In this study,the mechanism of the reduction-diffusion reaction in a Sm-Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)by the low...In this study,the mechanism of the reduction-diffusion reaction in a Sm-Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)by the low-temperature diffusion-reduction(LTRD)process using LiCl-KCl eutectic molten salts.Firstly,the Sm-Fe phase transformation depending on the Sm-Fe composition,the LTRD temperature,and time was investigated,and it is found that the obtained metastable phase is only TbCu_(7)-type SmFe_(~8.5),which is not a Fe-rich phase.This Fe content does not change even after an expended LTRD process,and the metastable TbCu_(7)-type SmFe_(~8.5)tends to transform to the stable Sm_(2)Fe_(17)phase.In addition,it is found that the Sm-Fe phase starts to synthesize from the Sm-rich phase in the order of SmFe_(2),SmFe_(3),and SmFe_(8.5)as the LTRD temperature increases(when the time was 10 h)or the LTRD time increases(when the temperature was 550℃).Core-shell-like particles are observed in the case of a short LTRD time,and the core and the shell are Fe and the Sm-rich Sm-Fe phase,respectively,indicating that the Sm-rich phase begins to produce on the surface of the Fe particles.It is difficult to synthesize a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)phase with the Sm-Fe binary system,suggesting that a different approach,such as addition of other elements,will be necessary.展开更多
In this study,molten salt was used as a solvent for calcium(Ca)to let a reduction-diffusion(R-D)reaction occur below the melting point of Ca(1115 K),which is the lower limit temperature of the co nventional RD process...In this study,molten salt was used as a solvent for calcium(Ca)to let a reduction-diffusion(R-D)reaction occur below the melting point of Ca(1115 K),which is the lower limit temperature of the co nventional RD process.When the R-D reaction is conducted below 923 K with LiCl molten salt,submicron-sized TbCu_(7)-type Sm-Fe powder is formed.The c/a ratio of the powder estimated by a synchrotron X-ray diffraction pattern is 0.8456,which is consistent with the Sm_(0.67)Fe_(5.667)(SmFe_(8.5))phase.An electron backscatter diffraction analysis reveals that single-crystalline TbCu_(7)-type SmFe_(8.5) powder was synthesized for the first time.展开更多
In this study,the temperature of the low-temperature reduction-diffusion(LTRD)process was successfully decreased to below 600℃by introducing LiClKCl eutectic molten salt with a low eutectic point(352℃)as a solvent f...In this study,the temperature of the low-temperature reduction-diffusion(LTRD)process was successfully decreased to below 600℃by introducing LiClKCl eutectic molten salt with a low eutectic point(352℃)as a solvent for Ca reductant.Therefore,the Sm-Fe binary compounds,which were synthesizable at previously-unexplored low temperatures by the LTRD process using LiCl-KCl eutectic molten salt,were investigated,including whether a new metastable or ThMn_(12)-type Sm-Fe binary phase was formed.The Sm-Fe phase transitions of the SmFe binary compounds at a low temperature were identified,and it was found that MgCu_(2)-type Sm-Fe,PuNi_(3)-type SmFe and TbCu_(7)-type Sm-Fe phases were synthesized and stable at 400,500 and 550℃respectively.Although no new metastable Sm-Fe and ThMn_(12)-type Sm-Fe compounds were discovered in this study,this work can demonstrate that it is possible to synthesize the Sm-Fe phase at very low temperatures by the LTRD process for the first time.展开更多
文摘In this study,the mechanism of the reduction-diffusion reaction in a Sm-Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)by the low-temperature diffusion-reduction(LTRD)process using LiCl-KCl eutectic molten salts.Firstly,the Sm-Fe phase transformation depending on the Sm-Fe composition,the LTRD temperature,and time was investigated,and it is found that the obtained metastable phase is only TbCu_(7)-type SmFe_(~8.5),which is not a Fe-rich phase.This Fe content does not change even after an expended LTRD process,and the metastable TbCu_(7)-type SmFe_(~8.5)tends to transform to the stable Sm_(2)Fe_(17)phase.In addition,it is found that the Sm-Fe phase starts to synthesize from the Sm-rich phase in the order of SmFe_(2),SmFe_(3),and SmFe_(8.5)as the LTRD temperature increases(when the time was 10 h)or the LTRD time increases(when the temperature was 550℃).Core-shell-like particles are observed in the case of a short LTRD time,and the core and the shell are Fe and the Sm-rich Sm-Fe phase,respectively,indicating that the Sm-rich phase begins to produce on the surface of the Fe particles.It is difficult to synthesize a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)phase with the Sm-Fe binary system,suggesting that a different approach,such as addition of other elements,will be necessary.
基金Project supported by JSPS KAKENHI(16K18230,18K13986,20K05072)。
文摘In this study,molten salt was used as a solvent for calcium(Ca)to let a reduction-diffusion(R-D)reaction occur below the melting point of Ca(1115 K),which is the lower limit temperature of the co nventional RD process.When the R-D reaction is conducted below 923 K with LiCl molten salt,submicron-sized TbCu_(7)-type Sm-Fe powder is formed.The c/a ratio of the powder estimated by a synchrotron X-ray diffraction pattern is 0.8456,which is consistent with the Sm_(0.67)Fe_(5.667)(SmFe_(8.5))phase.An electron backscatter diffraction analysis reveals that single-crystalline TbCu_(7)-type SmFe_(8.5) powder was synthesized for the first time.
基金financially supported by"Adaptable and Seamless Technology Transfer Program through Target-Driven R&D(A-STEP),(No.JPMJTM20EB)commissioned by the Japan Science and Technology Agency(JST)。
文摘In this study,the temperature of the low-temperature reduction-diffusion(LTRD)process was successfully decreased to below 600℃by introducing LiClKCl eutectic molten salt with a low eutectic point(352℃)as a solvent for Ca reductant.Therefore,the Sm-Fe binary compounds,which were synthesizable at previously-unexplored low temperatures by the LTRD process using LiCl-KCl eutectic molten salt,were investigated,including whether a new metastable or ThMn_(12)-type Sm-Fe binary phase was formed.The Sm-Fe phase transitions of the SmFe binary compounds at a low temperature were identified,and it was found that MgCu_(2)-type Sm-Fe,PuNi_(3)-type SmFe and TbCu_(7)-type Sm-Fe phases were synthesized and stable at 400,500 and 550℃respectively.Although no new metastable Sm-Fe and ThMn_(12)-type Sm-Fe compounds were discovered in this study,this work can demonstrate that it is possible to synthesize the Sm-Fe phase at very low temperatures by the LTRD process for the first time.
