Unusual impurity effects on the dielectric properties of CaCu3-xMnxTi4O12

CaCu3Ti4O12 has a large dielectric constant (epsilonsimilar to10(4) at 300 K), which is almost constant above 100 K, followed by a 100-fold reduction below 100 K. The physical mechanism of this anomalous behavior has been extensively investigated. We found that only 2% substitution of Mn for Cu dramatically quenches the huge epsilon of 10(4) down to 100 over the measured temperature range from 4.2 to 300 K. In usual substitution effects, 2% impurity induces a tiny change in E of the order of 2%. Thus the present substitution effect suggests that dipole moments cause fluctuating ferroelectric domains in CaCu3Ti4O12, as is similar to the frustrated dipole glass in LuFe2O4. (C) 2003 Elsevier Science B.V. All rights reserved.