Elemental substitution at Tl-site of TlSr2CaCu2O7 superconductor: A review

This review is on the effects of elemental substitutions at the Tl-site of TlSr₂CaCu₂O₇ (Tl-1212) superconductor. The objective of this paper was to determine the elements that enhance or suppress the superconducting transition temperature, T_c of (Tl_1-xM_x)Sr₂CaCu₂O₇ phase. The elements included in this review were M = Pb, Bi, Cr, V, Re, Zr, In, Er, Gd, Na, K, Rb and Se. The relations between transition temperature and the ionic radius, coordination number, valence state and optimization of the hole concentration of the selected elements were studied. The preparation methods, sintering temperature, Tl-1212 phase and structural stability were also discussed. All alkali metals (K, Na and Rb) suppressed the transition temperature of the Tl-1212 phase. The transition temperature generally decreased linearly with ionic radius except for Cr which showed the highest T_c although its ionic radius is smaller.     

A new technique to achieve thick Tl2Ba2CaCu2O8 films for advanced applications

Tl₂Ba₂CaCu₂O₈ (Tl-2212) high-temperature superconductors (HTS) exhibit excellent superconductivity performance as their critical temperature (T_c) is higher than 100 K. However, the emergence of microcracks on the film surface restricts the thickness of the obtained Tl-2212 films, thus greatly limiting their scientific research and engineering application. Here, we fabricate crack-free Tl₂Ba₂CaCu₂O₈ (Tl-2212) films with a thickness of up to 5 μm on LaAlO₃ (001) substrates synthesized by an improved strategy of a closed system. The impact of the thickness of the Tl-2212 films on their crystallographic orientations, T_c, critical current density (J_c) (0 T), critical current intensity (I_c) (0 T), and microwave surface resistance (R_s) was systemically explored. As the thickness increases, T_c values fluctuate slightly above 100 K while the variation of J_c follows the extended strong pinning theory. I_c of the 4 μm thick film stays around 80 A at 95 K, and the R_s result is less than 1 mΩ at 93 K, indicating their excellent performance at high temperatures. The interaction mechanism between the J_c and R_s of the Tl-2212 film is replenished in light of the quantitative exploration of J_c and R_s. This work on Tl-2212 films will promote their fundamental physics research and guide their potential applications in the electronics and electrical field. It can also serve as a reference for future research on other HTS materials.     

Superconducting fluctuation and infrared absorption of Cd-substituted Tl0.9Bi0.1Sr1.8Yb0.2Ca1−xCdxCu1.99Fe0.01O7−δ ceramics

Tl_0.9Bi_0.1Sr_1.8Yb_0.2Ca_1?xCd_xCu_1.99Fe_0.01O_7?δ (x=0–0.4) ceramics were prepared using the conventional solid-state synthesis method to investigate the effects of Cd²⁺ substitutions on superconducting fluctuation behavior, SFB and structural properties of the Tl1212 derivatives. Electrical resistivity measurements showed all the samples exhibit metallic normal-state behavior with zero resistivity critical temperature, T_{c zero} increasing from 40.0 K (x=0) to 76.4 K (x=0.3) before decreasing to 74.8 K (x=0.4) with increasing Cd²⁺. FTIR analysis in conjunction with XRD results indicates improved inter-plane coupling that is evidenced in the form of decreased c-axis length and softening of the apical oxygen mode when Cd concentration was increased. In order to study the effect of Cd substitutions on SFB, excess conductivity analysis above T_c was performed using the Aslamazov–Larkin, AL model in conjunction with the Lawrence–Doniach, LD model. The results showed cross-over between two-dimensional, 2D to three-dimensional, 3D SFB transition for all the samples (x=0.1–0.4) with decreasing temperature. The highest transition temperature, T_2D–3D was observed at x=0.3 which showed both the longest coherence length, ξ_c(0) and the highest inter-plane coupling constant, J within the series. Our results suggest that the increase in J and lowering of anisotropy, γ resulted in enhancement of superconductivity in the compound.     

Thermal stability improvement of dielectric properties and non-ohmic characteristic of CaCu3+xTi4O12 ceramics via a Cu-nonstoichiometric approach

In this work, the effects of Cu composition on the thermal stability of the dielectric and nonlinear properties of CaCu_3+xTi₄O₁₂ (?0.2 ≤ x ≤ 0.2) ceramics obtained via a polymer-pyrolysis chemical process were studied. The mean grain sizes of Cu-stoichiometric (x = 0), Cu-deficient (x < 0) and Cu-excess (x > 0) CaCu_3+xTi₄O₁₂ ceramics were found to be ~3.2, ~3.4 and ~3.7 μm, respectively. Interestingly, very good dielectric properties (0.020 ≤ tanδ ≤ 0.038 and 4000 ≤ ε′ ≤ 7065) were attained in CaCu_3+xTi₄O₁₂ (?0.2 ≤ x ≤ 0.1, excluding x = 0.2) ceramics. Moreover, the variation of dielectric constant (ε′) within a limit of ±15% (Δε′_{± 15%}) over a wide temperature range (T_R) of ?70 – 220 °C with low tanδ < 0.05 (tanδ_<0.05) over a T_R of ?70 to 80 °C were achieved in a CaCu_2.8Ti₄O₁₂ ceramic. These results suggest that this ceramic could be applicable for X9R capacitors and energy storage devices that require high thermal stability. Additionally, the nonlinear properties of Cu-nonstoichiometric ceramics could be improved when compared with those of the Cu-stoichiometric material. The incremental changes of dielectric and nonlinear properties of CaCu_3+xTi₄O₁₂ (?0.2 ≤ x ≤ 0.2) ceramics revealed the significant role of Cu composition on grain boundary resistance (R_gb), which was confirmed by impedance spectroscopy analysis. In addition, XANES results revealed the proper ratios of Cu⁺:Cu²⁺ and Ti³⁺:Ti⁴⁺ found in these ceramics, indicating the semiconducting behavior of these grains.     

The physical and photocatalytic properties of thallium doped cobalt ferrites for efficient hydrogen fuel production

Herein, a series of CoFe_2-xTl_xO₄ (0.03 ≤ x ≤ 0.15) nanoceramics were prepared via a meso-2,3-dimercaptosuccinic acid assisted solvothermal route. The influence of a thallium ion dopant on the structural, magnetoptical, electrical, and photocatalytic characteristics has been scrutinized. The X-ray diffraction demonstrated that CoFe_2-xTl_xO₄ nanoceramics have a cubic structure at all Tl ions concentrations. The Raman scattering spectroscopy revealed the reshuffling of the iron cation between the tetrahedral and octahedral sites of the structure of ferrite due to the substitution with Tl ions. The magnetic properties showed an increase of the saturation magnetization from 59.5 emu/g to 67.4 emu/g and an increase of the coercive field from 344.2 Gauss to 583.1 Gauss with increasing the amount of Tl cations. The optical band gap decreases with the increase of Tl ion concentration. The activation energy decreases from 0.44 eV to 0.26 eV with increasing the Tl ion concentration. These unique physical properties gave rise to the outstanding capability of the as-synthesized CoFe_2-xTl_xO₄ nanoceramics for the photocatalytic production of hydrogen fuel.     

Ferroelectric Phase Transition,Interfaces Quality,and Stress Evolution of TiOx/BaxSr1−xTiO3 Structures

Ba(Sr,Ti)O₃ material presents a remarkable property that lies in the possibility to change the permittivity by applying a dc electric field, i.e., BST is a tunable material. That makes BST a very interesting material for the development of reconfigurable devices in microelectronics. In this study, we focus our work on Ba(Sr,Ti)O₃ with Ba/Sr = 30/70, the films are deposited by radio‐frequency magnetron sputtering on Al₂O₃ (0001). A buffer layer of TiO_x is used to control the film orientation. The influence of this buffer layer on the dielectric properties, the interfaces quality with respect to the film thickness, and the temperature is analyzed. An increase of 30% of the relative permittivity was measured and a tunability of 50% was attained at 300 KV/cm. The dielectric measurements on BST/TiO_x as a function of the temperature show a shift of the Curie temperature (T_c = ?40°C) in comparison to BST without TiO_x layer (T_c = ?80°C). We demonstrate that the Curie temperature does not correspond to the maximum permittivity. The important stress measured on the films (930 MPa) could explain this behavior.     

Crystal structure and microwave dielectric properties of (Ba1−αSrα)6−3xSm8+2xTi18O54 solid solutions

The tungstenbronze-type-like (Ba_1−αSr_α)_6−3xR_8+2xTi₁₈O₅₄ (R = rare earth) solid solutions have been studied. Microwave dielectric properties of these solid solutions link to the substitution of large cations such as Ba ions by small Sr ions. In these solid solutions for x = 0, the quality factor (Q·f) exibits extremely low due to the inner strain resulting by the occupation of large Ba ions at relatively small A1-sites. However, dielectric constant (ɛ_r) of this composition show a high value. In this paper, improvement of quality factor (Q·f) by substituting small Sr ions for Ba ions in (Ba_1−αSr_α)_6−3xSm_8+2xTi₁₈O₅₄ solid solutions, where x = 0, is reported. In addition, the relationship between crystal structure and microwave dielectric properties is discussed from the viewpoint of structural formula and occupational state of large cations such as Ba, Sr and Sm in A1-sites.     

Effects of A1/A2‐Sites Occupancy upon Ferroelectric Transition in (SrxBa1−x)Nb2O6 Tungsten Bronze Ceramics

The dielectric and ferroelectric characteristics of (Sr_xBa_1?x)Nb₂O₆ unfilled tungsten bronze ceramics have been investigated together with the structure. The dielectric and ferroelectric characteristics of the present ceramics vary significantly with x, and the A1/A2‐sites occupancy has been determined as the primary parameter governing this variation tendency. Ba ions tend to occupy A2‐sites, Sr ions tend to occupy A1‐sites, and one A1‐site is empty. When the ratio of Sr/Ba is close to 1:4 (where four A2‐sites are just occupied by Ba ions, and one A1‐site is occupied by Sr ion while another A1‐site is empty), the normal ferroelectric transition is observed with one anomaly in the tanδ–T curve (x = 0.25). When the ratio of Sr/Ba is far away from 1:4, the typical relaxor behavior is indicated together with three anomalies in the tanδ–T curve (x = 0.75). The incommensurate oxygen octahedral tilting and A‐site random distribution are considered to be the structure origins for the relaxor ferroelectricity and low temperature dielectric relaxations.     

The low-temperature sintering of M-type hexaferrites

The sintering of the M-type hexaferrites, AFe₁₂O₁₉ (A = Ba, Sr), was studied. The effects of the A cation type, the partial CuO substitution for Fe₂O₃ and the Fe deficiency on the sintering were examined. Samples with nominal compositions of Ba_1?zSr_zCu_xFe_y?xO_19?δ (z = 0 or 0.5, x = 0–1.0 and y = 11–12) were prepared with a solid-state reaction at 1000 °C. The CuO addition enhanced significantly the sintering rate of the hexaferrites at temperatures below 1100 °C, while a moderate effect on the sintering was caused by a partial substitution of Sr for Ba. The diffusion studies showed that the CuO addition enabled the reactive liquid-phase sintering of hexaferrites at 1000 °C. The relative sintered densities of the Cu-containing hexaferrite ceramics sintered at 1000 °C for 3 h were around 90%. The addition of CuO had a strong effect on the coercivity, but only a moderate effect on the magnetization of the studied ceramics.     

Magnetic doping effects on the superconductivity of Y1-xMxBa2Cu3O7-δ (M = Fe,Co, Ni)

The discovery of superconductivity in copper oxide compounds has attracted considerable attention over the past three decades. The high transition temperature (T_c) in these compounds, exhibiting proximity to an antiferromagnetic order in their phase diagrams, remains one of the main areas of research. It is believed that magnetic fluctuations provide substance for the exotic superconductivity observed in these compounds. The present study attempts to introduce Fe, Co and Ni magnetic impurities into the superconducting cuprate YBa₂Cu₃O_7-δ with the aim of exploring the T_c behavior. The solid-state synthesis method is exploited to prepare fully oxygenated Y_1-xM_xBa₂Cu₃O_7-δ (Y_1-xM_x-123) (M = Co, Fe, Ni) samples with low levels of doping (0.00000 ≤ x ≤ 0.03000). Systematic measurements are then employed to assess the synthesized samples using AC magnetic susceptibility, electrical resistivity and X-ray diffraction (XRD). The measurements revealed an increase in T_c as a result of magnetic substitution for Y. However, the study of non-magnetic dopings on the fully oxygenated Y_1-xM'_xBa₂Cu₃O_7-δ (Y_1-xM'_x-123) (M' = Ca, Sr) samples showed a decrease in T_c. Quantitative XRD analysis further suggested that the internal pressure could have minor effects on the increase in T_c. The normal state resistivity vs temperature showed a linear profile, confirming that the samples are at an optimal doping of the carrier concentration.     

Sol-gel auto-combustion synthesis of Ba–Sr hexaferrite ceramic powders

We report the mechanism involved in sol-gel auto-combustion synthesis of Ba–Sr-hexaferrite (Ba_1-xSr_xFe₁₂O₁₉; x = 0, 0.25, 0.5, 0.75 and 1, BSFO) ceramic powders through the analysis of the phases evolved during annealing of the as-synthesized powders, along with their structure and morphological studies. The XRD patterns of the as-synthesized samples indicate the formation of barium/strontium monoferrite ((Ba/Sr)Fe₂O₄) and maghemite (γ-Fe₂O₃) phases along with a minute amount of hematite (α-Fe₂O₃) phase. Annealing of these samples facilitates formation of BSFO phase through the solid state reaction between BaFe₂O₄ and γ-Fe₂O₃ phase. Interestingly, after annealing the samples with x = 0, 0.5 and 1, at 1000 °C for 2 h, we observed that phase pure Ba–Sr hexaferrite structure forms, but for samples with x = 0.25 and 0.75, high amount of hematite (α-Fe₂O₃) phase is observed, especially for x = 0.75. The reason associated with this could be the large difference between the ionic radii of Ba²⁺ and Sr²⁺ ions occupying the oxygen site. Furthermore, our study on annealing dependent phase evolution confirms that, this difference in ionic radii forbids the formation of a single phase Ba–Sr hexaferrite. The growth of clear hexagonal-shaped plate-like particles with varied particle sizes was observed for all the samples. The particle size variation may be due to the influence of the ionic radii difference on the sinterability of the samples. Our study provides a better understanding of synthesis mechanism of Ba–Sr hexaferrite samples.     

Enhanced non-linear current-voltage response of Te-doped calcium copper titanate ceramics

The influence of partial replacement of Ti⁴⁺ ions by Te⁴⁺ in calcium copper titanate lattice on dielectric and non-linear current- voltage (I–V) characteristics was systematically studied. There was a remarkable increase in the values of the nonlinear coefficient (α) with Te⁴⁺ doping concentration in CaCu₃Ti_4-xTe_xO₁₂ (where, x=0, 0.1, 0.2).For instance, the α values increase from 2.9 (x=0) to 22.7 (x=0.2) for ceramics sintered at 1323 K/8 h. The room temperature value of current density (J) at the electrical field of 250 V/cm for CaCu₃Ti_3.8Te_0.2O₁₂ ceramics is almost 400 times higher than that of the pure CaCu₃Ti₄O₁₂ ceramics sintered at 1323 K. A systematic investigation into I–V behaviour as a function of temperature gave an insight into the conduction mechanisms of undoped and doped ceramics of calcium copper titanate (CCTO). The calculated potential barrier value for doped ceramics (~ 0.21 eV) dropped down to almost one third that of the undoped ceramics (~ 0.63 eV).     

Synthesis,structure, CO oxidation,and H2 production activities of CaCu3−xMnxTi4−xMnxO12 (x = 0, 0.5, and 1.0)

Synthesis of nanocrystalline pristine and Mn-doped calcium copper titanate quadruple perovskites, CaCu_3?xMn_xTi_4?xMn_xO₁₂ (x = 0, 0.5, and 1.0) by modified citrate solution combustion method has been reported. Powder X-ray diffraction patterns attest the phase purity of the perovskite materials. Average particle sizes of all the materials obtained from the Scherrer's formula are in the range of 55–70 nm. The specific surface areas for all the perovskites obtained from BET isotherms are found to be low as expected for the condensed oxide systems and fall in the range of 13–17 m² g^?1. Transmission electron microscopy studies show a reduction in particle size of CaCu₃Ti₄O₁₂ with increase in Mn doping. Ca and Ti are present in +2 and +4 oxidation states in all the materials as demonstrated by X-ray photoelectron spectroscopy analyses. Cu²⁺ gets reduced in CaCu₃Ti₄O₁₂ with higher Mn content. Mn is observed to be present only in +3 oxidation state. All the materials have been examined to be active in CO oxidation as well as H₂ production from methanol steam reforming. CaCu₃Ti₄O₁₂ with ~14 at.% Mn is found to show best catalytic activities among these materials. A comprehensive analysis of the catalytic activities of these perovskites toward CO oxidation and H₂ production from MSR reveal the cooperative activity of copper-manganese in the doped perovskites and it is more effective at lower manganese content.     

Effect of site occupancies of rare earth ions on electrical properties in Ni-MLCC based on BaTiO3

The site occupancies of rare earth ions for Ba-site to Ti-site were quantitatively estimated in (Ba_1−x,R_x)(Ti_1−x,R_x)O₃ (R = Eu, Ho), (Ba_1−3xEu_2x)TiO₃, and Ba(Ti_1−2xEu_2x)O_3−x systems by applying the Rietveld refinement to the data obtained from the synchrotron radiation powder diffraction measurement. The occupational ratio of Ba-site to Ti-site for the larger rare earth ion (Eu) was 49/51 (x = 0.10), whereas for the smaller ion (Ho) was 9/91 (x = 0.01) in (Ba_1−x,R_x)(Ti_1−x,R_x)O₃ system. Furthermore, the occupational ratio was greatly dependent on the Ba/Ti ratio, in (Ba_1−3xEu_2x)TiO₃ system it was 92/8 (x = 0.03), whereas that in Ba(Ti_1−2xEu_2x)O_3−x system was 20/80 (x = 0.01). The Curie point shifted to lower temperature effectively with increasing in the occupational ratio of rare earth ion into Ba-site.     

Effects of Al doping upon ac susceptibility of Pr0.5Ca0.5MnO3

Pr_0.5Ca_0.5Mn_1?xAl_xO₃ (0≤x≤0.07) compounds were prepared by standard solid-state reaction. The ac susceptibility of the samples at low temperatures was investigated. The real component χ′ peak at the freezing temperature T_f is suppressed with increasing the frequency. χ′ shows a linear relation between T_f and the logarithm of the frequency. The normalized slope P=ΔT_f/T_fΔ log₁₀ω is much lower than for canonical insulating spin glass systems (0.06≤P≤0.08). The intensity of imaginary component χ″ at T_f for the x=0, 0.01, 0.02 samples increases with increasing frequency. The results of χ′ and χ″ suggest that the x=0, 0.01, 0.02 samples have a cluster glass ground state. The intensity of χ″ at T_f for the x=0.05, 0.07 samples decreases with increasing frequency, suggesting a phase separation ground state. The intensity of χ″ at T_f for the x=0.03, 0.04 samples decreases with increasing frequency for ω≤701 Hz and increases with further increase of frequency. This complex behavior is ascribed to the competition between the effects of large and small ferromagnetic clusters in the sample. The ground state of the x=0.03, 0.04 samples is the transition state from cluster glass (for the x=0.02 sample) to phase separation (for the x=0.05 sample). AFM cluster blocking and the spin blocking were observed in the same sample.     

Microwave dielectric properties of tungstenbronze type like (Ba1−αSrα)6−3xR8+2xTi18O54 (R = Sm,Nd) solid solutions

Tungstenbronze type like Ba_6−3xR_8+2xTi₁₈O₅₄ (R = Sm or Nd) dielectric ceramics reveal high quality factor Q·f as well as high dielectric constant ɛ_r. We have investigated the effect of Sr substitution for Ba ions on the microwave dielectric properties of the compounds. (Ba_1−αSr_α)_6−3xR_8+2xTi₁₈O₅₄ (R = Sm or Nd) ceramics were prepared in the composition ranges of x = 0–0.2 and α = 0–0.312 and the microwave dielectric properties were investigated. (Ba_1−αSr_α)_6−3xSm_8+2xTi₁₈O₅₄, where x = 0.1 and α = 0.298, and (Ba_1−αSr_α)_6−3xNd_8+2xTi₁₈O₅₄, where x = 0.2, α = 0.296 revealed remarkably higher Q·f value among the solid solutions, indicating that Q·f increased with substituting Sr ions into Ba ions at the rhombic A1-site. This fact suggests that relaxation of local distortions at the A1-sites is closely related to improvement of Q·f.     

Effect of deposition parameters on the growth rate and dielectric properties of the Ba(SnxTi1−x)O3 thin films prepared by radio frequency magnetron sputtering

The growth rate and dielectric properties of the Ba(Sn_xTi_1−x)O₃ (BS_xT_1−x) thin films prepared by radio frequency (rf) magnetron sputtering at room temperature have been characterized as a function of deposition parameters. The BS_xT_1−x thin films are amorphous when deposited at low rf power (R_p = 100 and 125 W). The XRD result shows merely a single perovskite (BaTiO₃) structure and the intensity of reflection peaks increases with the rf power increasing from 125 to 150 and 175 W. When the BS_xT_1−x thin film is deposited at R_p = 150 W and room temperature, the deposition rate decreases with the increasing working pressure (W_p) and O₂/(O₂ + Ar) ratio (O_r). The refractive index of the BS_xT_1−x thin films is between 2.1 and 2.3, which shows that the variation of working pressure is not very significant. The dielectric constant of the BS_xT_1−x thin films increases with the R_p increasing from 100 to 150 W and decreases above 150 W. The leakage current density of the BS_0.15T_0.85 thin films nearly displays the ohmic behavior when the electric field is below 50 kV/cm. The conduction mechanism of the BS_0.15T_0.85 thin films involves the Schottky emission (SE) and Poole–Frenkel emission (PF) models. The BS_xT_1−x thin film shows a ferroelectric characteristic in the polarization-electric field plot.     

Effects of alkaline earths and rare earths added to sol-gel alumina on the thermostability and the oxidation activity of the mixed alumina-supported Pt catalysts

Various alumina-based supports were prepared by adding metal elements such as alkaline and rare earths to sol-gel alumina synthesized from aluminium isopropoxide using 2-methylpentane-2,4-diol as a solvent and the influence of the additives on the thermostability of the supports was investigated. It was found that Ba and Sr are the most effective in improving the thermostability of the alumina, La is moderately effective while Zr, Mg and Ca are ineffective. The influence of the additives on the catalytic activities of Pt/CeO _x /MO _y -Al₂O₃ (M=Ba, Sr, La) after the calculation at 1273 K was also investigated. Pt/CeO _x /BaO-Al₂O₃ and Pt/ CeO _x /La₂O₃-Al₂O₃ showed higher catalytic activity than Pt/CeO _x /Al₂O₃, while Pt/CeO _x / SrO-Al₂O₃ showed lower catalytic activity. The activity order was Ba > La = none > Sr in terms of CO and C₂H₄ oxidation.     

Role of gallium ion on the conducting properties of La0.7(Ba,Sr)0.3Mn1−xGaxO3 (x=0.0, 0.1 and 0.2) perovskite

The transport properties of Ga-doped La_0.7(Ba, Sr)_0.3Mn_1−xGa_xO₃ (x=0.0, 0.1 and 0.2) perovskite materials were investigated by admittance spectroscopy over a wide range of temperatures and frequencies. The electronic conduction was found to be dominated by thermally activated hopping and to depend strongly on Ga-content. Results have shown samples with x=0.0 and 0.1 exhibit a metallic behavior at low temperature and a semiconducting one at high temperature. The temperature (T_MI) of the metal–insulator transition was found to be about 180 and 120 K for samples with x=0.0 and 0.1, respectively. Ga doping leads to a depletion in the number of hopping electrons, which suppresses metallicity and pushes the system in semiconductor side. Besides, the activation energy (E_a) deduced from the variation of conductance as a function of temperature, was found to increase from 89 to 165 meV when x increased from 0.0 to 0.2. This increase can be explained by the decrease of charge carriers with increasing Ga-content.     

Phase formation and magnetic properties of M-type lanthanum substituted strontium ferrites

Rare earth ion substitution is one of the most important methods for adjusting the magnetic properties of M-type hexagonal ferrites; however, the regularity of these phase formations has rarely been studied. In this work, La substituted Sr hexaferrite La_xSr_1-xO·nFe₂O₃ (La-SrM, 4.9 ≤ n ≤ 6.0, 0 ≤ x ≤ 0.6) was prepared using the traditional ceramic method. The effects of the Fe/Sr molar ratio (n), calcining temperature, and La³⁺ substitution (x) on SrM phase formation, the crystalline structure, and magnetic properties were investigated. With an increase of x up to a maximum value of 0.5–0.6, a higher calcining temperature is required to form the single M-phase of La-SrM samples. However, the optimal n values of single-phase La-SrM samples differ as the La substitution varies: when x = 0.1, n = 5.5–6.0; x = 0.2, n = 5.5–5.9; x = 0.3, 0.4 and 0.5, n = 5.7–5.8. The magnetic measurements show that La_0.2Sr_0.8O·5.8Fe₂O₃ has the highest specific saturation magnetization (σ_s), which is 2.2% higher than that of unsubstituted SrM (SrO·6Fe₂O₃), while the anisotropic field (H_A), the anisotropic constant (K₁), and Neel point (T_N) of La³⁺ substituted SrM decreased. Detailed structure analyses were conducted to explain the changes in magnetic properties. Fe³⁺ in the spin-up 2a sublattice of La_xSr_1-xO·5.8Fe₂O₃ decreased by approximately 5% from 98.5% (x = 0) to 93.85% (x = 0.4) with an increase in x. Additionally, a small amount of Fe³⁺ was reduced to Fe²⁺ in the spin-down 4f₂ sublattice with the maximum reduction amount of 4.13% reached at x = 0.2, thereby improving σ_s. The decrease in the bond angle of (4f₁) Fe3–O2–Fe5 (12k), (2a) Fe1–O4–Fe3 (4f₁), and (4f₁) Fe3–O4–Fe5 (12k) lead to the weakening of Fe–O–Fe superexchange of La-SrM so that H_A, K_1, and T_n decreased with increasing values of x. This work lays a solid foundation for the study of process regulation and ion substitution of permanent magnet ferrite.