Li^+/H^+ Ion-exchanged Li2MO3 (M = Ir, Pt) and Carbonate Melt Oxidized IrOx pH Sensors
Analyses and characterizations of Li^+/H^+ ion-exchanged Li2MO3 (M = Ir, Pt) and carbonate melt oxidized IrOx pH sensors are presented and discussed. The resulting structures produced during Li^+/H^+ ion-exchange for Li2IrO3 and Li2PtO3 powders as well as carbonate melt oxidized Ir and Pt wires (0.25 mm dia.) are characterized and tested using XRD, SEM, TEM, and TGA. The protonation results in the formation of HIr2/3+xLi1/3-xO2, of the HCrO2 structure type. The LiM2 layers shift due to hydrogen bonding between successive layers, which is absent in the Li2MO3 parent structures. HIr2/3+xLi1/3-xO2 is observed in both the powder and the melt oxidized wire, with preferred orientation observed in the needle-like surface under particular melt oxidation conditions. The pH responses of the iridium oxide and platinum oxide electrodes produced using a new synthetic method are presented. The stability and reproducibility of the electrodes are good, with minimal inference from Li^+ and K^+.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:ph sensors metal oxides irox li2iro3 li2pto3
Date of Publication:01/01/2008