Materials Page 
Terminology
References 3 & 4

HfF4 (Hafnium Fluoride)

Bulk Properties

Melting Point: 
Density: 7.0 gm/cc

Film Properties

Evap. Temp.: 1200 ºC
Film Growth: 
Film Hardness:  Soft

Common uses:   IR antireflection coatings.

Comments:  Good substitute for Thorium Fluoride.