Here, we report on the high-pressure synthesis of zirconium and hafnium nitrides with the stoichiometry M 3 N 4, where M = Zr, Hf. Synthesis experiments were performed in a laser-heated diamond ...Web
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Zirconium is used to make the cladding for uranium oxide fuel elements. As mined, zirconium contains 1-3% per cent of hafnium, which is chemically very similar, and although it is difficult to separate the two elements this has to be done for the metal used in the nuclear industry because hafnium absorbs neutrons very strongly.Web
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The hafnium–zirconium oxide (HfZrO) films with an extensive doping range for the modification of the ferroelectric polarization characteristics have been expansively investigated in recent years . ... the tensile stress and tensile strain along the y axis direction possibly affect the transition of the o-phase during the PMA process ...Web
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Data on Zr and Hf in co-existing lunar minerals support the suggestion that Zr, possibly as Zr 3+, is excluded selectively from early-formed lunar minerals. Zr Hf fractionation has also been observed among the achondrites. ... Zirconium and hafnium abundances in some lunar materials and implications of their ratios; M.R. Dence et al.Web
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Zirconium (Zr), chemical element, metal of Group 4 (IVb) of the periodic table, used as a structural material for nuclear reactors. atomic number 40 atomic weight 91.22 melting point 1,852 °C (3,366 °F) boiling point 3,578 °C (6,472 °F) specific gravity 6.49 at 20 °C (68 °F) oxidation state +4.Web
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Zirconium and hafnium are contained in zircon at a ratio of about 50 to 1. Zircon is a coproduct or byproduct of the mining and processing of heavy-mineral sands for the titanium minerals, ilmenite and rutile, or tin minerals. The major end uses of zircon are refractories, foundry sands (including investment casting), and ceramic opacification.Web
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Separation of Zirconium and Hafnium: A Review. NASA Astrophysics Data System (ADS) Xu, L.; Xiao, Y.; van Sandwijk, A.; Xu, Q.; Yang, Y. Zirconium is an ideal material for nuclear reactors due to its low absorption cross-section for thermal neutrons, whereas the typically contained hafnium with strong neutron-absorption is very harmful for …Web
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The abundances of zirconium and hafnium have been determined in nine stony meteorites by a new, precise neutron-activation technique. ... Data on Zr and Hf in co-existing lunar minerals support the suggestion that Zr, possibly as Zr 3+, is excluded selectively from early-formed lunar minerals. Zr Hf fractionation has also been observed …Web
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A novel process for the preparation of high-purity zirconium, hafnium, tantalum and niobium alkoxides (alcoholates), novel tantalum and niobium compounds and a process for their preparation are provided. The process comprises the steps of mixing crude metal alkoxides M(OR) x having a halogen impurity of at least 0.05 wt. %, with an alcohol ROH, …Web
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The current zircon price is around US$1,013/t and the hafnium price is around US$850,000/t. Experts expect zircon prices to continue to rise over the mid-term, reaching US$1,400/t by 2021, driven …Web
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In nature, it is only found in combination with zirconium and thorium. The hafnium content in the Hafnon (Hf,Zr)SiO 4 and Alwit (H,Th,Zr)SiO 4 ∙xH 2 O zirconium minerals reaches up to 5%. However, its production is too limited—no more than 70 t per year, with most of the commercial hafnium being produced by zirconium refining.Web
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Titanium, zirconium and hafnium. S. Cotton. Materials Science, Chemistry. 2006. This chapter reviews the literature reported during 2007 on titanium, zirconium and hafnium. Because of the limitations of space, this review is very selective, and much fine work has not been cited,…. Expand.Web
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Zirconium and hafnium are likely not essential to human health and generally are considered to be of low toxicity to humans. The main exposure risks are …Web
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Zircon was also the primary source of hafnium; zirconium and hafnium are contained in zircon at a ratio of about 34:1 (Jones and others, 2017, p. V5). Zirconium and hafnium metals were produced in china, france, india, russia, and the united States. Production Zircon is a coproduct of the mining and processing ofWeb
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Zirconium and hafnium are corrosion-resistant metals that are widely used in the chemical and nuclear industries. Most zirconium is consumed in the form of the main ore mineral zircon (ZrSiO4, or as zirconium oxide or other zirconium chemicals. Zirconium and hafnium are both refractory lithophile elements that have nearly identical …Web
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A complex mechanism has been found that accounts for the formation of hafnium dioxynitride and possibly of three other hafnium oxynitrides, then of hafnium mononitride and hafnium monocarbonitride, along two different steps between 1613 and 1923 K. An evaluation has been made concerning the composition of these γ 1- HfO 2 …Web
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Zirconium and hafnium oxides exist in three crystallographic modifications: monoclinic (M), tetragonal (T), cubic (C), and are characterized by close lattice parameters. ... [11, 21] it possibly leads to a deterioration in mechanical characteristics (the area to the right of the extremum, Fig. 5). Thus, the nature of the extremum is most likely ...Web
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Hafnium was used in nuclear control rods because of its high thermal neutron absorption cross section. commercial-grade zirconium, unlike nuclear-grade, contains hafnium and …Web
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Zirconium (electronic configuration [Kr] 4d 2 5s 2) is the 40th element belonging to the Group 4 of the Periodic table, with properties closely resembling titanium and hafnium. It is a lustrous silver–grey metal, exceptionally ductile, malleable and strong, yet lighter than steel (density 6.51 g cm −3 ).Web
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Zirconium (Zr) and hafnium (Hf) are strategic resources for the development of advanced nuclear energy. The demand for Zr and Hf is increasing daily with the rapid development of nuclear power. However, Zr and Hf coexist permanently in natural minerals, mainly zircon (ZrSiO 4 ) and oblique zircon (ZrO 2 ), which usually contain …Web
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* Fractions of the sand are turned into sponge, then zirconium metal or zircaloy and hafnium -- used in control rods at some nuclear reactors to slow down or speed up the fission process. The ...Web
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The discovery that the thermal-neutron cross-section capture of zirconium containing the natural 2% hafnium content was largely due to the very high thermal-neutron cross section of the hafnium stimulated the present interest in the chemical and physical properties of these elements. The use of hafnium-free zirconium alloys for cladding …Web
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Zirconium and hafnium are typically contained in zircon at a ratio of about 36 to 1. Zirconium chemicals were produced by the metal producer in Oregon and by at least 10 …Web
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Zirconium and hafnium co-exist in nature in the form of ores [].Namely, there are no separate zirconium and hafnium ores. The content of zirconium in the earth's crust is 0.025%, and hafnium is approximately 2% of zirconium [2, 3].They have nearly identical electronegativity, atomic radius and ionic radius [].On account of the similarity, …Web
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The world's experience in using hafnium in two important parts of high-temperature thermal barrier coatings, such as the top thermal barrier layer and bond coat layer, was analyzed. In the top thermal barrier layer, hafnium is present as HfO2 completely or partially stabilized by yttria (or other rare-earth oxides). Another approach is to use …Web
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The role of crystal chemical effects in zirconium-Hafnium fractionation in oceanic basalts from Ascension Island. 1981, Chemical Geology ... Data on Zr and Hf in co-existing lunar minerals support the suggestion that Zr, possibly as Zr 3+, is excluded selectively from early-formed lunar minerals. Zr Hf fractionation has also been observed among ...Web
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It is not produced in-house, but is a by-product of the extraction of hafnium-free zirconium for fuel rods. Features . Physical Properties . Crystal structure of α-Hf, a = 320 pm,c = 505 pm. Hafnium is a silvery, shiny heavy metal of high density (13,31 g / cm 3). It crystallizes in two different modifications depending on the temperature.Web
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Zircon is the primary source of all hafnium. Zirconium and hafnium are contained in zircon at a ratio of about 50 to 1. Zircon is a coproduct or byproduct of the mining and …Web
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Hafnium radioisotope recovery from irradiated tantalum. DOEpatents. Taylor, Wayne A.; Jamriska, David J. . Hafnium is recovered from irradiated tantalum by: (a) contacting the irradiated tantalum with at least one acid to obtain a solution of dissolved tantalum; (b) combining an aqueous solution of a calcium compound with the solution of …Web
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Abstract Ceramic-forming zirconium (hafnium)-containing yttriumoxane alumoxanes, precursors of multicomponent ceramics based on alumina, yttria and zirconia/hafnia, were synthesized by co-condensation of chelated alkoxyalumoxanes, yttrium acetylacetonate hydrate (or organic yttriumoxane alumoxanes) and zirconium or …Web
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The occurrence of Ti/sub 2/Ni-type phases in binary and ternary alloys of titanium, zirconium, or hafnium with first, second, or third long-period transition metals and also in ternary systems in which oxygen is the third component was studied. The existence of eleven previously unreported isomorphs is reported and some approximate phase ...Web
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A simple spectrophotometric method for determination of zirconium or hafnium in selected molybdenum-base alloys. NASA Technical Reports Server (NTRS) Dupraw, W. A. ... A complex mechanism has been found that accounts for the formation of hafnium dioxynitride and possibly of three other hafnium oxynitrides, ...Web
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