Giant dielectric constant, dielectric relaxations, and tunable properties of Sm_2/3Cu₃Ti₄O₁₂ ceramics

Abstract

The polycrystalline Sm2/3Cu3Ti4O12 (SCTO) ceramics have been prepared by solid‐state reaction. The crystallinity of the compound has been investigated by Rietveld refinement which has revealed a cubic structure with space group Im3. It is observed that at low frequencies, SCTO ceramic exhibits tremendously high values of dielectric permittivity ε′, larger than 32,000, at room temperature. Two distinct, thermally triggered, dielectric relaxations have been noted. This mechanism has been confirmed through impedance analysis of the ceramics. The complex impedance plane shows three semicircles, which confirm the existence of two dielectric relaxations in SCTO ceramics. In general, the electrical as well as dielectric behavior of SCTO ceramics are seen to be reasonably analogous to those of CaCu3Ti4O12 (CCTO) ceramics. The emergence of the enormous dielectric constant in SCTO ceramic is accredited to the combined effect of polarization both at the sample‐electrode interface as well as at the insulating grain boundary interface. The SCTO ceramics are identical to the CCTO ceramics in their structure and composition and hence, as the above results indicate, the IBLC effect mechanism, originally put forward for CCTO ceramics, is furthermore plausible to account for the mammoth values of dielectric constant in SCTO ceramics.

Significantly Improved Colossal Dielectric Properties and Maxwell—Wagner Relaxation of TiO2—Rich Na1/2Y1/2Cu3Ti4+xO12 Ceramics

“…In addition to CCTO ceramics, the colossal dielectric properties of ACu 3 Ti 4 O 12 oxides (A = Na 1/2 Bi 1/2 [ 26 ], Na 1/2 Y 1/2 [ 27 , 28 , 29 , 30 ], Na 1/2 La 1/2 [ 31 ], Bi 2/3 [ 32 , 33 ], Y 2/3 [ 32 , 34 ], Cd [ 16 , 17 , 35 ], La 2/3 [ 32 ], Sm 2/3 [ 36 ], Na 1/3 Ca 1/3 Bi 1/3 [ 37 ], Na 1/3 Cd 1/3 Y 1/3 [ 38 ], Na 1/3 Sr 1/3 Y 1/3 [ 39 ] and Na 1/2 Sm 1/2 [ 40 ]) are very attractive, especially for the Na 1/2 Y 1/2 Cu 3 Ti 4 O 12 (NYCTO) ceramics [ 27 , 28 , 29 , 30 ]. The NYCTO ceramics exhibited a high ε ′ ~ 10 4 with low tanδ < 0.05 at 1 kHz compared to that of the CCTO ceramics [ 28 , 29 , 30 ].…”