Pengaruh Variasi Temperatur Uji ZEM-3 pada Properti Termoelektrik Lapisan Tipis Ti-doped ZnO

Lapisan tipis Ti-doped ZnO berhasil difabrikasi pada substrat kaca SiO2 dengan menggunakan metode DC Magnetron Sputtering. Proses sputtering dilakukan dalam waktu 30 menit dan dengan tegangan sebesar 339-349 Volt. Lapisan tipis yang terbentuk memiliki ketebalan 241.287 nm. Uji properti termoelektrik dilakukan pada temperatur 310 K, 373 K, 423 K, 473 K, 523 K, 573 K, dan 623 K. Hasilnya, nilai resistivitas listrik lapisan tipis menurun hingga 523 K, dengan nilai resistivitas terendahnya adalah 0.446 ρ (mΩ m). Nilai koefisien Seebeck yang dihasilkan adalah minus menandakan bahwa lapisan tipis merupakan semikonduktor tipe n. Nilai koefisien Seebeck selalu meningkat seiring dengan pertambahan temperatur. Semakin tinggi temperatur yang diberlakukan pada material semikonduktor, maka makin tinggi pula faktor dayanya. Faktor daya paling tinggi terjadi pada temperatur 573 K dengan 32 µWm-1K2

Penggunaan Metode DC Magnetron Sputtering dalam Pembuatan Lapisan Tipis Tipe N (AZO) Sebagai Modul Termoelektrik

Penelitian mengenai termoelektrik sedang gencar dikembangkan sejak tahun 1990. Pada tahun 2017, mulai dikembangkan termoelektrik yang menggunakan lapisan tipis. Pada penelitian ini, dilakukan fabrikasi termoelektrik lapisan tipis tipe N menggunakan material Zink Oxide (ZnO) di doping dengan Al2O3. Massa ZnO yang diperlukan sebanyak 20.680 gram dan Al2O3 10.079 gram. Proses fabrikasi lapisan tipis dilakukan menggunakan mesin DC Magnetron Sputtering. Tahapan-tahapan dalam melakukan penelitian ini terbagi ke dalam tiga tahapan utama yakni sintesis, fabrikasi (sputtering), dan pengujian. Proses sputtering dilakukan selama 10 menit dan substrat yang digunakan yakni kaca. Pengujian yang dilakukan yakni pengujian ketebalan menggunakan Tolansky Apparatus, pngujian XRD untuk mengetahui fasa yang terbentuk, pengujian ZEM-3 untuk mengetahui resistivitas, Koefisien Seebeck, dan power factor. Berdasarkan pengujian yang dilakukan, diperoleh ketebalan dari lapisan tipis yang terbentuk yakni 74.72 nm. Nilai Koefisien Seebeck dari lapisan tipis yang terbentuk semakin bertambah seiring kenaikan suhu sehingga dapat disimpulkan bahwa material AZO baik digunakan untuk aplikasi termoelektrik pada rentang suhu 200-350 °C

Selecting the suitable dopants: electronic structures of transition metal and rare earth doped thermoelectric sodium cobaltate

Engineered $Na_{0.75}CoO_2$ is considered a prime candidate to achieve high-efficiency thermoelectric systems to regenerate electricity from waste heat. In this work, three elements with outmost electronic configurations, (1) an open d shell (Ni), (2) a closed d shell (Zn), and (3) a half filled f shell (Eu) with maximum unpaired electrons, were selected to outline the dopants' effects on electronic and crystallographic structures of $Na_{0.75}CoO_2$. Systematic $ab$ $initio$ density functional calculations with $DMOL^3$ package showed that the Ni and Zn were more stable when substituting Co with formation energy $-2.35$ eV, $2.08$ eV when Fermi level equals to the valence band maximum. While Eu is more stable when it substitutes Na having formation energy of $-2.64$ eV. As these results show great harmony with existing experimental data, they provide new insights into the fundamental principle of dopant selection for manipulating the physical properties in the development of high-performance sodium cobaltate based multifunctional materials.Comment: 8 pages, 9 figure

Fabrication of p-type (MCCO) thin film using DC magnetron sputtering as a preparator for thermoelectric module

Based on existing research, thermoelectric efficiency can be improved through material selection. In this study, the material used is CaCO₃ doped with Mn and Co₂O₃ to form CaCo3.5Mn0.5O9 material as a p-type thermoelectric material. The substrate used is glass. The stages in this research are material synthesis, sputtering process using DC Magnetron Sputtering machine to form thin films, and testing. The synthesis process includes grinding, calcination, and sintering. Grinding is done using a Ball Mill machine with a rotation speed of 250 rpm for 5 hours. Furthermore, the calcination step was carried out by heating the sample into a furnace at a temperature of 800°C for 10 hours. Then the sintering process was carried out at a temperature of 850°C for 12 hours. After the synthesis process is complete, enter the sputtering process using a DC Magnetron Sputtering machine for approximately 10 minutes. The gas used in this research is Argon (Ar). After the sputtering process was carried out, several tests appeared, such as the XRD test to determine the type of crystal, the ZEM-3 test to determine the Seebeck coefficient and resistivity, the thickness of the thin film formed, and the power factor test to determine the maximum voltage and power generated by the module formed. Several power factor test results were obtained, consisting of 107 μW/mK² at 100°C, 108 μW/mK² at 200°C, and 332 μW/mK² at 300°C and a thickness of 90.34 nm

Characterization of electron and phonon transports in Bi-doped CaMnO3 for thermoelectric applications

Electron and phonon transports in CaMnO3 and its Bi-doped counterpart, Bi0.03Ca0.97MnO3, are investigated by thermoelectric transport measurements, Raman spectroscopy, and first-principles calculations. In particular, we focus on CaMnO3 and Bi0.03Ca0.97MnO3's electronic structures, temperature-dependent electron and phonon lifetimes, and their sound velocities. We find that the anti-ferromagnetic insulator CaMnO3 breaks the Wiedemann-Franz (WF) law with the Lorenz number reaching four times that of ordinary metals at room temperature. Bismuth doping reduces both the electrical resistivity and the Seebeck coefficient of CaMnO3, thus it recovers the WF law behavior. Raman spectroscopy confirms that Bi0.03Ca0.97MnO3 has a lower Debye frequency as well as a shorter phonon lifetime. As a result, Bi0.03Ca0.97MnO3 exhibits superior thermoelectric properties over the pristine CaMnO3 due to the lower thermal conductivity and electronic resistivity.Comment: 7 pages, 7 figure