Nonlinear Electrical Behavior of Solid State Sintered SiC Ceramics

doi:10.15541/jim20160171

Abstract

Abstract:

The solid state sintered SiC (SSiC) ceramics are mainly used for structural materials, but they are rarely used for electronic devices and resistance components. In this work, the electrical properties of the SSiC ceramics with different carbon additives were investigated, including V-I characteristic, the relationship between current and resistance, as well as the relationship between temperature and resistance. These results show that the SSiC ceramics present obvious nonlinear electrical behavior and their resistance decreases with the current increase. When the electrical field intensity is over 15.8 V/mm for the SSiC ceramics with 3wt% carbon additives, as well as 70.7 V/mm for the SSiC ceramics with 6wt% carbon additives, the boundary barrier is breakdown and the resistance becomes very low, due to the resistance being only controlled by the grain size. The resistance of the SSiC ceramics decreases with the temperature increase at the electrical field intensity of 1 V/mm, indicating thermo-sensitive characteristic of SSiC ceramics of which the resistance is changed from 10⁶ Ω·cm at 25℃ to 5 Ω·cm at 400℃.

Key words: SiC, solid state sintered, nonlinear resistance, thermistor

CLC Number:

TQ174

CHEN Jian, YIN Jie, ZHU Yun-Zhou, YANG Yong, CHEN Zhong-Ming, ZHANG Jing-Xian, LIU Xue-Jian, HUANG Zheng-Ren. Nonlinear Electrical Behavior of Solid State Sintered SiC Ceramics[J]. Journal of Inorganic Materials, 2017, 32(1): 45-50.

Figures/Tables 8

Table 1 Properties of SiC with different C contents at room temperature

C additives	Density/ (g·cm^-3)	Relative density/%	Flexural strength/MPa
3wt%	3.08±0.03	97%	303.7±17.3
4wt%	3.09±0.02	98%	378.3±10.1
5wt%	3.09±0.01	98%	405.4±19.2
6wt%	3.11±0.01	99%	486.2±20.4

Fig. 1 Microstructure of SSiC with different C contents(a) 3wt%; (b) 4wt%; (c) 5wt%; (d) 6wt%

Fig. 2 SEM images (a) and element distribution (b-Si/C/B, c-Si, d-C, e-B) of 6wt%C-SSiC ceramics

Fig. 3 Nyquist plots of SSiC ceramics with different C contents (a), theory Nyquist plots (b) and equivalent circuits (c).

Table 2 Grain resistance of SSiC ceramics with different carbon contents

C	3wt%	4wt%	5wt%	6wt%
R_G/(Ω·cm)	150	148	146	48

Fig. 4 V-I curves of SSiC ceramics with different C contents (a) and relationship between current density and resistance (b)

Table 3 Non-linear coefficient and varistor voltage of SSiC ceramics

C	3wt%	4wt%	5wt%	6wt%
α	1.80	1.60	1.44	1.16
U_1mA/(V·mm^-1)	2.2	3.7	4.2	10.6

Fig. 5 Thermosensitivity of SSiC ceramics with different C contents (a, b- logarithmic)

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