HAFNIUM FLUORIDE Property

Melting point:

310°C (subl.)

Boiling point:

970°C

Density 

7.100

solubility 

reacts with H2O

form 

Powder

color 

White

Water Solubility 

React with water.

Sensitive 

Moisture Sensitive

Exposure limits

ACGIH: TWA 2.5 mg/m3; TWA 0.5 mg/m3
NIOSH: IDLH 250 mg/m3; IDLH 50 mg/m3; TWA 0.5 mg/m3

CAS DataBase Reference

13709-52-9(CAS DataBase Reference)

Safety

Hazard Codes 

Xi,T

Risk Statements 

32-36/37/38-41-23-37/38

Safety Statements 

26-36-45-36/37/39

RIDADR 

UN 2923 8/PG 2

WGK Germany 

3

Hazard Note 

Irritant

TSCA 

Yes

HazardClass 

6.1

PackingGroup 

II

HS Code 

28261990

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Danger

Hazard statements

H315Causes skin irritation

H318Causes serious eye damage

H331Toxic if inhaled

H335May cause respiratory irritation

Precautionary statements

P280Wear protective gloves/protective clothing/eye protection/face protection.

P302+P352IF ON SKIN: wash with plenty of soap and water.

HAFNIUM FLUORIDE Chemical Properties,Usage,Production

Preparation

Hafnium tetrafluoride may be prepared by passing anhydrous hydrogen fluoride over hafnium tetrachloride at 300°C:
HfCl4 + 4HF HfF4 + HCl
Another method of preparation involves thermal decomposition of ammonium fluorohafnate, (NH4)2 HfF6 [16925-24-9] in the absence of air:
(NH4)2 HfF6 HfF4 + 2NH3 + 2HF
Also, HfF4 can be prepared by treating metallic hafnium with 40% aqueous HF. The monohydrate formed may be heated at 350°C for several days under a flow of fluorine and nitrogen to yield anhydrous HfF4.
Hf + 4HF (aq) → HfF4•H2O + 2H2

Chemical Properties

Off-white powder

Physical properties

White monoclinic crystals; refractive index 1.56; density 7.1 g/cm³; sublimes at 970°C.

Uses

Hafnium(IV) fluoride is used as Vacuum deposition.

Production Methods

Hafnium tetrafluoride is prepared by careful thermal decomposition of ammonium fluorohafniate in an oxygen- free atmosphere or by passing anhydrous hydrogen fluoride over hafnium tetrachloride at 300℃. Direct synthesis from the elements is incomplete because the product merely forms a film on the metal. Ammonium fluorohafniate can be prepared by crystallization from an aqueous hydrofluoric acid solution by adding ammonium fluoride.