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2. Master Thesis / Tesis Master
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Title:	Synthesis and characterisation of Ba0.2Sr0.8Fe0.2O3 8(BSCF) nano particles for cathodes in solid oxide fuel cells
Authors:	Mojgan Ahmadrezaei (P51488)
Supervisor:	Andanastuti Muchta, Prof.
Keywords:	Solid oxide fuel cell Cathode materials Universiti Kebangsaan Malaysia -- Dissertations
Issue Date:	2012
Description:	Solid oxide fuel cell (SOFC) is a device that can convert chemical energy directly into electrical energy. The high operating temperature of 1000oC has raised its manufacturing cost because shaping and scaling up for manufacture at the high temperatures are difficult and need advance technology. In order to reduce the cost, the operating temperature must be lowered. However, a reduction in the operating temperature indirectly decreases the performance of the electrolytes and electrodes. This thesis focuses on the development of appropriate cathode material for the use in intermediate temperature SOFC (IT-SOFC). BaxSr1-xCoyFe1-yO3−δ (BSCF) has been found to be a most promising IT-SOFC cathode material, and has captured the attention of researchers because of its superior properties compared to conventional cathode materials. In this research, BSCF powders with y = 0.8 and x = 0.2 have been synthesised by co-precipitation method. This was followed by calcination of the powders. The calcination temperature was varied between 900oC to 1100oC to study the effect of the calcination temperature on the powder morphology. Thermogravimetric analysis (TGA) was conducted from 27-1000oC to understand the decomposition and the formation of the final desired BSCF phase. The obtained powder was characterised using X-Ray diffraction (XRD). The particle size and the effect of calcination temperature were then observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In order to understand the behaviour of the material as it reacts with its surroundings via the surface, the specific surface area was analysed via Brunauer-Emmett-Teller (BET) analysis. Thermal expansion coefficient (TEC) was used to determine the thermal behaviour of the material from room temperature to 800oC. Half cells were fabricated by painting BSCF thin film on Sm0.2Ce0.8Ox (samarium doped ceria, SDC) electrolyte pellets.Impedance spectroscopy with two electrode configurations were used to identify the electrical conductivity of BSCF in the air at 600-800oC. The XRD patterns show only the cubic perovskite structure of BSCF. Based on SEM, EDX and TEM results, BSCF was found to have homogenous phase and small particle size in the range of 30-100 nm after calcination at 900oC. The sintering temperature of 900oC showed the best electrochemical performance: Ba0.2Sr0.8Co0.8Fe0.2O3−δ shows the highest conductivity at a temperature 700°C (153 Scm-1 ). The TEC of the BSCF cathode was 16.2×10−6 k −1 at measured range (27oC -800oC). Thus, this work has exhibited that BSCF is a most favourable cathode material for fuel cells operating at intermediate temperatures (600-800oC) to achieve excellent electrochemical performance.,Tesis ini tidak ada Perakuan Tesis Sarjana/Doktor Falsafah"
Pages:	92
Call Number:	TA418.9.N35A394 2012 3 tesis
Publisher:	UKM, Bangi
URI:	https://ptsldigital.ukm.my/jspui/handle/123456789/457724
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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