| abstract |
The present invention relates to nanoparticles, a process for their preparation and their use as a pinning center in superconductors. In particular, the present invention relates to nanoparticles comprising Sr, Ba, Y, La, Ti, Zr, Hf, Nb or oxides of Ta and having a weight average diameter of 1 to 30 nm, There are present on the surface an organic compound of the formula (I), (II) or (III) or an organic compound containing two or more carboxylic acid groups: In this formula, a is from 0 to 5, b and c are independently of each other 1 to 14, n is from 1 to 5, r is from 0 to 5, p and q are independently of each other 1 to 14, e and f are independently from 0 to 12; |