Abstract: The present invention is in the field of nanoparticles, their preparation and their use as pinning centers in superconductors. In particular the present invention relates to nanoparticles comprising an oxide of Sr, Ba, Y, La, Ti, Zr, Hf, Nb, or Ta, wherein the nanoparticles have a weight average diameter of 1 to 30 nm and wherein an organic compound of general formula (I), (II) or (III) or an organic compound containing at least two carboxylic acid groups on the surface of the nanoparticles (I) (II) (III) wherein a is 0 to 5, b and c are independent of each other 1 to 14, n is 1 to 5, f is 0 to 5, p and q are independent of each other 1 to 14, and e and f are independent of each other 0 to 12.

Abstract: A process for preparing polymeric, ionic compounds comprising imidazolium groups (polymeric, ionic imidazolium compounds for short) comprising reacting an a-dicarbonyl compound, an aldehyde, —at least one amino compound having at least two primary amino groups (referred to as oligoamine), if appropriate an amino compound having only one primary amino group (referred to as monoamine) and a protic acid, wherein the protic acid is placed in the reactor and the oligoamine or the aldehyde and o dicarbonyl compound or the oligoamine, the aldehyde and ?-dicarbonyl compound are fed to the protic acid.

Abstract: A process for preparing polymeric, ionic compounds comprising imidazolium groups (polymeric, ionic imidazolium compounds for short) comprising reacting—an ?-dicarbonyl compound,—an aldehyde,—at least one amino compound having at least two primary amino groups (referred to as oligoamine),—if appropriate an amino compound having only one primary amino group (referred to as monoamine) and a—protic acid, wherein the molar ratio of the ?-dicarbonyl compound to the oligoamine is greater than 1.