Compression of CdCu3Ti4O12 perovskite to 55 GPa

Synchrotron x-ray diffraction measurements of CdCu3Ti4O12 (CDCTO) were performed up to 55.5 GPa. There is no structural phase transformation in this pressure range. The irregular curvature shifts of the P–VP–V curve are attributed to the grain surface effect. Analysis indicates that the grain surface of CDCTO is stiffer than the grain interior at higher pressures. We point out that the atoms on grain surfaces must be either densely packed or have a strong correlation with the gain interior in order to have a high dielectric constant, as in CaCu3Ti4O12. The derived bulk modulus KOT of CDCTO is approximately 235±7 GPa with K′=5.1±0.4K′=5.1±0.4.