Perovskite layered materials with A2B2O7 structures for high-temperature sensor applications – A comparative study

Perovskite layered materials with A 2 B 2 O 7 structure such as Ca 2 Nb 2 O 7 , Sr 2 Nb 2 O 7 , Nd 2 Ti 2 O 7 , La 2 Ti 2 O 7 , Sm 2 Ti 2 O 7 and Pr 2 Ti 2 O 7 possess very high Curie temperature (Tc > 1000°C). The above materials in powder form were synthesised using mixed oxide method by calcining well-mixed constituent powders between 1000°C and 1300°C for 2 h. Circular disc samples of 12 mm diameter were prepared and sintered at 1200–1450°C, with a soaking duration of 2 h. The sintered density, X-ray diffractometer, scanning electron microscope and electrical resistivity were measured for all samples. The samples experience a linear decrease in electrical resistivity from 10 13 to 10 5 Ω.cm as temperature increases between 100 and 900°C. In this paper, a comparative study on electrical resistivity for the above materials was carried out to determine their suitability for sensing applications at high temperatures.