SIPS 2018

DETAILLED PROGRAM OVERVIEW

Properties of the Composite SnO2-Ag (Semiconductor Metal) Ceramic Material
Vladimir Kirko¹; Sergey Dobrosmislov²; Genadii Nagibin²; Z.i. Popov³;
¹RESEARCH INSTITUTE OF PHYSICS AND ENGINEERING, Krasnoyarsk, Russian Federation; ²ASSOCIATE PROFESSOR, Krasnoyarsk, Russian Federation; ³SIBERIAN STATE AEROSPACE UNIVERSITY, Krasnoyarsk, Russian Federation;
PAPER: 66/Manufacturing/Regular (Oral)
SCHEDULED: 12:35/Tue./Sao Conrado (50/2nd)

ABSTRACT:
The SnO<sub>2</sub>-based ceramics are being widely used in many industries. Tin dioxide is a semiconductor with the forbidden band energy 3.54 eV, and has unique properties of high electrical conductivity and chemical resistance. Chemically resistant ceramics with high electrical conductivity is of great interest as electrode material operating at high temperatures, for instance in aluminium electrolysis and glass production. In semiconductors, the total electric current is a sum of partial currents, provided by p- and n-type conductivities. In case of contact between a p-type semiconductor and a metal, a space charge region of ionized donors appears, and the blocking contact, or Schottky barrier, forms. This means that the addition of Ag superdispersed particles into the ceramics structure will allow an additional number of charge carriers to appear in the semiconductor-metal contact zone, that will increase the electrical conductivity. Following the research performed, the superdispersed silver particles significantly affect the electrical conductivity of the material. Firstly, a significant drop of the temperature of the percolation beginning is observed. Secondly, the shape of the curve suggests that there is a possibility of the electron passage from the metallic particles into the tin dioxide conduction band. It can also be noted that when the silver portion increases, saturation of the conduction band by charge carriers takes place, and the resistivity no longer depends on the silver concentration. The usage of the silver oxide additives when making SnO2-based ceramics allows the composite material resistivity to significantly decrease, especially at low temperatures, which is associated with silver reduction from its oxide. This effect is associated with the formation of the space charge region in the semiconductor-metal contact zone. Temperature dependencies of the resistivity for materials with 4 and 8 weight % of silver and sintered at 1300°С are practically the same. For the ceramics sintered at 1400°С, an obvious dependence of the resistivity on the concentration is observed. The percolation beginning temperature increases by 150°С compared to that of the material sintered at 1300°С. The sintering temperature increase may lead to silver particles being distributed more uniformly along the grains' boundaries.

References:
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[2] S. S. Dobrosmislov, Issledovanie fisiko-mehanicheskih i electrofisicheskih svoystv electroprovodyashih ogneupornih keramik na osnove SnO-Sb2O3-CuO / S. S.Dobrosmislov, V.I. Kirko, etc., Ogneupori i tehnicheskaya keramika, 6, 7-10 pp., 2010;