The influence of dopant concentration and sintering parameters on properties of Sb-doped BaSnO3 ceramics

Abstract

The influence of dopant concentration and sintering parameters on properties of Sb-doped BaSnO3 ceramics Jelena Mitrović1, Milica Počuča-Nešić1, Zorica Branković1, Goran Branković1 1Institute for Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia In recent years, the modern industry and technology development has focused on non-magnetic, non-inductive, and electroconductive materials that can be used in conditions unfavorable for metals and alloys, such as constant high voltage, current and energy, with a particular emphasis on operating in acidic and humid environments. These conditions could be satisfied using chemically inert and thermally stable ceramic resistors with linear current-voltage (I-U) characteristic and low and almost constant electrical resistivity in the wide temperature range. Barium stannate (BaSnO3, BSO) is perovskite-type oxide with almost ideal cubic crystal structure, good thermal and chemical stability. Undoped BSO exhibits semiconductor behviour, but doping with an appropriate concentration of antimony can lead to changes in the electrical properties of BSO, making its metallic-like conductor. In this study, we investigate the influence of antimony concentration and sintering parameters on properties of antimony-doped barium stannate, BaSn1-xSbxO3 (BSSO, x = 0,00; 0,04; 0,06; 0,08 and 0,10) to obtain conductive electroceramic samples with linear current-voltage (I-U) characteristic and constant electrical resistivity in the temperature range of 25 °C to 150 °C. Ceramic samples were obtained by three different sintering techniques conventional, spark plasma and cold sintering. XRD analysis confirmed the existence of single-phase cubic BaSnO3 in all conventionally sintered samples at 1600 °C for 3 h, and also in spark plasma sintered samples at 1100 °C for 5 min. However, the spark plasma sintering at 1200 °C for 5 min led to the formation of secondary phase, tetragonal Ba2SnO4 in BSSO samples, whose content is significantly decreased by Sb doping. On the other hand, XRD analysis revealed the presence of unreacted starting components, SnO2 and BaCO3 in cold sintered BaSn0.92Sb0.08O3 sample (310 °C for 5 min, 20 wt.% 1 M acetic acid). The presence of low angle grain boundaries (LAGBs) was observed in conventionally (1600 °C for 3 h) and spark plasma sintered (1200 °C for 5 min) samples with x = 0.08. The results of DC (I-U characteristic) and AC (Impedance spectroscopy) measurements confirmed the semiconducting properties of all BSSO sample, except the spark plasma sintered BaSn0.92Sb0.08O3 (1200 °C for 5 min) sample. Metallic-like behavior of this sample is manifested through the linear I-U characteristic and low electrical resistivity, which remained almost constant in the investigated temperature range, due to the loss of potential barriers at the grain boundary region as a consequence of LAGBs present in BaSn0.92Sb0.08O3 ceramic sample.