A series of Ni modified hexaaluminates LaNi y Al 12- y O 19- δ ( y =0 3, 0 6, 0 9, 1 0) were prepared by decomposition of nitrates and calcination at high temperature. The crystalline structure and catalytic properti...A series of Ni modified hexaaluminates LaNi y Al 12- y O 19- δ ( y =0 3, 0 6, 0 9, 1 0) were prepared by decomposition of nitrates and calcination at high temperature. The crystalline structure and catalytic properties for CO 2 reforming of methane to synthesis gas were investigated by using XRD, XPS, TPR and TGA techniques. The results showed that a pure hexaaluminate LaNi y Al 12- y O 19- δ phase is formed only when y value is in 0< y ≤1. The reduced hexaaluminates LaNi y Al 12- y O 19- δ exhibit significant catalytic activity and stability for the reaction of CO 2 reforming of methane to synthesis gas at 780 ℃, and no deactivation resulting from carbon deposition is found. In the meantime, the catalytic activity is obviously affected by the modifier Ni in the hexaaluminate lattices. Under the same reaction conditions, the conversion of CH 4 and CO 2 increase with increase in the amount ( y value) of the modifier Ni.展开更多
We present a comparison for the effect of condensation on the morphology and magnetic prop erties of oleic acid modified BaFe_(12)O_(19) nanoparticles.Two different samples of BaFe_(12)O_(19) nanoparticles were synthe...We present a comparison for the effect of condensation on the morphology and magnetic prop erties of oleic acid modified BaFe_(12)O_(19) nanoparticles.Two different samples of BaFe_(12)O_(19) nanoparticles were synthesized by dehydration(Z1) and rotary evaporation(Z2) method,respectively.Oleic acid was used as the surface modification agent to observe the morphological and magnetic changes.The nanoparticles were analyzed by XRD,FTIR,TGA,SEM,and VSM techniques for structural and physicochemical characteris tics.Crystallographic analysis reveals the phase as hexaferrite and the average crystallite size of Z1 and Z2 is 21±3 nm and 17±2 nm,respectively.Rotary evaporator accelerates the condensation process in viscous gel(Z2).Due to the use of rotary evaporator,the coating with oleic acid for Z2 product has been accomplished very well,as compared with Z1.As a result,saturation magnetization of Z2 sample is much lower than that of Z1 sample.展开更多
The magnetic field provided by magnetized SrFe_(12)O_(19)particles in FeSi/SrFe_(12)O_(19)composites is used to replace the applied transverse magnetic field,which successfully reduces the magnetic loss of the composi...The magnetic field provided by magnetized SrFe_(12)O_(19)particles in FeSi/SrFe_(12)O_(19)composites is used to replace the applied transverse magnetic field,which successfully reduces the magnetic loss of the composites with minor reduction of permeability.This magnetic loss reduction mainly comes from the decrease in hysteresis loss,while the eddy current loss is basically unaffected.The hysteresis loss reduction in magnetized composites is believed to be due to the decrease in domain wall displacement caused by the increase in the average magnetic domain size in a DC magnetic field.This is an effective method for reducing the magnetic loss of soft magnetic composites with wide application potential,and there is no problem of increasing the cost and the volume of the magnetic cores.展开更多
Exchange coupling interaction in sintered magnetic materials is generally isotropic.In this study,the anisotropic exchange coupling interaction was found in sintered oblate cylindrical SrFe_(12)O_(19)(SrM)specimens ob...Exchange coupling interaction in sintered magnetic materials is generally isotropic.In this study,the anisotropic exchange coupling interaction was found in sintered oblate cylindrical SrFe_(12)O_(19)(SrM)specimens obtained by the SrM nanopowders synthesized via a hydrothermal method.According to Henkel plots,the exchange coupling interaction between hard-hard magnetic grains was found in both as-pressed and sintered specimens.However,the exchange coupling interaction can only be found in the in-plane direction but not in the out-of-plane direction for thel sintered specimens.By building a model of a grain configuration,this anisotropy of the exchange coupling interaction was ascribed to the vertically arranged plate-like SrM grains with micrometers in width but nanometers in thickness,which was confirmed by morphologies of cross sections in fractured specimens.展开更多
文摘A series of Ni modified hexaaluminates LaNi y Al 12- y O 19- δ ( y =0 3, 0 6, 0 9, 1 0) were prepared by decomposition of nitrates and calcination at high temperature. The crystalline structure and catalytic properties for CO 2 reforming of methane to synthesis gas were investigated by using XRD, XPS, TPR and TGA techniques. The results showed that a pure hexaaluminate LaNi y Al 12- y O 19- δ phase is formed only when y value is in 0< y ≤1. The reduced hexaaluminates LaNi y Al 12- y O 19- δ exhibit significant catalytic activity and stability for the reaction of CO 2 reforming of methane to synthesis gas at 780 ℃, and no deactivation resulting from carbon deposition is found. In the meantime, the catalytic activity is obviously affected by the modifier Ni in the hexaaluminate lattices. Under the same reaction conditions, the conversion of CH 4 and CO 2 increase with increase in the amount ( y value) of the modifier Ni.
基金the Fatih University,Research Pro ject Foundation (Contract No:P50020902-2)Turkish Ministry of Industry and TUBITAK (Contract No:110T487) for financial support of this study
文摘We present a comparison for the effect of condensation on the morphology and magnetic prop erties of oleic acid modified BaFe_(12)O_(19) nanoparticles.Two different samples of BaFe_(12)O_(19) nanoparticles were synthesized by dehydration(Z1) and rotary evaporation(Z2) method,respectively.Oleic acid was used as the surface modification agent to observe the morphological and magnetic changes.The nanoparticles were analyzed by XRD,FTIR,TGA,SEM,and VSM techniques for structural and physicochemical characteris tics.Crystallographic analysis reveals the phase as hexaferrite and the average crystallite size of Z1 and Z2 is 21±3 nm and 17±2 nm,respectively.Rotary evaporator accelerates the condensation process in viscous gel(Z2).Due to the use of rotary evaporator,the coating with oleic acid for Z2 product has been accomplished very well,as compared with Z1.As a result,saturation magnetization of Z2 sample is much lower than that of Z1 sample.
基金supported by the National Natural Science Foundation of China(Grant Nos.51872004 and 51802002)the Key Program of the Education Department of Anhui Province,China(Grant No.KJ2019ZD03)the Science Foundation of the National Key Laboratory of Science and Technology on Advanced Composites in Specials Environments(Grant No.6142905202112)。
文摘The magnetic field provided by magnetized SrFe_(12)O_(19)particles in FeSi/SrFe_(12)O_(19)composites is used to replace the applied transverse magnetic field,which successfully reduces the magnetic loss of the composites with minor reduction of permeability.This magnetic loss reduction mainly comes from the decrease in hysteresis loss,while the eddy current loss is basically unaffected.The hysteresis loss reduction in magnetized composites is believed to be due to the decrease in domain wall displacement caused by the increase in the average magnetic domain size in a DC magnetic field.This is an effective method for reducing the magnetic loss of soft magnetic composites with wide application potential,and there is no problem of increasing the cost and the volume of the magnetic cores.
基金supported by the National Natural Science Foundation of China(Grant No.51772004).
文摘Exchange coupling interaction in sintered magnetic materials is generally isotropic.In this study,the anisotropic exchange coupling interaction was found in sintered oblate cylindrical SrFe_(12)O_(19)(SrM)specimens obtained by the SrM nanopowders synthesized via a hydrothermal method.According to Henkel plots,the exchange coupling interaction between hard-hard magnetic grains was found in both as-pressed and sintered specimens.However,the exchange coupling interaction can only be found in the in-plane direction but not in the out-of-plane direction for thel sintered specimens.By building a model of a grain configuration,this anisotropy of the exchange coupling interaction was ascribed to the vertically arranged plate-like SrM grains with micrometers in width but nanometers in thickness,which was confirmed by morphologies of cross sections in fractured specimens.
