Improved dielectric properties in A′‐site nickel‐doped CaCu₃Ti₄O₁₂ ceramics

Abstract

The improved dielectric properties and voltage‐current nonlinearity of nickel‐doped CaCu3Ti4O12 (CCNTO) ceramics prepared by solid‐state reaction were investigated. The approach of A′‐site Ni doping resulted in improved dielectric properties in the CaCu3Ti4O12 (CCTO) system, with a dielectric constant ε′≈1.51×105 and dielectric loss tanδ≈0.051 found for the sample with a Ni doping of 20% (CCNTO20) at room temperature and 1 kHz. The X‐ray photoelectron spectroscopy (XPS) analysis of the CCTO and the specimen with a Ni doping of 25% (CCNTO25) verified the co‐existence of Cu+/Cu2+ and Ti3+/Ti4+. A steady increase in ε′(f) and a slight increase in α observed upon initial Ni doping were ascribed to a more Cu‐rich phase in the intergranular phase caused by the Ni substitution in the grains. The low‐frequency relaxation leading to a distinct enhancement in ε′(f) beginning with CCNTO25 was confirmed to be a Maxwell‐Wagner‐type relaxation strongly affected by the Ni‐related phase with the formation of a core‐shell structure. The decrease of the dielectric loss was associated with the promoted densification of CCNTO and the increase of Cu vacancies, due to Ni doping on the Cu sites. In addition, the Ni dopant had a certain effect on tuning the current‐voltage characteristics of the CCTO ceramics. The present A′‐site Ni doping experiments demonstrate the extrinsic effect underlying the giant dielectric constant and provides a promising approach for developing practical applications.

From Synthesis to Applications: Copper Calcium Titanate (CCTO) and its Magnetic and Photocatalytic Properties

“…Nickel doped CCTO were prepared and studied by Senda et al, [72] Wang et al, [73] Boonlakhorn et al [74] and Sun et al [9] In the aim of increasing the relative permittivity and decreasing the dielectric loss of CCTO, Sun et al [9] prepared CaCu 3À x Ni x Ti 4 O 12 (x = 0, 0.05, 0.1, 0.2) powders by the sol-gel method. The pellets were sintered at 1000-1060°C for 8 h. A very low tanδ value~0.025 was found at the CaCu 2.…”

“…Wang et al . showed that the doping of CCTO by 5 % of Co improved the dielectric properties and gave dielectric constant ϵ′≈7.4×10 4 and dielectric loss tanδ≈0.034 at room temperature and 1 KHz.…”

“…Reprinted with permission from (Wang et al.) by Oxford University Press and Copyright Clearance Center 2018 …”

“…Nickel doped CCTO were prepared and studied by Senda et al ., Wang et al ., Boonlakhorn et al . and Sun et al …”

“…Wang et al . reported good dielectric properties, a dielectric permittivity of ∼1.5×10 5 and a low loss tangent of ∼0.051, were obtained by optimization of dopant levels (CaCu 2.80 Ni 0.20 Ti 4 O 12 ) and sintering conditions (1100 °C for 3 h).…”