Potassium fluorido-oxido-tantalate phases

Even a portion of fluorido-oxido-tantalates with different counter cations was investigated here, the focus being given to a more detailed investigation of the selected compounds - KjTaOF and K3Ta02F4 - based on X-ray single crystal analysis. X-ray powder diffraction, secondary ionised mass spectroscopy (SIMS) and XPS spectroscopy. The available structural data for both compounds are summarised in Table 3.3.1. 

No complete structural determination has been reported so far and the formula is based on elemental analysis or X-ray powder data. Single crystals suitable for X-ray single-crystal analysis were separated only in one case from the series of experiments directed to the preparation of pure KjTaOFg or K3Ta02F4. As they were collected from the experiment directed to K3TaOFg preparation it was expected that the structure of 

Compound Method System Cell parameters (A) Reference 

Finally it can be concluded that, as new data occur, a new interpretation might be needed. It should be noted that this is applicable also for those systems that seems to considered as well known. 

There are still missing unambiguous proofs that could confirm or disprove the existence of K3TaOF6 or K3Ta02F4. Even the presented stmcture is based on a relatively complicated model with several assumptions and restrictions. However, this model was supported by additional results from XRD, SIMS and XPS experiments. 

---