Pub Date : 2022-06-23DOI: 10.25073/2588-1124/vnumap.4670
Ta Phuong Linh, T. Doan, B. G. Duong
The low noise amplifier (LNA) plays an important role in the radiofrequency receiver front-ends, its main function is to amplify the weak receiving signal from the ground noise, as well as improving the receiver sensitivity. For LNAs which operate in the frequencies higher than the S-band, the printed circuit board (PCB) with high cost substrate materials have been used in almost designs so far, thus increasing the total price of the entire receiving unit. This paper introduces a new approach, in which a LNA has been designed using the FR-4 material, a common, low-cost substrate in PCB fabrication. The proposed LNA will maintain the quality of all of the important parameters such as gain, noise figure in compared with the LNAs designed by high cost material substrates. The stepped impedance matching technique is used in order to reach a balance between the circuit dimension and its efficiency. The frequency range of the proposed LNA lies within the X-band, which is a suitable range for military RADAR applications. Furthermore, it is possible to apply the desired LNA in the ground station receiver front-ends of a Low Earth Orbit (LEO) Earth Observation Satellite system
{"title":"Design and Fabrication of an X-Band Low Noise Amplifier Using FR-4 for Military Radar and Ground Station Receiver Applications","authors":"Ta Phuong Linh, T. Doan, B. G. Duong","doi":"10.25073/2588-1124/vnumap.4670","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4670","url":null,"abstract":" The low noise amplifier (LNA) plays an important role in the radiofrequency receiver front-ends, its main function is to amplify the weak receiving signal from the ground noise, as well as improving the receiver sensitivity. For LNAs which operate in the frequencies higher than the S-band, the printed circuit board (PCB) with high cost substrate materials have been used in almost designs so far, thus increasing the total price of the entire receiving unit. This paper introduces a new approach, in which a LNA has been designed using the FR-4 material, a common, low-cost substrate in PCB fabrication. The proposed LNA will maintain the quality of all of the important parameters such as gain, noise figure in compared with the LNAs designed by high cost material substrates. The stepped impedance matching technique is used in order to reach a balance between the circuit dimension and its efficiency. The frequency range of the proposed LNA lies within the X-band, which is a suitable range for military RADAR applications. Furthermore, it is possible to apply the desired LNA in the ground station receiver front-ends of a Low Earth Orbit (LEO) Earth Observation Satellite system","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134369444","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}
Pub Date : 2022-06-23DOI: 10.25073/2588-1124/vnumap.4663
Tran Thi Quynh Nhu, Pham Huu Kien, Pham Dinh Quang, N. H. Yen, V. T. Hương, D. N. Dung, G. Trang
In this work, we have performed a simulation to study the structural characteristics and phase transformation in Al2O3 glass under compression. The structural characteristics of Al2O3 glass were examined via AlOx units, OAly linkages, the average bond distance distributions, order parameters, and visualization of simulation data. The result showed that the network structure of Al2O3 glass is built mainly by AlOx (x = 3, 4, 5, 6, 7) units that are linked to each other via common O atoms. We found that the distribution of AlOx units in network structure is not uniform but tends to form clusters contained AlOx units. In addition, during a moderately long time, the glass has a two-phase that consists of separate low-density (LD) and high-density (HD) phases. The size of these phases significantly depends on the compression.
{"title":"The Structural Characteristics and Phase Transformation in Al2O3 Glass. A Molecular Dynamics Simulation","authors":"Tran Thi Quynh Nhu, Pham Huu Kien, Pham Dinh Quang, N. H. Yen, V. T. Hương, D. N. Dung, G. Trang","doi":"10.25073/2588-1124/vnumap.4663","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4663","url":null,"abstract":"In this work, we have performed a simulation to study the structural characteristics and phase transformation in Al2O3 glass under compression. The structural characteristics of Al2O3 glass were examined via AlOx units, OAly linkages, the average bond distance distributions, order parameters, and visualization of simulation data. The result showed that the network structure of Al2O3 glass is built mainly by AlOx (x = 3, 4, 5, 6, 7) units that are linked to each other via common O atoms. We found that the distribution of AlOx units in network structure is not uniform but tends to form clusters contained AlOx units. In addition, during a moderately long time, the glass has a two-phase that consists of separate low-density (LD) and high-density (HD) phases. The size of these phases significantly depends on the compression.","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132570548","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}
Pub Date : 2022-06-23DOI: 10.25073/2588-1124/vnumap.4642
T. Ha, Bach Thanh Cong, P. N. Hai, Nguyễn Hoàng, H. V. Chinh, Bui Thu Huong, N. T. Linh, Bui Truong Son, Tran Thi Quynh Hoa, Tuyen Nguyen Viet
CuO nanorods were prepared by thermal oxidation method in ozone ambient. The effect of annealing temprature in the range from 400 to 600 oC on morphology and structure of nanorods was studied thouroughly by scanning electron microscopy (SEM) and X-ray diffraction, combining with energy dispersive spectroscopy (EDS) and Raman spectroscopy. The results showed that annealing temprature strongly affected the structure and morphology of the produced CuO nanorods. The most uniform nanorods with highest crystal quality were obtained when annealing temperature is from 450 to 500 °C and annealing time was 2 h as suggested by SEM images together with Raman results.
{"title":"Preparation of CuO Nanorods by Thermal Oxidation in Ozone Ambient","authors":"T. Ha, Bach Thanh Cong, P. N. Hai, Nguyễn Hoàng, H. V. Chinh, Bui Thu Huong, N. T. Linh, Bui Truong Son, Tran Thi Quynh Hoa, Tuyen Nguyen Viet","doi":"10.25073/2588-1124/vnumap.4642","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4642","url":null,"abstract":"CuO nanorods were prepared by thermal oxidation method in ozone ambient. The effect of annealing temprature in the range from 400 to 600 oC on morphology and structure of nanorods was studied thouroughly by scanning electron microscopy (SEM) and X-ray diffraction, combining with energy dispersive spectroscopy (EDS) and Raman spectroscopy. The results showed that annealing temprature strongly affected the structure and morphology of the produced CuO nanorods. The most uniform nanorods with highest crystal quality were obtained when annealing temperature is from 450 to 500 °C and annealing time was 2 h as suggested by SEM images together with Raman results.","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130949450","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}
Pub Date : 2022-06-23DOI: 10.25073/2588-1124/vnumap.4679
N. L. Tuyen, P. Trieu, N. Dinh, N. Trung, D. Thanh
This report presented an effective way to synthesize MnO2/graphene nanocomposites using the plasma electrolysis method for photocatalytic degradation of methyl orange dye in water. The morphology, structure, and chemical composition of MnO2/graphene nanocomposites materials were investigated through scanning electron microscopy (SEM), Raman spectra, and Fourier-transform infrared (FTIR) spectroscopy, respectively. SEM results showed that MnO2 nanoparticles with particle sizes of 30-50 nm were attached uniformly on the surface of graphene nanosheets. The photodegradation activity was performed under UV-visible irradiation to evaluate the potential application of MnO2/graphene nanocomposites.
{"title":"Synthesis of MnO2/Graphene Nanocomposites using Plasma Electrolysis Method for Photocatalytic Degradation of Methyl Orange Dye in Water","authors":"N. L. Tuyen, P. Trieu, N. Dinh, N. Trung, D. Thanh","doi":"10.25073/2588-1124/vnumap.4679","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4679","url":null,"abstract":"This report presented an effective way to synthesize MnO2/graphene nanocomposites using the plasma electrolysis method for photocatalytic degradation of methyl orange dye in water. The morphology, structure, and chemical composition of MnO2/graphene nanocomposites materials were investigated through scanning electron microscopy (SEM), Raman spectra, and Fourier-transform infrared (FTIR) spectroscopy, respectively. SEM results showed that MnO2 nanoparticles with particle sizes of 30-50 nm were attached uniformly on the surface of graphene nanosheets. The photodegradation activity was performed under UV-visible irradiation to evaluate the potential application of MnO2/graphene nanocomposites.","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126724701","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}
Pub Date : 2022-03-24DOI: 10.25073/2588-1124/vnumap.4665
N. Co, Bui Thi Thu Thuy, Nguyen Thi Luong, Dong Quoc Viet, Le Viet Cuong, Dang Duc Dung, Ngo Duc Quan, Tran Mau Danh, Pham Duc Thang, Bui Dinh Tu
Lead-free Bi0.5(Na0.80K0.20)0.5TiO3 (BNKT) particles were synthesized by using sol-gel method. The samples were investigated by X-ray diffractometry (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometer (VSM). The absorption of microwaves of the lead-free BNKT powders is determined from the magnetic (permeability) and dielectric (permittivity) properties at the frequency range from 2 to 18 GHz. Absorption characteristics of paraffin(wax)-mixed BNKT compounds at different sample thicknesses were also investigated. The microwave absorption properties show that the maximum reflection loss is -21.72 dB (99.9%) at 13.66 GHz with a thickness of 3.2 mm. BNKT composites are thought to be used as a promising microwave absorption material.
{"title":"Characterization and Microwave Absorption Properties of Lead-Free Bi0.5(Na0.80K0.20)0.5TiO3 Synthesized by Sol-Gel Method","authors":"N. Co, Bui Thi Thu Thuy, Nguyen Thi Luong, Dong Quoc Viet, Le Viet Cuong, Dang Duc Dung, Ngo Duc Quan, Tran Mau Danh, Pham Duc Thang, Bui Dinh Tu","doi":"10.25073/2588-1124/vnumap.4665","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4665","url":null,"abstract":"Lead-free Bi0.5(Na0.80K0.20)0.5TiO3 (BNKT) particles were synthesized by using sol-gel method. The samples were investigated by X-ray diffractometry (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometer (VSM). The absorption of microwaves of the lead-free BNKT powders is determined from the magnetic (permeability) and dielectric (permittivity) properties at the frequency range from 2 to 18 GHz. Absorption characteristics of paraffin(wax)-mixed BNKT compounds at different sample thicknesses were also investigated. The microwave absorption properties show that the maximum reflection loss is -21.72 dB (99.9%) at 13.66 GHz with a thickness of 3.2 mm. BNKT composites are thought to be used as a promising microwave absorption material. \u0000 ","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123923176","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}
Pub Date : 2022-03-24DOI: 10.25073/2588-1124/vnumap.4662
Chu Thoi Nam, Le Tran Quang Linh, D. Hartanto, Tran Hoai Nam, Nguyen Kien Cuong, Vu Thanh Mai
This paper presents the analysis of sensitivity and uncertainty for the infinite multiplication factor (kinf) for the VVR-M2 typed HEU and LEU fuel assemblies of the Dalat nuclear research reactor (DNRR) using the MCNP6.1-Whisper1.1 code. Sensitivity calculations were performed for the ENDF/B-VII.0 and ENDF/B-VII.1 nuclear data libraries. In Whisper, the keff uncertainty due to nuclear data was evaluated by the uncertainty propagation law using the sensitivities obtained by MCNP and the available covariance matrix. The most significant sensitivity coefficients in positive contribution are the coefficient total n and fission reaction of U-235, elastic scattering reaction of H-1 and inelastic scattering of thermal neutrons and in negative contribution are capture reactions of U-235, H-1, Al-27, U-238 and U-234 isotopes. The large discrepancy between sensitivities of elastic scattering reaction cross section of H-1 and inelastic scattering of thermal neutrons between two libraries are found because of the change in neutron spectra of HEU and LEU fuel assemblies using the two library versions. The uncertainty of the kinf from the ENDF/B-VII.0 nuclear library error for all isotopes was found to be significant (about 0.45% of reactivity effect) with the largest contribution from isotope U-235 contributions (about 0.3% to 0.40%).
{"title":"Sensitivity and Uncertainty Analysis on Reactivity for HEU and LEU Fuel Assemblies of Dalat Nuclear Research Reactor using Monte Carlo Code and ENDF/B-VII.0 and ENDF/B-VII.1 Nuclear Libraries","authors":"Chu Thoi Nam, Le Tran Quang Linh, D. Hartanto, Tran Hoai Nam, Nguyen Kien Cuong, Vu Thanh Mai","doi":"10.25073/2588-1124/vnumap.4662","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4662","url":null,"abstract":"This paper presents the analysis of sensitivity and uncertainty for the infinite multiplication factor (kinf) for the VVR-M2 typed HEU and LEU fuel assemblies of the Dalat nuclear research reactor (DNRR) using the MCNP6.1-Whisper1.1 code. Sensitivity calculations were performed for the ENDF/B-VII.0 and ENDF/B-VII.1 nuclear data libraries. In Whisper, the keff uncertainty due to nuclear data was evaluated by the uncertainty propagation law using the sensitivities obtained by MCNP and the available covariance matrix. The most significant sensitivity coefficients in positive contribution are the coefficient total n and fission reaction of U-235, elastic scattering reaction of H-1 and inelastic scattering of thermal neutrons and in negative contribution are capture reactions of U-235, H-1, Al-27, U-238 and U-234 isotopes. The large discrepancy between sensitivities of elastic scattering reaction cross section of H-1 and inelastic scattering of thermal neutrons between two libraries are found because of the change in neutron spectra of HEU and LEU fuel assemblies using the two library versions. The uncertainty of the kinf from the ENDF/B-VII.0 nuclear library error for all isotopes was found to be significant (about 0.45% of reactivity effect) with the largest contribution from isotope U-235 contributions (about 0.3% to 0.40%). \u0000 ","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129024042","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}
Pub Date : 2022-03-24DOI: 10.25073/2588-1124/vnumap.4599
N. T. Lan, C. Hoang
In this paper, we report on a process for fabricating silica nanoparticle monolayer based on chemical synthesis and spin-coating. Spherical silica nanoparticles were synthesized by Stöber method using tetraethylorthosilicate as precursor. Close-packed silica nanoparticle monolayer was realized by optimizing the speed of spin-coating. Based on analyzing field emission scanning electron microscope (FE-SEM) images, the average diameter of silica spheres was determined and found of about 196 nm, with a standard deviation approximately ± 40 nm. The reflectance for the silicon substrate with spherical silica nanoparticle monolayers has been experimentally investigated at various spin-coating speeds. The experimental results are compared to those obtained from simulation data. The obtained results are useful for developing substrates having nanostructures for various applications in photonics and plasmonics. Keywords: Silica nanoparticles, Stöber method, spin coating, self-assembled monolayer
{"title":"Fabrication and Characteristics of Silica Nanoparticle Monolayer Assembled by Spin Coating","authors":"N. T. Lan, C. Hoang","doi":"10.25073/2588-1124/vnumap.4599","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4599","url":null,"abstract":"In this paper, we report on a process for fabricating silica nanoparticle monolayer based on chemical synthesis and spin-coating. Spherical silica nanoparticles were synthesized by Stöber method using tetraethylorthosilicate as precursor. Close-packed silica nanoparticle monolayer was realized by optimizing the speed of spin-coating. Based on analyzing field emission scanning electron microscope (FE-SEM) images, the average diameter of silica spheres was determined and found of about 196 nm, with a standard deviation approximately ± 40 nm. The reflectance for the silicon substrate with spherical silica nanoparticle monolayers has been experimentally investigated at various spin-coating speeds. The experimental results are compared to those obtained from simulation data. The obtained results are useful for developing substrates having nanostructures for various applications in photonics and plasmonics. \u0000Keywords: Silica nanoparticles, Stöber method, spin coating, self-assembled monolayer","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114894636","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}
Pub Date : 2022-03-24DOI: 10.25073/2588-1124/vnumap.4681
H. D. Long, Nguyen Ngoc Hieu, Chau Thi Huyen Trang, L. Phuong
In this work, we investigate the magneto-optical absorption in a phosphorene monolayer subjected to a perpendicular static magnetic field. The magneto-optical absorption power is calculated using the projection operator technique taking account of the effect of electron – optical phonon interaction. Numerical results showed that in the case of absence of any interaction, the higher the resonant frequency, the smaller absorbed power was. If the electron - phonon interaction exists, there appear the cyclotron-phonon resonant peaks which show the electron transitions between Landau levels by absorbing a photon accompanied by absorbing/emitting an optical phonon. The obtained results are important for further studies and applications of the phosphorene based structures in optoelectronic devices.
{"title":"Effect of Electron – Phonon Interaction on the Magneto-optical Absorption in Monolayer Phosphorene","authors":"H. D. Long, Nguyen Ngoc Hieu, Chau Thi Huyen Trang, L. Phuong","doi":"10.25073/2588-1124/vnumap.4681","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4681","url":null,"abstract":"In this work, we investigate the magneto-optical absorption in a phosphorene monolayer subjected to a perpendicular static magnetic field. The magneto-optical absorption power is calculated using the projection operator technique taking account of the effect of electron – optical phonon interaction. Numerical results showed that in the case of absence of any interaction, the higher the resonant frequency, the smaller absorbed power was. If the electron - phonon interaction exists, there appear the cyclotron-phonon resonant peaks which show the electron transitions between Landau levels by absorbing a photon accompanied by absorbing/emitting an optical phonon. The obtained results are important for further studies and applications of the phosphorene based structures in optoelectronic devices. \u0000 ","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129355622","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}
Pub Date : 2022-03-24DOI: 10.25073/2588-1124/vnumap.4640
Dao Viet Thang, Nguyen Manh Hung, Nguyen Thi Phuong Thao, Nguyen Cao Khang, Le Thi Mai Oanh, Ngo Thi Cam Linh, Bui Dinh Tu
Bi1-xEuxFeO3 (BEFO) (x = 0.00 ÷ 0.10) materials were prepared by sol-gel method. The crystal structural, Raman scattering, magnetic and optical properties of BEFO were investigated by X-ray diffraction (XRD), Raman scattering spectroscopy, magnetic hysteresis (M-H) loops and fluorescence spectroscopy (FL), respectively. Obtained results of the characterization showed that Eu-doping affected structural, optical and magnetic properties of BFO materials. All samples were crystallized in the rhombohedral structure with R3C space group with crystal lattice parameters of a = 5.585 Å, c = 13.832 Å and the average crystal size of LXRD = 581 Å for BFO materials whereas the a, c and LXRD of Eu-doped samples decrease with the increasing of Eu3+ concentration. The analysis result of Raman scattering spectroscopy showed that the position of the characteristic peak for Bi-O covalent bonds shifts toward higher frequency when Eu3+ concentration increases, confirming the dopping substitution of Eu3+ ions into Bi-sites. Fluorescence spectra showed the enhancement of characteristic emission peaks with the increase of Eu concentration. All samples exhibited weak ferromagnetic behaviour with saturation magnetization of Ms = 0.006 emu/g and remnant magnetization of Mr = 0.004 emu/g for BFO materials. The value of Ms and Mr of Eu-doped BFO increases compared to those of undoped-BFO. The origin of ferromagnetism and fluorescence improvement has been discussed.
{"title":"Effect of Eu Doping on Structural, Optical and Magnetic Properties of BiFeO3 Materials","authors":"Dao Viet Thang, Nguyen Manh Hung, Nguyen Thi Phuong Thao, Nguyen Cao Khang, Le Thi Mai Oanh, Ngo Thi Cam Linh, Bui Dinh Tu","doi":"10.25073/2588-1124/vnumap.4640","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4640","url":null,"abstract":"Bi1-xEuxFeO3 (BEFO) (x = 0.00 ÷ 0.10) materials were prepared by sol-gel method. The crystal structural, Raman scattering, magnetic and optical properties of BEFO were investigated by X-ray diffraction (XRD), Raman scattering spectroscopy, magnetic hysteresis (M-H) loops and fluorescence spectroscopy (FL), respectively. Obtained results of the characterization showed that Eu-doping affected structural, optical and magnetic properties of BFO materials. All samples were crystallized in the rhombohedral structure with R3C space group with crystal lattice parameters of a = 5.585 Å, c = 13.832 Å and the average crystal size of LXRD = 581 Å for BFO materials whereas the a, c and LXRD of Eu-doped samples decrease with the increasing of Eu3+ concentration. The analysis result of Raman scattering spectroscopy showed that the position of the characteristic peak for Bi-O covalent bonds shifts toward higher frequency when Eu3+ concentration increases, confirming the dopping substitution of Eu3+ ions into Bi-sites. Fluorescence spectra showed the enhancement of characteristic emission peaks with the increase of Eu concentration. All samples exhibited weak ferromagnetic behaviour with saturation magnetization of Ms = 0.006 emu/g and remnant magnetization of Mr = 0.004 emu/g for BFO materials. The value of Ms and Mr of Eu-doped BFO increases compared to those of undoped-BFO. The origin of ferromagnetism and fluorescence improvement has been discussed.","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115299073","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}
Pub Date : 2022-03-24DOI: 10.25073/2588-1124/vnumap.4653
P. D. Khang, L. L. Hai, Nguyen Thi Tham Hong, Vu V Tuan
In this work, we have studied the (N2, H2, O2, NO, NO2, CO, CO2, SO2, H2S, H2O, and NH3) gases adsorption properties on the O-vacancy-containing Sc2CO2 monolayer by first-principles calculations. We have determined the preferred adsorption positions and the structural features of the O-vacancy-containing Sc2CO2 monolayer after adsorption of different gas molecules. The adsorption energy and charge transfer from the monolayer to the gas molecules have been calculated. The calculated results show that H2, N2, NH3, H2S and H2O molecules are physisorbed, while CO2, CO, NO2, NO, O2 and SO2 molecules are chemisorbed in the neighboring area of the O-vacancy of the Sc2CO2 monolayer. The existence of the O-vacancy significantly enhances the CO and CO2 adsorption intensity of the defect Sc2CO2 monolayer compared to the original Sc2CO2 monolayer. Our results show that the O-vacancy-containing Sc2CO2 monolayer can be used for detecting NO gas as a resistive sensor.
{"title":"Study on Gas Adsorption Properties (N2, H2, O2, NO, NO2, CO, CO2, SO2, H2S, H2O and NH3) on the O-vacancy-containing Sc2CO2 Monolayer","authors":"P. D. Khang, L. L. Hai, Nguyen Thi Tham Hong, Vu V Tuan","doi":"10.25073/2588-1124/vnumap.4653","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4653","url":null,"abstract":"In this work, we have studied the (N2, H2, O2, NO, NO2, CO, CO2, SO2, H2S, H2O, and NH3) gases adsorption properties on the O-vacancy-containing Sc2CO2 monolayer by first-principles calculations. We have determined the preferred adsorption positions and the structural features of the O-vacancy-containing Sc2CO2 monolayer after adsorption of different gas molecules. The adsorption energy and charge transfer from the monolayer to the gas molecules have been calculated. The calculated results show that H2, N2, NH3, H2S and H2O molecules are physisorbed, while CO2, CO, NO2, NO, O2 and SO2 molecules are chemisorbed in the neighboring area of the O-vacancy of the Sc2CO2 monolayer. The existence of the O-vacancy significantly enhances the CO and CO2 adsorption intensity of the defect Sc2CO2 monolayer compared to the original Sc2CO2 monolayer. Our results show that the O-vacancy-containing Sc2CO2 monolayer can be used for detecting NO gas as a resistive sensor.","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132543623","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}
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