Microstructure and nonohmic properties of SnO₂–Ta₂O₅–TiO₂ varistor system doped with CuO

Abstract

The microstructure and nonohmic properties of SnO 2– Ta 2 O 5– TiO 2- CuO varistor system were investigated. The proposed samples were doped with different contents of CuO (0–6 mol%) and sintered at 1400°C for 2 h with conventional ceramic processing method. In all the samples, the commonly identified phase was SnO 2 (rutile); however, with increasing doping amount of CuO , the peaks of CuO phase emerged in the X-ray diffraction (XRD) patterns. Scanning electron microscopy (SEM) examination on the fractured surfaces of the samples revealed that a minor amount of CuO dopant can facilitate the sintering of the varistor ceramics, but excessive CuO would mainly segregate at grain-boundaries. The doped CuO may also act as a modifier in the SnO 2 based varistors. The measured electric-field versus current-density characteristics of the samples indicated that both nonlinear exponent and varistor voltage increased with increasing doping amount of CuO up to 3 mol% and then decreased with excessive CuO .

High‐performance varistors prepared by hot‐dipping tin oxide thin films in Sb2O3 powder: Influence of temperature

“…The measured E‐J characteristic curves (see Figure ) reveal that the as‐deposited tin oxide film is a linear electrical resistor of Ohmic behavior, while all the hot‐dipped samples exhibited typical nonlinear characteristics (see the obvious nonlinear platform in this figure). It is known that SnO 2 ‐based varistors exhibit the nonlinear characteristics originating from the double Schottky barrier between the grain and boundary . In this work, because Sb 2 O 3 was staying at the tin oxide grain boundary as the high‐resistant isolating layer, thus a more complete structure of Sb 2 O 3 isolating layer would result in a higher α for the obtained samples.…”

“…It is known that SnO 2 -based varistors exhibit the nonlinear characteristics originating from the double Schottky barrier between the grain and boundary. 4,31,32 In this work, because Sb 2 O 3 was staying at the tin oxide grain boundary as the high-resistant isolating layer, thus a more complete structure of Sb 2 O 3 isolating layer would result in a higher a for the obtained samples. From Figure S4, the a and I L of the obtained samples were calculated, and the results are displayed in Figure 4A.…”