Indium stable phase

In aqueous solution, indium only exists in the trivalent state. The stable phase of indium is In(OH)g(s) (Baes and Mesmer, 1976). The solubility reaction for the... 

This paper reports the synthesis and characterization of a new family of indium silicate microporous materials, designated InSi-n. The InSi-n phases have been synthesized with 11 novel framework topologies and contain In/Si ratios of 0.25-1. Most InSi-n phases are stable to calcination to at least 500 °C and show adsorption behavior that is zeolitic in character. Ion exchange behavior similar to zeolites has also been observed in InSi-n materials. Preliminary structural details include a crystal structure determination of a new topology with 8-ring channels and HREM evidence for large pores in members of the InSi-n family. 

Oxides are normally stable at the operating temperatures necessary to enhance the interaction between their surface and the gas phase, much more stable compared to organic materials. They are normally operated between 500 and 800 K where the conduction is electronic and oxygen vacancies are doubly ionized. Different oxides have been proposed for conductometric chemical sensors, the most studied is by far tin dioxide that has also been commercialized in form of thick film sensors. Other oxides studied are titanium oxide, tungsten oxide, zinc oxide, indium oxide and iron oxide, first in form of thick and then in form of thin films. Furthermore, the use of mixed oxides, as well as the addition of noble metals, has been studied to improve not only selectivity but also stability. 

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