Influence of pulsed-electric-current sintering conditions on the non-stoichiometry and thermoelectric properties of Ti1 + xS2. (15th January 2017)

• Record Type: Journal Article
• Authors: Sever, Tilen; Maček Kržmanc, Marjeta; Bernik, Slavko; Suvorov, Danilo; Jančar, Boštjan
• Is Part Of: Materials & design. Volume 114(2017)
• Page Start: 642
• Page End: 651
• Publication Date: 2017-01-15
• Subjects: Titanium disulphide -- Thermoelectric materials -- Pulsed electric current sintering -- Structure-property relationship -- Transport properties; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2016.11.086
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Nearly stoichiometric Ti1.005 S2 was prepared by a solid-state synthesis of the constituent elements and consolidated under a variety of processing conditions applied using pulsed-electric-current sintering. The non-stoichiometry in the Ti1 + x S2 induced during the sintering was quantitatively determined with a Rietveld structural refinement and a thermogravimetric analysis combined with inductively coupled plasma atomic emission spectroscopy. Significant cation off-stoichiometry and sulphur losses were already observed at a sintering temperature of 700 °C, resulting in heavily self-intercalated Ti1.076 S2, which significantly altered the thermoelectric properties in comparison with the nearly stoichiometric compound. By applying a high sintering pressure of 500 MPa the Ti1.005 S2 could be consolidated at 500 °C with no detectable sulphur loses and with a high bulk density of 97.6%. The sulphur volatilization in the TiS2 was also effectively suppressed up to 800 °C by using a gas-tight sintering mould, which resulted in the composition Ti1.017 S2, prepared at 800 °C and 200 MPa, with an optimal thermoelectric figure of merit ZT equal to 0.32 at 375 °C. Graphical abstract: Highlights: Sintering TiS2 can result in off-stoichiometry and the intercalation of Ti atoms. Such structural changes greatly affect the thermoelectric properties of TiS2 . S/Ti ratio decreases with sintering temperature upon the volatilization of sulphur. Highest S/Ti ratio is obtained by high-pressure sintering at lower temperatures. Sulphur volatilisation is restrained when using a gas tight-sintering mould.