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I am a PhD Researcher that focuses on characterising the microstructural behaviour of superalloys.


Follow this pinboard to understand the science behind thermoelectrcs

In 10 Seconds? Energy efficiency is a worldwide concern; it is generally known that the largest loss of energy is through wasted heat – which is why so much research is being carried out to improve the properties of thermoelectric materials. The basic principle behind thermoelectricity is that the thermoelectric material must be within a temperature gradient (temperature difference) i.e. one side hot and the other side cold.

Don’t believe it? Review the pinned articles to observe the novel research that is being done to improve the conversion efficiency – one particular paper focuses on charged colloidal particles, which showed positive results for future research.

Where are they used? Thermoelectric modules can be found extensively within the automotive industry – where the waste heat is converted into an electrical output. Similarly, they can be found in power plants doing the same job.

The science behind thermoelectric modules

These thermoelectric modules consist of two thermoelectric materials - one to form the n-type semiconductor and the other to form the p-type semiconductor, which are all contained within a temperature gradient.

To allow for a successful conversion of heat to electricity one particular material property is critical – low thermal conductivity. This is because it is crucial to retain the temperature gradient. Therefore, having a low thermal conductivity means the heat will not pass through the material to the cooler section of the module.


Effect of Ba-doping on high temperature thermoelectric properties of Sr2TiMoO6 double perovskites

Abstract: Oxides based thermoelectrics have the advantage over other materials due to their low processing cost, better temperature stability and environmental friendly nature. However, it is difficult to achieve good electrical conductivity along with high Seebeck coefficient in oxides. Recently double perovskites based oxides have shown great potential to optimize various thermoelectric (TE) parameters in order to achieve high figure-of-merit, ZT values for TE power generations. In the present work we investigated the effect of Ba-doping on the high temperature thermoelectric properties of double perovskite Sr2TiMoO6 (STM), which exhibits metal like conductivity (∼105 S/m). Dense ceramic samples of BaxSr2-xTiMoO6 with 0 ≤ x ≤ 2.0 were synthesized using solid-state reaction route. Rietveld refinement of XRD data confirmed the cubic crystal structure in these double perovskites with space-group <img height="14" border="0" style="vertical-align:bottom" width="41" alt="View the MathML source" title="View the MathML source" src="http://origin-ars.els-cdn.com/content/image/1-s2.0-S0925838817310666-si1.gif">Pm3¯m. It is shown in this paper that complete substitution of barium in place of strontium actually increases the Seebeck coefficient without compromising much in electrical conductivity values, resulting better thermoelectric power factor in Ba2TiMoO6 (BTM) compared to STM composition. Thermopower (S) measurement showed the conductivity switching from p-type to n-type behavior in all the compositions at higher temperature although the switching temperature decreases with increase in Ba-concentration. Temperature dependent Seebeck coefficient was further explained using an analytical model for coexistence of both types of charge carriers in these oxides. Conductivity mechanism of these double perovskites was found to be governed by small polaron hopping model.

Pub.: 27 Mar '17, Pinned: 22 Apr '17

Scalable production of silicon-tin yin-yang hybrid structure with graphene coating for high performance lithium ion battery anodes.

Abstract: Alloy anodes possessed of high theoretical capacity show great potential for next generation advanced lithium ion battery. Even though huge volume change during lithium insertion and extraction leads to severe problems, such as pulverization and unstable Solid-Electrolyte Interphase (SEI), various nanostructures including nanoparticles, nanowires and porous networks can address related challenges to improve electrochemical performance. However, the complex and expensive fabrication process hinders the widespread application of nanostructured alloy anodes, which generate urgent demand of low cost and scalable processes to fabricate building blocks with fine controls of size, morphology and porosity. Here, we demonstrate a scalable and low cost process to produce porous yin-yang hybrid composite anode with graphene coating through high energy ball-milling and selective chemical etching. With void space to buffer the expansion, the produced functional electrodes demonstrate stable cycling performance of 910 mAh g-1 over 600 cycles at a rate of 0.5C for Si-graphene "yin" particles and 750 mAh g-1 over 300 cycles at 0.2C for Sn-graphene "yang" particles. Therefore, we open up a new approach to fabricate alloy anode materials at low cost, low energy consumption and large scale. This type of porous silicon or tin composite with graphene coating can also potentially play a significant role in thermoelectrics and optoelectronics applications.

Pub.: 18 Apr '17, Pinned: 22 Apr '17