Administrative Information المعلومات االدارية 01-10-10 :المرجع Project Title - )عنوان المشروع (عربي وأجنبي تطبق في استشعار الغازSnO2 دراسة نظرية وتجريبية لرقا ﺌق Theoretical and experimental investigations of SnO2 thin film for gas sensor application Principal Investigator - الباحث الرئيسي رقم الهاتف العنوان االلكتروني Telephone e-mail + 03 333814 email@example.com العنوان Address Faculty of sciences Elhadath الوظيفية Post Professor المؤسسة Institution Lebanese University االسم Name Fouad El Haj Hassan Co-Workers - الباحثون المشاركون العنوان االلكتروني e-mail Two years المؤسسة Institution Lebanese University Lebanese University االسم Name Chafic Salameh Wafaa Noun : Duration -المدة التعاقدية للمشروع Scientific Information العلمية المعلومات ّ Objectives - الهدف The main objective of this project is to improve the technology of the gas sensor to locate easily the pollution that can be very harmful to the humane health. The thermodynamic properties of SnO2 under pressure have sustained rare investigations especially in theoretical up to now. Achievements -أالنجازات المحققة In this project, we have investigated the structural and electronic properties of SnO2 at equilibrium volume as well as under high pressure up to 80 GPa, by using FP-LAPW method in frame of DFT. Also, the quasi-harmonic Debye model was successfully applied to determine the thermal properties. Experimentally, we have prepared the experimental materials in the LPM (Laboratoire de physique de matériaux) laboratory, faculty of sciences I-Lebanese university. The necessary references have been also found. We have started the experimental work. An additional measurement needed, it will be done by Dr. W. Noun in France. Perspectives - آفاق البحث The reported calculations provide new structural and electronic results from first principles for tin dioxide. Hence, this study is part of large theoretical effort to explore the properties of this compound. The achieved results will be useful to fabricate a new gas sensor based in SnO2 in order to use it in effective manner. Publications & Communications - المنشورات والمساهمات في المؤتمرات The following paper has been submitted recently to journal of “computational materials sciences” Ref. No.: COMMAT-D-12-01669 “Theoretical calculations of the High-Pressure phases of SnO2” F. El Haj Hassan, S. Moussawi, W. Noun, C. Salameh and A. V. Postnikov Abstract - موجز عن نتائج البحث We have applied a FP-LAPW method to study the structural, electronic and thermal properties of SnO2 compound at equilibrium as well as at high pressure. The main results can be summarized as follows: (i) Starting from the rutile-type structure six phase transitions under high-pressure conditions have been found at 11.6, 16.8, 20, 41, 61 and 68 GPa, which corresponding to the CaCl2-type, α-PbO2, pyrite-type, ZrO2 orthorhombic, fluorite, and cotunnite structures, respectively. (ii) The zero-pressure values of the band gap energy have been calculated by using the Becke-Johnson (mBJ) of the exchange-correlation potential for the first time: rutiletype, 2.76 eV; CaCl2-type, 3.021 eV; α-PbO2, 3.222 eV; pyrite-type, 2.536 eV; ZrO2 orthorhombic, 2.015 eV; fluorite, 2.001 eV; and cotunnite-type 1.936 eV. (iii) The thermodynamic properties of SnO2 have been predicted systematically using the density functional theory (DFT) and quasi-harmonic Debye model. It is found that the high temperature leads to a smaller bulk modulus, a large heat capacity, a smaller Debye temperature, a larger Grüneisen parameter and a larger thermal expansion coefficient for a given structure. The heat capacity and the thermal expansion coefficient tend to be constant value at high temperatures.