Substituted Strontium Hexaferrite Research Articles

Synthesis and Characterization of Cu-Co Substituted Strontium Hexaferrite for Magnetic Applications

In this study, the structural and magnetic characterizations of a series of SrCoxCuxFe12-2xO19; 0.0 ≤ x ≤ 0.5 samples, which were produced by the conventional ceramic method, were carried out. The structure was examined by X-ray diffraction (XRD) technique and optical microscopy. A vibrating sample magnetometer (VSM) was used to characterize the ferrimagnetic properties. XRD patterns confirmed the presence of a single phase as Sr-hexaferrite while there were not any peaks of unreacted Fe2O3 phase. The densities varied between 92 – 98 %. XRD patterns of the Sr-hexaferrite samples were slightly modified because of the co-substitution of Cu-Co; however, the magnetic properties changed remarkably. The sample with Cu-Co of x = 0.1 content had the highest saturation magnetization (33.52 emu/g), remanence (19.74 emu/g), and coercivity (4.3 kOe). The synthesized magnetic samples were found to be suitable for the development of attractive ferrimagnetic properties for the current ferrite magnets.

Effect of 10 MeV electron irradiation on structural and magnetic properties of Ti- and Al- substituted strontium hexaferrite SrFe11.3Ti0.4Al0.3O19

The irradiation stability of Ti- and Al-substituted SrFe11.3Ti0.4Al0.3O19 strontium hexaferrite to 10 MeV electron irradiation with the fluences of 1014 and 2·1017 cm−2 was investigated using various characterization techniques such as scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectrum microanalysis, atomic force microscopy, Raman spectroscopy, vibrating sample magnetometry and magnetic force microscopy. Notable changes in lattice vibrations, magnetic domain microstructure and magnetization behavior were obtained after the electron irradiation with the fluence of 2·1017 cm−2. Phonon hardening observed by Raman spectroscopy confirms the increasing disorder in crystalline structure and the presence of spin-phonon coupling in the samples after electron irradiation with the fluence 2·1017 cm−2. It was found that the strongest spin-phonon interactions correspond to A1g vibration modes at trigonal bipyramidal 2b, 2a octahedral, 4f1 tetrahedral sites and E1g mode at 4f2 octahedral site in electron-irradiated SrFe11.3Ti0.4Al0.3O19 hexaferrite, while the most radiation-resistant phonon mode is A1g vibration of the Fe–O bonds at the 4f2 octahedral site. No significant change was observed in magnetic saturation magnitude after electron irradiation. The increase in coercivity and significant decrease of magnitude of the dM/dH derivative of magnetization curves with increasing radiation fluence is attributed to the increase in uniaxial magnetic-crystalline anisotropy. It is found that the fractal dimension of hierarchical magnetic domain structure in SrFe11.3Ti0.4Al0.3O19 continuously decreases with increasing fluence of 10 MeV electron irradiation, which can be caused by the distortion in uniaxial magnetocrystalline anisotropy and irradiation-induced defects.

Structural, ferromagnetic, ferroelectric, and bio-medical behaviour of yttrium doped strontium hexaferrite (SrFe12-xYxO19) nano materials, assisted with sol-gel cost effective technique

Rare earth Yttrium (Y3+) substituted strontium hexaferrite (SrFe12-xYxO19) with X = (0.25–1.0), is synthesized using an economical and chemical-based sol–gel technique. The reflected planes in the XRD patterns justify that samples possessed hexagonal symmetry (P63/mmc space group). Crystallite size and strain calculations for SrFe12-xYxO19 samples were performed with a W-H plot. Lattice constants change minutely but regularly with Y3+ composition. The morphological structure of the sample SrFe12O19, SrFe11.50Y0.50O19, and SrFe11Y1O19 have been visualized from SEM micrographs, which reveal hexagonal crystal symmetry, possessing agglomeration with an average particle size of 49.84 nm, 73 nm, and 39.66 nm respectively. TEM, HRTEM, and SAED have been performed for confirming the lattice fringe distance, the grain size of nanoparticles (NPs), and diffraction planes. Grain size is 44.15 nm and 37.27 nm for X = 0.00 and X = 1.0 composition of Y3+. Raman spectral pattern exhibited that all the peak of the synthesized sample is indexed to Raman vibration modes and strontium hexaferrite (SHF) structure. FTIR analysis supports the stretching of metal-oxygen bonding and helps to find the force constant, bond length, and functional group of samples. The highest luminescent peak is observed at 481 nm, using the PL spectrum. Using UV-Visible spectroscopy direct band gap (Eg) of the synthesized sample was evaluated and is found to decrease from 2.3 eV-1.93 eV with Y3+ concentration. With an increase in the composition of non-magnetic ions of Y3+, Ms and Mr parameters decrease systematically. In contrast, the coercivity value increases drastically from 5983–6595 Oe and is one of the novel works of this report. The occupancy of Y3+ ions in SrFe12-xYxO19 lattice obstructs electrical leakage to generate remnant polarization (Pr) and coercive polarization (Pc) of values 25.45 μC cm−2 and 2.91 kV cm−1 respectively. Moreover, cytotoxicity assay reveals that at lower concentrations up to 250 μg ml−1, the synthesized material SrFe12-xYxO19 for X = 0.00 and X = 1.0 promotes the growth of cell and hence represents non-toxic and biocompatible behavior with cell. Hence anticipation can be made that it may be used for biological and biomedical applications such as bone replacement, magnetic drug delivery, and coating on metal implants. Thus, improved physical properties of Y3+ doped SHF nanomaterials pave the way for promising optical, magnetic, electrical, biological, and biomedical applications.

Multi-susceptible single-phased hexaferrite with significant magnetic switching properties by selectively doping

An effective combustion technique is used to synthesize Sr0.8La0.2Fe12-xCuxO19 (x = 0,1) M-type strontium hexagonal ferrite nanoparticles (SHFNPs). The impact of La and La-Cu substitution on the structural, microstructural, and magnetic characteristics of SHFNPs is scrutinized. The samples are characterized using several experimental techniques, such as x-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and vibrating sample magnetometer (VSM). The obtained results reveal that the single lattice structure of the substituted strontium hexaferrite can be acquired by transforming Fe3+ to Fe2+ on the 2a site. Raman spectroscopy (RS) verifies the formation of all crystallographic sites of hexaferrite. The broadening of 4f2 and 12k peaks indicates the presence of disorder at the crystal sites resulting from the change in the chemical environment after doping with Cu2+ ions. FESEM images reveal flat hexagonal facets of the particle that signify the magneto-plumbite structure. The magnetic results provide high values of both intrinsic coercivity and (BH)max. The obtained data constitute good magnetic characteristics for perpetual magnet applications. Furthermore, the reduced coercivity of the Sr0.8La0.2Fe11CuO19 (SLCHF) sample with high magnetizations can be used to create microwave absorbing and data storage materials.

Enhanced magnetic properties in Sm3+ substituted SrFe12O19

M- Type hexaferrite captivates researchers and industrialists for its diverse usage and applications in different fields such as permanent magnets, storage devices, recording media, radar absorbing materials and many more. In this work, Sm3+ substituted Strontium hexaferrite, Sr1-xSmxFe12O19 (x = 0, 0.05) is synthesized by using ethylene glycol aided sol–gel auto combustion technique. X-Ray Diffraction Technique is employed for the understanding of various structural features. Phase purity of the prepared samples is authenticated by performing Rietveld refinement method. All the studied samples crystallizes in hexagonal magneto-plumbite phase with P63/mmc space group. Crystallite sizes are determined using Scherer equation. Field Emission Scanning Electron Microscopy is used for morphological analysis. Average particle size decreases with Sm3+ substitution in comparison with parent one. Both field and temperature dependent magnetization measurements are accomplished for magnetic properties analysis. Hysteresis curves show Coercivity (Hc) value increases more than two times and saturation magnetization (MS) decreases slightly as compared to parent sample which clearly indicates that the sample can be used as hard ferrites. M−T measurements are carried out with the application of 500 Oe field. Both the sample show transition around 500 °C temperature. Substituted sample also shows a prominent Hopkinson peak in comparison with parent sample.

Effect of configurational entropy on phase formation, structure, and magnetic properties of deeply substituted strontium hexaferrites

Solid solutions based on SrFe 12 O 19 strontium hexaferrite with deep (up to at.67%) co-substitution of triply charged Fe 3+ iron cations by triply charged diamagnetic Al 3+ aluminum, Ga 3+ gallium, and In 3+ indium cations, as well as by paramagnetic Co 3+ cobalt and Cr 3+ chromium cations, were obtained by conventional ceramic technology. This type of substitution leads to the formation of high-entropy phases. The phase composition of the obtained samples was studied by powder X-ray diffraction. The configurational mixing entropy was calculated for all the obtained samples, and its influence on the processes of phase formation was studied. The unit cell parameters are calculated and their dependences on the 〈r B 〉 average ionic radius of the iron sub-lattice are plotted. The average grain size varied within 2–5 μm. The field and temperature properties of the magnetization of the obtained samples were studied. The M s saturation magnetization is determined using the Law of Approach to Saturation. The M r residual magnetization, SQR loop squareness and H c coercivity are also determined. Based on the obtained data, the k magnetic crystallographic anisotropy coefficient and the H a anisotropy field are calculated. All the obtained and calculated values are plotted depending on the 〈r B 〉 average ionic radius of the iron sub-lattice. All plotted dependencies are non-linear. The T mo magnetic ordering and T f freezing temperatures are obtained from the ZFC and FC magnetization data. The cluster nature of the magnetic behavior for all the samples is revealed. The average cluster diameter reaches ∼ 400 nm. The interpretation of the magnetic properties is made taking into account the effect of high configurational mixing entropy and magnetic dilution of the iron sub-lattice.

Improved Electrical Properties of Strontium Hexaferrite Nanoparticles by Co2+ Substitutions.

In this work, the sol-gel route was employed to synthesize a series of Co2+-substituted strontium hexaferrite nanoparticles (Sr1-x Co x Fe12O19, x = 0.0-0.50) to study the effect of cobalt ions doping on the magnetic, electrical, and structural properties of the nanoparticles. The structural analysis of the synthesized nanoparticles, performed by X-ray diffraction, showed the formation of a hexagonal structure having no secondary phases. The morphological analysis, performed through scanning electron microscopy, revealed spherical shaped nanoparticles with uniform distribution. Fourier transform infrared spectra demonstrated two consistent absorption bands indicating the intrinsic stretching vibrations around 600 and 400 cm-1 for tetrahedral and octahedral sites, respectively. It was observed through VSM that with cobalt addition, the saturation magnetization increased and the coercivity decreased. Also, a typical decreasing trend of DC electrical resistivity with increasing temperature measured by a two-probe method confirmed the semiconducting behavior of the synthesized samples. An impedance analyzer was used for the dielectric measurements at room temperature against the alternating frequency range of 250 Hz to 5 MHz, and it was found that the dielectric constant decreased with the increase in cobalt content, suggesting that the doped nanomaterials can be used for microwave absorption, electronics, telecommunication, and other high-frequency applications.

Yttrium doped strontium nano hexaferrites: Influence of yttrium on the structural and magnetic properties of sol-gel synthesized nanocrystalline strontium hexaferrite

Yttrium (Y3+)-substituted strontium hexaferrite nanoparticles with composition SrFe12-x Y x O19 have been synthesized using the sol-gel method. Diverse analytical tools have been applied to characterize the prepared strontium hexaferrite nanoparticles and to analyse the influence of yttrium (Y3+) substitution on the structural and magnetic properties. X-ray diffraction patterns confirm the presence of single phase M-type hexagonal crystalline structure. In fourier-transform infrared spectroscopy, the absorption bands at low wavenumber confirmed the formation of hexagonal ferrites. The vibrating sample magnetometer has been employed to study the magnetic behavior of Y3+ ions substituted strontium hexaferrite. The decrease in saturation magnetization (Ms) and coercivity (Hc) value has been explained on the basis of alteration in magnetic interactions due to the replacement of both Fe3+ ions by the non-magnetic Y3+ ions.

Cation distribution and site occupancy of nanoscale Cu2+-Er3+ substituted strontium hexaferrites via Raman and Mössbauer spectroscopy

In this research, we report on the cation distribution and site occupancy of Cu2+ and Er3+ ions in the hexagonal lattice of M-type strontium hexagonal ferrites with chemical composition Sr1-xCuxFe12-yEryO19 (x=0.0, 0.1, 0.2, and y=0.0, 0.4, 0.5) fabricated using sol-gel autocombustion technique. Raman analysis of the synthesized samples was conducted based on the group theory analysis of hexagonal ferrites based on the D6h symmetry. The Raman active modes based on the mode assignment and symmetry and were typical of M-type hexaferrite. Mössbauer spectroscopy shows the density of the s electron cloud at the 12k, 4f2, and 4f1 is affected by Cu2+-Er3+ substitution which indicate that all the five sexets originate from Fe3+ ion with high spin and that Er3+ ion (with d10 orbitals) occupies Fe3+ ion position at 12k, 4f2, 2a, and 2b sites in different proportion based on the Ligand theory.

Tuning of structural, elastic, luminescence, magnetic, and multiferroic properties of rare earth Ce3+ substituted strontium hexaferrite Ceramic magnetic nanomaterials for its industrial applications

Tuning of structural, elastic, luminescence, magnetic, and multiferroic properties of rare earth Ce3+ substituted strontium hexaferrite Ceramic magnetic nanomaterials for its industrial applications

High magnetic coercive field in Ca‐Al‐Cr substituted strontium hexaferrite

The structural and magnetic properties of Sr0.67Ca0.33Fe9Al3−xCrxO19 submicrometric powders with substitution levels ranging from x = 0 up to x = 3, prepared by sol-gel synthesis method, have been investigated. The powders were characterized by high resolution synchrotron X-ray diffraction, scanning electron microscopy, powder neutron diffraction and MPMS-SQUID magnetometer. The structural analysis shows that upon Ca-substitution of SrFe12O19 at the Sr site and Al–Cr at the Fe sites, the magnetoplumbite structure is preserved, even for large levels of substitutions. The X-ray powder diffraction peak broadening and Williamson-Hall plots analyses indicate an increase of crystallites size and relaxation of the microstrain with increasing amounts of Chromium. The magnetic hysteresis loops reveal high coercivity fields at room temperature, with the highest value of HC = 1125 kA/m (1.41 T) obtained for Sr0.67Ca0.33Fe9Al2.5Cr0.5O19 powder interesting to develop free-Rare Earth high coercivity magnets. The saturation magnetization and remanence values increase monotonically with increasing Cr content while the switching field decreases. The structural Rietveld refinement of combined X-ray/neutron diffraction data shows the affinity of Al3+ and Cr3+ cations to migrate mainly towards (2a) Fe-Oh2 and (12k) Fe-Oh3 sites and only minor amounts is found on the (4f1) Fe-Oh1 octahedral sites. The structural observations corroborate the magnetic properties, demonstrating a correlation between the structure and magnetic properties in Ca–Al–Cr substituted strontium hexaferrite. The role of the particle size to maximize the coercivity properties is discussed.

Compact Self-Biased Q-Band Circulators

This article deals with the design and fabrication of compact self-biased $Q$ -band circulators. A pre-oriented substituted strontium hexaferrite that has a high anisotropy field was used to design a planar circulator at 38 GHz. The component has been measured in the 32–40 GHz frequency band at different temperatures. Measured insertion loss as low as 0.45 dB together with a high isolation level has been demonstrated. Moreover, the component demonstrated a quite stable temperature behavior. However, a slight shift toward low frequencies is observed compared to the simulation. Retro-simulations showed that small variations of the metallic strips’ dimensions induce significant S-parameters changes. These experimental results demonstrate that substituted strontium hexaferrites have a high potential for the realization of ultra-compact $Q$ -band circulator but also that the metallization process resolution is crucial for performance reproducibility.

Dual Ca–Zn substituted strontium hexaferrite; investigation of structural, magnetic and optical properties

In this work, the Sr1-xCaxFe12-yZnyO19 (x = 0, 0.05, 0.1, 0.15; y = 0, 0.25, 0.5, 0.75) hexaferrite were prepared employing the sol-gel combustion method and their structural, magnetic and optical properties were investigated. The formation of the hexaferrite phase was confirmed in all the samples using the X-ray diffraction and Fourier transform-infrared spectroscopy measurements. The field emission scanning electron microscopy images revealed agglomerated particles with rod-like shapes. A vibrating sample magnetometer was used to record the hysteresis loop at room temperature. The results obtained showed a drop in the saturation magnetization from 47.14 to 21.02 emu/g upon an increase in the substitution concentration and an increase in the coercivity from 5520 Oe to 5645 Oe. The bandgap energy values were obtained using the reflectance spectra; they increased from 1.59 eV to 1.72 eV with an increase in the substitution contents.

Erbium-chromium substituted strontium hexaferrite particles: Characterization of the physical and Ku-band microwave absorption properties

A series of erbium-chromium substitution strontium hexaferrite particles with the nominal composition of SrErxCrxFe12-2xO19 was synthesized using the sol-gel auto-combustion method. The crystalline structure, magnetic and microwave absorption properties of the materials were investigated in detail. The TGA/DSC and XRD evaluations by the FULLPROF confirmed the successful substitution of Er and Al cations in the strontium hexaferrite lattice. Moreover, the VSM measurements confirmed that HC, and Mr continuousely decreased by increasing the erbium and chromium substitutions, while MS increases up to x = 0.2, followed by a reduction with the increased amount of the substitution. We also investigate the cause of the changes in the magnetic and microwave absorption properties through simultaneous substitution. The maximum reflection loss of −34.71 dB was observed in the SrEr0.5Cr0.5Fe11O19 sample with a bandwidth that covered the entire measured microwave frequency range of 12–18 GHz (Ku band). This finding suggested that x = 0.5 had effective absorbing characteristics, which is of great interests for the military radar in the Ku band.

Sr(CeNd)xFe12−2xO19/polythiophene nano-particles: Structral investigation, magnetic properties and photocatalyic activity

This paper reports the synthesize of M-Type substituted Strontium hexaferrite via chemical coprecipitation technique in aqueous solution. Moreover, MB degradation by Sr(CeNd)x Fe12−2xO19 (SCNH)(x = 0.2) and polymerized Sr(CeNd)xFe12−2xO19/polythiophene (SCNH/PTh) (x = 0.2) with two stichometry amount (1:1, 1:2) was studied. For more characterization, the FTIR spectrum and X-ray diffractometer represent the pure phase and the structure of aimed nanoparticles while confirm polymerization took place. The hexagonal structure of prepared samples has shown by Surface images of FESEM, the micrographs illuminate, polymer-coated the plate-like hexaferrite which approves polymerization was complete. Hysteresis loops of SCNH and SCNH/PTh depict that they possess magnetic properties that are helpful for magnetical collection from water solution. The photodegradation activity of prepared photocatalysts studied under Uv–vis light. According to data SCNH/PTH (1:2) represented the best photocatalysis degradation ability by 98%. The photodegradation kinetic curve approved that photocatalysis activity obeys first order. The reusability of prepared samples was measured in 3 times repeated experiment and shows although their capability decreased to 89% in SCNH/PTh (1:2), it illuminates acceptable photodegradation ability as well.

Exchange correlation and critical temperature in calcium substituted strontium hexaferrites: Experimental and theoretical evaluation

For magnetic materials, a quantitative description of exchange correlation and critical temperature would be of significance for the electronic devices operating at rather a high temperature. In this work, we fabricated the composition of Sr1−xCaxFe12O19 hexaferrites with a conventional ceramic method. According to the experimental lattice constants, the crystal and electronic structure were optimized employing the density functional theory (DFT), generalized gradient approximation (GGA), and local spin density approximation (LSDA). The GGA + U and LSDA + U methods were adopted to improve the description of strongly correlated 3d electron of Fe. Thirteen independent exchange correlations in these systems were determined by establishing the relationship between total energy of different collinear spin configurations and exchange integral with the Heisenberg model. Derived from the calculation of random-phase approximation (RPA) and mean-filed approximation (MFA), we evaluated the critical temperature of hexaferrites, as compared with the experimental result.

Tb3+ substituted strontium hexaferrites: Structural, magnetic and optical investigation and cation distribution

In this study, SrFe12−xTbxO19 (0.00 ≤ x ≤ 0.1) hexaferrites (HFs) were prepared successfully by citrate sol-gel approach. X-ray powder diffraction analyses affirm the hexagonal structure of products. Impurity phase starts to appear for x ≥ 0.04. The crystallites sizes were estimated to be in the range of 33–46 nm. All the products exhibit inhomogeneous distribution of grain size detected through SEM. The analyses of magnetization versus applied magnetic field, M(H), were performed. Magnetization measurements were done at room (300 K; RT) and low (10 K) temperatures. The different magnetic parameters including saturation magnetization Ms, remanence Mr, squareness ratio (SQR = Mr/Ms), coercivity Hc, and magnetic moment nB are deduced and discussed in detail. At both considered temperatures, M(H) results show ferrimagnetic nature for all compositions. It is shown that the Tb substitutions significantly affect M(H) data. A significant increase in the Ms, Mr, and nB is observed for x = 0.02 sample. The SQR values are around 0.5 indicating the single domain nature with uniaxial anisotropy. The obtained magnetic results were investigated deeply with relation to structural and microstructural properties. Mössbauer spectroscopy results were also investigated. According to Mössbauer results, the Tb3+ ions preferentially occupy 12k and 4f2 sites.

Influence of site preferences on structural and magnetic properties of Cr-Sn substituted SrAl4Fe8O19 hexa-ferrite, an improved ceramic permanent magnet

Chromium and tin substituted strontium hexaferrites {SrAl4(Cr0.5Sn0.5)xFe8 − xO19 with x = 0.0, 0.2, 0.4, 0.6, and 0.8} were synthesized by the sol-gel auto-combustion route. Rietveld refinement of X-ray Diffraction patterns was performed to reveal the phase purity, crystal structure, and unit cell parameters, such as lattice constants, bond angles, and bond lengths. Types of bonds were also verified using Fourier Transform Infrared Spectroscopy. Scanning Electron Microscope was used to explore the effect of substitution on the microstructure. Furthermore, the effect of Cr+3 and Sn+4 substitution on magnetic properties was studied using the Magnetic Property Measurement System. The relationship among the allocation of cations over the 5 sublattices of Fe+3 with substitutions was also analyzed. The saturation magnetization and magnetocrystalline anisotropy were calculated by the “Law of Approach to Saturation magnetization (Ms)” technique at room temperature. The maximum Br and (BH)max was theoretically calculated about 7.62 kG and 7.60 MGOe, respectively, for x = 0.60 composition. Cr-Sn substituted Sr-hexaferrite can be proposed for applications as a permanent magnet with a good deal of consistency.

Y3+ substituted Sr-hexaferrites: sol-gel synthesis, structural, magnetic and electrical characterization

Abstract Y3+ substituted strontium hexaferrites having chemical composition SrYxFe12-xO19 (x= 0.0, 0.5, 1.0, 1.5) were successfully synthesized by sol-gel auto-combustion method. The structural and morphological studies of prepared samples were investigated by using X-ray diffraction technique, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy. The X-ray diffraction pattern confirmed the single-phase hexagonal structure of yttrium substituted strontium ferrite and the lattice parameters a and c increased with the substitution of Y3+ ions. The crystallite size also varied with x content from 60 to 80 nm. The morphology was studied by FE-SEM, and the grain size of nanoparticles ranged from 44 to 130 nm. The magnetic properties were investigated by using vibrating sample magnetometer. The value of saturation magnetization decreased from 49.60 to 35.40 emu/g. The dielectric constant decreased non-linearly whereas the electrical dc resistivity increased with the yttrium concentration in strontium hexaferrite.

Site preference and magnetic properties of Zn-Sn-substituted strontium hexaferrite

The site preference and magnetic properties of Zn, Sn, and Zn-Sn substituted M-type strontium hexaferrite (SrFe12O19) have been investigated using first-principles total-energy calculations based on density-functional theory. The site occupancy of substituted atoms was estimated by calculating the substitution energies of different configurations. The distribution of different configurations during the annealing process at high temperature was determined using the formation probabilities of configurations to calculate magnetic properties of substituted strontium hexaferrite. We found that the magnetization and magnetocrystalline anisotropy are closely related to the distributions of Zn-Sn ions on the five Fe sites. Our calculation shows that in SrFe11.5Zn0.5O19, Zn atoms prefer to occupy 4f1, 12k, and 2a sites with occupation probabilities of 78%, 19%, and 3%, respectively, while in SrFe11.5SnO19, Sn atoms occupy the 12k and 4f2 sites with occupation probabilities of 54% and 46%, respectively. We also found that in SrFe11Zn0.5Sn0.5O19, (Zn,Sn) atom pairs prefer to occupy the (4f1, 4f2), (4f1, 12k), and (12k, 12k) sites with occupation probabilities of 82%, 8%, and 6%, respectively. Our calculation shows that the increase of magnetization and the reduction of magnetic anisotropy in Zn-Sn substituted M-type strontium hexaferrite as observed experimentally are due to the occupation of (Zn,Sn) pairs at the (4f1, 4f2) sites.