12055-23-1 Usage
Description
Hafnium Oxide, also known as Hafnia, is a colorless, inert solid and one of the most common and stable compounds of hafnium. It is an electrical insulator with high stability and high thermal neutron absorption values. Hafnium Oxide is a white crystalline solid with a density of 9.68 g/cm3, melting at 2,774°C, and insoluble in water. It dissolves slowly in hydrofluoric acid at ordinary temperatures. At high temperatures, it reacts with chlorine in the presence of graphite or carbon tetrachloride, forming hafnium tetrachloride. Hafnium-based oxides are important materials to replace silicon oxide as a gate insulator due to their high dielectric constant.
Uses
Used in Nuclear Industry:
Hafnium Oxide is used as a high-temperature refractory material for control rods in nuclear reactors, benefiting from its high stability and high thermal neutron absorption values.
Used in Ceramics Industry:
Hafnium Oxide is used in various compounds such as hafnium boride, hafnium carbide, hafnium nitride, hafnium silicate, and hafnium titanate, which have extensive applications in the ceramics industry due to their resistance to corrosion.
Used in Optical Industry:
Hafnium Oxide is used in special optical glasses and glazes, as well as in optical coatings, due to its unique properties.
Used in Electronics Industry:
Hafnium (IV) oxide is used as intermediates, paint additives, and coating additives in the electronics industry. It is also used as a high-k dielectric in dynamic random-access memory (DRAM) capacitors and as a gate insulator in field-effect transistors, where it may help in the continuing effort to replace silicon oxide.
Used in Manufacturing of Hafnium Metal:
Hafnium Oxide is an intermediate in some processes that give hafnium metal, which has various applications in different industries.
Preparation
Hafnium dioxide may be prepared by heating the metal with air or oxygen at elevated temperatures (above 400°C). Also, the oxide can be obtained by igniting hafnium salts, such as hydroxide, oxalate, sulfate, nitride, carbide, boride or tetrachloride in air. Hafnium carbide converts to dioxide when heated with oxygen at 500°C. The commercial products generally contain about 95-97% hafnium dioxide mixed with small amount of zirconium oxide. The compound can be prepared at 99.9% purity.
Reactions
Hafnium dioxide reacts with chlorine in the presence of carbon at elevated temperatures to yield hafnium tetrachloride, HfCl4. When ammonium hydroxide solution is added to an acid solution of hafnium dioxide, the hydrous oxide, HfO2?xH2O precipitates.
When heated with concentrated sulfuric acid, the product is hafnium sulfate, Hf(SO4)2.
Reaction with carbon at 1,500°C produces hafnium carbide, HfC.
Reaction with sodium fluorosilicate, Na2SiF6 at elevated temperatures yields sodium fluorohafnate, Na2HfF6.
Flammability and Explosibility
Nonflammable
Potential Exposure
Hafnium metal has been used as a
control rod material in nuclear reactors. Thus, those
engaged in fabrication and machining of such rods may be
exposed.
Shipping
UN1326 Hafnium powder, wetted with not
<,25% water (a visible excess of water must be present)
(1) mechanically produced, particle size<53 μm; (2)
chemically produced, particle size<840 μm, Hazard Class:
4.1; Labels: 4.1-Flammable solid. UN2545 Hafnium pow der, dry, Hazard Class: 4.1; Labels: 4.1-Flammable solid.
UN1346 Hafnium powder, wetted with not less than 25%
water (a visible excess of water must be present)
(1) mechanically produced, particle size less than 53 μm;
(2) chemically produced, particle size less than 840 μm,
Hazard Class: 4.1; Labels: 4.1-Flammable solid.
Incompatibilities
Fine powder or dust may form explosive
mixture in air. The powder is highly flammable and a strong
reducing agent. The powder or dust reacts with moisture
forming flammable hydrogen gas; may spontaneously ignite
on contact with moist air; and at higher temperatures, with
nitrogen, phosphorous, oxygen, halogens, and sulfur; contact
with hot nitric acid; heat, shock, friction, strong oxidizers;
or ignition sources may cause explosions.
Waste Disposal
Recovery. Consider recycling,
otherwise, this chemical must be disposed of in compliance
with existing federal and local regulations.
Check Digit Verification of cas no
The CAS Registry Mumber 12055-23-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,2,0,5 and 5 respectively; the second part has 2 digits, 2 and 3 respectively.
Calculate Digit Verification of CAS Registry Number 12055-23:
(7*1)+(6*2)+(5*0)+(4*5)+(3*5)+(2*2)+(1*3)=61
61 % 10 = 1
So 12055-23-1 is a valid CAS Registry Number.
InChI:InChI=1/Hf.2O/rHfO2/c2-1-3
12055-23-1Relevant articles and documents
Infrared spectrum and structure of the Hf(OH)4 molecule
Wang, Xuefeng,Andrews, Lester
, p. 7189 - 7193 (2008/10/09)
Laser-ablated Hf atoms react with H2O2 and with H2 + O2 mixtures in solid argon to form the Hf(OH) 2 and Hf(OH)4 molecules, which are identified from the effect of isotopic substitution on the matrix infrared spectra. Electronic structure calculations at the MP2 level varying all bond lengths and angles converge to nearly linear and tetrahedral molecules, respectively, and predict frequencies for these new product molecules and mixed isotopic substituted molecules of lower symmetry that are in excellent agreement with observed values, which confirms the identification of these hafnium hydroxide molecules. This work provides the first evidence for a metal tetrahydroxide molecule and shows that the metal atom reaction with H2O2 in excess argon can be used to form pure metal tetrahydroxide molecules, which are not stable in the solid state.