Reported in EPA TSCA Inventory.

OSHA PEL: TWA 0.5 mg/m³
ACGIH TLV: TWA 0.5 mg/m³
DFG MAK: 0.5 mg/m³
DOT Classification:  4.2; Label: Spontaneously Combustible (UN 2545); DOT Class: 4.1; Label: Flammable Solid (UN 1326)

The IUPAC name of this chemical is Hafnium. With the CAS registry number 7440-58-6 and EINECS registry number 231-166-4, it is also named as Celtium. In addition, the molecular formula is Hf and the molecular weight is 178.49. It is the penultimate stable isotope element to be discovered. And it belongs to the classes of Inorganics; Hafnium; Metal and Ceramic Science; Metals.

Preparation of Hafnium: it can be prepared by hafnium(IV) chloride in the presence of magnesium. In this reaction, the magnesium is used as reducing agent. The equation is as follows: HfCl₄ + 2 Mg (1100 °C) → 2MgCl₂ + Hf. And it can be prepared by hafnium tetriodide through thermal decomposition. Further purification is effected by a chemical transport reaction. In a closed vessel, hafnium reacts with iodine at temperatures of 500 °C, forming hafnium(IV) iodide; at a tungsten filament of 1700 °C the reverse reaction happens, and the iodine and hafnium are set free. The equations are as follows: Hf + 2 I₂ (500 °C) → HfI₄; HfI₄ (1700 °C) → Hf + 2I₂.

Uses of Hafnium: it is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nm and smaller feature lengths. And it is a good material for neutron absorption in control rods in nuclear power plants. Moreover, it is useful for nuclear-reactor applications.

When you are using this chemical, please be cautious about it as the following:
This chemical is highly flammable and harmful by inhalation, in contact with skin and if swallowed. When you are using it, wear suitable protective clothing, gloves and eye/face protection. In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. And you should take off all contaminated clothing immediately. In addition, take precautionary measures against static discharges and keep away from sources of ignition - No smoking. At last, you should keep container in a well-ventilated place.

You can still convert the following datas into molecular structure:
(1)SMILES: [Hf]
(2)InChI: InChI=1/Hf
(3)InChIKey: VBJZVLUMGGDVMO-UHFFFAOYAL