New metal-oxide-type pH sensors

P. Shuk, K. V. Ramanujachary, M. Greenblatt

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Abstract

Two new types of metal-oxide pH sensors with a direct solid-state contact have been developed and tested. Their performance was demonstrated near ambient temperatures with a samarium substituted ceria ceramic membrane and single crystals of several molybdenum oxide bronzes. The pH sensors with Na-molybdenum-oxide bronzes show near-ideal Nernstian behaviour in the pH range 3-9. The response was not affected by the direction of the pH change. In contrast, the pH sensor with the Na-tungsten bronze sensitive electrode (SE) shows a deviation from linearity, as well as non-Nernstian behaviour with a slope - 76.3 mV/pH at 25 °C. The response time of most molybdenum bronze pH sensors is less than 5 s for 90% response. The pH sensors with stabilized ceria membrane show close to ambient temperature non-Nernstian behaviour in the pH range 3-10 with a slope - 23.8 mV/pH at 25 °C. With increasing temperatures the behaviour of ceria membrane pH sensors approaches more and more a Nernstian response with slope -39.9 mV/pH at 60 °C. Both pH sensors also can be used to follow acid-base titrations.

Original languageEnglish (US)
Pages (from-to)1115-1120
Number of pages6
JournalSolid State Ionics
Volume86-88
Issue numberPART 2
DOIs
StatePublished - Jul 1996

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Keywords

  • Metal oxide electrode
  • Molybdenum oxide bronze
  • Oxide ion conducting solid electrolyte
  • Single crystal
  • Stabilized cerium oxide
  • pH sensor

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