The structural and magnetic features of perovskite oxides La1-xSrxMnO3+? (x=0.05, 0.10, 0.20) depending on the strontium doping content and heat treatment

Sr-doped (00.2) ceramic samples of the lanthanum manganite oxides were obtained via sol-gel method to investigate the influence of doping on structural, magnetic end electronic responses, and their correlations. Synthesized samples of non-stoichiometric compositions are rhombohedral single-phase. After annealing the formation of a phase-separated system as a mixture of orthorhombic phases was found.The R-3c and PnmaI, PnmaII* and PnmaII phases have been studied using Mo spacing diaeresis ssbauer spectroscopy, XRD, SEM analysis and magnetic measurements. The magnetic temperature-concentration phase diagram of La1-xSrxMnO3+delta (x = 0.05, 0.10, 0.20) was obtained. The Jahn-Teller effect or the orbital order breaking, as well as the competition between Mn3+-O2-Mn4+ double-and Mn3+-O2--Mn3+ superexchange interaction was demonstrated under the effect of cation doping compound and interstitial oxygen value (delta). The relaxation character of the Mo spacing diaeresis ssbauer spectra and the type of magnetization dependences revealed nanosized magnetic clusters with fluctuation of their magnetic moment in all perovskite phases. Results are interpreted in terms of matrix - clusters: regions of sample with ferromagnetic type of ordering (cluster) exist in antiferromagnetically or ferromagnetically (with different exchange parameter) ordered matrix. Exchange interaction frustrations of the cluster with the matrix can lead to relaxation behavior of the magnetic moment of the cluster. The clusters size vary from about 3.9 to 5.7 nm. All samples are charac-terized by the presence of particles agglometates with a typical size about 0.4-0.8 mu m; for annealed samples additional non-conducting regions with 80-220 nm in size were found. It is shown that the annealing time significantly affects the production of materials with determined properties and be useful in the applied field in technological processes.

Automated summary

Sr-doped (00.2) ceramic samples of lanthanum manganite oxides were synthesized and their structural, magnetic, and electronic responses were investigated. The doping induced the formation of a mixture of orthorhombic phases in the annealed samples. The study revealed the presence of nanosized magnetic clusters with fluctuating magnetic moments and the influence of matrix-clusters interactions on the relaxation behavior. Additionally, the annealing time affected the production of materials with specific properties, making it useful in technological processes.