Among different sensing platforms, metamaterials composed of subwavelength or deep subwavelength sized metal resonance elements arrays that are etched on semiconductor substrates or dielectric substrates exhibit excellent characteristics due to the strong localization and enhancement of resonance electromagnetic fields. As a new type of detection method, metamaterial sensors can break through the resolution limit of traditional sensors for a small amount of substance and have the advantages of high sensitivity, fast response, and simple measurement. Significant enhancement of the sensing characteristics of metamaterial sensors was realized by optimizing microstructures (single split-ring, double split-ring, nested split-ring, asymmetric split-ring, three-dimensional split-ring, etc.), using ultrathin substrates or low-index substrate materials, etching away local substrate, and integrating microfluidic channel, etc. This paper mainly reviews the research advance on the improvement of sensing characteristics from optimizing resonance structures and changing substrate materials and morphology. Furthermore, the sensing mechanism and main characteristic parameters of metamaterial sensors are introduced in detail, and the development trend and challenge of metamaterial sensing applications are prospected. It is believed that metamaterial sensors will have potential broader application prospects in environmental monitoring, food safety control, and biosensing in the future.
{"title":"Research Advance on the Sensing Characteristics of Refractive Index Sensors Based on Electromagnetic Metamaterials","authors":"Zongli Wang, Xin Wang, Junlin Wang","doi":"10.1155/2021/2301222","DOIUrl":"https://doi.org/10.1155/2021/2301222","url":null,"abstract":"Among different sensing platforms, metamaterials composed of subwavelength or deep subwavelength sized metal resonance elements arrays that are etched on semiconductor substrates or dielectric substrates exhibit excellent characteristics due to the strong localization and enhancement of resonance electromagnetic fields. As a new type of detection method, metamaterial sensors can break through the resolution limit of traditional sensors for a small amount of substance and have the advantages of high sensitivity, fast response, and simple measurement. Significant enhancement of the sensing characteristics of metamaterial sensors was realized by optimizing microstructures (single split-ring, double split-ring, nested split-ring, asymmetric split-ring, three-dimensional split-ring, etc.), using ultrathin substrates or low-index substrate materials, etching away local substrate, and integrating microfluidic channel, etc. This paper mainly reviews the research advance on the improvement of sensing characteristics from optimizing resonance structures and changing substrate materials and morphology. Furthermore, the sensing mechanism and main characteristic parameters of metamaterial sensors are introduced in detail, and the development trend and challenge of metamaterial sensing applications are prospected. It is believed that metamaterial sensors will have potential broader application prospects in environmental monitoring, food safety control, and biosensing in the future.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77129317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electric field control of magnetic properties has been achieved across a number of different material systems. In diluted magnetic semiconductors (DMSs), ferromagnetic metals, multiferroics, etc., electrical manipulation of magnetism has been observed. Here, we study the effect of an electric field on the carrier spin polarization in DMSs ( GaAsMn ); in particular, emphasis is given to spin-dependent transport phenomena. In our system, the interaction between the carriers and the localized spins in the presence of electric field is taken as the main interaction. Our results show that the electric field plays a major role on the spin polarization of carriers in the system. This is important for spintronics application.
{"title":"Electric Field Controlled Itinerant Carrier Spin Polarization in Ferromagnetic Semiconductors","authors":"Gezahegn Assefa","doi":"10.1155/2021/6663876","DOIUrl":"https://doi.org/10.1155/2021/6663876","url":null,"abstract":"Electric field control of magnetic properties has been achieved across a number of different material systems. In diluted magnetic semiconductors (DMSs), ferromagnetic metals, multiferroics, etc., electrical manipulation of magnetism has been observed. Here, we study the effect of an electric field on the carrier spin polarization in DMSs (\u0000 \u0000 GaAsMn\u0000 \u0000 ); in particular, emphasis is given to spin-dependent transport phenomena. In our system, the interaction between the carriers and the localized spins in the presence of electric field is taken as the main interaction. Our results show that the electric field plays a major role on the spin polarization of carriers in the system. This is important for spintronics application.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85012745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Saman Ahmadi Nooraldinvand, H. Sedighi, A. Yaghootian
In this paper, two models of elastic metamaterial containing one and two resonators are proposed to obtain the bandgaps with the aim of providing broadband vibration suppression. The model with one DOF is built by assembling several unite cells in which each unite cell consists of a rectangular frame as the base structure and a rack-and-pinion mechanism that is joined to the frame with a linear spring on both sides. In the second model with two DOF, a small mass is added while its center is attached to the center of the pinion on one side and the other side is connected to the rectangular frame via a linear spring. In the first mechanism, the pinion is considered as the single resonator, and in the 2DOF model, on the other hand, the pinion and small mass acted as multiple resonators. By obtaining the governing equations of motion for a single cell in each model, the dynamic behavior of two metastructures is thoroughly investigated. Therefore, the equations of motion for the two models are written in matrix form, and then, the dispersion relations are presented to analyze the influences of system parameters on the bandgaps’ starting/ending frequencies. Finally, two models are successfully compared and then numerically simulated via MATLAB-SIMULINK and MSC-ADAMS software. With the aid of closed-form expressions for starting/ending frequencies, the correlation between the system parameters and bandgap intervals can be readily recognized.
{"title":"A Novel Elastic Metamaterial with Multiple Resonators for Vibration Suppression","authors":"Saman Ahmadi Nooraldinvand, H. Sedighi, A. Yaghootian","doi":"10.1155/2021/3914210","DOIUrl":"https://doi.org/10.1155/2021/3914210","url":null,"abstract":"In this paper, two models of elastic metamaterial containing one and two resonators are proposed to obtain the bandgaps with the aim of providing broadband vibration suppression. The model with one DOF is built by assembling several unite cells in which each unite cell consists of a rectangular frame as the base structure and a rack-and-pinion mechanism that is joined to the frame with a linear spring on both sides. In the second model with two DOF, a small mass is added while its center is attached to the center of the pinion on one side and the other side is connected to the rectangular frame via a linear spring. In the first mechanism, the pinion is considered as the single resonator, and in the 2DOF model, on the other hand, the pinion and small mass acted as multiple resonators. By obtaining the governing equations of motion for a single cell in each model, the dynamic behavior of two metastructures is thoroughly investigated. Therefore, the equations of motion for the two models are written in matrix form, and then, the dispersion relations are presented to analyze the influences of system parameters on the bandgaps’ starting/ending frequencies. Finally, two models are successfully compared and then numerically simulated via MATLAB-SIMULINK and MSC-ADAMS software. With the aid of closed-form expressions for starting/ending frequencies, the correlation between the system parameters and bandgap intervals can be readily recognized.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79452933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The geometrical structures, phase stabilities, electron energy band structures, electron density of states, and atom recombination together with the electron conduction behaviors of the sandwiched Ca2Co2O5 with external stress of 1 GPa are intensively studied by the density functional theory method. The studying results show that the symmetry remains undisturbed; the strain to the stress response is anisotropic. The strain of microarchitecture induced by external stress is also anisotropic. There is stronger covalent binding between Co and O. The binding between Co and O within CdI2 like CoO2 is very much even covalent, and it is weakened under external stress. But the covalent Co-O binding within the rock salt like CaCoO layer is enhanced. The Ca-O binding strength is insensitive to external stress. An energy gap of 0.1 eV below Fermi level for the spin-up electron band disappears, and the two energy gaps are narrowed for the spin-down electron bands. The p orbital electrons form primarily the bands below Fermi level and the d orbital electrons form primarily the bands above Fermi level. The transitions from p orbital electrons to d orbital electrons produce the conduction. The CdI2 like CoO2 layer has been enhanced in terms of participating in the conduction properties with external stress of 1 GPa, and the capability of Co is enhanced while the capability of O is decreased.
{"title":"Stress-Driven Evolution on Mismatched Ca2Co2O5 Oxide Material: From Geometry to the Electronic States","authors":"F. P. Zhang, Y. Sun, G. Zhang, X. Shi, G. Qin","doi":"10.1155/2021/5538056","DOIUrl":"https://doi.org/10.1155/2021/5538056","url":null,"abstract":"The geometrical structures, phase stabilities, electron energy band structures, electron density of states, and atom recombination together with the electron conduction behaviors of the sandwiched Ca2Co2O5 with external stress of 1 GPa are intensively studied by the density functional theory method. The studying results show that the symmetry remains undisturbed; the strain to the stress response is anisotropic. The strain of microarchitecture induced by external stress is also anisotropic. There is stronger covalent binding between Co and O. The binding between Co and O within CdI2 like CoO2 is very much even covalent, and it is weakened under external stress. But the covalent Co-O binding within the rock salt like CaCoO layer is enhanced. The Ca-O binding strength is insensitive to external stress. An energy gap of 0.1 eV below Fermi level for the spin-up electron band disappears, and the two energy gaps are narrowed for the spin-down electron bands. The p orbital electrons form primarily the bands below Fermi level and the d orbital electrons form primarily the bands above Fermi level. The transitions from p orbital electrons to d orbital electrons produce the conduction. The CdI2 like CoO2 layer has been enhanced in terms of participating in the conduction properties with external stress of 1 GPa, and the capability of Co is enhanced while the capability of O is decreased.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77010388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The coalescence and melting process of different sizes and arrangements of Ag and Cu nanoparticles is studied through the molecular dynamics (MD) method. The results show that the twin boundary or stacking fault formation and atomic diffusion of the nanoparticles play an important role in the different stages of the heating process. At the beginning of the simulation, Cu and Ag nanoparticles will contact to each other in a very short time. As the temperature goes up, Cu and Ag nanoparticles may generate stacking fault or twin boundary to stabilize the interface structure. When the temperature reaches a critical value, the atoms gain a strong ability to diffuse and eventually melt into one liquid sphere. The coalescence point and melting temperature increase as cluster diameter increases. Moreover, the arrangement of Cu and Ag nanoparticles has a certain effect on the stability of the initial joint interface, which will affect subsequent coalescence and melting behavior.
{"title":"Molecular Dynamics Simulation of the Coalescence and Melting Process of Cu and Ag Nanoparticles","authors":"Huiting Guo, Linfu Zhang, Q. Zhu, Chuanjie Wang, Gang Chen, Peng Zhang","doi":"10.1155/2021/9945723","DOIUrl":"https://doi.org/10.1155/2021/9945723","url":null,"abstract":"The coalescence and melting process of different sizes and arrangements of Ag and Cu nanoparticles is studied through the molecular dynamics (MD) method. The results show that the twin boundary or stacking fault formation and atomic diffusion of the nanoparticles play an important role in the different stages of the heating process. At the beginning of the simulation, Cu and Ag nanoparticles will contact to each other in a very short time. As the temperature goes up, Cu and Ag nanoparticles may generate stacking fault or twin boundary to stabilize the interface structure. When the temperature reaches a critical value, the atoms gain a strong ability to diffuse and eventually melt into one liquid sphere. The coalescence point and melting temperature increase as cluster diameter increases. Moreover, the arrangement of Cu and Ag nanoparticles has a certain effect on the stability of the initial joint interface, which will affect subsequent coalescence and melting behavior.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80454460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Micropyramid vertical GaN-based ultraviolet (UV) light-emitting diodes (LEDs) on Si(111) substrate have been fabricated by selective area growth to reduce threading dislocations and the polarization effects. There is no-light emission at the bottom and six planes of the pyramid at lower current due to the leakage current and nonradiative recombination of the dislocation at the bottom and the 90° threading dislocations (TDs) at six planes of the pyramid, and the top of the pyramid is the high-brightness region. The micropyramid UV LED has a high optical output intensity under a small current injection, and the series resistance of unit area is only a quarter of the conventional vertical LEDs, so the micropyramid UV LED would have a high output power under the drive circuit. The reverse leakage current of a single micropyramid UV LED is 2 nA at −10 V.
{"title":"Micropyramid Vertical Ultraviolet GaN/AlGaN Multiple Quantum Wells LEDs on Si(111)","authors":"Yuebo Liu, Honghui Liu, Hang Yang, Wanqing Yao, Fengge Wang, Yuan Ren, Junyu Shen, Minjie Zhang, Zhisheng Wu, Yang Liu, Baijun Zhang","doi":"10.1155/2021/9990673","DOIUrl":"https://doi.org/10.1155/2021/9990673","url":null,"abstract":"Micropyramid vertical GaN-based ultraviolet (UV) light-emitting diodes (LEDs) on Si(111) substrate have been fabricated by selective area growth to reduce threading dislocations and the polarization effects. There is no-light emission at the bottom and six planes of the pyramid at lower current due to the leakage current and nonradiative recombination of the dislocation at the bottom and the 90° threading dislocations (TDs) at six planes of the pyramid, and the top of the pyramid is the high-brightness region. The micropyramid UV LED has a high optical output intensity under a small current injection, and the series resistance of unit area is only a quarter of the conventional vertical LEDs, so the micropyramid UV LED would have a high output power under the drive circuit. The reverse leakage current of a single micropyramid UV LED is 2 nA at −10 V.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86376275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wei Wei, Keyou Shi, Yupeng Xie, Shoufu Yu, Jiawei Li, Min Chen, Zengmin Tang, A. Zhu, Qiucai Zhang, Yong Liu
In this work, the dense glass matrix of uranium tailings was successfully fabricated via microwave sintering process with Na2CO3 as a sintering aid. The effects of Na2CO3 additive and sintering temperature on the microstructure and mechanical properties of as-prepared solids were systematically investigated. XRD results confirmed the vitrified forms can be achieved at 1200°C within 30 min with 20 wt.% Na2CO3 addition. Importantly, the Na2CO3 additive significantly reduced the firing temperature from 1500°C to 1200°C and promoted densification. FT-IR analysis demonstrated that the main characteristic peaks of the sintered samples were attributed to the vibration of Si-O-Si. Microstructural studies presented the homogeneous distribution of glass phases. The results of mechanical properties of the sintered forms show that bulk density and Vickers hardness increased with increasing Na2CO3 content as well as sintering temperature, and the highest bulk density (2.45 ± 0.01 g/cm3) and Vickers hardness (823 ± 25 HV) were obtained at the temperature of 1300°C with 20 wt.% Na2CO3 addition, the heating rate of 20°C/min, and the soaking time of 30 min. It implied that the combination of microwave sintering with the appropriate addition of Na2CO3 would provide an efficient method for the immobilization of radionuclides in uranium tailings.
{"title":"Microwave Vitrification of Uranium Tailings: Microstructure and Mechanical Property","authors":"Wei Wei, Keyou Shi, Yupeng Xie, Shoufu Yu, Jiawei Li, Min Chen, Zengmin Tang, A. Zhu, Qiucai Zhang, Yong Liu","doi":"10.1155/2021/5544835","DOIUrl":"https://doi.org/10.1155/2021/5544835","url":null,"abstract":"In this work, the dense glass matrix of uranium tailings was successfully fabricated via microwave sintering process with Na2CO3 as a sintering aid. The effects of Na2CO3 additive and sintering temperature on the microstructure and mechanical properties of as-prepared solids were systematically investigated. XRD results confirmed the vitrified forms can be achieved at 1200°C within 30 min with 20 wt.% Na2CO3 addition. Importantly, the Na2CO3 additive significantly reduced the firing temperature from 1500°C to 1200°C and promoted densification. FT-IR analysis demonstrated that the main characteristic peaks of the sintered samples were attributed to the vibration of Si-O-Si. Microstructural studies presented the homogeneous distribution of glass phases. The results of mechanical properties of the sintered forms show that bulk density and Vickers hardness increased with increasing Na2CO3 content as well as sintering temperature, and the highest bulk density (2.45 ± 0.01 g/cm3) and Vickers hardness (823 ± 25 HV) were obtained at the temperature of 1300°C with 20 wt.% Na2CO3 addition, the heating rate of 20°C/min, and the soaking time of 30 min. It implied that the combination of microwave sintering with the appropriate addition of Na2CO3 would provide an efficient method for the immobilization of radionuclides in uranium tailings.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88765077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electronic structure of GaSe/silicane (GaSe/SiH) van der Waals (vdW) heterostructure in response to a vertical electric field and strain was studied via first-principle calculations. The heterostructure had indirect band gap characteristics in the range [−1.0, −0.4] V/Å and direct band gap features in the range [−0.3, 0.2] V/Å. Furthermore, a type-II to type-I band alignment transition appeared at −0.7 and −0.3 V/Å. Additionally, the GaSe/SiH vdW heterostructure had a type-II band alignment under strain, but an indirect to direct band gap semiconductor transition occurred at −3%. These results indicated that the GaSe/SiH vdW heterostructure may have applications in novel nanoelectronic and optoelectronic devices.
{"title":"Tuning Electronic Properties of GaSe/Silicane Van der Waals Heterostructure by External Electric Field and Strain: A First-Principle Study","authors":"Gang Xu, H. Lei","doi":"10.1155/2021/5514897","DOIUrl":"https://doi.org/10.1155/2021/5514897","url":null,"abstract":"The electronic structure of GaSe/silicane (GaSe/SiH) van der Waals (vdW) heterostructure in response to a vertical electric field and strain was studied via first-principle calculations. The heterostructure had indirect band gap characteristics in the range [−1.0, −0.4] V/Å and direct band gap features in the range [−0.3, 0.2] V/Å. Furthermore, a type-II to type-I band alignment transition appeared at −0.7 and −0.3 V/Å. Additionally, the GaSe/SiH vdW heterostructure had a type-II band alignment under strain, but an indirect to direct band gap semiconductor transition occurred at −3%. These results indicated that the GaSe/SiH vdW heterostructure may have applications in novel nanoelectronic and optoelectronic devices.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82496186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The permeability and electrical resistivity of barium hexaferrite magnetic materials can be used in various products such as magnetic recording media, computers, electronic devices, materials for permanent magnets, and communication devices. This work focuses on the synthesis of rare earth lanthanum (La3+)-doped manganese in barium hexaferrite (Ba1−xLaxMnyFe12−yO19) (x = 0.02–0.10 and y = 0.02–0.10) prepared by using the coprecipitation method. The intensity peak is increased with increasing the concentration of lanthanum, which shows the enhancement in the degree of crystallinity and increase in the size of crystallite. The band gap energy decreased gradually with the increase of concentration of lanthanum. The micrographs observed that the material is basically made up of some rings or rods such as particles in pure La-Ma in barium hexaferrite. The agglomeration was observed because of heat behavior at 600°C or may be concentration effect. The structural studies are done using X-ray diffraction, UV, FT-IR, and SEM techniques.
钡六铁氧体磁性材料的磁导率和电阻率可用于磁性记录介质、计算机、电子器件、永磁体材料、通信器件等各种产品。本文研究了用共沉淀法合成稀土镧(La3+)掺杂锰的六铁体钡(Ba1−xLaxMnyFe12−yO19) (x = 0.02-0.10, y = 0.02-0.10)。强度峰随镧浓度的增加而增大，表明结晶度增强，晶粒尺寸增大。带隙能量随镧浓度的增加而逐渐减小。显微照片观察到，该材料基本上是由一些环或棒组成的，如纯六铁体钡中的La-Ma颗粒。在600°C时，由于热行为或浓度效应而出现了结块现象。结构研究是用x射线衍射、紫外、红外光谱和扫描电镜技术完成的。
{"title":"Enhancement in Optical Properties of Lanthanum-Doped Manganese Barium Hexaferrites under Different Substitutions","authors":"M. Alzaid","doi":"10.1155/2021/8849595","DOIUrl":"https://doi.org/10.1155/2021/8849595","url":null,"abstract":"The permeability and electrical resistivity of barium hexaferrite magnetic materials can be used in various products such as magnetic recording media, computers, electronic devices, materials for permanent magnets, and communication devices. This work focuses on the synthesis of rare earth lanthanum (La3+)-doped manganese in barium hexaferrite (Ba1−xLaxMnyFe12−yO19) (x = 0.02–0.10 and y = 0.02–0.10) prepared by using the coprecipitation method. The intensity peak is increased with increasing the concentration of lanthanum, which shows the enhancement in the degree of crystallinity and increase in the size of crystallite. The band gap energy decreased gradually with the increase of concentration of lanthanum. The micrographs observed that the material is basically made up of some rings or rods such as particles in pure La-Ma in barium hexaferrite. The agglomeration was observed because of heat behavior at 600°C or may be concentration effect. The structural studies are done using X-ray diffraction, UV, FT-IR, and SEM techniques.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74341566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In recent years, some laboratories have been able to prepare calcium hydrobromide (CaHBr) by melting hydride and anhydrous bromide or metal and bromide in a hydrogen atmosphere at 900°C and have studied some of its properties. But there are few theoretical studies, especially the theoretical studies of monolayer CaHBr. We use the first-principles method to calculate the structure, elastic properties, and lattice thermal conductivity of the monolayer CaHBr based on the Boltzmann transport equation. We obtain a stable crystal structure by the optimization of monolayer CaHBr. By calculating the elastic constant of monolayer CaHBr, its mechanical stability is proved, and the elastic limit of monolayer CaHBr is obtained by biaxial tensile strain on monolayer CaHBr. And the corresponding phonon spectra show no imaginary frequency, indicating the dynamic stability of the monolayer CaHBr. By the ShengBTE code, we calculate the lattice thermal conductivity of the monolayer CaHBr, the iterative solution of BTE and RTA at 300 K–1200 K is obtained, and the lattice thermal conductivity at room temperature is κBTE ι � 2.469W/m · K and κRTA ι � 2.201W/m · K, respectively. It can be seen that the lattice thermal conductivity of monolayer CaHBr is low. And by analyzing the phonon spectrum, the scattering rate, and the mean free path of the phonons, the lattice thermal conductivity of monolayer CaHBrmainly depends on the acoustic modes.We hope this study can provide theoretical guidance for the experiments and practical application of monolayer CaHBr.
{"title":"First-Principles Study of Structure, Elastic Properties, and Thermal Conductivity of Monolayer Calcium Hydrobromide","authors":"Sirui Li, Cui-E. Hu, Xiao-Lu Wang, Yan Cheng","doi":"10.1155/2021/6619252","DOIUrl":"https://doi.org/10.1155/2021/6619252","url":null,"abstract":"In recent years, some laboratories have been able to prepare calcium hydrobromide (CaHBr) by melting hydride and anhydrous bromide or metal and bromide in a hydrogen atmosphere at 900°C and have studied some of its properties. But there are few theoretical studies, especially the theoretical studies of monolayer CaHBr. We use the first-principles method to calculate the structure, elastic properties, and lattice thermal conductivity of the monolayer CaHBr based on the Boltzmann transport equation. We obtain a stable crystal structure by the optimization of monolayer CaHBr. By calculating the elastic constant of monolayer CaHBr, its mechanical stability is proved, and the elastic limit of monolayer CaHBr is obtained by biaxial tensile strain on monolayer CaHBr. And the corresponding phonon spectra show no imaginary frequency, indicating the dynamic stability of the monolayer CaHBr. By the ShengBTE code, we calculate the lattice thermal conductivity of the monolayer CaHBr, the iterative solution of BTE and RTA at 300 K–1200 K is obtained, and the lattice thermal conductivity at room temperature is κBTE ι � 2.469W/m · K and κRTA ι � 2.201W/m · K, respectively. It can be seen that the lattice thermal conductivity of monolayer CaHBr is low. And by analyzing the phonon spectrum, the scattering rate, and the mean free path of the phonons, the lattice thermal conductivity of monolayer CaHBrmainly depends on the acoustic modes.We hope this study can provide theoretical guidance for the experiments and practical application of monolayer CaHBr.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2021-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84779644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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