| Search for content and authors |
Characterization of nanopowders |
| Agnieszka Opalińska 1,2, Wojciech Dzwolak 1, Roman Pielaszek 1, Witold Łojkowski 1, Tadeusz Chudoba 1, Cristina Leonelli 3, Hubert Matysiak 2, Tomasz Wejrzanowski 2,4, Krzysztof J. Kurzydlowski 2, Ewa Grzanka 1 |
|
1. Polish Academy of Sciences, Institute of High Pressure Physics (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland |
| Abstract |
Characterisation of the nanostructure of powders is a challenge frequently not properly met by researchers in this field. The properties measured strongly depend on:
As far as crystallite size distribution, we developed an analytical equation that permits to determine two parameters: crystallite size and their dispersion at the same time (d and sigma, where d is particle diameter and sigma is its disorpsion). Broadening of the XRD peaks will lead to a considerable error when used to estimate crystallite sizes and their distribution is not taken not account. Fitting of an analytical expression to the XRD data is a relatively easy procedure that can be followed in any laboratory, providing the XRD data are of sufficient quality. We defined also criteria of quality of XRD patterns for crystallite size and their distribution determination. As far as the degree of crystallinity of the powders is concerned, we have shown that pycnometric density is an excellent tool to discriminate between ‘good powders” with little non crystalline phases, and poor powders, with a lot of hydroxides on surface or other phases. We postulate that the pair of data (specific surface area, density) should be always requested for characterization of nanopowders. |