In this comparative study,Tb and Tm substituted Sr-hexafe rrites(HFs) with the chemical compositions of SrTb_(x)Fe_(12-x)O_(19) and SrTm_(x)Fe_(12-x)O_(19)(x=0.00,0.02 and 0.04) were fabricated via citrate sol-gel app...In this comparative study,Tb and Tm substituted Sr-hexafe rrites(HFs) with the chemical compositions of SrTb_(x)Fe_(12-x)O_(19) and SrTm_(x)Fe_(12-x)O_(19)(x=0.00,0.02 and 0.04) were fabricated via citrate sol-gel approach.The AC susceptibility and FC-ZFC magnetization were investigated.The product structure and morphologies were also investigated via XRD,TEM and SEM along with EDX.Measurements of temperature dependence of magnetization M-T and AC magnetic susceptibility versus temperature were carried out.The various synthesized HFs displayed ferrimagnetic behavior within 10-325 K.At lower temperatures,super-spin glass-like behavior was noticed.Neel-Arrhenius and Vogel-Fulcher models were employed to explore the experimental data of AC susceptibility.展开更多
In this article we proved so-called strong reflection principles corresponding to formal theories Th which has omega-models or nonstandard model with standard part. A possible generalization of Löb’s theorem...In this article we proved so-called strong reflection principles corresponding to formal theories Th which has omega-models or nonstandard model with standard part. A possible generalization of Löb’s theorem is considered. Main results are: 1) , 2) , 3) , 4) , 5) let k be inaccessible cardinal then .展开更多
Zero field cooled (ZFC) and field cooled (FC) DC magnetization and AC susceptibility of sintered SrRuO 3 were measured over the magnetic ordering temperature. The peak in susceptibility against temperature shifts ...Zero field cooled (ZFC) and field cooled (FC) DC magnetization and AC susceptibility of sintered SrRuO 3 were measured over the magnetic ordering temperature. The peak in susceptibility against temperature shifts to lower temperature when the bias field increases. As the field still increases, the peak breaks into two peaks. One peak still shifts to lower temperature; the other shifts to higher temperature. Zero bias field susceptibility was measured at different frequencies. The peak value decreases as the increase of frequency, but it does not shift to higher temperature as reported previously. The results show that SrRuO 3 is not spin glass, but ferromagnet.展开更多
This study presents the influence of Zn and Nd co-substitution on structure,morphology,AC susceptibility and ZFC-FC magnetizations of Sr nanohexaferrites(NHFs),SrFe12-x(Zn,Nd)xO19(0.0≤x≤1.0),which was produced by so...This study presents the influence of Zn and Nd co-substitution on structure,morphology,AC susceptibility and ZFC-FC magnetizations of Sr nanohexaferrites(NHFs),SrFe12-x(Zn,Nd)xO19(0.0≤x≤1.0),which was produced by sol-gel approach.XRD powder patterns,scanning electron microscopy(SEM) and high-resolution transmission electron spectroscopy(HR-TEM) approve the synthesis of Sr M-type hexaferrite.Mossbauer spectra show that Zn^2+ions occupy 2 b and 4f1 sites while Nd3+ions locate at 2 a,4f2 and 12 k sites.The magnetic properties of the produced Sr-NHFs were investigated also by ZFC-FC magnetizations and AC susceptibility.According to the MFC-MZFC results(between 2 and 400 K),no blocking temperature was detected which indicates the ferromagnetic(FM) behavior of NHFs.At lower temperatures,a super-spin glass like behavior is discerned.The AC susceptibility indicates that the magnetic interactions are improved due to the inclusion of low content(x=0.1) of Nd^3+and Zn^2+ions into the Sr-NHFs.However,with further increasing the Nd^3+and Zn^2+contents(x=0.9),the magnetic interactions are weakened.展开更多
文摘In this comparative study,Tb and Tm substituted Sr-hexafe rrites(HFs) with the chemical compositions of SrTb_(x)Fe_(12-x)O_(19) and SrTm_(x)Fe_(12-x)O_(19)(x=0.00,0.02 and 0.04) were fabricated via citrate sol-gel approach.The AC susceptibility and FC-ZFC magnetization were investigated.The product structure and morphologies were also investigated via XRD,TEM and SEM along with EDX.Measurements of temperature dependence of magnetization M-T and AC magnetic susceptibility versus temperature were carried out.The various synthesized HFs displayed ferrimagnetic behavior within 10-325 K.At lower temperatures,super-spin glass-like behavior was noticed.Neel-Arrhenius and Vogel-Fulcher models were employed to explore the experimental data of AC susceptibility.
文摘In this article we proved so-called strong reflection principles corresponding to formal theories Th which has omega-models or nonstandard model with standard part. A possible generalization of Löb’s theorem is considered. Main results are: 1) , 2) , 3) , 4) , 5) let k be inaccessible cardinal then .
文摘Zero field cooled (ZFC) and field cooled (FC) DC magnetization and AC susceptibility of sintered SrRuO 3 were measured over the magnetic ordering temperature. The peak in susceptibility against temperature shifts to lower temperature when the bias field increases. As the field still increases, the peak breaks into two peaks. One peak still shifts to lower temperature; the other shifts to higher temperature. Zero bias field susceptibility was measured at different frequencies. The peak value decreases as the increase of frequency, but it does not shift to higher temperature as reported previously. The results show that SrRuO 3 is not spin glass, but ferromagnet.
基金supported by the Institute for Research&Medical Consultations(IRMC)of Imam Abdulrahman Bin Faisal University(IAU-Saudi Arabia)(2017-IRMC-S-3,2018-IRMC-S-1,2018-IRMC-S-2).
文摘This study presents the influence of Zn and Nd co-substitution on structure,morphology,AC susceptibility and ZFC-FC magnetizations of Sr nanohexaferrites(NHFs),SrFe12-x(Zn,Nd)xO19(0.0≤x≤1.0),which was produced by sol-gel approach.XRD powder patterns,scanning electron microscopy(SEM) and high-resolution transmission electron spectroscopy(HR-TEM) approve the synthesis of Sr M-type hexaferrite.Mossbauer spectra show that Zn^2+ions occupy 2 b and 4f1 sites while Nd3+ions locate at 2 a,4f2 and 12 k sites.The magnetic properties of the produced Sr-NHFs were investigated also by ZFC-FC magnetizations and AC susceptibility.According to the MFC-MZFC results(between 2 and 400 K),no blocking temperature was detected which indicates the ferromagnetic(FM) behavior of NHFs.At lower temperatures,a super-spin glass like behavior is discerned.The AC susceptibility indicates that the magnetic interactions are improved due to the inclusion of low content(x=0.1) of Nd^3+and Zn^2+ions into the Sr-NHFs.However,with further increasing the Nd^3+and Zn^2+contents(x=0.9),the magnetic interactions are weakened.
