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Abstrak :

Diantara tiga struktur TiO₂, anatase TiO₂ telah mendapat banyak perhatian karena sifatnya yang menarik serta potensinya untuk dimanfaatkan dalam berbagai aplikasi. Berbagai aplikasi tersebut bergantung pada sifat transpor material ini. Beberapa penelitian terdahulu mengenai sifat transport anatase TiO₂ menunjukkan adanya kopling antara elektron dan fonon yang membentuk suatu kuasi partikel bernama polaron. Namun, belum ada penjelasan mengenai bagaimana keberadaan polaron pada anatase TiO₂ mempengaruhi sifat transpor terutama resistivitas. Oleh karena itu, kami melakukan studi teoretik terhadap sifat transport anatase TiO₂ yang dipengaruhi oleh kehadiran polaron. Kami menggunakan model Holstein, di mana menggunakan dua pita anatase TiO₂ yaitu pita konduksi dan pita valensi yang diselesaikan dalam kerangka Dynamical Mean Field Theory (DMFT) untuk menjelaskan interaksi antar elektron dan fonon. Kami menghitung densitas keadaan sistem dan nilai dari invers kuadrat dari densitas keadaan yang berkorespondensi pada potensial kimia, di mana nilai ini sebanding dengan nilai resistivitas, sebagai fungsi temperatur. Dengan menggunakan nilai densitas pembawa muatan seperti pada eksperimen, hasil perhitungan menunjukkan pada resistivitas turun seiring dengan pertambahan temperatur pada seluruh nilai densitas pembawa muatan. Hal ini menunjukkan bahwa model yang digunakan hanya baik dalam mendeskripsikan efek trapping namun kurang baik dalam menjelaskan efek hamburan.

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We present a theoretical study on the effects of electron-phonon interactions on the transport properties of anatase TiO₂. Temperature-dependent resistivity measurement on anatase TiO₂ thin film has shown that carrier concentrations and temperatures affect the resistivity of this material. At low carrier concentrations, a metal to insulator transition could be observed, while at high carrier concentrations this material only shows metal-like resistivity. In this study we aim to investigate the behavior of temperature-dependent resistivity at various carrier concentrations as revealed in the experimental study. We hypothesize that electron-phonon interactions with intermediate coupling constant govern the transport properties of this material. We construct Holstein model Hamiltonian incorporating both conduction and valence bands of anatase TiO₂ within parabolic dispersion approximation. We solve the model within the Dynamical Mean Field Theory (DMFT). We calculate the density of states of the system and the corresponding inverse of the square of the density of states at the chemical potential, which is approximately proportional to the resistivity, as a function of temperature. Using carrier concentration values taken as in the experimental data, the calculations show that only the trends of decreasing resistivity with increasing temperature is found in all carrier concentrations value. The results show that our model is good in the describing the trapping effects due to the electron-phonon interaction but the model is doing poorly in capturing the scattering effects.

 

Abstrak :
This book provides valuable information on polymer composite manufacturing, with a focus on liquid molding processes and the resin transfer molding technique (RTM). It presents and discusses emerging topics related to the foundations, engineering applications, advanced modeling and experiments regarding the RTM process. A valuable resource for engineers, professionals in industry and academics involved in this advanced interdisciplinary field, it also serves as a comprehensive reference book for undergraduate and postgraduate courses.

Abstrak :
This text provides a teachable and readable approach to transport phenomena (momentum, heat, and mass transport) by providing numerous examples and applications, which are particularly important to metallurgical, ceramic, and materials engineers. Because the authors feel that it is important for students and practicing engineers to visualize the physical situations, they have attempted to lead the reader through the development and solution of the relevant differential equations by applying the familiar principles of conservation to numerous situations and by including many worked examples in each chapter. The book is organized in a manner characteristic of other texts in transport phenomena. Section I deals with the properties and mechanics of fluid motion; Section II with thermal properties and heat transfer; and Section III with diffusion and mass transfer. The authors depart from tradition by building on a presumed understanding of the relationships between the structure and properties of matter, particularly in the chapters devoted to the transport properties (viscosity, thermal conductivity, and the diffusion coefficients). In addition, generous portions of the text, numerous examples, and many problems at the ends of the chapters apply transport phenomena to materials processing.