych pierwiastków widoczne jest zarówno dla pierwiastków głównych, jak i śladowych. Pierwiastki najbardziej diagnostyczne to Na, Mg, Fe, K, Ca, również Si, choć w tym przypadku zakres zmienności jest nieco mniejszy. W przypadku pierwiastków śladowych są to S, P, Mn, Ti, Sr, Zr, Ba, Rb i Zn, które można również analizować za pomocą przenośnych spektrometrów pXRF. Wykonane porównanie wyników składu chemicznego uzyskiwanych przenośnym spektrometrem pXRF oraz w laboratorium Actlabs wykazało, że możliwe jest wykorzystanie na większą skalę samych pomiarów spektrometrem pXRF. Dla większości pierwiastków diagnostycznych uzyskano wystarczająco precyzyjne wyniki przy wykorzystaniu przenośnych spektrometrów pXRF.

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Okamoto, Hiroaki. „Supplemental Literature Review of Binary Phase Diagrams: Al-Pt, As-U, C-Li, C-Mg, Cd-Nd, Co-Ta, Fe-Re, Ga-Y, La-Ni, O-V, P-Si, and Re-Zr“. Journal of Phase Equilibria and Diffusion 41, Nr. 5 (Oktober 2020): 722–33. http://dx.doi.org/10.1007/s11669-020-00839-9.

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Jiang, Yueshan, Yanlin He, Weisen Zheng, Jianlei Zhang, Dekui Zhang und Xiaogang Lu. „Thermodynamic Analysis for Molten Corium Stratification with U-Zr-O-Fe Database“. Journal of Nuclear Materials, Dezember 2022, 154180. http://dx.doi.org/10.1016/j.jnucmat.2022.154180.

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Stefanovsky, S. V., S. V. Yudintsev, B. S. Nikonov, B. I. Omelianenko, A. I. Gorshkov, A. V. Sivtsov, M. I. Lapina und R. C. Ewing. „Pyrochlore-Type Phases for Actinides and Rare Earth Elements Immobilization“. MRS Proceedings 556 (1999). http://dx.doi.org/10.1557/proc-556-27.

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AbstractPyrochlore is a complex oxide with the nominal formula A2B2X6Y, where A and B are cations in VIII and VI-fold co-ordination, X and Y are anions. Its structure is derived from the cubic fluorite structure. In natural pyrochlores A = Na, Mg, K, Ca, Mn, Fe, Sr, Sb, Cs, Ba, REEs, Pb, Bi, Th, and U; B = Nb, Ta, Ti, Zr, Sn, W, Fe, and Al; X = O; Y = O, OH, or F. Synthetic pyrochlores have been repeatedly described as matrices designed for actinide-bearing waste immobilization. In synthetic pyrochlores site "A" is mainly occupied by Ca, U, An, and REEs; B = Ti and Zr; X and Y = O. In this work we have studied pyrochlores in crystalline titanate-based waste forms. The ceramics were fabricated in the system: Ca-Mn-U-REE-Zr-Ti-Al-O by cold pressing and sintering, melting in a high-temperature furnace, and inductive melting in a cold crucible. All specimens were studied by XRD, SEM/EDS and TEM methods. The amount of pyrochlore in the samples varied from 10 to 70%. Other phases in these ceramics were brannerite, perovskite, zirconolite, murataite, hibonite, loverengite, pseudobrookite, and rutile. Compositions of the pyrochlores correspond to stoichiometry: A2B2O7-x, 0.1<x<0.4, where A = Ca, Mn, REEs, U, Zr; B = Ti, Zr, Al, Mn. The positions and intensities of the peaks of pyrochlores from various ceramics were: d222=2.89-2.93A, 1=100; d400=2.51, 1=10-25; d440=1.779-1.809, 1=20-60; d622=1.512-1.540, 1=20-35; d444=1.451-1.477, I=10-15; d662=1.158-1.173, I=10-15. These data allowed the determination of the unit-cell dimensions of the pyrochlores as 1.00-1.02 nm. Results obtained from TEM research agree well with these values. Distribution of U and REEs among all phases of the ceramics was characterized. The main substitutions which have influenced the pyrochlore compositions are discussed.

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Ding, Hao, Clémence Gausse, Malin C. Dixon Wilkins, Lucy M. Mottram, Martin C. Stennett, Daniel Grolimund, Ryan Tappero et al. „Chemical characterisation of degraded nuclear fuel analogues simulating the Fukushima Daiichi nuclear accident“. npj Materials Degradation 6, Nr. 1 (02.02.2022). http://dx.doi.org/10.1038/s41529-022-00219-3.

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AbstractThe Fukushima Daiichi accident generated degraded nuclear fuel material, mixed with other reactor components, known as molten core-concrete interaction (MCCI) material. Simulant MCCI material was synthesised, excluding highly radioactive fission products, containing depleted U, and incorporating Ce as a surrogate for Pu. Multi-modal µ-focus X-ray analysis revealed the presence of the expected suite of U-Zr-O containing minerals, in addition to crystalline silicate phases CaSiO3, SiO2-cristobalite and Ce-bearing percleveite, (Ce,Nd)2Si2O7. The formation of perclevite resulted from reaction between the U-Zr-O-depleted Ce-Nd-O melt and the silicate (SiO2) melt. It was determined that the majority of U was present as U4+, whereas Ce was observed to be present as Ce3+, consistent with the highly reducing synthesis conditions. A range of Fe-containing phases characterised by different average oxidation states were identified, and it is hypothesised that their formation induced heterogeneity in the local oxygen potential, influencing the oxidation state of Ce.

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Sinitsyn, V. A., D. A. Kulik, M. Skhodorivski, V. A. Kurepin, A. Y. Abramis, I. L. Kolyabina und N. A. Shurpach. „Stability of Mineral Matter in Aqueous Media of the Chernobyl Unit-4 Shelter: Thermodynamic Evaluation“. MRS Proceedings 465 (1996). http://dx.doi.org/10.1557/proc-465-1327.

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ABSTRACTA special geochemical environment exists within the Shelter (”Sarcophagus”) erected in 1986 over the destroyed Unit-4 of Chernobyl nuclear power plant (NPP). Based upon the available in situ and compositional data, thermodynamic models of solid-aqueous interactions were developed to clarify the leaching behaviour of various materials within the Shelter. The “Selektor-A” code, based on a convex programming approach to Gibbs free energy minimization, was used for the calculations. A built-in flexible hybrid thermodynamic database for the system Na-K-Ca-Mg-Cl-S-N-H-O-Si-P-Fe-Al-Sr-Cs was extended with the critically selected and matched parameters for aqueous species and solid phases in the U-Zr-Si-O-H subsystem, secondary U-minerals, mineral phases of fully hydrated Portland cements and U-bearing zircons. Modeling results show that the “Shelter waters” can selectively leach a significant quantity of U and Si from the fuel-containing masses, while Zr, Fe, Ca, Mg and some other components are rather insoluble. Serpentinite, assemblages of fully-hydrated phases of Portland cements, and oxidation products of steel structural elements are estimated to be sufficiently stable in the aqueous environment of the Shelter. Our calculations also define some feasible pathways for secondary mineral formation from evaporation of Shelter water solutions and interactions between these waters with the mineral matter inside the Shelter.

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Cavalcante, Francisco Andrey Jucá, Ulysses Rodrigues dos Prazeres, José Tavares Machado Neto, Hélido Gleidson de Oliveira Sena und José Maria do Vale Quaresma. „AVALIAÇÃO MECÂNICA E ELÉTRICA DE LIGAS Al-Fe-Zr PARA FINS ELÉTRICOS APÓS ENVELHECIMENTO NATURAL DE 18 MESES“. Engevista 8, Nr. 2 (02.02.2010). http://dx.doi.org/10.22409/engevista.v8i2.193.

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Em virtude da crescente busca por ligas mais eficientes para transmissão Tx e distribuição Dx de energia elétrica, foram investigadas as características mecânicas e elétricas antes e após 18 meses de envelhecimento natural de ligas do sistema Al-Fe-Zr produzidas em laboratório em presença de argônio. Partindo-se do Al-EC ajustando-se o Fe aos níveis aconselhado pela literatura especializada, para em seguida variar-se o Zr em (0,0238, 0,025, 0,0289, 0,0345 e 0,038)%. As ligas assim constituídas foram solidificadas em um molde na forma de “U”, bi-partido, com 22mm de diâmetro interno e 300mm de altura e temperatura de vazamento de 750oC. A peça fundida foi usinada para o diâmetro de 11mm e trabalhada até o de 2,89mm. Os fios foram finalmente submetidos a ensaios de condutividade elétrica e tração, antes e após tratamento a 230oC por 1 h (teste de termorresistividade) e, as fraturas sendo analisadas via MEV. Cada ensaio foi executado com repetibilidade de 3 CP’s. Após 18 meses todos os ensaios foram repetidos. Os resultados sugerem que o aumento de Zr provoca aumento no LRT e queda de condutividade, após o T.T.. Entretanto, quando submetidas ao teste de Termorresistividade, os resultados variaram dentro do limite de 10%, indicando comportamento termorresistente. Após 18 meses as ligas apresentaram discretas variações nos valores do LRT e da condutividade elétrica antes e após o teste de termorresistividade. As fraturas geradas foram analisadas via MEV. Avaliando-se dessa forma a passividade das ligas e seu potencial como liga termorresistente em virtude do teor de Zr.

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Stefanovsky, S. V., S. V. Yudintse, B. S. Nikonov, B. I. Omelianenko und A. G. Ptashkin. „Murataite-based ceramics for actinide waste immobilization“. MRS Proceedings 556 (1999). http://dx.doi.org/10.1557/proc-556-121.

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AbstractStudying the Synroc, doped with a simulated HLW, we have found, along with conventional Synroc phases (zirconolite, perovskite, hollandite), an extra phase with a stoichiornetry (Ca, Mn, U, TR)4(U, TR, Zr, Ti) 2(AI, Ti)7O22. XRD and TEM study has shown this phase is related to a very rare mineral murataite. In the present work a ceramic based on murataite is studied. The ceramic samples in the system: Ca-Mn-Ti-Zr-U-Ce-AI-Fe-O were produced and examined in details using XRD, SEM/EDS, TEM, and optical microscopy. Total amount of actinide (U) and rare earth (Ce, Gd) elements in the murataite exceeds 20 wt%. Isomorphic substitution schemes in the structures of synthetic and natural murataites are discussed. High isomorphic capacity of the murataite structure towards actinides and REEs, flexibility of its composition, feasibility of synthesis by melting, including a cold crucible melting, and very high chemical durability under hydrothermal conditions make the murataite-based ceramics very promising for actinides and excess weapon Pu fixation.

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Jian Cao, Ming, Noreen J. Evans, Pete Hollings, David R. Cooke, Brent I. A. McInnes und KeZhang Qin. „Apatite Texture, Composition, and O-Sr-Nd Isotope Signatures Record Magmatic and Hydrothermal Fluid Characteristics at the Black Mountain Porphyry Deposit, Philippines“. Economic Geology, 02.03.2021. http://dx.doi.org/10.5382/econgeo.4827.

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Abstract The trace elemental and isotopic signatures in apatite can be modified during hydrothermal alteration. This study investigates the suitability of apatite as an indicator of the source, chemistry, and evolution of magma and hydrothermal fluids. In situ textural, elemental, and O-Sr-Nd isotope analyses were performed on apatite in thin sections, from fresh and propylitically altered pre- and synmineralized dioritic porphyries from the Black Mountain porphyry Cu deposit in the Philippines. All studied apatite crystals have similar subhedral to euhedral shapes and are homogeneous in the grayscale in backscattered electron images. In cathodoluminescence images, the apatite in fresh and altered rocks displays yellow to yellow-green and green to brown luminescence, respectively. Apatite in fresh rocks has a higher Cl and Mn content, and lower Fe, Mg, Sr, Pb, and calculated XOH-apatite, compared to apatite in altered rocks. The content of F, rare earth elements (REEs), Y, U, Th, and Zr, and the Sr-Nd isotope signatures of apatite from fresh and altered rocks are similar in all apatite grains (87Sr/86Sr = 0.7034–0.7042 vs. 0.7032–0.7043, εNd(t) = 5.3–8.0 vs. 5.1–8.4). The X-ray maps and elemental and oxygen isotope signatures across individual apatite crystals are typically homogeneous in apatite from both fresh and altered rocks. The distinct luminescence colors, coupled with distinct mobile element compositions (Cl, OH, Mn, Mg, Fe, Sr, Pb), indicate modification of primary magmatic apatite during interaction with hydrothermal fluids. The similarities in Sr isotope ratios (87Sr/86Sr = 0.7032–0.7043) but slight differences in O isotope signatures (δ18O = 6.0 ± 0.3‰ vs. 6.6 ± 0.3‰) in apatite from fresh and altered rocks are consistent with the magma and hydrothermal fluids having the same source and suggest significant phase separation in the hydrothermal fluids given that 18O preferentially fractionates into the residual liquid relative to 16O during phase separation. The similarity of immobile element (REE, Y, U, Th, and Zr) contents in both populations of apatite, consistency of textures and Nd isotope compositions, and absence of obvious dissolution-reprecipitation features all suggest that altered apatite retains some magmatic characteristics. The apatite in fresh rocks has oxygen isotope compositions similar to that of zircons from the same sample (δ18O = 5.9 ± 0.3‰), indicating little to no oxygen isotope fractionation between zircon and apatite and that apatite can be a good proxy for the oxygen isotope composition of the magma. Based on the Cl contents of the magmatic and replacement apatite, and assuming their equilibrium with high-temperature magma fluid and replacement hydrothermal fluid, respectively, the calculated Cl content of the early magmatic fluid and the later replacement fluid can be estimated to be 6.4 to 15.1 wt % and ~0.25 ± 0.03 wt %, respectively. This indicates a depletion of Cl from the early high-temperature fluid to the replacement fluid, consistent with phase separation. This study demonstrates that cathodoluminescence, elemental compositions (such as Cl, Mn, Mg, Fe, Sr, Pb) and Sr-O isotope signatures in apatite can be modified during hydrothermal alteration, whereas other components (REE, Y, U, Th, and Zr) and the Nd isotope composition are preserved. These features can be used to constrain the origin, chemistry, and evolution of the primary magma and ore-forming hydrothermal fluids.

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