Single-phase phosphors have potential advantages such as simple processability, competitive cost, and other optical and optoelectronic properties. Hence, in this study, the silicate phosphors (Ba1.3Ca0.7−xSiO4:xDy3+) doped with Dy3+ ions (x = 0.01–0.05) were synthesized and characterized in detail. X-ray diffraction patterns showed that all the silicate phosphors have a τ-phase hexagonal unit cell independent of doping. However, d-spacing was reduced for the doped samples, indicating that the interplanar interactions were enhanced. Resultantly, the doped phosphors exhibited relatively larger domains with connectivity than the host, although there were sometimes microscale pores. Photoluminescence spectra stipulated that the optimized doping concentration is x = 0.03 for the silicate Ba1.3Ca0.7-xSiO4:xDy3+ phosphors. Finally, the CIE coordinates (0.30, 0.33) confirm that the Dy3+-doped silicate phosphors are well applicable to the white light-emitting diodes for solid-state lighting and display devices.
{"title":"Single-Phase Silicate Phosphors (Ba1.3Ca0.7−xSiO4:xDy3+) Doped with Dysprosium for White Solid-State Lighting","authors":"Desta R. Golja, Francis B. Dejene, Jung Yong Kim","doi":"10.1155/2022/4317275","DOIUrl":"https://doi.org/10.1155/2022/4317275","url":null,"abstract":"Single-phase phosphors have potential advantages such as simple processability, competitive cost, and other optical and optoelectronic properties. Hence, in this study, the silicate phosphors (Ba<sub>1.3</sub>Ca<sub>0.7−<i>x</i></sub>SiO<sub>4</sub>:<i>x</i>Dy<sup>3+</sup>) doped with Dy<sup>3+</sup> ions (<i>x</i> = 0.01–0.05) were synthesized and characterized in detail. X-ray diffraction patterns showed that all the silicate phosphors have a <i>τ</i>-phase hexagonal unit cell independent of doping. However, <i>d</i>-spacing was reduced for the doped samples, indicating that the interplanar interactions were enhanced. Resultantly, the doped phosphors exhibited relatively larger domains with connectivity than the host, although there were sometimes microscale pores. Photoluminescence spectra stipulated that the optimized doping concentration is <i>x</i> = 0.03 for the silicate Ba<sub>1.3</sub>Ca<sub>0.7-<i>x</i></sub>SiO<sub>4</sub>:<i>x</i>Dy<sup>3+</sup> phosphors. Finally, the CIE coordinates (0.30, 0.33) confirm that the Dy<sup>3+</sup>-doped silicate phosphors are well applicable to the white light-emitting diodes for solid-state lighting and display devices.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138514150","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}
This research demonstrates the fast synthesis of CH3NH3PbBr3 perovskite powder via antisolvent addition and further thin-film synthesis by one-step spin coating. The structural and optical properties are investigated via X-ray diffraction, Fourier-transform infrared spectroscopy, and UV–Vis spectroscopy. Crystallite sizes are compared by three different size estimation techniques, which range between 95.8 nm and 105 nm. The perovskite showed a higher absorption coefficient over 104 cm−1 and a refractive index from 3.4 to 2.3 in the visible spectrum. The bandgap was estimated via three district methods, which revealed a very slightly varied bandgap in the range of 2.29 eV–2.32 eV.
本研究证明了通过反溶剂加成快速合成CH3NH3PbBr3钙钛矿粉末，并进一步采用一步自旋镀膜法合成薄膜。通过x射线衍射、傅里叶变换红外光谱和紫外可见光谱对其结构和光学性质进行了研究。通过三种不同的尺寸估计技术比较了晶体尺寸，其范围在95.8 nm到105 nm之间。钙钛矿的吸收系数在104 cm−1以上，可见光谱的折射率在3.4 ~ 2.3之间。通过三区方法估计了带隙，发现带隙在2.29 eV - 2.32 eV范围内变化很小。
{"title":"Comparative Study on the Crystallite Size and Bandgap of Perovskite by Diverse Methods","authors":"M. T. Ahmed, S. Islam, Fannana Ahmed","doi":"10.1155/2022/9535932","DOIUrl":"https://doi.org/10.1155/2022/9535932","url":null,"abstract":"This research demonstrates the fast synthesis of CH3NH3PbBr3 perovskite powder via antisolvent addition and further thin-film synthesis by one-step spin coating. The structural and optical properties are investigated via X-ray diffraction, Fourier-transform infrared spectroscopy, and UV–Vis spectroscopy. Crystallite sizes are compared by three different size estimation techniques, which range between 95.8 nm and 105 nm. The perovskite showed a higher absorption coefficient over 104 cm−1 and a refractive index from 3.4 to 2.3 in the visible spectrum. The bandgap was estimated via three district methods, which revealed a very slightly varied bandgap in the range of 2.29 eV–2.32 eV.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89625054","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 this study, amino-functionalized magnetic graphene-based composite TEPA-GO/CoFe2O4 (TGOM) was prepared by a simple one-step hydrothermal reaction and applied to the removal of Cr (VI) from wastewater. The removal of Cr (VI) by TGOM has the characteristics of high removal efficiency and excellent cycle performance. The maximum adsorption capacity is 114.81 mg/g, and the adsorption efficiency can still reach 62% after four cycles. The mass percentage of amino in TGOM material is about 1.97% according to thermogravimetric analysis. The modification by TEPA increased the adsorption sites and improved the adsorption capacities due to the synergistic effect of chelation with Cr (VI). The effects of pH, contact time, and temperature on the removal of Cr (VI) were studied. The removal process accorded with the pseudo-second-order kinetics and Langmuir isotherm model, and the thermodynamic parameters showed that the adsorption process was exothermic and spontaneous. The characterization analysis before and after adsorption showed that there were complexation reaction, electrostatic adsorption, and reduction mechanism in the removal process. The above results indicate that TGOM is an effective adsorption material for the removal of Cr (VI) in wastewater.
{"title":"Synthesis of CoFe2O4/Graphene Oxide-Grafted Tetraethylenepentamine for Removal of Cr (VI) from Aqueous Solution","authors":"H. Pan, Donglin Zhao, Li Wang","doi":"10.1155/2022/8961039","DOIUrl":"https://doi.org/10.1155/2022/8961039","url":null,"abstract":"In this study, amino-functionalized magnetic graphene-based composite TEPA-GO/CoFe2O4 (TGOM) was prepared by a simple one-step hydrothermal reaction and applied to the removal of Cr (VI) from wastewater. The removal of Cr (VI) by TGOM has the characteristics of high removal efficiency and excellent cycle performance. The maximum adsorption capacity is 114.81 mg/g, and the adsorption efficiency can still reach 62% after four cycles. The mass percentage of amino in TGOM material is about 1.97% according to thermogravimetric analysis. The modification by TEPA increased the adsorption sites and improved the adsorption capacities due to the synergistic effect of chelation with Cr (VI). The effects of pH, contact time, and temperature on the removal of Cr (VI) were studied. The removal process accorded with the pseudo-second-order kinetics and Langmuir isotherm model, and the thermodynamic parameters showed that the adsorption process was exothermic and spontaneous. The characterization analysis before and after adsorption showed that there were complexation reaction, electrostatic adsorption, and reduction mechanism in the removal process. The above results indicate that TGOM is an effective adsorption material for the removal of Cr (VI) in wastewater.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73227307","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}
L. Shan, R. Fan, Y. Sun, F. M. Zhang, G. Zhang, G. Qin
The stability, geometry, microstructure, and specie combination together with the electronic states of the anatase TiO2 with oxygen defect content of 0%, 3.125%, 6.25%, and 12.5% have been intensively studied within the framework of the density functional theory method. The results show that the TiO2 with an oxygen defect is not as stable as intrinsic TiO2. The compound formation enthalpy Ef and the oxygen defect formation energy value tend to be larger for a higher defect content, and the oxygen defect gets harder to be formed. The bonds within the TiO6 polyhedron are different and not geometrically symmetrical. The bond strengths show distinct diversity, and the primitive cell of anatase TiO2 show spatial expansion when there are oxygen defects. All bands moved down to the low energy region, and two impurity energy band levels emerged for the anatase TiO2 with oxygen defect. The energy band gap is decreased from 3.085 eV to 1.165 eV, 1.0015 eV, and 0.43 eV. There are generally 7 peaks for the spin density of states function, corresponding to their 5 main bands. For the anatase TiO2 with an oxygen defect content of 12.5%, the spin density of states functions are not horizontal ordinate symmetrical near −1.12 eV and 0.31 eV. They are formed by oxygen defect energy levels, which is the result of the Ti d and O p state electron polarization. Transitions from weak paramagnetic to antiferromagnetic are found for the anatase TiO2 with oxygen defect.
{"title":"Oxygen Dependence of Formation, Electronic State Transition, and Spin Polarization for Anatase TiO2: A Comprehensive Study","authors":"L. Shan, R. Fan, Y. Sun, F. M. Zhang, G. Zhang, G. Qin","doi":"10.1155/2022/4709525","DOIUrl":"https://doi.org/10.1155/2022/4709525","url":null,"abstract":"The stability, geometry, microstructure, and specie combination together with the electronic states of the anatase TiO2 with oxygen defect content of 0%, 3.125%, 6.25%, and 12.5% have been intensively studied within the framework of the density functional theory method. The results show that the TiO2 with an oxygen defect is not as stable as intrinsic TiO2. The compound formation enthalpy Ef and the oxygen defect formation energy value tend to be larger for a higher defect content, and the oxygen defect gets harder to be formed. The bonds within the TiO6 polyhedron are different and not geometrically symmetrical. The bond strengths show distinct diversity, and the primitive cell of anatase TiO2 show spatial expansion when there are oxygen defects. All bands moved down to the low energy region, and two impurity energy band levels emerged for the anatase TiO2 with oxygen defect. The energy band gap is decreased from 3.085 eV to 1.165 eV, 1.0015 eV, and 0.43 eV. There are generally 7 peaks for the spin density of states function, corresponding to their 5 main bands. For the anatase TiO2 with an oxygen defect content of 12.5%, the spin density of states functions are not horizontal ordinate symmetrical near −1.12 eV and 0.31 eV. They are formed by oxygen defect energy levels, which is the result of the Ti d and O p state electron polarization. Transitions from weak paramagnetic to antiferromagnetic are found for the anatase TiO2 with oxygen defect.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79962502","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}
First-principle calculations based on the spin-polarized density functional theory (DFT) with vdW corrections by DFT-D2 approach have been carried out to study structural, electronic, and magnetic properties of water-adsorbed graphene/MoS2 heterostructures (system-I), and water-adsorbed graphene/MoS2 heterostructures with vacancy defects in Mo sites (systems-II). We consider vacancy defects in different Mo sites such as centre-1Mo atom vacancy defect (system-IIa), left-1Mo atom vacancy defect (system-IIb), and 2Mo atom vacancy defects (system-IIc). All the systems considered in this study are structurally stable; however, the stability of defected systems decreases with an increase in defect concentrations. The calculated binding energies of HS used in this study agree with the reported work. Electronic properties of system-I and systems-II reveal that they have metallic characteristics. Our investigation shows that system-I is nonmagnetic and systems-II are magnetic. The magnetic moment in the defected systems (system-IIa, system-IIb, and system-IIc) is developed by unpaired up and down-spins of electrons created in the orbitals of atoms due to vacancy defects in Mo atoms.
{"title":"Adsorption of Water Molecule in Graphene/MoS2 Heterostructure with Vacancy Defects in Mo Sites","authors":"H. K. Neupane, N. Adhikari","doi":"10.1155/2022/2135213","DOIUrl":"https://doi.org/10.1155/2022/2135213","url":null,"abstract":"First-principle calculations based on the spin-polarized density functional theory (DFT) with vdW corrections by DFT-D2 approach have been carried out to study structural, electronic, and magnetic properties of water-adsorbed graphene/MoS2 heterostructures (system-I), and water-adsorbed graphene/MoS2 heterostructures with vacancy defects in Mo sites (systems-II). We consider vacancy defects in different Mo sites such as centre-1Mo atom vacancy defect (system-IIa), left-1Mo atom vacancy defect (system-IIb), and 2Mo atom vacancy defects (system-IIc). All the systems considered in this study are structurally stable; however, the stability of defected systems decreases with an increase in defect concentrations. The calculated binding energies of HS used in this study agree with the reported work. Electronic properties of system-I and systems-II reveal that they have metallic characteristics. Our investigation shows that system-I is nonmagnetic and systems-II are magnetic. The magnetic moment in the defected systems (system-IIa, system-IIb, and system-IIc) is developed by unpaired up and down-spins of electrons created in the orbitals of atoms due to vacancy defects in Mo atoms.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76686699","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}
We report a hybrid quantum-classical simulation approach for simulating the optical phase transition observed experimentally in the ultrahigh-density type-II InAs quantum dot array. A hybrid simulation scheme, which contains stochastic gradient Langevin dynamics (a well-known Bayesian machine learning algorithm for big data) along with adiabatic quantum annealing, is developed to reproduce the experimentally observed phase transition. By implementing the simulation scheme into a quantum circuit, we successfully verified the phase transition observed in the experiment. Our work demonstrates for the first time the feasibility of hybridizing quantum computation with classical Langevin dynamics for the analysis of carrier dynamics and quantum phase transition of the quantum dot.
{"title":"Quantum Dot Phase Transition Simulation with Hybrid Quantum Annealing via Metropolis-Adjusted Stochastic Gradient Langevin Dynamics","authors":"Shiba Kodai, Ryo Sugiyama, Koichi Yamaguchi, Tomah Sogabe","doi":"10.1155/2022/9711407","DOIUrl":"https://doi.org/10.1155/2022/9711407","url":null,"abstract":"We report a hybrid quantum-classical simulation approach for simulating the optical phase transition observed experimentally in the ultrahigh-density type-II InAs quantum dot array. A hybrid simulation scheme, which contains stochastic gradient Langevin dynamics (a well-known Bayesian machine learning algorithm for big data) along with adiabatic quantum annealing, is developed to reproduce the experimentally observed phase transition. By implementing the simulation scheme into a quantum circuit, we successfully verified the phase transition observed in the experiment. Our work demonstrates for the first time the feasibility of hybridizing quantum computation with classical Langevin dynamics for the analysis of carrier dynamics and quantum phase transition of the quantum dot.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138514134","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}
Honghui Liu, Z. Liang, C. Yan, Yuebo Liu, Fengge Wang, Yanyan Xu, Junyu Shen, Z. Xiao, Zhisheng Wu, Yang Liu, Qi Wang, Xinqiang Wang, Baijun Zhang
The AlGaN/GaN Schottky barrier diodes (SBDs) working as high-power mixer and multiplier show great potential in millimeter wave (MMW) field owing to their high breakdown voltage. Nevertheless, its further application is severely limited by large reverse leakage current (Jr) since the two-dimensional electron gas (2DEG) channel is hard to be pinched off at low voltage. To address this limitation, a graded AlGaN/GaN heterostructure is introduced to extend the 2DEG channel into a quasi-three-dimensional electron slab. By comparing the fixed Al composition AlGaN/GaN SBD, Jr of the graded AlGaN/GaN SBD is significantly reduced due to the extension of channel carriers, confirming the effective Jr suppression effect of this structure. Furthermore, on this basis, a recessed anode structure is utilized to expect a smaller Jr. The results indicated that the graded AlGaN/GaN SBDs with air-bridge structure have achieved a pretty low Jr value (1.6 × 10−13 A at -15 V), and its cutoff frequency is as high as 60.6 GHz. It is expected that such SBDs with low Jr have significant advantages in future applications.
{"title":"AlGaN/GaN Heterostructure Schottky Barrier Diodes with Graded Barrier Layer","authors":"Honghui Liu, Z. Liang, C. Yan, Yuebo Liu, Fengge Wang, Yanyan Xu, Junyu Shen, Z. Xiao, Zhisheng Wu, Yang Liu, Qi Wang, Xinqiang Wang, Baijun Zhang","doi":"10.1155/2022/5885992","DOIUrl":"https://doi.org/10.1155/2022/5885992","url":null,"abstract":"The AlGaN/GaN Schottky barrier diodes (SBDs) working as high-power mixer and multiplier show great potential in millimeter wave (MMW) field owing to their high breakdown voltage. Nevertheless, its further application is severely limited by large reverse leakage current (Jr) since the two-dimensional electron gas (2DEG) channel is hard to be pinched off at low voltage. To address this limitation, a graded AlGaN/GaN heterostructure is introduced to extend the 2DEG channel into a quasi-three-dimensional electron slab. By comparing the fixed Al composition AlGaN/GaN SBD, Jr of the graded AlGaN/GaN SBD is significantly reduced due to the extension of channel carriers, confirming the effective Jr suppression effect of this structure. Furthermore, on this basis, a recessed anode structure is utilized to expect a smaller Jr. The results indicated that the graded AlGaN/GaN SBDs with air-bridge structure have achieved a pretty low Jr value (1.6 × 10−13 A at -15 V), and its cutoff frequency is as high as 60.6 GHz. It is expected that such SBDs with low Jr have significant advantages in future applications.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73134415","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}
C4F7N, C5F10O, etc., as new environmental-friendly alternative gases decompose under partial discharge and produce a series of products such as CO, CF4, C2F6, C3F8, CF3CN, C2F5CN, and COF2. Based on the first-principles calculation method of density functional theory (DFT), the adsorption characteristics of intrinsic state graphene and Mo-doped graphene adsorbing SF6 and its substitute gas decomposition products are calculated and analyzed. By comparing the adsorption energy, adsorption distance, density of state, Mulliken charge population, charge transfer amount, and molecular orbital energy for adsorbing different decomposition gases, it can be seen that the system structure is the most stable when Mo is doped at the T site of the graphene surface. The adsorption of Mo-doped graphene on gas molecules is significantly stronger than that of intrinsic graphene, and the order of adsorption is: SO2F2 > H2S > SO2 > CF4. The adsorption of H2S gas molecules by intrinsic state and Mo-doped graphene is n-type adsorption, while the adsorption of SO2F2, CF4, and SO2 gas molecules is p-type adsorption. Mo-doped graphene can be used as a detection device for SO2F2 gas resistance sensors.
{"title":"Study on the Adsorption Characteristics of Mo-Doped Graphene on the Decomposition Products of SF6 Substitute Gas Based on First-Principle Calculations","authors":"Can Ding, Xing Hu, Lu Feng","doi":"10.1155/2022/7740210","DOIUrl":"https://doi.org/10.1155/2022/7740210","url":null,"abstract":"C4F7N, C5F10O, etc., as new environmental-friendly alternative gases decompose under partial discharge and produce a series of products such as CO, CF4, C2F6, C3F8, CF3CN, C2F5CN, and COF2. Based on the first-principles calculation method of density functional theory (DFT), the adsorption characteristics of intrinsic state graphene and Mo-doped graphene adsorbing SF6 and its substitute gas decomposition products are calculated and analyzed. By comparing the adsorption energy, adsorption distance, density of state, Mulliken charge population, charge transfer amount, and molecular orbital energy for adsorbing different decomposition gases, it can be seen that the system structure is the most stable when Mo is doped at the T site of the graphene surface. The adsorption of Mo-doped graphene on gas molecules is significantly stronger than that of intrinsic graphene, and the order of adsorption is: SO2F2 > H2S > SO2 > CF4. The adsorption of H2S gas molecules by intrinsic state and Mo-doped graphene is n-type adsorption, while the adsorption of SO2F2, CF4, and SO2 gas molecules is p-type adsorption. Mo-doped graphene can be used as a detection device for SO2F2 gas resistance sensors.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83289987","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}
K. Legesse, Vijaya Bhaskar Rao Poluri, Elangovan Sampandam
Ferroelectrics refer to groups of dielectrics having the property of spontaneous polarization. Lead magnesium niobate-potassium bismuth titanate ((1 − x) PbMg1/3Nb2/3O3-(x)K1/2Bi1/2TiO3)) x = 0.15, 0.25, and 0.35 are prepared by solid-state reaction rout technique. The electric modulus of the prepared samples is studied using the complex impedance spectroscopic method at 400°C, 450°C, and 500°C in various frequency ranges. In the lower frequency range, the real modulus (M′ (ω)) decreased with increasing the temperature. Furthermore, the real modulus (M′ (ω)) increased with increasing frequency and the concentration of the doping component. The imaginary modulus (M″ (ω)) increased with increasing the temperature. The significant variations in the real and imaginary coefficients signify the existence of thermally activated dielectric relaxation between the selected components. Moreover, the magnitude of grain capacitance increased with increasing the temperature, confirming the negative temperature coefficient of resistance of the material.
铁电体是指具有自发极化特性的介电体群。采用固相反应路由技术制备了铌镁铅-钛酸铋钾((1−x) pbm1 / 3nb2 / 3o3 -(x)K1/2Bi1/2TiO3) x = 0.15、0.25和0.35。采用复阻抗谱法对制备的样品在400°C、450°C和500°C不同频率范围内的电模量进行了研究。在低频范围内，实模量(M′(ω))随温度的升高而减小。实模量(M′(ω))随掺杂频率和掺杂浓度的增加而增加。虚模量(M″(ω))随温度的升高而增大。实系数和虚系数的显著变化表明在所选组分之间存在热激活的介电弛豫。晶粒电容的大小随温度的升高而增大，证实了材料的电阻温度系数为负。
{"title":"Electric Modulus Analysis of (1 − x) PbMg1/3Nb2/3O3-(x)K1/2Bi1/2TiO3 Ceramics","authors":"K. Legesse, Vijaya Bhaskar Rao Poluri, Elangovan Sampandam","doi":"10.1155/2022/2450578","DOIUrl":"https://doi.org/10.1155/2022/2450578","url":null,"abstract":"Ferroelectrics refer to groups of dielectrics having the property of spontaneous polarization. Lead magnesium niobate-potassium bismuth titanate ((1 − x) PbMg1/3Nb2/3O3-(x)K1/2Bi1/2TiO3)) x = 0.15, 0.25, and 0.35 are prepared by solid-state reaction rout technique. The electric modulus of the prepared samples is studied using the complex impedance spectroscopic method at 400°C, 450°C, and 500°C in various frequency ranges. In the lower frequency range, the real modulus (M′ (ω)) decreased with increasing the temperature. Furthermore, the real modulus (M′ (ω)) increased with increasing frequency and the concentration of the doping component. The imaginary modulus (M″ (ω)) increased with increasing the temperature. The significant variations in the real and imaginary coefficients signify the existence of thermally activated dielectric relaxation between the selected components. Moreover, the magnitude of grain capacitance increased with increasing the temperature, confirming the negative temperature coefficient of resistance of the material.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82481905","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}
Apurba Poddar, Suman Halder, S. I. Liba, S. M. Hoque, S. S. Sikder
Mg1-xCuxFe2O4 (x = 0.0–0.5) was prepared by the double sintering ceramic method, which sintered at 1100°C and 1200°C for 3 hours and investigated for structural, microstructural, and magnetic properties as a function of the Cu content and cooling process. XRD analysis of 1100°C sintered samples revealed that all the samples were crystallized in a single-phase cubic spinal structure. The microstructural and magnetic properties of slow cooled (furnace-cooled) and fast cooled (quenched) Mg-Cu ferrites have been studied using the scanning electron microscope (SEM), vibrating sample magnetometer (VSM), and Mössbauer spectroscopy after sintering at 1200°C. Homogeneous coaxial grains did not form for any furnace-cooled samples, while for the quenched sample, homogeneous grains were clearly visible even without doping with Cu. Substantial grain growth was witnessed by the samples with higher copper content for both cooling conditions, whereas quenched samples possessed a smaller grain size compared to furnace-cooled samples. The saturation magnetization experienced a higher value for quenched samples compared to furnace-cooled samples with increasing Cu content except for x = 0.4. The sextet pattern of Mössbauer spectroscopy confirmed all the samples were ferromagnetic in nature. Chemical shift, quadrupole shift, hyperfine field, and site occupancy of Fe3+ were also obtained using Mössbauer spectroscopy.
{"title":"Study of the Effect of Quenching on Microstructural and Magnetic Properties of Cu-Doped Mg-Ferrite","authors":"Apurba Poddar, Suman Halder, S. I. Liba, S. M. Hoque, S. S. Sikder","doi":"10.1155/2022/3354087","DOIUrl":"https://doi.org/10.1155/2022/3354087","url":null,"abstract":"Mg1-xCuxFe2O4 (x = 0.0–0.5) was prepared by the double sintering ceramic method, which sintered at 1100°C and 1200°C for 3 hours and investigated for structural, microstructural, and magnetic properties as a function of the Cu content and cooling process. XRD analysis of 1100°C sintered samples revealed that all the samples were crystallized in a single-phase cubic spinal structure. The microstructural and magnetic properties of slow cooled (furnace-cooled) and fast cooled (quenched) Mg-Cu ferrites have been studied using the scanning electron microscope (SEM), vibrating sample magnetometer (VSM), and Mössbauer spectroscopy after sintering at 1200°C. Homogeneous coaxial grains did not form for any furnace-cooled samples, while for the quenched sample, homogeneous grains were clearly visible even without doping with Cu. Substantial grain growth was witnessed by the samples with higher copper content for both cooling conditions, whereas quenched samples possessed a smaller grain size compared to furnace-cooled samples. The saturation magnetization experienced a higher value for quenched samples compared to furnace-cooled samples with increasing Cu content except for x = 0.4. The sextet pattern of Mössbauer spectroscopy confirmed all the samples were ferromagnetic in nature. Chemical shift, quadrupole shift, hyperfine field, and site occupancy of Fe3+ were also obtained using Mössbauer spectroscopy.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84273230","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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