Abstract—Ceramic-forming zirconium (hafnium)-containing yttriumoxane alumoxanes, precursors of mul-ticomponent ceramics based on alumina, yttria and …

Nature - New proton-Containing Oxides of Titanium, Zirconium and Hafnium. ... New proton-Containing Oxides of Titanium, Zirconium and Hafnium Download PDF. Article; Published: ...

Zirconium is produced by the same process as that used for titanium. These zirconium minerals generally have a hafnium content that varies from a few tenths of 1 percent to several percent. For some purposes separation of the two elements is not important: zirconium containing about 1 percent of hafnium is as acceptable as pure …

EDTA titrations of zirconium and hafnium can be performed in boiling solutions containing 0.9 plus or minus 0.3N free hydrochloric acid using xylenol orange as an indicator. The color change is from red to yellow which should persist on boiling for one minute. Interferences are not caused by 1 g of uranium(VI), iron(II), aluminum, zinc, tin, …

The syntheses and crystal structures of a series of zirconium(IV) and hafnium(IV) complexes with Dawson monovacant phosphotungstate [alpha2-P2W17O61](10-) and in situ-generated Keggin monovacant phosphotungstate [alpha-PW11O39](7-), which was obtained by a reaction of [alpha-PW12O40](3-) with Na2CO3, …

Zircon is the primary source of all hafnium, containing it at a ratio of about 50 to 1. Hafnium is particularly resistant to corrosion and can absorb neutrons at a high rate, making it sought after by the nuclear …

The solution is diluted with water to 3.5 percent by volume of sulfuric acid and transferred to an anion-exchange column. The hafnium is eluted with a 3.5 percent sulfuric acid solution and then the zirconium is eluted with a 10 percent sulfuric acid solution. For samples containing more than about 20 percent of zirconium the hafnium fraction ...

Abstract. >The existence of seven Ti/sub 2/Ni-type phases containing zirconium or hafnium is reported, and lattice parameters are given. For some of these phases there ls evidence that oxygen is required for stabllity. (auth) Authors: Nevitt, M V; Schwartz, L H. Publication Date:

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 Precautions

Titanium can exist in solution in a number of oxidation states. The titanium (IV) exists in acidic solutions as the oxo-cation, TiO 2+, rather than Ti 4+. Zirconium is used in the ceramics industry and in nuclear industry as a cladding material in reactors where its reactivity towards hydrolysis reactions and precipitation of oxides may result ...

Nanoparticles containing TiC have been used in precursor powders for the production of cutting tools, coatings for heat shields and wear-resistant tools and ceramic-metal composites [3,4]. ... milling and annealing of metal-carbon powder mixtures for the production of carbon-encapsulated nanoparticles of zirconium and hafnium carbides …

We investigated the catalytic performance of Zr- and Hf-containing MOF-808 and UiO-66 catalysts for the transfer hydrogenation of carbonyl compounds to their corresponding alcohols. The Lewis acidic MOF-808(Hf) was the most active for transfer hydrogenation of benzaldehyde and the most selective to corresponding alcohols, with …

Abstract and Figures. Nanosized refractory titanium, zirconium, and hafnium carbides were manufactured from highly dispersed metal dioxide-carbon starting mixtures at moderate temperatures of 1200 ...

Crystal structures of the heteroligand fluoro-containing complex compounds of zirconium and hafnium are systematized on the basis of the nL : Zr(Hf) ratio in the complex (complexed anion of the ...

The zirconium and hafnium solutions were pre pared by dissolving the "reactor grade" metals, usually about 50 mg, in sulfuric-hydrofluoric acid solutions. The zirconium was nearly hafnium-free, but the hafnium contained several percent of zirconium. The solution was evaporated several times to fumes of sulfuric acid, and the walls of the ...

Anthropogenic sources of zirconium, and likely hafnium, are from industrial zirconium-containing byproducts and emissions from the processing of sponge …

The influence of oxide ions on the speciation in molten KF containing ZrF 4 and HfF 4 has been studied by using Raman spectroscopy, and identification of the structures is carried out by density functional theory calculations within the polarization continuum model. Zirconium and hafnium fluorides are present as MF 6 2– and MF 7 …

New Magnetic nanocomposites containing biological polymer (i.e. chitosan and cellulose) as reinforcers were synthesized. Successful fabrication of the magnetic cellulose-chitosan (MCCh) nanocomposites with norvaline (MCCh-N) and 8-hydroxyquinoline (MCCh-8H), respectively were achieved and investigated as a …

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.

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 processing of heavy-mineral sands for the titanium minerals, ilmenite and rutile, or tin …

The inorganic and coordination chemistry of zirconium and hafnium is described. The physical properties of the metals, as well as their isolation, purification, and commercial and industrial uses are discussed. A section on the binary compounds of zirconium and hafnium containing hydride and main group elements follows. Oxoacid …

This work greatly expands the number of zirconium and hafnium complexes that contain η 2-pyrazolato ligands. (© Wiley-VCH Verlag & Co. KGaA, 69451 Weinheim, Germany, 2005) (© Wiley-VCH Verlag & Co. KGaA, 69451 Weinheim, Germany, 2005)

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

The inorganic and coordination chemistry of zirconium and hafnium is described. The physical properties of the metals, as well as their isolation, purification, and commercial and industrial uses are discussed. A section on the binary compounds of zirconium and hafnium containing hydride and main group elements follows.

In summary, an unprecedented zirconium- and hafnium-catalyzed C−C single bond activation and subsequent hydroboration is realized using a catalytic system …

Hafnium is a lustrous metal with the chemical symbol Hf. When exposed to air, it forms a durable oxide film which is highly resistant to corrosion. Hafnium is almost always found together with the element zirconium …

The mixtures of zirconium–hafnium dioxides partially stabilized by Y 2 O 3 in harsh plasma spraying conditions create a pure metastable t ... The advantages of adding Hf are well recorded in the papers focusing on different hafnium-containing cast alloys such as Co–10 wt.% Cr–11 wt.% Al + Hf [28,29,30,31], Ni–10 wt.% Cr–8 wt.% Al + Hf ...

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 …

The physicochemical properties of zirconium (hafnium)-containing yttriumoxane alumoxanes were studied. Computational models of the group and elemental composition of oligomeric Zr(Hf)-containing yttriumoxane alumoxane molecules were proposed. According to X-ray dif-fraction and scanning electron microscopy data, pyrolysis of the oligomers at ...

@article{Rahaman2022MechanismOT, title={Mechanism of transfer hydrogenation of carbonyl compounds by zirconium and hafnium-containing metal-organic frameworks}, author={Mohammad Shahinur Rahaman and Sarttrawut Tulaphol and Md. Anwar Hossain and Matthew C. Mulvehill and Joshua M. Spurgeon and Thana …