Effects of silicon content on properties of gas-atomized Fe-Si-Cr powders
Fe-Si soft magnetic composites, SMC have some advantages such as excellent dc current superimposed permeability and low core loss over ferrite and Fe-Si bulk cores.
The B2 and DO3 Ordering Reactions in Iron–Silicon Alloys in the Vicinity of the Curie Temperature
AbstractThe ordering reactions in iron–silicon alloys have been studied by transmission electron microscopy in the composition range 10–17 at.-%Si and the temperature range 535–822°C. It has been found that: The A2 → B2 ordering reaction appears to occur homogeneously (i.e. in the non-classical manner) both above and below the Curie temperature, Te . The magnetic interaction suppresses the A2 → B2 critical temperature by about 100°C in Fe–10 at.-%Si. The B2 → DO3 ordering reaction appears to occur homogeneously above Tc , but by nucleation and growth below Tc . Antiphase boundaries nucleate phases with lower degrees of order than has the matrix but not phases with higher degrees of order. Long-range-order fluctuations occur near the critical points of the homogeneous A2 → B2 and B2 → DO3 transformations.
A bifunctional Cr/Yb/Tm:Ca3Ga2Ge3O12 phosphor with near-infrared long-lasting phosphorescence and upconversion luminescence.
Currently, upconversion nanocrystals and long-lasting phosphorescent particles have attracted extensive research interest for their possible applications as bioimaging probes. However, there are few reports concerning the achievement of both upconversion luminescence of lanthanide ions and long-lasting phosphorescence of transition metal ions in a sole host so far. Herein, we demonstrate a novel calcium gallium germanium garnet (Ca3Ga2Ge3O12) host where lanthanide ions such as Tm(3+)/Yb(3+) and transition metal ions such as Cr(3+) can be easily incorporated through substituting the Ca(2+) and Ga(3+) respectively. This Cr/Yb/Tm:Ca3Ga2Ge3O12 phosphor exhibits both broadband near-infrared long-lasting phosphorescence of Cr(3+) with an afterglow time of more than 7000 s and near-infrared to near-infrared upconversion luminescence of Tm(3+). Impressively, it is evidenced that the addition of Yb(3+)/Tm(3+) into Cr:Ca3Ga2Ge3O12 not only results in Tm(3+) upconversion luminescence but also greatly increases Cr(3+) afterglow time. Based on excitation/emission, three-dimensional thermoluminescence, and time-resolved luminescence spectra, the related long-lasting phosphorescence and upconversion luminescent mechanisms are systematically discussed as well.