Gas Sensing with Perovskite-like Oxides Having ABO3 and BO3 Structures

• Published in: Journal of electroceramics Vol. 13; no. 1-3; pp. 721 - 726
• Main Authors: Lantto, V, Saukko, S, Toan, N N, Reyes, L F, Granqvist, C G
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.07.2004
• Subjects: Crystal structure; Semiconductors
• ISSN: 1385-3449; 1573-8663
• DOI: 10.1007/s10832-004-5182-z

WO3 and LaFeO3 are members of the BO3 and ABO3 perovskite-like oxide groups, respectively. The structure consists of corner-sharing octahedral oxygen networks with the transition metal B cations occupying octahedral cages of oxygen anions. WO3 is an n-type semiconductor and LaFeO3 a p-type semiconductor. Thick films of WO3 nanoparticles, with the metastable tetragonal crystal structure, were produced by reactive gas deposition at temperatures of 300-400 C. The electrical conductivity was very sensitive to H2S at room temperature without heat treatment, making the film a sensitive sensor for this gas. Nanocrystalline LaFeO3, both pure and doped with Sr or Mg, was synthesised by the sol-gel citrate method. Doping significantly increased the electrical conductivity of the films, and a dual conductance response was exhibited at low temperatures on exposure to the reducing gases CO, C2H4 and CH4. The conductivity increased by a factor of approximately 300 on exposure to 200 ppm CO in synthetic air at 100 C. 23 refs.