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Factors affecting the resistance and performance of fluoride ion‐selective electrodes
Author(s) -
Shen Wei,
Wang Xue D.,
Cattrall Robert W.,
Nyberg Graeme L.,
Liesegang John
Publication year - 1995
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140071004
Subject(s) - membrane , fluoride , crystal (programming language) , materials science , conductivity , electrode , doping , ion , analytical chemistry (journal) , chemistry , inorganic chemistry , optoelectronics , chromatography , organic chemistry , biochemistry , computer science , programming language
Abstract Some lanthanide fluoride (LnF 3 , Ln = Ce, Nd, Sm) crystals have been grown, and fluoride ion‐selective electrodes (F‐ISE) have been constructed using these and some commercial LaF 3 , single crystal membranes. Aspects of crystal growing, particularly the high‐temperature dimorphism of SmF 3 , are addressed, and the effects on the electrode resistance and response characteristics of crystal quality, doping and membrane geometric dimensions are studied. The results show that, while doping is effective in increasing the membrane conductivity, membrane geometric dimensions also affect the electrical resistance substantially. Undoped membranes have noise‐free Nernstian response to F − solutions, provided appropriate geometric dimensions are chosen. The crystal orientation of the membrane does not have noticeable effect on the performance. The crystal quality also affects the membrane resistance and performance. Single crystal membranes with minor and localized visual defects show little difference in conductivity and no difference in performance compared with a ‘perfect’ single crystal membrane. Membranes grown from lower grade starting materials do not show poorer performance although these membranes were slightly cloudy. Membranes with severe visual defects have much lower conductivity, and deteriorated performance.