Hydrothermal Synthesis And Ferirmagnetism Of Substituted Garnets

Rare earth ferrite garnets are widely used in microwave communication throughmobile and satellite and are of significant interest for numerous applications includingmagnetic materials, laser, phosphorescent sources and electrochemical devices. Rareearth ferrite garnets which can be described by chemical unit formula Re₃Fe₅O₁2whose cell contains eight Re₃Fe₅O₁2molecules and crystal lattice contains threecrystallographic sites,dodecahedral site24c {Re³⁺}, octahedral site16a [Fe³⁺] andtetrahedral site24d (Fe³⁺)，which can be substituted by other ions. This paper iscommitted to synthesis and ferrimagnetism of the large radius Nd³⁺or Pr³⁺withalkaline earth metal ions Ca²⁺or Sr2+to fill dodecahedral in an ferrite garnet.1. Nd₃xSr_xFe₅O₁2（x=0.2,0.4,0.6and0.8） crystals, which are of cubic structure with_the space group of Ia3d and lattice constants over12.600, were prepared usingthe hydrothermal method. M ssabuer spectroscope demonstrates the coexistenceof Sr2+and Nd³⁺at the C sites of the dodecahedrons. The crystals also appeardodecahedrons with similar sizes as can be seen from the SEM image. Byrecording the magnetic hysteresis loops and M-T curves at high temperature, wefind that with the x increasing, saturation magnetization values decrease while thecoercive forces go up. The curie temperatures of all the samples remain almostunchanged, namely570K, regardless of the x variation.2. Nd₃xSr_xFe₅O₁₂（x=0.2,0.4,0.6,0.8and1.0） crystals were prepared using thehydrothermal method. M ssabuer spectroscope demonstrates the coexistence ofCa²⁺and Nd³⁺at the C sites of the dodecahedrons. By recording the magnetichysteresis loops and M-T curves at high temperature, we find that with the xincreasing, saturation magnetization values decrease while the coercive forces goup.3. Pr_2.2Sr（0.8）Fe₅O₁₂and Pr_2.2Sr（0.8）Fe₅O₁₂were prepared using the hydrothermalmethod. The crystals also appear dodecahedrons with similar sizes as can be seenfrom the SEM image. M ssabuer spectroscope demonstrates the coexistence of Sr²⁺and Nd³⁺at the C sites of the dodecahedrons.