@article{nozariasbmarz_vashaee_2020, title={Effect of Microwave Processing and Glass Inclusions on Thermoelectric Properties of P-Type Bismuth Antimony Telluride Alloys for Wearable Applications}, volume={13}, ISSN={["1996-1073"]}, DOI={10.3390/en13174524}, abstractNote={Depending on the application of bismuth telluride thermoelectric materials in cooling, waste heat recovery, or wearable electronics, their material properties, and geometrical dimensions should be designed to optimize their performance. Recently, thermoelectric materials have gained a lot of interest in wearable electronic devices for body heat harvesting and cooling purposes. For efficient wearable electronic devices, thermoelectric materials with optimum properties, i.e., low thermal conductivity, high Seebeck coefficient, and high thermoelectric figure-of-merit (zT) at room temperature, are demanded. In this paper, we investigate the effect of glass inclusion, microwave processing, and annealing on the synthesis of high-performance p-type (BixSb1−x)2Te3 nanocomposites, optimized specially for body heat harvesting and body cooling applications. Our results show that glass inclusion could enhance the room temperature Seebeck coefficient by more than 10% while maintaining zT the same. Moreover, the combination of microwave radiation and post-annealing enables a 25% enhancement of zT at room temperature. A thermoelectric generator wristband, made of the developed materials, generates 300 μW power and 323 mV voltage when connected to the human body. Consequently, MW processing provides a new and effective way of synthesizing p-type (BixSb1−x)2Te3 alloys with optimum transport properties.}, number={17}, journal={ENERGIES}, author={Nozariasbmarz, Amin and Vashaee, Daryoosh}, year={2020}, month={Sep} }
 @article{nozariasbmarz_dycus_cabral_flack_krasinski_lebeau_vashaee_2021, title={Efficient self-powered wearable electronic systems enabled by microwave processed thermoelectric materials}, volume={283}, ISSN={["1872-9118"]}, DOI={10.1016/j.apenergy.2020.116211}, abstractNote={The integrated body sensor networks are expected to dominate the future of healthcare, making a critical paradigm shift that will support people in the comfort and security of their own homes. Thermoelectric generators, in this regard, can play a crucial role as they can steadily generate electricity from body heat and enable self-powered wearable or implantable medical, health, and sports devices. This work provides a comprehensive analysis of the operation and the optimization of wearable thermoelectric generators under different human body conditions. Thermoelectric design principles, wearable system considerations, and a novel method to synthesize the materials specially designed for body heat harvesting are presented. The limitations of the materials and systems for wearable applications are deliberated in detail, and the feasibility of eliminating the heatsink for enhancing body comfort is examined. N-type Bi2Te3-xSex was synthesized using a novel approach based on field-induced decrystallization by microwave radiation to achieve the optimum properties. This method resulted in amorphous-crystalline nanocomposites with simultaneously large thermopower and small thermal conductivity around the body temperature. Thermoelectric generators were fabricated from the optimized materials and packaged in flexible elastomers. The devices generated up to 150% higher voltage and 600% more power on the body compared to the commercial ones and, so far, are the best in class for body heat harvesting in wearable applications.}, journal={APPLIED ENERGY}, author={Nozariasbmarz, Amin and Dycus, J. Houston and Cabral, Matthew J. and Flack, Chloe M. and Krasinski, Jerzy S. and LeBeau, James M. and Vashaee, Daryoosh}, year={2021}, month={Feb} }
 @article{nozariasbmarz_hosseini_vashaee_2019, title={Interfacial ponderomotive force in solids leads to field induced dissolution of materials and formation of non-equilibrium nanocomposites}, volume={179}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2019.08.017}, abstractNote={We report that microwave radiation can decompose continuous solid-solution materials into their constituent phases – a process that is thermodynamically unfavorable at equilibrium. A detailed analysis of the interaction of the electromagnetic wave with the material showed that a strong ponderomotive force preferentially separates the constituent phases via an enhanced mass transport process amplified particularly near the interfaces. The proof of concept experiments showed that the material, whether it is a solid-solution of two elements, e.g. (Si1-xGex), or two compounds, e.g. (Bi2Te3)1-x(Sb2Te3)x, decomposes into the constituent phases when radiated by a polarized microwave field. The dissolution happens in the bulk of the material and even below the melting point. The degree of decomposition can be controlled by radiation parameters to produce structures composed of gradient phases of the solid-solution. This offers a novel and facile method for synthesizing gradient composite and complex structures for application in thermoelectricity as well as fabrication of core-shell structures for catalysts and biomedical applications.}, journal={ACTA MATERIALIA}, author={Nozariasbmarz, Amin and Hosseini, Mahshid and Vashaee, Daryoosh}, year={2019}, month={Oct}, pages={85–92} }
 @article{nozariasbmarz_krasinski_vashaee_2019, title={N-Type Bismuth Telluride Nanocomposite Materials Optimization for Thermoelectric Generators in Wearable Applications}, volume={12}, ISSN={["1996-1944"]}, DOI={10.3390/ma12091529}, abstractNote={Thermoelectric materials could play a crucial role in the future of wearable electronic devices. They can continuously generate electricity from body heat. For efficient operation in wearable systems, in addition to a high thermoelectric figure of merit, zT, the thermoelectric material must have low thermal conductivity and a high Seebeck coefficient. In this study, we successfully synthesized high-performance nanocomposites of n-type Bi2Te2.7Se0.3, optimized especially for body heat harvesting and power generation applications. Different techniques such as dopant optimization, glass inclusion, microwave radiation in a single mode microwave cavity, and sintering conditions were used to optimize the temperature-dependent thermoelectric properties of Bi2Te2.7Se0.3. The effects of these techniques were studied and compared with each other. A room temperature thermal conductivity as low as 0.65 W/mK and high Seebeck coefficient of −297 μV/K were obtained for a wearable application, while maintaining a high thermoelectric figure of merit, zT, of 0.87 and an average zT of 0.82 over the entire temperature range of 25 °C to 225 °C, which makes the material appropriate for a variety of power generation applications.}, number={9}, journal={MATERIALS}, author={Nozariasbmarz, Amin and Krasinski, Jerzy S. and Vashaee, Daryoosh}, year={2019}, month={May} }
 @misc{nozariasbmarz_collins_dsouza_polash_hosseini_hyland_liu_malhotra_ortiz_mohaddes_et al._2020, title={Review of wearable thermoelectric energy harvesting: From body temperature to electronic systems}, volume={258}, ISSN={["1872-9118"]}, url={https://publons.com/publon/30967440/}, DOI={10.1016/j.apenergy.2019.114069}, abstractNote={Global demand for battery-free metrics and health monitoring devices has urged leading research agencies and their subordinate centers to set human energy harvesting and self-powered wearable technologies as one of their primary research objectives. After an overview of wearables market trends, different active and passive methods of body energy harvesting for powering low-consumption electronic devices are introduced, and challenges of device fabrication are discussed. The discussion continues with the primary emphasis on thermoelectric generators for body heat harvesting. The physiological aspects of the human body involved in heat generation are elaborated. System requirements and the influence of different parameters on the performance of thermoelectric generators are studied at the material, device, and system levels. Finally, the advancements in the development of rigid and flexible thermoelectric generators for wearable and textile integration are presented.}, journal={APPLIED ENERGY}, author={Nozariasbmarz, Amin and Collins, Henry and Dsouza, Kelvin and Polash, Mobarak Hossain and Hosseini, Mahshid and Hyland, Melissa and Liu, Jie and Malhotra, Abhishek and Ortiz, Francisco Matos and Mohaddes, Farzad and et al.}, year={2020}, month={Jan} }
 @article{nozariasbmarz_suarez_dycus_cabral_lebeau_ozturk_vashaee_2020, title={Thermoelectric generators for wearable body heat harvesting: Material and device concurrent optimization}, volume={67}, ISSN={["2211-3282"]}, DOI={10.1016/j.nanoen.2019.104265}, abstractNote={Body heat harvesting systems based on thermoelectric generators (TEGs) can play a significant role in wearable electronics intended for continuous, long-term health monitoring. However, to date, the harvested power density from the body using TEGs is limited to a few micro-watts per square centimeter, which is not sufficient to turn on many wearables. The thermoelectric materials research has been mainly focused on enhancing the single parameter zT, which is insufficient to meet the requirements for wearable applications. To develop TEGs that work effectively in wearable devices, one has to consider the material, device, and system requirements concurrently. Due to the lack of an efficient heatsink and the skin thermal resistance, a key challenge to achieving this goal is to design systems that maximize the temperature differential across the TEG while not compromising the body comfort. This requires favoring approaches that deliver the largest possible device thermal resistance relative to the external parasitic resistances. Therefore, materials with low thermal conductivity are critically important to maximize the temperature gradient. Also, to achieve a high boost converter efficiency, wearable TEGs need to have the highest possible output voltage, which calls for a high Seebeck coefficient. At the device level, dimensions of the legs (length versus the base area) and fill factor are both critical parameters to ensure that the parasitic thermal resistances are again negligible compared to the resistance of the module itself. In this study, the concurrent impact of material and device parameters on the efficiency of wearable TEGs is considered. Nanocomposite thermoelectric materials based on bismuth telluride alloys were synthesized using microwave processing and optimized to meet the requirements of wearable TEGs. Microwave energy decrystallized the material leading to a strong reduction of the thermal conductivity while maintaining a high zT at the body temperature. A comprehensive quasi-3D analytical model was developed and used to optimize the material and device parameters. The nanocomposite TEG produced 44 μW/cm2 under no air flow condition, and 156.5 μW/cm2 under airflow. In comparison to commercial TEGs tested under similar conditions, the nanocomposite based TEGs exhibited 4–7 times higher power density on the human body depending on the convective cooling conditions.}, journal={NANO ENERGY}, author={Nozariasbmarz, Amin and Suarez, Francisco and Dycus, J. Houston and Cabral, Matthew J. and LeBeau, James M. and Ozturk, Mehmet C. and Vashaee, Daryoosh}, year={2020}, month={Jan} }
 @article{nozariasbmarz_dsouza_vashaee_2018, title={Field induced decrystallization of silicon: Evidence of a microwave non-thermal effect}, volume={112}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.5020192}, DOI={10.1063/1.5020192}, abstractNote={It is rather strange and not fully understood that some materials decrystallize when exposed to microwave radiation, and it is still debatable if such a transformation is a thermal or non-thermal effect. We hereby report experimental evidences that weight the latter effect. First, a single crystal silicon wafer exposed to microwaves showed strong decrystallization at high temperature. Second, when some areas of the wafer were masked with metal coating, only the exposed areas underwent decrystallization. Transmission electron microscopy analysis, x-ray diffraction data, and thermal conductivity measurements all indicated strong decrystallization, which occurred in the bulk of the material and was not a surface effect. These observations favor the existence of a non-thermal microwave effect.}, number={9}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Nozariasbmarz, Amin and Dsouza, Kelvin and Vashaee, Daryoosh}, year={2018}, month={Feb}, pages={093103} }
 @misc{nozariasbmarz_agarwal_coutant_hall_liu_liu_malhotra_norouzzadeh_oeztuerk_ramesh_et al._2017, title={Thermoelectric silicides: A review}, volume={56}, ISSN={["1347-4065"]}, url={http://dx.doi.org/10.7567/jjap.56.05da04}, DOI={10.7567/jjap.56.05da04}, abstractNote={Traditional research on thermoelectric materials focused on improving the figure-of-merit zT to enhance the energy conversion efficiency. With further growth and commercialization of thermoelectric technology beyond niche applications, other factors such as materials availability, toxicity, cost, recyclability, thermal stability, chemical and mechanical properties, and ease of fabrication become important for making viable technologies. Several silicide alloys were identified that have the potential to fulfill these requirements. These materials are of interest due to their abundancy in earth’s crust (e.g., silicon), non-toxicity, and good physical and chemical properties. In this paper, an overview of the silicide thermoelectrics from traditional alloys to advanced material structures is presented. In addition, some of the most effective approaches as well as fundamental physical concepts for designing and developing efficient thermoelectric materials are presented and future perspectives are discussed.}, number={5}, journal={JAPANESE JOURNAL OF APPLIED PHYSICS}, author={Nozariasbmarz, Amin and Agarwal, Aditi and Coutant, Zachary A. and Hall, Michael J. and Liu, Jie and Liu, Runze and Malhotra, Abhishek and Norouzzadeh, Payam and Oeztuerk, Mehmet C. and Ramesh, Viswanath P. and et al.}, year={2017}, month={May} }
 @article{nozariasbmarz_roy_zamanipour_dycus_cabral_lebeau_krasinski_vashaee_2016, title={Comparison of thermoelectric properties of nanostructured Mg2Si, FeSi2, SiGe, and nanocomposites of SiGe-Mg2Si, SiGe-FeSi2}, volume={4}, ISSN={["2166-532X"]}, DOI={10.1063/1.4966138}, abstractNote={Thermoelectric properties of nanostructured FeSi2, Mg2Si, and SiGe are compared with their nanocomposites of SiGe–Mg2Si and SiGe–FeSi2. It was found that the addition of silicide nanoinclusions to SiGe alloy maintained or increased the power factor while further reduced the thermal conductivity compared to the nanostructured single-phase SiGe alloy. This resulted in ZT enhancement of Si0.88Ge0.12–FeSi2 by ∼30% over the broad temperature range of 500-950 °C compared to the conventional Si0.80Ge0.20 alloy. The Si0.88Ge0.12–Mg2Si nanocomposite showed constantly increasing ZT versus temperature up to 950 °C (highest measured temperature) reaching ZT ∼ 1.3. These results confirm the concept of silicide nanoparticle-in-SiGe-alloy proposed earlier by Mingo et al. [Nano Lett. 9, 711–715 (2009)].}, number={10}, journal={APL MATERIALS}, author={Nozariasbmarz, Amin and Roy, Palash and Zamanipour, Zahra and Dycus, J. Houston and Cabral, Matthew J. and LeBeau, James M. and Krasinski, Jerzy S. and Vashaee, Daryoosh}, year={2016}, month={Oct} }
 @article{suarez_nozariasbmarz_vashaee_ozturk_2016, title={Designing thermoelectric generators for self-powered wearable electronics}, volume={9}, ISSN={["1754-5706"]}, DOI={10.1039/c6ee00456c}, abstractNote={Computational efficient, quasi-3D model for designing body wearable thermoelectric generators and experimental verification.}, number={6}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, author={Suarez, Francisco and Nozariasbmarz, Amin and Vashaee, Daryoosh and Ozturk, Mehmet C.}, year={2016}, pages={2099–2113} }
 @article{nozariasbmarz_zamanipour_norouzzadeh_krasinski_vashaee_2016, title={Enhanced thermoelectric performance in a metal/semiconductor nanocomposite of iron silicide/silicon germanium}, volume={6}, ISSN={2046-2069}, url={http://dx.doi.org/10.1039/C6RA01947A}, DOI={10.1039/c6ra01947a}, abstractNote={The metal–semiconductor nanocomposite of n-type thermoelectric SiGe–FeSi2 was successfully developed and characterized versus electrical, thermal, and microstructural properties.}, number={55}, journal={RSC Advances}, publisher={Royal Society of Chemistry (RSC)}, author={Nozariasbmarz, Amin and Zamanipour, Zahra and Norouzzadeh, Payam and Krasinski, Jerzy S. and Vashaee, Daryoosh}, year={2016}, pages={49643–49650} }
 @article{rastegari_kani_salahinejad_fadavi_eftekhari_nozariasbmarz_tayebi_vashaee_2016, title={Non-hydrolytic sol-gel processing of chloride precursors loaded at forsterite stoichiometry}, volume={688}, ISSN={["1873-4669"]}, DOI={10.1016/j.jallcom.2016.07.187}, abstractNote={This paper for the first time investigates the sol-gel reaction of magnesium chloride and silicon tetrachloride, directed at the forsterite (Mg2SiO4) stoichiometry, using dry ethanol and glacial acetic acid as the solvent and chelating agent, respectively. The synthesized particles before and after calcination were characterized by transmission electron microscopy equipped with energy-dispersive X-ray spectroscopy mapping, X-ray diffraction and Fourier transform infrared spectroscopy. According to the results, the calcined nanoparticles showed a magnesia/forsterite structure along with silicon depletion, despite loading the forsterite stoichiometry. On the other hand, silicon-acetoxy bonds were detected in the xerogel (before calcination) as a result of the chelation reaction, albeit with a relatively uniform distribution of the essential elements. Since no non-alcoholyzed silicon-chlorine bond was detected in the xerogel, the development of the calcined structure was explained by the deficient sol-gel condensation and subsequent evaporation of silicon tetraacetate. It was inferred that the excessive amount of hydrogen chloride as the coproduct of the ethanolysis and chelation reactions of the precursors inhibits the condensation step, as confirmed by a supplementary test in an exaggerated circumstance. In conclusion, the silicon-containing species acts like a limiting reagent in the sol-gel condensation of forsterite using the chloride precursors and acetic acid chelator, in spite of loading the related stoichiometry.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={Rastegari, S. and Kani, O. Seyed Mehdi and Salahinejad, E. and Fadavi, S. and Eftekhari, N. and Nozariasbmarz, A. and Tayebi, L. and Vashaee, D.}, year={2016}, month={Dec}, pages={235–241} }
 @article{norouzzadeh_nozariasbmarz_krasinski_vashaee_2015, title={Thermal conductivity of nanostructured SixGe1-x in amorphous limit by molecular dynamics simulation}, volume={117}, ISSN={["1089-7550"]}, DOI={10.1063/1.4921536}, abstractNote={We report the thermal conductivity of amorphous SixGe1−x compound calculated versus composition and temperature. The result sets the minimum value of thermal conductivity which is achievable by nanostructuring. We employed molecular dynamics with Tersoff's potential for the calculations. It was found that, contrary to the crystalline SixGe1−x, the thermal conductivity of amorphous phase is a weak function of the material composition. For the most popular composition Si0.8Ge0.2, the thermal conductivity of the amorphous phase is less than 1 W m−1 K−1 with small reduction as the temperature increases from 300 K to 1400 K. The thermal conductivity of amorphous SixGe1−x for any value of x is approximately an order of magnitude smaller than the minimum thermal conductivity of crystalline SixGe1−x alloy, which occurs near x = 0.5. It is known that alloying with germanium is more efficient than nanostructuring to reduce the thermal conductivity of silicon; however, it was found that the amorphization process is even more effective than alloying for that purpose. It was also shown that the reduction of the thermal conductivity of silicon due to alloying with germanium is more efficient in crystalline phase than in amorphous phase.}, number={21}, journal={JOURNAL OF APPLIED PHYSICS}, author={Norouzzadeh, Payam and Nozariasbmarz, Amin and Krasinski, Jerzy S. and Vashaee, Daryoosh}, year={2015}, month={Jun} }