Hafnium(IV) oxide

Hafnia

Colorless solid

Fixed

9.68 g · cm -3

2812 ° C

5400 ° C

Low

Insoluble in water

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Hafnium dioxide is a chemical compound of the elements hafnium and oxygen. It belongs to the class of oxides.

Production and representation

Hafnium dioxide is represented by annealing of the hydroxide, oxalate, sulfate Oxidchlorids or at 600-1000 ° C. The hydrolysis of Hf (OR) 4 (R = i -amyl ) provides high-purity hafnium dioxide.

Properties

Hafnium dioxide is in the pure state, a white, microcrystalline powder having a monoclinic crystal structure which has a very high melting and boiling point and a density of 9.68 g · cm -3. The refractive index is 1.95 to 2.00. The oxide is virtually insoluble in water and organic solvents.

It has high hardness, low thermal expansion and is chemically zirconium dioxide ( ZrO2 ) are very similar. At 1700 ° C, it turns into a modification of tetragonal crystal system.

Use

It is used in the semiconductor industry as a high- k dielectric or as compensation or Mirror material in the optical industry.

Due to its higher dielectric constant compared to silica saw hafnium dioxide as a material in which, for example could be substituted for the silicon dioxide used so far in the production of semiconductor devices with 45 nm structure.