Effects of oxygen partial pressure control on the microstructure and PTCR properties of Ho doped BaTiO3

Effects of oxygen partial pressure ( \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\hbox{P}}_{{\hbox{O}}_{\hbox{2}} } $$\end{document}) control on the electrical properties and microstructural development of (Ba1-xHox)0.997TiO3 were studied. An oxidation condition (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\hbox{P}}_{{\hbox{O}}_{\hbox{2}} } $$\end{document} ∼ 1.0 atm) was maintained during the heating process, and then the specimen was sintered in a reducing atmosphere (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\hbox{P}}_{{\hbox{O}}_{\hbox{2}} } $$\end{document} < 10−9 atm) at 1350 °C, followed by the annealing process at 1000 °C and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\hbox{P}}_{{\hbox{O}}_{\hbox{2}} } $$\end{document} = 1 atm. The switching temperature (TS) from the oxidation atmosphere to the reducing condition was changed from 1100 to 1350 °C. A significant decrease in the room-temperature resisitivity (ρ25) was observed as TS was increased. The temperature coefficient of resistance (TCR) was independent of the change in TS, and closed pores decreased with increasing TS.