Synthesis Using Zirconium Turnings

The weighed tetrahalide is first transferred into the cap-welded end of a tantalum tube of size noted above (tube volume 1.5 cm3/g ZrX). The appropriate weight of turnings ( 0.1%) is then packed into the tube. Reactants are loaded in this order to prevent welding difficulties from the volatile tetrahalides. 

After the second cap is welded in place, the tube is jacketed in fused silica and the assembly is placed in a tube furnace with an Inconel liner. The temperature is then slowly raised from 350° to 850° over a period of 7-10 days and maintained there for 3-5 days. 

Zirconium monochloride and monobromide are black powders or highly reflective microcrystals. Although the monohalides appear to be stable in air for days to weeks, they should be kept and handled under inert atmospheres if high purity is required, owing to a probable slow reduction of water vapor to form the hydrides (see below) and Zr02. These monohalides possess a rhombohedral (R3m), three-slab structure in which each slab consists of four tightly bound, 

The zirconium monohalides are essentially two-dimensional metals with good delocalization and conduction within the double metal sheets. The metallic conductivity has been established by both X-ray photoelectron spectroscopy2 and conductivity measurements where single-crystal data (obtained by an unspecified method) indicated a conductivity of 55 ohm-1 cm-1 parallel to the plates and about 10-3 ohm-1 cm-1 normal to them.9 

The monohalides are useful reducing agents for the preparation of a number of intermediate zirconium chloride and bromide phases since their reactivities are considerably greater than those of the refractory metal. Thus, ZrX-ZrX4 reactions have been used to obtain the trihalides in 100% yields as well as ZrCl2(3f -NbS2 type) and a different polytype of ZrBr2.  

---