Studies on microstructure and density of sintered ZnO-based non-linear resistors

Improvement of thermoelectric properties with the addition of Sb to ZnO

“…In addition to the Zn 1−x Sb x O phase, only a small amount of cubic spinel ␣-Zn 7 Sb 2 O 12 (a = 8.589Å) was detected in the Zn 1−x Sb x O samples, also, is in good agreement with previous studies [20,23]. The Zn 7 Sb 2 O 12 (a = 8.589Å) phase appeared at 1173 K and retarded the grain growth of ZnO by impeding migration of the grain boundaries [20][21][22][23]. The added Sb 2 O 3 (0.01 ≤ x ≤ 0.05) did not fully dissolve in the ZnO crystal lattice, but dissolved to a limited solubility due mainly to its rather low solubility.…”

“…1(a-d), respectively. The primary phase of the as-sintered Sb 2 O 3 -added Zn 1−x Sb x O (0.01 ≤ x ≤ 0.05) samples was the solid solution of Zn 1−x Sb x O with a wurtzite structure, which conforms with previous studies [18,[20][21][22]. In addition to the Zn 1−x Sb x O phase, only a small amount of cubic spinel ␣-Zn 7 Sb 2 O 12 (a = 8.589Å) was detected in the Zn 1−x Sb x O samples, also, is in good agreement with previous studies [20,23].…”

“…The effects of Sb 2 O 3 on the sintering behavior of ZnO have been interpreted in terms of Zener drag [22,25,28,29]. Kim et al [22] observed that the addition of 0.01 Sb 2 O 3 appreciably suppressed densification, and raised the densification temperature by 400 K. The Zn 7 Sb 2 O 12 phase exists frequently at the grain boundaries and occasionally within individual grains [20,21]. The grain size and the porosity of the prepared Zn 1−x Sb x O (0 ≤ x ≤ 0.05) samples are given in Table 1.…”

“…2, indicating that Sb 2 O 3 inhibits grain growth of ZnO. This decrease can be attributed to the fact that the Zn 7 Sb 2 O 12 phase acts to lower the grain-boundary mobility owing to a pinning effect during sintering [20][21][22][25][26][27], thus enabling the pores to stay attached to the moving grain boundaries. The effects of Sb 2 O 3 on the sintering behavior of ZnO have been interpreted in terms of Zener drag [22,25,28,29].…”

Grain growth kinetics for B2O3-doped ZnO ceramics

“…3a -d) and also reported in the literature [27,30,31], the addition of B 2 O 3 significantly promoted the grain growth of ZnO and resulted in the uniform microstructure due to the low melting temperature of B 2 O 3 [32]. As mentioned previously, the grain growth exponent value (n) of 3 was consistently observed for pure ZnO [2,[27][28][29].…”