Giant dielectric response in two-dimensional charge-ordered nickelate ceramics

Abstract

Dielectric relaxations of charge-ordered Ln1.5Sr0.5NiO4 (Ln=La and Nd) ceramics were investigated over a broad temperature range. The giant dielectric constant (over 70 000) with a low dielectric loss of ∼0.1 was determined at high frequencies (up to 5 MHz) over a broad temperature range. There are two dielectric relaxations in the vicinity of charge ordering temperatures. The thermal activated small polaronic hopping between two charge ordering temperatures should contribute to the giant dielectric response in the present ceramics. Compared to other giant dielectric constant materials, the present materials have the notable advantage for high frequency applications.

Influence of interface point defect on the dielectric properties of Y doped CaCu3Ti4O12 ceramics

“…The resistances of both grain and grain boundary decrease with increasing temperature, and the ratio of R gb /R g is much lower than that of the other giant dielectric constant materials, such as Sm 1:5 Sr 0:5 NiO 4 , 26 so the dielectric contribution from the grain boundary barrier layer capacitor model may be suppressed. 27 The capacitances of grain boundaries significantly increase with increasing temperature, while the capacitances of grain interiors first slightly increase and then decrease when the temperature above 445 K, which is similar to that of the temperature dependence for dielectric constant although the occurred temperature is somewhat different. The above results show that the origin of giant dielectric constant of the sample should be dominated by grain interior instead of grain boundary.…”

Giant dielectric response and mixed-valent structure in the layered-ordered double-perovskite ceramics

“…This is particularly noticeable in the curves measured at lower frequencies (1 kHz and 10 kHz). Two thermally activated relaxation processes are well defined in the corresponding curves of tan d. These are typical dielectric relaxations and they are common features of giant dielectric constant materials [14][15][16][17][18][19]. To analyze the low temperature dielectric relaxation, the frequency dependence of peak temperature for the dielectric loss is plotted (see the insets in Fig.…”

Giant dielectric constant in Nd2NiO4+δ ceramics obtained by spark plasma sintering

“…Upon cooling the temperature down to 150 K, a sharp decrease of dielectric constant is observed, and the dropping temperature increases with increasing the applied frequency. Also, a peak at the corresponding temperature is appeared on the curve for the temperature dependence of tan d. This is a typical of dielectric relaxation, and it is the common feature of giant dielectric constant materials [8][9][10][11][12]. According to the previous work [4,7], the charge ordering temperature of Nd 2 NiO 4.192 ceramics is about 150 K, which is coincided with the temperature of dielectric relaxation.…”

“…The giant dielectric constant should be mainly attributed to the adiabatic small polaronic hopping process, and the polaronic hopping process is closely related to the charge ordering in these materials [8,9]. Recently, the giant dielectric response up to high frequency is also observed in the La 2Àx Sr x NiO 4 (x = 1/8, 1/3) single crystal, and results also show the dielectric response is closely related to the charge stripe ordering [10][11][12].…”