“…The larger coercivity of ~400 kA/m in the Y samples is a consequence of finer grain sizes compared to the X samples [see Section III (3) ]. Such a significant decrease in the coercivity due to the grain growth was reported before in. At the same time, the secondary phases, which are only present in the X samples, can also affect the coercivity as a source of internal demagnetizing fields .…”
We have investigated the sintering behavior of Sr hexaferrite (SrFe 12 O 19 ) and the effects of adding CuO, which partly substituted for the Fe 2 O 3 and the Fe deficiency during the sintering. For the experiments, samples with nominal compositions of SrCu x Fe yÀx O 19Àd (x = 0-1.0, y = 11-12) were prepared with a solid-state reaction at 1000°C. The overall shrinkages and the shrinkage rates were followed using dilatometry during the sintering. The addition of CuO was found to enhance the sintering rate of the Sr hexaferrite significantly at temperatures below 1100°C, whereas the Fe deficiency had only a moderate effect on the sintering above 1100°C. The relative densities of the Sr hexaferrite ceramics containing Cu sintered at 1000°C for 3 h were above 90%, whereas the Cu-free Sr hexaferrite ceramics only started to sinter at 1000°C. We have shown that the addition of CuO enabled the reactive liquidphase sintering of Sr hexaferrite at 1000°C. P. Joy-contributing editor Manuscript No. 30767.
“…The larger coercivity of ~400 kA/m in the Y samples is a consequence of finer grain sizes compared to the X samples [see Section III (3) ]. Such a significant decrease in the coercivity due to the grain growth was reported before in. At the same time, the secondary phases, which are only present in the X samples, can also affect the coercivity as a source of internal demagnetizing fields .…”
We have investigated the sintering behavior of Sr hexaferrite (SrFe 12 O 19 ) and the effects of adding CuO, which partly substituted for the Fe 2 O 3 and the Fe deficiency during the sintering. For the experiments, samples with nominal compositions of SrCu x Fe yÀx O 19Àd (x = 0-1.0, y = 11-12) were prepared with a solid-state reaction at 1000°C. The overall shrinkages and the shrinkage rates were followed using dilatometry during the sintering. The addition of CuO was found to enhance the sintering rate of the Sr hexaferrite significantly at temperatures below 1100°C, whereas the Fe deficiency had only a moderate effect on the sintering above 1100°C. The relative densities of the Sr hexaferrite ceramics containing Cu sintered at 1000°C for 3 h were above 90%, whereas the Cu-free Sr hexaferrite ceramics only started to sinter at 1000°C. We have shown that the addition of CuO enabled the reactive liquidphase sintering of Sr hexaferrite at 1000°C. P. Joy-contributing editor Manuscript No. 30767.
“…The calculated M r /M s in this study was found to be in the range of 0.63 to 0.65, indicating that all the samples are predominantly in single magnetic domain structure [43]. M r /M s equal to or above 0.5 indicates that the particles are in the single magnetic domain and below 0.5 may be attributed to the formation of multidomain structure [43, 44]. Fig.…”
Synthesis of nanocrystalline strontium ferrite (SrFe12O19) via sol–gel is sensitive to its modification parameters. Therefore, in this study, an attempt of regulating the pH as a sol–gel modification parameter during preparation of SrFe12O19 nanoparticles sintered at a low sintering temperature of 900 °C has been presented. The relationship of varying pH (pH 0 to 8) on structural, microstructures, and magnetic behaviors of SrFe12O19 nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning microscope (FESEM), and vibrating sample magnetometer (VSM). Varying the pH of precursor exhibited a strong effect on the sintered density, crystal structure and magnetic properties of the SrFe12O19 nanoparticles. As the pH is 0, the SrFe12O19 produced relatively largest density, saturation magnetization, Ms, and coercivity, Hc, at a low sintering temperature of 900 °C. The grain size of SrFe12O19 is obtained in the range of 73.6 to 133.3 nm. The porosity of the sample affected the density and the magnetic properties of the SrFe12O19 ferrite. It is suggested that the low-temperature sintered SrFe12O19 at pH 0 displayed Ms of 44.19 emu/g and Hc of 6403.6 Oe, possessing a significant potential for applying in low-temperature co-fired ceramic permanent magnet.
“…17 On the other hand, we have recently shown that the δm may take both positive and negative values even for powder samples if the grains are in single domain limit and the secondary phases are existent in addition to the main BaFe 12 O 19 phase. 18 Studied samples are neither in single domain limit nor including impurity phases. That is, bulk natures of the studied samples may be the reason of observed positive and negative plots.…”
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