This paper provides an overview of the processes for separating hafnium from zirconium. The separation processes are …Web

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

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

Hafnium is chemically very similar to zirconium and can be called its twin brother. In this chapter its properties are mentioned. The similarities as well as the …Web

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

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

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

Properties and Applications of some Zirconium and Hafnium Compounds. Decomposition of Zirconium Ores. Preparation of Zirconium Compounds and …Web

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

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

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

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

The current dominant zirconium production route involves pyrometallurgical ore cracking, multi-step hydrometallurgical liquid-liquid extraction for hafnium removal and the reduction of zirconium tetrachloride to the pure metal by the Kroll process. Do Zr and Hf occur together in nature? The atomic radii of Zr (160 pm) and Hf (159 pm) is almost …Web

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

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

2.1.1 Characterization of Hafnium-oxide Nanoparticles. Hydrolysis and condensation of hafnium iso-propoxide led to the formation of a Hf-O-Hf network which is similar to hafnium oxide.Infrared spectra of the hafnium oxide nanoparticles indicates both the anionic and the protonated forms of the carboxylic acid are present, suggesting the ligation to Hf ions is …Web

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

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

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

Hafnium is invariably found in zirconium ores, and the separation is difficult. Commercial-grade zirconium contains from 1 to 3% hafnium. Zirconium has a low absorption cross section for neutrons, and is therefore used for nuclear energy applications, such as for cladding fuel elements. Commercial nuclear power generation now takes more than 90 ...Web

A mixture of diffraction patterns, possibly due to starting material, oxyfluoro intermediates and the product, were observed from 400 °C upwards for both zirconium and hafnium. At 525 °C (for zirconium) and 580 °C (for hafnium) it is accepted (by considering mass change) that the fluorination reactions are essentially complete, although ...Web

* 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

Literature Resources on Zirconium and Hafnium. Discovery and History. Occurrence. Commercial Deposits. General Properties and Applications of the Elements and some of their Alloys and Compounds. Applications of the Metals and their Alloys other than in the Nuclear and Chemical Industries. Safety PrecautionsWeb

Introduction to Hafnium. Identified in 1923 by Dirk Coster and George de Hevesy, hafnium is a lustrous, silver-grey transition metal. The name "hafnium" originated from Hafnia, the Latin name for Copenhagen, which is where hafnium was discovered.Hafnium chemically resembles zirconium, as they have the same number of valence electrons and are in …Web

Hafnium radioisotope recovery from irradiated tantalum. DOEpatents. Taylor, Wayne A.; Jamriska, David J. . Hafnium is recovered from irradiated tantalum by: (a) contactiWeb

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

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 …Web

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

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