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Microstructures and electrical properties of Mn/Co/Ni-doped BaBiO3 perovskite-type NTC ceramic systems
Ist Teil von
Journal of materials science. Materials in electronics, 2019-03, Vol.30 (5), p.4688-4695
Ort / Verlag
New York: Springer US
Erscheinungsjahr
2019
Quelle
SpringerLink
Beschreibungen/Notizen
Mn/Co/Ni-modified BaBiO
3
-based negative temperature coefficient (NTC) ceramics with the formula,
x
[(3-
y
-
z
)Mn/
y
Co/
z
Ni-ions]+(1−
x
)BaBiO
3
(
x
= 0.0–0.4,
y
= 0.96 and
z
= 0.48), were synthesized using a conventional solid state reaction. The effects of Mn/Co/Ni-substitute content on the phase structures and composition, microstructures and electrical properties were characterized by X-ray diffraction (XRD), scanning electron microscope and resistance–temperature measurements, respectively. XRD pattern analysis results revealed that the compound phases consisted of a main monoclinal BaBiO
3
phase and a secondary phase of Ba(Mn, Co, Ni)O
3
solid-solution with a hexagonal structure, which were detected at
x
= 0.05–0.2. In addition, according to the XRD patterns, the main phase changed from BaBiO
3
to a rhombohedral Bi
8.11
Ba
0.89
O
13.05
phase at
x
= 0.3, and this phase content increased dramatically as the
x
value increased to 0.4. For the related electrical properties, all of the samples demonstrated the typical characteristics of NTC thermistors across a relatively wide range of temperatures. The values obtained for
B
constant (
B
25/85
) and the room-temperature resistivity (
ρ
25
) were in the range of 2297–5235 K and 760 Ω cm
−1
, 620 kΩ cm, respectively, which implied that the electrical properties of the present ceramic systems could be optimized via various substitutions in the Mn/Co/Ni-ions content. The variable values of
ρ
25
were affected strongly by the changes in crystal structure and the decrease in charge carrier concentration. These composite ceramic materials are suitable candidates for a variety of NTC thermistor applications due to their widely adjustable electrical properties.