Annals of West University of Timisoara Physics最新文献_第4页

Diffusion Magnetic Resonance Imaging with Applications to Cardiac Muscle: Short Review 扩散磁共振成像在心肌中的应用综述

Annals of West University of Timisoara Physics Pub Date : 2020-11-24 DOI: 10.2478/awutp-2020-0007

M. Pop, N. Stefu

引用次数: 0

Electronic and Thermoelectric Properties of Li-Based Half-Heusler Alloys: A DFT Study 锂基半heusler合金的电子和热电性能:DFT研究

Annals of West University of Timisoara Physics Pub Date : 2020-11-05 DOI: 10.2478/awutp-2020-0006

F. Issaad, A. Maafa, H. Rozale, M. Boukli Hacene, A. Bouabça

{"title":"Electronic and Thermoelectric Properties of Li-Based Half-Heusler Alloys: A DFT Study","authors":"F. Issaad, A. Maafa, H. Rozale, M. Boukli Hacene, A. Bouabça","doi":"10.2478/awutp-2020-0006","DOIUrl":"https://doi.org/10.2478/awutp-2020-0006","url":null,"abstract":"Abstract In this paper, we have studied the electronic, elastic and thermoelectric properties of the half-Heusler LiCrZ (Z = C, N, Si, and P) materials in Type II phase, in this structure the atomic occupations are X (1/2,1/2,1/2), Y (0,0,0) and Z(1/4,1/4,1/4). The ferromagnetic state of Type II structure was found to be the most stable phase for all studied alloys. After calculating the elastic constants, we found out that the conditions of mechanical stability were verified only for LiCrSi and LiCrP alloys in Type II phase, at both equilibrium a0 and half metallic ahm lattice constants, which indicates that these two compounds can be synthesized experimentally. We should also mention that the half metallic behavior in Type II structure, for LiCrSi and LiCrP compounds, was obtained by straining the equilibrium lattice constants by 2% and 6%, respectively. At ahm, these two systems were identified to be true half metals due to their complete spin polarization and integer value of total magnetic moment. These last ones have reached 3μB per unit cell when Z = Si, and 4μB when Z = P. Using the mean field approximation (MFA), the Curie temperatures of Type II structure were also determined, where the values are estimated to be 456.2 K and 302.8 K, respectively. Finally, the thermoelectric performance has been explored by the classical Boltzmann theory. At low temperatures, the figure of merit has reached 0.73 and 0.93 for LiCrSi and LiCrP, respectively. The considerable ZT values and all calculated physical properties make these two systems promising candidates for thermoelectric applications.","PeriodicalId":31012,"journal":{"name":"Annals of West University of Timisoara Physics","volume":"7 1","pages":"95 - 107"},"PeriodicalIF":0.0,"publicationDate":"2020-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75612471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimizing Configurations for Determining the Electromagnetic Properties of CsFeF3, NaFeF3, and RbFeF3 Fluorides: GGA vs GGA+U and TB-mBj Approaches 测定CsFeF3、NaFeF3和RbFeF3氟化物电磁特性的优化配置:GGA vs GGA+U和TB-mBj方法

Annals of West University of Timisoara Physics Pub Date : 2020-10-11 DOI: 10.2478/awutp-2020-0005

Filalli Sihem, Hamdad Noura

引用次数: 0

Structural Stability and Magnetic Ordering in BiFeO3 Perovskite Oxide: A Comparative Study GGA+U vs L(S)DA+U bfeo3钙钛矿氧化物GGA+U与L(S)DA+U的结构稳定性和磁性有序性比较

Annals of West University of Timisoara Physics Pub Date : 2020-08-03 DOI: 10.2478/awutp-2020-0004

M. Derras, N. Hamdad

{"title":"Structural Stability and Magnetic Ordering in BiFeO3 Perovskite Oxide: A Comparative Study GGA+U vs L(S)DA+U","authors":"M. Derras, N. Hamdad","doi":"10.2478/awutp-2020-0004","DOIUrl":"https://doi.org/10.2478/awutp-2020-0004","url":null,"abstract":"Abstract Ab initio calculations of BiFeO3 magnetic perovskite are carried. Accurate density functional theory calculations were performed considering a U-Hubbard correction (DFT+U) to account for on-site Coulomb interactions of the 3d-Fe states. We have applied the Full-potential linearized augmented plane waves (FP-LAPW) method. Exchange-correlation effects are treated using the Local Spin Density approximation (L(S)DA+U) vs generalized gradient approximations (GGA+U). Equilibrium lattices agree very well with other theoretical and experimental data. The magnetization energy differences between Spin Up and Spin Dn states are small. Spin effect and magnetic moment obtained from subsequent (L(S)DA+U) and (GGA+U) calculations are also discussed in different magnetic configurations: The Ferromagnetic cubic phase (Pm-3m), The A-type Antiferromagnetic (P4/mmc) and The G-type Antiferromagnetic (Fm-3m). The nature of magnetism arises mainly from the Fe-site exhibiting a G-type antiferromagnetic ordering. The electronic structure shows that BiFeO3 has a metallic band gap. This multiferroic exhibit strong hybridization of the 3d-Fe and 2p-O orbitals. Therefore, the Multiferroic BiFeO3 perovskite has driven significant research interest due to their promising technological potential. It’s a good candidate for potential applications in spintronic, and to aid the development of the next generation of data storage and multi-functional technological devices.","PeriodicalId":31012,"journal":{"name":"Annals of West University of Timisoara Physics","volume":"48 1","pages":"52 - 70"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79638068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Electro-Magnetic Behavior of Highly Correlated Fluorides KFeF3, KCoF3 and KNiF3: A Comparative Ab-initio Study of Cation Effect 高相关氟化物KFeF3、KCoF3和KNiF3的电磁行为:阳离子效应的比较从头算研究

Annals of West University of Timisoara Physics Pub Date : 2020-07-09 DOI: 10.2478/awutp-2020-0003

Sihem Filalli, N. Hamdad

{"title":"Electro-Magnetic Behavior of Highly Correlated Fluorides KFeF3, KCoF3 and KNiF3: A Comparative Ab-initio Study of Cation Effect","authors":"Sihem Filalli, N. Hamdad","doi":"10.2478/awutp-2020-0003","DOIUrl":"https://doi.org/10.2478/awutp-2020-0003","url":null,"abstract":"Abstract Fluorides-based perovskites are currently the typical materials being used in spintronic devices, optoelectronic and magneto-resistance colossal fields. Solar cells made of Fluoro-perovskite hold much promise for the future of solar energy. The electronic structure and magnetic properties of KFeF3, KCoF3 and KNiF3 Fluorides are studied using ab initio Calculation. We have analysed the structural phases, total and partial electronic densities and band structures within the (DFT) vs the DFT+U description. We show the Electro-Magnetic Behavior using L(S)DA+U vs L(S)DA in a comparative study of cation effect by integrating three types of crystal structures (Cubic (Pm-3m), Four-Layered Hexagonal (P6/mmc), and Orthorhombic (Pnma)). Equilibrium lattices agree very well with experimental and theoretical data. Magnetic moment of each phase is discussed. The obtained results confirmed that the three crystal structures invested here exhibit Ferromagnetic (FM) behavior. The introduction of the Hubbard’s parameter U increases lattice parameters and magnetic moment. We deduce that the second cation plays an important role in the magnetic effects. L(S)DA+U show correctly that KFeF3, KCoF3 and KNiF3 are insulators.","PeriodicalId":31012,"journal":{"name":"Annals of West University of Timisoara Physics","volume":"55 1","pages":"23 - 51"},"PeriodicalIF":0.0,"publicationDate":"2020-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73803804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Theoretical Study of the Electronic Properties of X2YZ (X = Fe, Co; Y = Zr, Mo; Z = Ge, Sb) Ternary Heusler: Abinitio Study X2YZ (X = Fe, Co)电子性质的理论研究Y = Zr, Mo;Z = Ge, Sb)三元Heusler: Abinitio研究

Annals of West University of Timisoara Physics Pub Date : 2020-03-27 DOI: 10.2478/awutp-2020-0001

A. Maafa, H. Rozale, A. Oughilas, A. Boubaça, A. Amar, D. Lucache

{"title":"Theoretical Study of the Electronic Properties of X2YZ (X = Fe, Co; Y = Zr, Mo; Z = Ge, Sb) Ternary Heusler: Abinitio Study","authors":"A. Maafa, H. Rozale, A. Oughilas, A. Boubaça, A. Amar, D. Lucache","doi":"10.2478/awutp-2020-0001","DOIUrl":"https://doi.org/10.2478/awutp-2020-0001","url":null,"abstract":"Abstract In the purpose of exploring new Heusler alloys with different magnetic applications, we have employed first principles calculations method within density functional theory. After checking the structural stability of X2YZ Heusler alloys (X = Fe, Co; Y =Zr, Mo and Z = Ge, Sb), we found that Cu2MnAl type structure is more favorable for most compounds except for X2MoGe and Co2MoSb, were the Hg2CuTi structure is energetically more stable. The trends in magnetic and electronic structures can be predicted by the structure types as well as the different kinds of hybridizations between the constituents. Among the two series only two compounds were identified to be true half metals with potential applications in spintronic devices. While one compound was classified as a nonmagnetic semiconductor with a small band gap. For the rest of materials, we found that the metallic behavior is dominant. These materials show possible interesting features in technical applications as well. The effect of distortion on the magnetic properties of Co2ZrGe and Fe2ZrSb showed that the half metallic character was preserved within a moderate range of volume changes, which makes it possible to grow these materials as thin films with modern techniques.","PeriodicalId":31012,"journal":{"name":"Annals of West University of Timisoara Physics","volume":"13 1","pages":"1 - 14"},"PeriodicalIF":0.0,"publicationDate":"2020-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79040901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Electronic and Thermoelectric Properties in Li-Based Half-Heusler Compounds: A First Principle Study 锂基半heusler化合物的电子和热电性质:第一性原理研究

Annals of West University of Timisoara Physics Pub Date : 2019-12-01 DOI: 10.2478/awutp-2019-0004

Y. Benazouzi, H. Rozale, M. Boukli Hacene, M. Khethir, A. Chahed, D. Lucache

引用次数: 7

Germanium Gradient Optimization for High-Speed Silicon Germanium Hetero-Junction Bipolar Transistors 高速硅锗异质结双极晶体管的锗梯度优化

Annals of West University of Timisoara Physics Pub Date : 2019-12-01 DOI: 10.2478/awutp-2019-0002

A. Khadir, N. Sengouga, M. K. Abdelhafidi

引用次数: 1

Removal of Methylene Blue by Activated Glass Foams with TiO2 in Dark and Simulated Solar Light 二氧化钛活化玻璃泡沫在暗光和模拟日光下去除亚甲基蓝的研究

Annals of West University of Timisoara Physics Pub Date : 2019-12-01 DOI: 10.2478/awutp-2019-0003

F. S. Rus, S. Novaconi, P. Vlăzan, M. Ivanovici

引用次数: 0

Fabrication and Characterisation of ZnO Thin Film by Sol–Gel Technique 溶胶-凝胶法制备ZnO薄膜及其表征

Annals of West University of Timisoara Physics Pub Date : 2019-12-01 DOI: 10.2478/awutp-2019-0006

S. Benramache

引用次数: 7