Samples Containing Zirconium or Hafnium

The atomic radii of zirconium (Zr) and hafnium (Hf) as well as the radii of the ions (Zr⁺⁴ and Hf ⁺⁴) are almost identical. This explains, in part, the fact that the chemistry of these two elements is more similar than any other elemental pair.

Sampling and Handling

The sampling and handling of Zr and Hf materials is not generally a problem because they are relatively inert and nontoxic. No toxicity is known and no industrial health hazards are reported. This is likely due to the very limited solubility of their compounds. The toxicity of Zr compounds is generally classified with a maximum working concentration (MAK) of 5 (mg m^-3), and a threshold limit value/time weighted average of 5 (mg m^-3). Hf compounds are classified a factor of ten lower. Zirconium tetrachloride is not as reactive as the TiCl₄ where hydrolysis results in the formation of derivatives such as the oxychloride, ZrOCl₂, instead of the oxide as is the case with TiCl₄.

Materials containing Zirconium and Hafnium compounds are also relatively non-hazardous and do not present unique sampling and handling problems. However, many analytical measurement techniques require a solution of the sample and HF is most often required. Safety considerations appropriate to the use of HF will apply. In materials where titanium is present in minor or trace amounts sampling and handling considerations relative to the sample matrix will apply.

For additional details, see the following information on sampling and subsampling.

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