"

Cookies ussage consent

Our site saves small pieces of text information (cookies) on your device in order to deliver better content and for statistical purposes. You can disable the usage of cookies by changing the settings of your browser. By browsing our site without changing the browser settings you grant us permission to store that information on your device.

I agree, do not show this message again.

Sorptive properties of thin TiO 2 and humic acid layers to NH3 , estimated by a QCM

V. GEORGIEVA1,* , L. SPASSOV1, A. MOGILEVSKY2, A. GRECHNOKOV2, N. DONKOV3, TS. YORDANOV1, V. GADJANOVA1

Affiliation

  1. Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
  2. Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
  3. Academician Emil Djakov Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria

Abstract

A Quartz Crystal Microbalance (QCM) coated with two different sensitive layers has been investigated for the determination of NH 3 concentrations. For this purpose, AT-cut 16 MHz resonators were constructed and investigated. In this work, we report results on the gas-sensing characteristics for NH3 of two kinds of thin layers: TiO2 and humic acids. The first studied layer was electron-beam evaporated thin TiO 2 deposited on both sides of a QCM. The sensing characteristics of TiO 2 were measured in the concentration range of NH3 from 100 to 1000 ppm. All studied TiO 2 layers were found to possess good sensitivity and reversibility in the examined range of NH3 concentrations. The second layer was humic acid, extracted from soil and deposited on a QCM by a drop-coating method. The main analytical parameters of such sensors, including the sensitivity, selectivity and reproducibility were evaluated. It was found that a QCM with humic acid is characterized by a higher sensitivity but a lower stability compared to metal oxides. Good linearity of the concentration dependence was obtained in the concentration range 2 to 100 ppm. The presented results demonstrate that both studied types of sensitive layer can be used for ammonia detection..

Keywords

TiO2 thin films, QCM sensor, NH.

Submitted at: Nov. 5, 2008
Accepted at: Oct. 3, 2009

Citation

V. GEORGIEVA, L. SPASSOV, A. MOGILEVSKY, A. GRECHNOKOV, N. DONKOV, TS. YORDANOV, V. GADJANOVA, Sorptive properties of thin TiO 2 and humic acid layers to NH3 , estimated by a QCM, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 10, pp. 1367-1370 (2009)