共查询到20条相似文献,搜索用时 593 毫秒
1.
Mengmeng Jiao Qinfeng Xu Yimei Xu Yalin Li Chuanlu Yang Mingliang Liu 《Ceramics International》2018,44(13):15243-15248
Series of UV excited Ba3Lu(PO4)3:Tb3+,Mn2+ phosphors with tunable green to red emissions had been prepared using solid state reactions. Powder X-ray diffraction and Rietveld structure refinement were used to investigate the phase purity and crystal structure of the prepared samples. Under UV excitation, the Ba3Lu(PO4)3:Tb3+,Mn2+ samples exhibited not only the typical Tb3+ emission peaks but also the broad emission band of Mn2+ ions due to the efficient Tb3+→Mn2+ energy transfer which had been verified by luminescence spectra and decay curves. Utilizing the Inokuti-Hirayama model, the Tb3+→Mn2+ energy transfer mechanism was determined to be the electronic dipole–quadrupole interaction. Moreover, the emission spectra of Ba3Lu(PO4)3:0.80Tb3+,0.015Mn2+ sample at different temperatures manifested that our prepared phosphors possessed good thermal stability. The luminescence properties investigation results revealed the potential value of Ba3Lu(PO4)3F:Tb3+,Mn2+ in application for UV excited phosphor converted white light emitting diodes. 相似文献
2.
A series of Ba2Mg1−xMnxP4O13 (x = 0-1.0) and Ba1.94Eu0.06Mg1−xMnxP4O13 (x = 0-0.15) phosphors were prepared by conventional solid-state reaction. X-ray powder diffraction (XRD), the photoluminescence spectra, and the decay curves are investigated. XRD analysis shows that the maximum tolerable substitution of Mn2+ for Mg is about 50 mol% in Ba2MgP4O13. Mn2+-singly doped Ba2MgP4O13 shows weak red-luminescence peaked at about 615 nm. The Eu2+/Mn2+ co-doped phosphor emits two distinctive luminescence bands: a blue one centered at 430 nm originating from Eu2+ and a broad red-emitting one peaked at 615 nm from Mn2+ ions. The luminescence of Mn2+ ions can be greatly enhanced with the co-doping of Eu2+ in Ba2MgP4O13. The efficient energy transfer from Eu2+ to Mn2+ is verified by the excitation and emission spectra together with the luminescence decay curves. The emission colors could be tuned from the blue to the red-purple and eventually to the deep red. The resonance-type energy transfer via a dipole-quadrupole interaction mechanism is supported by the decay lifetime data. The energy transfer efficiency and the critical distance are calculated and discussed. The temperature dependent luminescence spectra of the Eu2+/Mn2+ co-doped phosphor show a good thermal stability on quenching effect. 相似文献
3.
F. Pedro-García A.M. Bolarín-Miró F. Sánchez-De Jesús C.A. Cortés-Escobedo Z. Valdez-Nava G. Torres-Villaseñor 《Ceramics International》2018,44(7):8087-8093
We report a study on the effect of the substitution of Bi3+ by Sr2+ on the stabilization of R3c structure of Bi1?xSrxFeO3 (0 ≤ x ≤ 0.3, Δx = 0.05), and its effect in the magnetic and dielectric behavior. Stoichiometric mixtures of Bi2O3, Fe2O3 and SrO were mixed and milled for 5?h using a ball to powder weight ratio of 10:1 by high-energy ball milling. The obtained powder were pressed at 900?MPa to obtain cylindrical pellets and sintered at 800?°C for 2?h. X-ray diffraction and Rietveld refinement were used to evaluate the effect of Sr2+ on the crystal structure. In addition, vibrating sample magnetometry (VSM) and dielectric tests were used for describing the multiferroic behavior. The results show that Sr-doped BiFeO3 particles present rhombohedral structure (R3c) characteristic of α-BiFeO3 when the doping is below 0.10?mol of Sr. Additionally, a gradual decrease in the amount of secondary phases with the increase of the amount of strontium is observed. For doping concentration higher than 0.15?mol of Sr, a phase transition to an orthorhombic symmetry (β-BiFeO3, Pbnm) is detected. Besides, changes in relative intensities of reflection peaks planes (110) and (104) are associated with the phase transformations and with the magnetic and dielectric behavior. The α-BiFeO3 phase show antiferromagnetic behavior and high values of dielectric permittivity, whereas the β-BiFeO3 phase show a ferromagnetic behavior and low dielectric permittivity. 相似文献
4.
M.A. Almessiere Y. Slimani H. Güngüneş H.S. El Sayed A. Baykal 《Ceramics International》2018,44(9):10470-10477
Ce3+ ion substituted SrFe12O19, SrFe12-xCexO19 (0.0?≤?x?≤?0.5), nanohexaferrites were fabricated by citrate sol-gel combustion approach. X–ray diffractometry (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscope (EDX), EDX Elemental mapping, Fourier transform infrared spectroscopy (FT-IR) were used to study the structure and morphology of the samples. AC magnetic susceptibility and 57Fe Mossbauer spectroscopy have been operated to examine the hyperfine structure, static and dynamic magnetic properties. The values of variations in line width, quadrupole splitting, hyperfine magnetic field, and isomer shift have been estimated. The impact of Ce-ion substitution on AC magnetic susceptibility properties of Sr-hexaferrite were explored. The AC-susceptibility measurements reveal the frequency dependence of the magnetic responses, indicating strong magnetic interactions among the nanoparticles of the various products. In addition, it is determined that the magnetic interaction between the nanoparticles is weakened in the substituted products, due to the substitution of Fe3+ ions by Ce3+ ions. 相似文献
5.
Nanocrystalline Mn2+ doped Zn1−xMnxO, where x=0.1, 0.15, 0.2, 0.25, 0.3 and 0.4 mol of Mn2+ diluted magnetic semiconductors (DMSs), were synthesized by the combustion reaction for spintronic applications. The effect of Mn2+ ion doping on the structural, morphological and magnetic properties of ZnO was investigated. The products of the reactions were characterized by X-ray diffraction (XRD), nitrogen adsorption (BET), transmission electron microscopy (TEM), and magnetic measurements (VSM). XRD spectra data revealed the formation of a ZnO phase at all the Mn2+ doping concentrations used, indicating that the synthesis was efficient in diluting the Mn2+ ions in the ZnO lattice. Increasing the Mn2+ ion concentrations reduced the maximum reaction and ignition temperature and contributed to reduce crystallite and particle sizes. The samples showed the typical behavior of soft magnetic materials at all the Mn2+ concentrations evaluated here. The Curie temperature (Tc) was higher than room temperature at all the Mn2+ concentrations. 相似文献
6.
《Ceramics International》2023,49(16):26675-26682
Phase formation, microstructure, magnetic properties, and dielectric properties of Ba1.5Sr1.5Co2Fe(23−x)CrxO41 (0.0 ≤ x ≤ 1.0) ceramics, in which Fe3+ ions were substituted by Cr3+ ions, were systematically investigated. X-ray diffraction results reveal that Z-type hexagonal ferrite was formed by sintering at 1250 °C, and Cr3+ ions successfully enter lattice without destroying crystal structure. Analysis of the microstructure reveals that Cr3+ ion doping has significant effect on crystal micromorphology. Samples with x = 0.4 have the most homogeneous micromorphology and the highest sintering density of 5.12 g/cm3. In addition, under the influence of external magnetic field, all samples exhibit typical soft magnetic character and hysteresis characteristics, with saturation magnetization up to 63.86 emu/g (x = 0.6). Particularly, compared with undoped sample, Cr-doped samples have outstanding magnetic–dielectric properties. Firstly, with increasing Cr3+ amount, real part of the permeability (μ′) reaches the maximum value of 10.70 at x = 0.4, while cutoff frequency exceeds 2 GHz, and Snoek constant reaches ∼19.50 GHz. Furthermore, due to more homogeneous microstructure, samples with x = 0.4 have low magnetic loss and can maintain high quality factor (Q) over a broad frequency range. Moreover, real part of the permittivity (ε′) reaches the maximum value of 16.90 at x = 0.6, and dielectric loss remains lower than 0.013 for frequencies below 0.7 GHz. Consequently, magnetic–dielectric materials prepared in this work are expected to have extensive application prospects for ultrahigh-frequency devices. 相似文献
7.
Evolution of the microstructure, optical, and magnetic properties have been investigated systematically in multiferroic CuFe1-xSnxO2 (x?=?0–0.05) ceramics. Substitution of Sn4+ for Fe3+ results in expansion of CuFeO2 lattice, and reduces the density of the material, but the metal oxidation states are unchanged. Observation of the optical properties shows that the value of the direct optical band gap (Eg) decreases with increasing Sn doping level, and that the CuFe1-xSnxO2 (x?=?0–0.04) series with values >?3.1?eV. Magnetic susceptibility measurements show that Sn4+ doping decreases the Curie-Weiss temperature, i.e. weakens the strength of the antiferromagnetic interaction between high-spin Fe3+ ions, but does not affect the stability of the antiferromagnetic phase, and all samples undergo successive magnetic transitions at about TN1 =?15?K and TN2 =?11?K. However, magnetization curves show that changes occur in the magnetic interactions and both ferromagnetism and antiferromagnetism co-exist in the Sn4+-doped samples. The maximum value of the saturation magnetization of 1.8?emu·g?1 was observed for the x?=?0.03 sample in a 2.5?kOe field. The changes in the magnetic behavior are closely related to the lattice distortion and charge compensation, which are discussed in detail in this work. 相似文献
8.
G. Seeta Rama Raju E. Pavitra L. Krishna Bharat Gattupalli Manikya Rao Tae-Joon Jeon Yun Suk Huh Young-Kyu Han 《Ceramics International》2018,44(12):13852-13857
Upconversion Sr2(Gd.98-xEr.02Ybx)8Si6O26 (SGSO:2Er3+/xYb3+) phosphor materials were synthesized using a citrate sol-gel process. X-ray diffraction patterns confirmed their hexagonal structure. Field emission scanning electron microscopy images of SGSO:2Er3+/xYb3+ phosphors depicted submicron particles. The enhanced upconversion luminescence properties of SGSO:2Er3+/xYb3+ phosphors were analysed as a function of Yb3+ ion concentration and laser power. The energy transfer induced enhanced emission of the Er3+/ Yb3+ ions co-doped SGSO phosphors was ascribed to multi-phonon relaxation. The calculated chromaticity coordinates of the SGSO:2Er3+/xYb3+ phosphors showed emissions could be tuned by changing Yb3+ ion concentration. Optimized sample exhibited the chromaticity coordinate values near to the ultra-high definition television standard green emission coordinates. 相似文献
9.
Imad Hussain S.N. Khan Eun Ji Kim So Eun Jeon Bon Heun Koo 《Ceramics International》2018,44(3):2892-2899
A systematic study focusing on the effect of Niobium (Nb) doping on the structural, magnetic and magnetocaloric properties of Ba2FeMoO6 samples is presented here. The samples of interest Ba2FeMo1?xNbxO6 (0 ≤ x ≤ 0.4) were prepared using the solid state reaction method and were confirmed to possess a cubic structure with Fm-3m space group using the X-ray diffraction analysis and Rietveld refinement. A second order of ferromagnetic phase transition was recorded in both the pure as well as the Nb doped samples using the temperature dependent magnetization and Arrott plots analysis. The pristine Ba2FeMoO6 (BFMO) sample indicated a spontaneous magnetization (34.6 emu/g at 100 K) with a relatively sharp magnetic transition at the Curie temperature (TC) of 315 K as compared to the doped samples. A magnetic entropy change of 0.93 Jkg?1K?1 at an applied magnetic field of 2.5 T was measured for the pure BFMO sample. The doped BFMO samples with Mo partially substituted by Nb however, were observed to effectively modify the TC accompanied by a decrease in magnetization. The results investigated in this work suggest that the magnetic and magnetocaloric properties of the BFMO can be tailored by controlled Nb doping which is of significant importance in order to realize the numerous potential applications of the material in the magnetic refrigeration technology. 相似文献
10.
《Ceramics International》2022,48(10):13580-13588
In this work, Mg2+-doped CaBi2Nb2O9 (CBN-xMg) lead-free piezoceramics were prepared by a common solid-state method to investigate the effects of Mg2+ doping content on crystal structure, electrical resistivity, and dielectric and ferroelectric properties. XRD and Raman spectroscopy show that the Mg atoms enter the B-site to form a solid solution of the pure CBN phase. In addition, the XRD refinement results show that Mg2+ doping increases the distortion of the NbO6 octahedron and simultaneously enhances the total contribution of the spontaneous polarization of each position along the a-axis, and that the Ps increases from -28.678 μC/cm2 for x = 0 to -31.768 μC/cm2 for x = 0.02. However, when x > 0.02, the polarization decreases due to the oxygen vacancy pinning effect. According to SEM analysis, Mg2+ doping strengthened the growth rate of CBN ceramic grains on the a-b plane, resulting in a more obvious plate-like structure. The reduced anti-site defects of the CBN ceramic samples strengthened the structure of (Bi2O2)2+ and improved the resistivity of the samples. The internal dipole moment was also strengthened, resulting in a significant increase in the dielectric constant and a decrease in the dielectric loss. In general, Mg2+ doping significantly improved the comprehensive properties of CBN ceramics, with improved values including a d33 of 11.1 pC/N, Pr of 7.22 μC/cm2, tanδ (600 °C) of 3.0%, and ρdc (600 °C) of 108 Ω?cm. 相似文献
11.
L.H. Francisco J.E. Rodrigues W.R. Correr A.C. Hernandes 《Ceramics International》2018,44(9):10806-10812
High proton conductivity and good chemical stability are keys to development of new electrolytes for PC-SOFCs as the next-future energy generation systems. However, the extensive use of new polycrystalline materials as solid electrolytes is still avoided, since the grain boundary response usually leads to a decrease in total conductivity due to electrical blocking effect. Here, we present our results on the space-charge modeling of impedance spectroscopy data obtained for Ba3Ca1.18Nb1.82-xRxO9-δ proton conducting ceramics, where x?=?0, 0.30 and R =?Y3+, Gd3+, Sm3+, Nd3+ are doping agents. Non-stoichiometric barium calcium niobate perovskites have received much attention as potential solid electrolytes for proton conducting solid oxide fuel cells. We show that despite their increased grain conductivity, the doped ceramics possess Schottky barriers that are higher than those observed for undoped Ba3Ca1.18Nb1.82O9-δ. In view of the space-charge model, proton depletion at the space-charge layer is the reason for the reduction of grain boundary conductivity in the doped compositions. Our findings are important for the understanding of proton conduction mechanisms in polycrystalline materials, which may allow future optimization of new doped electrolytes based on barium calcium niobate perovskites. 相似文献
12.
《Ceramics International》2019,45(14):17157-17162
The (S, N) co-doped Ba2In2-xCrxO5+y (0 ≤ x ≤ 0.5) oxides are successfully obtained by mixing the Ba2In2-xCrxO5+y oxides and thiourea through a simple ball milling method followed by sintering at 400 °C for 3 h. The colors of the compounds change from orange-brown to yellow-green after reacting with thiourea. When Cr amount is small (x = 0.1), the crystal structure of (S, N) co-doped Ba2In2-xCrxO5+y is orthorhombic Ba2In2O5 phase. When x ≥ 0.3, the crystal structure of the sample is cubic BaInO2.5 phase. And this phase transition is the same as Ba2In2-xCrxO5+y. XPS results reveal that Cr6+ in Ba2In2-xCrxO5+y (0 ≤ x ≤ 0.5) oxides are reduced to Cr3+ after sintering. S exists in both cation and anion forms, and N exists in substitutional forms. UV–Vis analysis indicates that the yellow-green hue comes from the d-d transition of Cr3+, and the doping of S, N ions leads to a red shift of the absorption edge of the samples. 相似文献
13.
Min Zhang Xiaoyan Zhang Xiwei Qi Hongen Zhu Ying Li Yaohang Gu 《Ceramics International》2018,44(17):21269-21276
A lead–free multiferroic ceramic 0.7BiFeO3–0.3BaTiO3 showed strong ferroelectric and piezoelectric properties, but weak magnetic and magnetoelectric properties. We herein expected that the electrical and magnetic properties of 0.7BiFeO3–0.3BaTiO3 ceramics could be enhanced by introducing LaFeO3. (0.7–x) BiFeO3–0.3BaTiO3–xLaFeO3 (x?=?0–0.2) were synthesized by solid-state reaction. All the ceramics formed a perovskite structure, and a morphotropic phase boundary (MPB) between rhombohedral and orthorhombic phases formed at x?=?0.025. The ceramics with MPB composition had high unipolar strain (Smax = 0.14%), piezoelectricity (d33 = 223 pC/N, d33 * = 350?pm/V), ferroelectricity (Pr = 25.67 mC/cm2) and magnetoelectricity (aME = 466.6?mV/cm·Oe), which can be attributed to addition of La ions. The improved phase angle also demonstrated augmentation of ferroelectricity on the microscopic view. The ferromagnetism was evidently improved after LaFeO3 doping, and the remanent magnetization Mr increased from 0.0207 to 0.0622?emu/g with rising x from 0 to 0.075. In conclusion, with strong magnetoelectric properties, the prepared ceramics may be applicable as promising lead–free multiferroic ceramic materials for novel electronic devices. 相似文献
14.
In this work, we prepared CaSr1-xAl2SiO7:xCe3+ (0.03 ≤ x ≤ 0.12) and CaSr0.94Al2SiO7:0.03Ce3+,0.03 M+ (M+ = Li+ and Na+) phosphors via solid-state reaction method. Structural and photoluminescence (PL) properties of the phosphors were also investigated. The prepared phosphors formed an orthorhombic crystal structure with the P212121 space group. CaSr1-xAl2SiO7:xCe3+ phosphors were effectively excited by near-ultraviolet (UV) light (345 nm), which is suitable with the emission of near-UV light emitting diode chips. A broad blue emission (402 nm) was detected in CaSr1-xAl2SiO7:xCe3+ and CaSr0.94Al2SiO7:0.03Ce3+,0.03 M+ phosphors; this was attributed to the 4f05d1 → 4f1 transition of Ce3+. To maintain charge equilibrium, charge compensators, such as monovalent Li+ and Na+ ions, were doped into the CaSr0.97Al2SiO7:0.03Ce3+ phosphor, significantly improving its PL properties. The strongest emission intensity was achieved in CaSr0.94Al2SiO7:0.03Ce3+,0.03Li+ phosphor. Addition of Li+ charge compensator was highly effective in improving PL properties of CaSr0.97Al2SiO7:0.03Ce3+ phosphors. 相似文献
15.
《Ceramics International》2017,43(16):13661-13669
We report nanoparticles of Mn2+ doped Mg0.5Zn0.5−xMnxFe2O4 (x = 0, 0.125, 0.250, 0.375, 0.500) ferrites synthesized via co-precipitation route for hyperthermia applications. The prepared samples have been characterized by XRD, FT-IR, FE-SEM, VSM and Photoluminescence spectroscopy for various physical properties. The variation in structural parameters has been obtained with Mn2+ substitution. The confirmation of intrinsic vibration of metal ions at octahedral sites and tetrahedral sites obtained with the help of FT-IR spectra has been reported. The inception of soft-ferri-magnetic behaviour with Mn2+ substitution (x > 0) has been obtained. The variation in magnetic behaviour with Mn2+ substitution indicates enhancement in A-B super-exchange interaction. The confirmation of enhancement in A-B super-exchange interaction with the help of Yafet-Kittel angles and proposed cation distribution has also been reported. The room temperature photoluminescence spectra show a non-linear variation in band edge emission with Mn2+ substitution. The nanoparticles have shown soft ferri-magnetic behaviour for Mn2+ doped samples and results support the candidature of synthesized nanoparticles for hyperthermia applications. 相似文献
16.
Mehrdad Zahedi S.A. Hassanzadeh-Tabrizi A. Saffar-Teluri 《Ceramics International》2018,44(9):10169-10174
Ba2SiO4:Sm3+ nanostructure phosphors have been synthesized by a simple sol-gel method. Phase evaluation, structural characteristics and photoluminescence properties of the synthesized Ba2SiO4:Sm3+ powders were studied using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FTIR), and photoluminescence spectroscopy (PL). X-ray diffraction results showed that all synthesized samples were single-phase barium silicate (Ba2SiO4) and samarium (Sm) ions were incorporated into the lattice of Ba2SiO4. Adding samarium to barium silicate changed the microstructure from vermicular to spherical structures. The Photoluminescence spectrum of Ba2SiO4:Sm3+ phosphors exhibited characteristic emission peaks at 562?nm which is due to the 4G5/2 →6H7/2 transition of samarium ions and corresponds to the orange region. The results showed that the barium silicate activated with 0.08?mol samarium exhibited the highest PL intensity. 相似文献
17.
We studied the influence of Ba2+ doping on the thermoelectric properties of the p-type Bi1–xBaxCuSeO (0?≤?x?≤?0.21) fabricated by spark plasma sintering. The substitution of Ba2+ for Bi3+ gradually increased the electrical and thermal conductivities and decreased the Seebeck coefficient, which were due to the increased hole concentration. The largest value of dimensionless figure-of-merit (0.57) was obtained for the Bi0.86Ba0.14CuSeO at 500?°C, which was over three times greater than that of pristine BiCuSeO (0.18) at 500?°C. We believe that the thermoelectric properties of BiCuSeO were substantially enhanced through the partial substitution of Ba2+ for Bi3+. 相似文献
18.
Linjie Gao Shengjun Zhai Ran Liu Nian Fu Jianglong Wang Guangsheng Fu Shufang Wang 《Journal of the American Ceramic Society》2015,98(10):3285-3290
Polycrystalline Cd1?xBaxO (0 ≤ x ≤ 0.08) ceramics were synthesized via conventional solid‐state reaction method, and the effect of Ba2+ doping on the microstructure as well as the thermoelectric transport properties of the samples were investigated. It was found that doping of Ba2+ can inhibit the grain growth of CdO, resulting in a considerable reduction in grain size. Moreover, with the increase in Ba2+ doping content, both the electrical conductivity and the thermal conductivity of Cd1?xBaxO decreased, whereas the Seebeck coefficient increased. A high ZT value of 0.47 was achieved for Cd0.99Ba0.01O at 1000 K, 38% higher than the undoped CdO, mostly due to reduction of the thermal conductivity. 相似文献
19.
M. Sukumar L. John Kennedy J. Judith Vijaya B. Al-Najar M. Bououdina 《Ceramics International》2018,44(15):18113-18122
Barium doped La2CuO4 perovskite nanoparticles were synthesized via microwave assisted combustion method. The effects of Ba2+ doping on structural, optical, magnetic and catalytic activity of La2CuO4 have been studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) and vibrating sample magnetometer (VSM) techniques. The XRD patterns of pure La2CuO4 and La1.9Ba0.1CuO4 confirmed the formation of perovskite structure without impurities. However, with increasing Ba2+ content in the range 0.2–0.5, phase transformation from orthorhombic to tetragonal structure, occurred. The average crystallite size of orthorhombic and tetragonal phases were in the range 45.2–52.2?nm and 0.5–41?nm, respectively. The appearance of FT-IR bands at around 685 and 517?cm?1 were correlated to the La-O and Cu-O stretching modes of orthorhombic La2CuO4 phase. The direct band gap estimated using Kubelka–Munk (K–M) method decreased with the increase in Ba2+ content (1.88–1.64?eV), due to the formation of sub-bands in the energy band gap. Magnetic measurements of doped La2CuO4 samples showed either para- or ferro-/para- magnetic behaviour at room temperature. The catalytic activity (oxidation) tests carried out in a batch reactor operating under atmospheric conditions indicated that the prepared catalysts, in particular (La1.7Ba0.3CuO4), showed excellent catalytic activity. 相似文献
20.
We have prepared Ba1-xSrxCoFe11O19 hexaferrite nanoparticles (NPs) by using a co-precipitation method. The crystal/electronic structures and magnetic properties were then studied. Results revealed that all Ba1-xSrxCoFe11O19 NPs with particle sizes of 100–300?nm crystallized in a hexagonal structure. Both the particle shape and the unit-cell parameters are changed when Sr content (x) increases. The analysis of the electronic structure based on the Fe and Co K-edge XAS spectra proved the oxidation states of Fe and Co to be 3?+?and 2?+?, respectively, which are stable versus an x change in Ba1-xSrxCoFe11O19. Local-structural studies also revealed the average bond length between Fe and O of 1.89–1.91?Å less changed by Sr doping. Though the electronic structures of Fe and Co were unchanged, the studies about the magnetic property demonstrated a strong dependence of Ms and Hc on Sr doping. While Ms decreases from 46.1?emu/g for x?=?0–34.2?emu/g for x?=?1, Hc tends to increase from 1630?Oe for x?=?0 to ~ 2200?Oe for x?=?0.5, but slightly decreases to 2040?Oe for x?=?1. We think that the addition of the exchange interaction between Fe3+ and Co2+ ions and the changes of local-geometric structures and microstructures influenced directly Ms and Hc of NPs. 相似文献