A phenomenological quantization of electromagnetic field is introduced in the presence of the anisotropic magnetodi- electric metamaterial. For a single layer structure with the anisotropic metamaterial, input-output ...A phenomenological quantization of electromagnetic field is introduced in the presence of the anisotropic magnetodi- electric metamaterial. For a single layer structure with the anisotropic metamaterial, input-output relations of quantized radiation are derived using the Green-function approach. Based on these relations, the reflectance of the linearly polarized wave through this structure is calculated. The results show that different resonant peaks of reflectance appear for different polarized waves and indicate the use of the anisotropic metamaterial as a reflector for a certain polarized wave. Furthermore it is found that such a structure can realize the resonant gap with the increase of the thickness. Finally the effects of the absorption are considered and we find that the above properties do not change with the introduction of the absorption.展开更多
Different magnetodielectric effects were observed in Bi1-xGdxFeOa ceramics depending on gadolinium content. A positive one was observed in the samples with x ≤ 0.10 at 295 K and 16 K, and a negative one in the sample...Different magnetodielectric effects were observed in Bi1-xGdxFeOa ceramics depending on gadolinium content. A positive one was observed in the samples with x ≤ 0.10 at 295 K and 16 K, and a negative one in the sample with x = 0.4 at 16 K. Structure analysis by x-ray diffraction （XRD） reveals that the samples crystallize in the R3c structure （ferroelectrics） for x 〈 0.08 and in the Pbnm structure （paraelectrics） for x ≥ 0.3 at room temperature. Temperaturedependent dielectric response and x-ray diffraction confirm the occurrence of a structural transition in the Pbnm phase at low temperature for the samples with x ≤0.4. While the positive magnetodielectric effects can be attributed to a coupling of magnetic and crystallographic structures of the R3c phase, the observed negative magnetodielectric effect in the Pbnm phase can be associated with a low-temperature modification of the Pbnm structure. The observed dualsigned magnetodielectric effects suggest that the Bi1-xGdxFeO3 oxides are a good prototype for understanding the magnetodielectric coupling mechanism in this kind of materials.展开更多
Materials with strongly coupled magnetic and electronic degrees of freedom provide new possibilities for practical applications.In this paper,we have investigated the structure,magnetic property,and magnetodielectric(...Materials with strongly coupled magnetic and electronic degrees of freedom provide new possibilities for practical applications.In this paper,we have investigated the structure,magnetic property,and magnetodielectric(MD) effect in Ho_(2)Cu_(2)O_(5) and Yb_(2)Cu_(2)O_(5) poly crystalline samples,which possess a non-centrosymmetric polar structure with space group Pna2_(1).In Ho_(2)Cu_(2)O_(5),Ho^(3+) and Cu^(2+) sublattices order simultaneously,exhibiting a typical paramagnetic to antiferromagnetic transition at 13.1 K.While for Yb_(2)Cu_(2)O_(5),two magnetic transitions which originate from the orderings of Yb^(3+)(7.8 K) and Cu^(2+)(13.5 K) sublattices are observed.A magnetic field induced metamagnetic transition is obtained in these two cuprates below Neel temperature(T_(N)).By means of dielectric measurement,distinct MD effect is demonstrated by the dielectric anomaly at T_(N.)Meanwhile,the MD effect is found to be directly related to the metamagnetic transition.Due to the specific spin configuration and different spin evolution in the magnetic field,a positive MD effect is formed in Ho_(2)Cu_(2)O_(5),and a negative one is observed in Yb_(2)Cu_(2)O_(5).The spontaneous dielectric anomaly at T_(N) is regarded as arising from the shifts in optical phonon frequencies,and the magnetoelectric coupling is used to interpret the magnetic field induced MD effect.Moreover,an H-T phase diagram is constructed for Ho_(2)Cu_(2)O_(5) and Yb_(2)Cu_(2)O_(5) based on the results of isothermal magnetic and dielectric hysteresis loops.展开更多
To understand possible interaction between magnetic and electric order parameters of Fe-doped Sr_(x)Ba_(1-x)Nb_(2)O_(6)(SBN),Fe-doped Sr_(0.5)Ba_(0.5)Nb_(2)O_(6)(SBN50)and Sr_(0.4)Ba_(0.6)Nb_(2)O_(6)(SBN40)are synthes...To understand possible interaction between magnetic and electric order parameters of Fe-doped Sr_(x)Ba_(1-x)Nb_(2)O_(6)(SBN),Fe-doped Sr_(0.5)Ba_(0.5)Nb_(2)O_(6)(SBN50)and Sr_(0.4)Ba_(0.6)Nb_(2)O_(6)(SBN40)are synthesized and investigated.Synthesis has been carried out via ceramic route.The paper reports synthesis,crystal structure,dielectric properties,P-E hysteresis loops,M-H hysteresis loops and magneto-capacitance of the Fe-doped SBN compositions.All the compositions are observed to exhibit a useful value of magnetocapacitance,especially at frequencies less than 10 kHz.展开更多
Lead-free multiferroic composites of 1−x(K_(0.5)Na_(0.5)NbO_(3−x))(Co_(0.6)Zn_(0.4))(Fe_(1.7)Mn_(0.3))O_(4)(KNN-CZFMO),where x=0.0,0.1,0.2,0.3,0.4,0.5 and 1.0,have been investigated for their structural,morphological,...Lead-free multiferroic composites of 1−x(K_(0.5)Na_(0.5)NbO_(3−x))(Co_(0.6)Zn_(0.4))(Fe_(1.7)Mn_(0.3))O_(4)(KNN-CZFMO),where x=0.0,0.1,0.2,0.3,0.4,0.5 and 1.0,have been investigated for their structural,morphological,electrical,magnetic,dielectric and magneto-dielectric properties.Presence of KNN and CZFMO crystal structure in each composite has been confirmed from X-ray diffrac-tion analysis(XRD).Cuboidal-shaped grains of KNN and spherical-shaped grains of CZFMO have been observed by scanning electron microscopy(SEM).The room temperature ferroelectric behavior as confirmed by polarization versus electric field(P-E)hysteresis loops has been found to be decreasing with increasing CZFMO concentration.Increasing magnetic ordering with the increase in CZFMO concentration in the prepared composites has been observed by magnetization versus magnetic field(M-H)hysteresis loops.The electrical conductivity of composites has been studied using Jonscher’s universal power law.The room temperature dielectric constant(ε′)and dielectric loss(tanδ)have been observed to decrease with the increase in the frequency of the applied external electric field.The dielectric relaxation behavior has been observed using curve fitting analysis via the Havriliak-Negami relaxation model.Maximum value of the magnetodielectric(MD)effect~−11%at a frequency of 1 kHz with the applied magnetic field of 1 T has been achieved for 0.9 KNN−0.1 CZFMO(x=0.1)composite in the present research work.展开更多
Due to advanced technology,electromagnet interference and dissipation problems in the electronic and portable devices at GHz range are increasing daily.Magnetic absorbing materials with outstanding electromagnetic pro...Due to advanced technology,electromagnet interference and dissipation problems in the electronic and portable devices at GHz range are increasing daily.Magnetic absorbing materials with outstanding electromagnetic properties,wide bandwidth,and strong absorption are highly desirable.The present investigation deals with the preparation of Ni-Mg-Cu-Zn(NMCZ)substituted nano ferrites with composition of Ni_(0.3)Mg_(0.2)Cu_(0.3)Zn_(0.2)X_(0.02)Fe_(1.98)O_(4)(X=Nd,Ho,Pr,Gd,Yb).X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),a vibratory sample magnetometer(VSM),and a Vector network analyzer(VNA)were used to investigate these rare earth-doped nanocrystalline ferrites'features.XRD reveals the single spinel phase structure in all Ni-Mg-Cu-Zn ferrites.FTIR spectroscopy shows the presence of tetrahedral and octahedral bands of spinel ferrites.FESEM images reveal the lowest agglomeration for the Ho-doped NMCZ nano-spinel ferrites sample.TEM images show the hexagon shapes of the Yb-and Nd-doped NMCZ ferrites.Pr-doped NMCZ ferrites show more coercivity than other rare earth metals substituted NMCZ nanocrystalline ferrites.VSM analysis was used to calculate the magnetic features like initial permeability,magnetic anisotropy constant,remanence,coercivity,and magnetic moment.High-frequency switching field distributions(SFD)analyses were also investigated.Magnetodielectric characteristics such as losses,permittivity,modulus,Q,ac conductivity,and impedance of the Nd^(-),Ho^(-),Pr^(-),Gd^(-),Yb-doped Ni-Mg-Cu-Zn ferrites were evaluated.The minimum reflection loss(-57.3 dB)is found at 1.4 GHz for Pr-doped Ni-Mg-Cu-Zn ferrite absorber.However,the reflection loss(RL)of-53.9 dB at 2.9 GHz is observed for Ho-doped Ni-Mg-Cu-Zn ferrite absorber.Soft magnetization,low coercivity,outstanding magnetodielectric,and absorption properties of theNd^(-),Ho^(-),Pr^(-),Gd^(-)and Yb^(-)doped Ni-Mg-Cu-Zn ferrites are suitable candidates for absorption in telecommunication,defense,and technological industries.展开更多
Rare earths(REs) play a key role in distorting spinel structure by creating some defects at the lattice sites and make them suitable for magnetodielectric applications.In the present study,the nanoferrites of CuRE0.02...Rare earths(REs) play a key role in distorting spinel structure by creating some defects at the lattice sites and make them suitable for magnetodielectric applications.In the present study,the nanoferrites of CuRE0.02Fe1.98O4,where REs=Y^(3+),Yb^(3+),Gd^(3+),were prepared using one step sol-gel method.The prepared samples are copper ferrite(CFO),yttrium doped copper ferrite(Y-CFO),ytterbium doped copper ferrite(Yb-CFO) and gadolinium doped copper ferrite(Gd-CFO),respectively.The single-phase structure of all the REs doped nanoferrites was determined by X-ray diffraction(XRD) analysis.The porosity,agglomerations and grain size of the REs doped copper ferrite were examined using field emission scanning electron microscopy(FESEM) analysis.Fourier transform infrared spectroscopy(FTIR)elaborates the phase formation and environmental effects on the REs doped nanoparticles(NPs).The recorded room temperature M-H loops from a vibrating sample magnetometer(VSM) elucidate the magnetic properties of the REs doped spinel nanoferrites.The magnetic saturation(Ms) was calculated in the range of 23.08 to 51.78 emu/g.The calculated coercivity values(272.6 to 705.60 Oe) confirm the soft magnetic behavior of REs doped copper ferrites.Furthermore,the electromagnetic and dielectric properties were assessed using a Vector network analyzer(VNA) from 1 to 6 GHz.The permeability,permittivity,dielectric tangent loss and electric modulus of the REs doped spinel ferrites illustrate that the prepared NPs may be suitable for microwave and high frequency applications.展开更多
Pure phase Y_(3)Fe_(5)O_(12)(YIG)ceramic was successfully produced by tape-casting forming process and one-step solid-state sintering method.The activation energy for densification was calculated to be 183.81 kJ/mol.P...Pure phase Y_(3)Fe_(5)O_(12)(YIG)ceramic was successfully produced by tape-casting forming process and one-step solid-state sintering method.The activation energy for densification was calculated to be 183.81 kJ/mol.Pure YIG ceramic with a relative density as high as 99.8%was fabricated.The existence of O vacancy and Fe^(2+)ions was determined by XPS and EPR spectra.The RT saturation magnetization was measured to be 28.2 emu/g,and the hysteresis loss was calculated to be smaller than 10 mJ/kg in the temperature range of 230~360 K and be as high as 238.8 mJ/kg at 30 K.The dielectric loss tangent tanδ_(ε)was nearly zero at 6~7 GHz and 11~12 GHz.For complex permeability in the frequency range of 5~18 GHz,the magnetic loss tangent tanδ_(μ)fluctuated at around zero.Therefore,the low values of tanδ_(ε)and tanδ_(μ)indicate that it is a low loss ceramic material.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11104071)
文摘A phenomenological quantization of electromagnetic field is introduced in the presence of the anisotropic magnetodi- electric metamaterial. For a single layer structure with the anisotropic metamaterial, input-output relations of quantized radiation are derived using the Green-function approach. Based on these relations, the reflectance of the linearly polarized wave through this structure is calculated. The results show that different resonant peaks of reflectance appear for different polarized waves and indicate the use of the anisotropic metamaterial as a reflector for a certain polarized wave. Furthermore it is found that such a structure can realize the resonant gap with the increase of the thickness. Finally the effects of the absorption are considered and we find that the above properties do not change with the introduction of the absorption.
基金Project supported by the National Basic Research Program of China (Grant No. 2007CB925003)the National Natural Science Foundation of China (Grant No. 50872148)
文摘Different magnetodielectric effects were observed in Bi1-xGdxFeOa ceramics depending on gadolinium content. A positive one was observed in the samples with x ≤ 0.10 at 295 K and 16 K, and a negative one in the sample with x = 0.4 at 16 K. Structure analysis by x-ray diffraction （XRD） reveals that the samples crystallize in the R3c structure （ferroelectrics） for x 〈 0.08 and in the Pbnm structure （paraelectrics） for x ≥ 0.3 at room temperature. Temperaturedependent dielectric response and x-ray diffraction confirm the occurrence of a structural transition in the Pbnm phase at low temperature for the samples with x ≤0.4. While the positive magnetodielectric effects can be attributed to a coupling of magnetic and crystallographic structures of the R3c phase, the observed negative magnetodielectric effect in the Pbnm phase can be associated with a low-temperature modification of the Pbnm structure. The observed dualsigned magnetodielectric effects suggest that the Bi1-xGdxFeO3 oxides are a good prototype for understanding the magnetodielectric coupling mechanism in this kind of materials.
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.11704091)the Open Project of Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology(Grant No.NLK2021-10)the Open Project of Key Laboratory of Novel Materials for Sensor of Zhejiang Province,China(Grant No.ZJKLNMS2021010)。
文摘Materials with strongly coupled magnetic and electronic degrees of freedom provide new possibilities for practical applications.In this paper,we have investigated the structure,magnetic property,and magnetodielectric(MD) effect in Ho_(2)Cu_(2)O_(5) and Yb_(2)Cu_(2)O_(5) poly crystalline samples,which possess a non-centrosymmetric polar structure with space group Pna2_(1).In Ho_(2)Cu_(2)O_(5),Ho^(3+) and Cu^(2+) sublattices order simultaneously,exhibiting a typical paramagnetic to antiferromagnetic transition at 13.1 K.While for Yb_(2)Cu_(2)O_(5),two magnetic transitions which originate from the orderings of Yb^(3+)(7.8 K) and Cu^(2+)(13.5 K) sublattices are observed.A magnetic field induced metamagnetic transition is obtained in these two cuprates below Neel temperature(T_(N)).By means of dielectric measurement,distinct MD effect is demonstrated by the dielectric anomaly at T_(N.)Meanwhile,the MD effect is found to be directly related to the metamagnetic transition.Due to the specific spin configuration and different spin evolution in the magnetic field,a positive MD effect is formed in Ho_(2)Cu_(2)O_(5),and a negative one is observed in Yb_(2)Cu_(2)O_(5).The spontaneous dielectric anomaly at T_(N) is regarded as arising from the shifts in optical phonon frequencies,and the magnetoelectric coupling is used to interpret the magnetic field induced MD effect.Moreover,an H-T phase diagram is constructed for Ho_(2)Cu_(2)O_(5) and Yb_(2)Cu_(2)O_(5) based on the results of isothermal magnetic and dielectric hysteresis loops.
文摘To understand possible interaction between magnetic and electric order parameters of Fe-doped Sr_(x)Ba_(1-x)Nb_(2)O_(6)(SBN),Fe-doped Sr_(0.5)Ba_(0.5)Nb_(2)O_(6)(SBN50)and Sr_(0.4)Ba_(0.6)Nb_(2)O_(6)(SBN40)are synthesized and investigated.Synthesis has been carried out via ceramic route.The paper reports synthesis,crystal structure,dielectric properties,P-E hysteresis loops,M-H hysteresis loops and magneto-capacitance of the Fe-doped SBN compositions.All the compositions are observed to exhibit a useful value of magnetocapacitance,especially at frequencies less than 10 kHz.
基金support(Basic Scientific Research Start-Up Project Grant No.F.30-401/2017(BSR))to carry out this research work.
文摘Lead-free multiferroic composites of 1−x(K_(0.5)Na_(0.5)NbO_(3−x))(Co_(0.6)Zn_(0.4))(Fe_(1.7)Mn_(0.3))O_(4)(KNN-CZFMO),where x=0.0,0.1,0.2,0.3,0.4,0.5 and 1.0,have been investigated for their structural,morphological,electrical,magnetic,dielectric and magneto-dielectric properties.Presence of KNN and CZFMO crystal structure in each composite has been confirmed from X-ray diffrac-tion analysis(XRD).Cuboidal-shaped grains of KNN and spherical-shaped grains of CZFMO have been observed by scanning electron microscopy(SEM).The room temperature ferroelectric behavior as confirmed by polarization versus electric field(P-E)hysteresis loops has been found to be decreasing with increasing CZFMO concentration.Increasing magnetic ordering with the increase in CZFMO concentration in the prepared composites has been observed by magnetization versus magnetic field(M-H)hysteresis loops.The electrical conductivity of composites has been studied using Jonscher’s universal power law.The room temperature dielectric constant(ε′)and dielectric loss(tanδ)have been observed to decrease with the increase in the frequency of the applied external electric field.The dielectric relaxation behavior has been observed using curve fitting analysis via the Havriliak-Negami relaxation model.Maximum value of the magnetodielectric(MD)effect~−11%at a frequency of 1 kHz with the applied magnetic field of 1 T has been achieved for 0.9 KNN−0.1 CZFMO(x=0.1)composite in the present research work.
基金Princess Nourah bint Abdulrahman University Researchers Supporting Project number(PNURSP2024R42),Princess Nourah bint Abdulrahman University,Riyadh,Saudi Arabiathe Deanship of Scientific Research at King Khalid University for funding this work through large group Research Project(RGP2/387/44)。
文摘Due to advanced technology,electromagnet interference and dissipation problems in the electronic and portable devices at GHz range are increasing daily.Magnetic absorbing materials with outstanding electromagnetic properties,wide bandwidth,and strong absorption are highly desirable.The present investigation deals with the preparation of Ni-Mg-Cu-Zn(NMCZ)substituted nano ferrites with composition of Ni_(0.3)Mg_(0.2)Cu_(0.3)Zn_(0.2)X_(0.02)Fe_(1.98)O_(4)(X=Nd,Ho,Pr,Gd,Yb).X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),a vibratory sample magnetometer(VSM),and a Vector network analyzer(VNA)were used to investigate these rare earth-doped nanocrystalline ferrites'features.XRD reveals the single spinel phase structure in all Ni-Mg-Cu-Zn ferrites.FTIR spectroscopy shows the presence of tetrahedral and octahedral bands of spinel ferrites.FESEM images reveal the lowest agglomeration for the Ho-doped NMCZ nano-spinel ferrites sample.TEM images show the hexagon shapes of the Yb-and Nd-doped NMCZ ferrites.Pr-doped NMCZ ferrites show more coercivity than other rare earth metals substituted NMCZ nanocrystalline ferrites.VSM analysis was used to calculate the magnetic features like initial permeability,magnetic anisotropy constant,remanence,coercivity,and magnetic moment.High-frequency switching field distributions(SFD)analyses were also investigated.Magnetodielectric characteristics such as losses,permittivity,modulus,Q,ac conductivity,and impedance of the Nd^(-),Ho^(-),Pr^(-),Gd^(-),Yb-doped Ni-Mg-Cu-Zn ferrites were evaluated.The minimum reflection loss(-57.3 dB)is found at 1.4 GHz for Pr-doped Ni-Mg-Cu-Zn ferrite absorber.However,the reflection loss(RL)of-53.9 dB at 2.9 GHz is observed for Ho-doped Ni-Mg-Cu-Zn ferrite absorber.Soft magnetization,low coercivity,outstanding magnetodielectric,and absorption properties of theNd^(-),Ho^(-),Pr^(-),Gd^(-)and Yb^(-)doped Ni-Mg-Cu-Zn ferrites are suitable candidates for absorption in telecommunication,defense,and technological industries.
基金the Researcher Supporting Project number (RSP-2020/61),King Saud University,Riyadh,Saudi Arabia for the financial support。
文摘Rare earths(REs) play a key role in distorting spinel structure by creating some defects at the lattice sites and make them suitable for magnetodielectric applications.In the present study,the nanoferrites of CuRE0.02Fe1.98O4,where REs=Y^(3+),Yb^(3+),Gd^(3+),were prepared using one step sol-gel method.The prepared samples are copper ferrite(CFO),yttrium doped copper ferrite(Y-CFO),ytterbium doped copper ferrite(Yb-CFO) and gadolinium doped copper ferrite(Gd-CFO),respectively.The single-phase structure of all the REs doped nanoferrites was determined by X-ray diffraction(XRD) analysis.The porosity,agglomerations and grain size of the REs doped copper ferrite were examined using field emission scanning electron microscopy(FESEM) analysis.Fourier transform infrared spectroscopy(FTIR)elaborates the phase formation and environmental effects on the REs doped nanoparticles(NPs).The recorded room temperature M-H loops from a vibrating sample magnetometer(VSM) elucidate the magnetic properties of the REs doped spinel nanoferrites.The magnetic saturation(Ms) was calculated in the range of 23.08 to 51.78 emu/g.The calculated coercivity values(272.6 to 705.60 Oe) confirm the soft magnetic behavior of REs doped copper ferrites.Furthermore,the electromagnetic and dielectric properties were assessed using a Vector network analyzer(VNA) from 1 to 6 GHz.The permeability,permittivity,dielectric tangent loss and electric modulus of the REs doped spinel ferrites illustrate that the prepared NPs may be suitable for microwave and high frequency applications.
基金the National Key R&D Program of China(2017YFB0403200)the National Natural Science Foundation of China(No.51872327)。
文摘Pure phase Y_(3)Fe_(5)O_(12)(YIG)ceramic was successfully produced by tape-casting forming process and one-step solid-state sintering method.The activation energy for densification was calculated to be 183.81 kJ/mol.Pure YIG ceramic with a relative density as high as 99.8%was fabricated.The existence of O vacancy and Fe^(2+)ions was determined by XPS and EPR spectra.The RT saturation magnetization was measured to be 28.2 emu/g,and the hysteresis loss was calculated to be smaller than 10 mJ/kg in the temperature range of 230~360 K and be as high as 238.8 mJ/kg at 30 K.The dielectric loss tangent tanδ_(ε)was nearly zero at 6~7 GHz and 11~12 GHz.For complex permeability in the frequency range of 5~18 GHz,the magnetic loss tangent tanδ_(μ)fluctuated at around zero.Therefore,the low values of tanδ_(ε)and tanδ_(μ)indicate that it is a low loss ceramic material.
