AgCrTiS 4 : Synthesis, Properties, and Analytical Application
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INTRODUCTION
AN ecological monitoring of the environment is made possible due to modern methods of chemical analysis.[1] Rapid determination of microquantities of ions in complex objects has become one of the substantial requirements to analytical techniques. Direct potentiometry (ionometry) is an analysis method using electrochemical sensors[2] of which ion-selective electrodes found wide application in ecological studies.[3] This identification technique is used in the analysis of both intermediate products of industrial chemical synthesis and objects of environment. The development and the study of new sensitive, reliable, and durable sensors widens the possibilities of using electrochemical analysis methods in solving the ecological problems. The semiconductor compounds are promising sensor materials due to unique sorption properties. The compounds with layered structure have interesting properties due to the anisotropy of bonding. The use of such chalcogenides as electrodes and chemical sensors draws attention by selective sorption abilities and high mobility of electric charge in the substance bulk.[4–7] References 8 and 9 describe ISE on the basis of titanium chalcogenides. In this article, we study the crystal structure of a new compound AgCrTiS4 and show its applicability as an electroactive substance for potentiometric determination of Ag+ ions.
A.V. LAGANOVSKY and Z.O. KORMOSH, Department of Analytical Chemistry, and V.P. SACHANYUK and O.V. PARASYUK, Department of General and Inorganic Chemistry, are with Volyn State University, 43021 Lutsk, Ukraine. Contact e-mail: [email protected] A.O. FEDORCHUK is with the Department of General and Inorganic Chemistry, Ivan Franko National University of Lviv, 79005 Lviv, Ukraine. Manuscript submitted June 1, 2007. Article published online April 29, 2008. METALLURGICAL AND MATERIALS TRANSACTIONS B
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EXPERIMENTAL
A complex chalcogenide AgCrTiS4 was obtained by the solid-state synthesis method from high-purity elements (at least 99.999 wt pct purity). The charge batches were placed in quartz containers that were evacuated to 10-2 Pa. The synthesis was performed in a shaft-type furnace in two stages. At the first stage, the samples were gradually heated (heating rate 5 K h-1) to 1370 K with an intermediate exposure at 770 K during 24 hours. After reaching the maximum temperature, the alloys were cooled to room temperature at the rate of 10 K h-1. The ampoules were then depressurized; their contents were quantitatively removed to an agate mortar, thoroughly crushed into powder, and pressed into tablets. The tablets were placed again into quartz ampoules and evacuated. The second stage of the synthesis consisted of rapid heating of the samples (heating rate 50 K h-1) to 1420 K followed by cooling at the rate of 10 K h-1. The annealing was held at 670 K during 250 hours. The synthesis process ended with quenching the samples into cold water. The X-ray diffraction reflection set was recorded by a DRON 4–13 diffractometer using Cu Ka radiation in the 10 to 100 deg rang
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