Gas Sensing and Dielectric Studies on Cobalt Doped Hydroxyapatite thick films

¹School of Physical Sciences, S.R.T.M. University, Nanded 431606, India
²School of Engineering, Matoshri Group of Institutions, Nanded 431606 (MS), India

Adv. Mater. Lett., 2013, 'ICNANO 2011', 4 (1), pp 46-52

DOI: 10.5185/amlett.2013.icnano.146

Publication Date (Web): Oct 14, 2012

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E-mail: rskhairnarsps@gmail.com

Abstract

This present paper deals with the investigation on effective utilization of cobalt doped hydroxyapatite (Co-HAp) thick films for improvement in gas sensing and dielectric properties. Chemical precipitation route is used for synthesis of nanocrystalline hydroxyapatite (HAp) bioceramic and ion exchange process is carried out for the partial substitution of cobalt ions in HAp matrix. Hydroxyapatite thick films, prepared using screen printing technique, are used as samples for gas sensing and dielectric measurements. The structural identification of HAp thick films is carried out using X-ray diffraction and the presence of functional groups in pure and doped HAp is confirmed by means FTIR spectroscopy. The surface morphology of these films is visualized by means of SEM and AFM analysis. Detailed study on CO₂ gas sensing performance of pure and Co-HAp thick films is carried out wherein operating temperature, response/recovery times and gas uptake capacity are determined. It is remarkable to note that Co-HAp film with 0.01M cobalt concentration shows maximum sensitivity to CO₂ gas at relatively lower operating temperature of 135^oC in comparison with pure HAp as well as other concentrations of cobalt doped HAp films. The frequency dependent variation of dielectric constant (K) and dielectric loss (tan δ) of HAp thick films are also studied in the range of 10 Hz-1MHz at room temperature. The result shows that increase of cobalt concentration in HAp matrix leads to increase in dielectric constant. The study reveals clear influence of cobalt substitution on dielectric properties and gas sensing properties HAp matrix.

Keywords

Hydroxyapatite, screen printing process, thick films, gas Sensor, dielectric study, XRD, AFM.