The experimental results show that the coercivity of Nd-Fe-B sintermagnet decreases with increasing of the grain alignment degree of the magnets (i.e. decreasing of the orientation distribution coefficient σ).The coe...The experimental results show that the coercivity of Nd-Fe-B sintermagnet decreases with increasing of the grain alignment degree of the magnets (i.e. decreasing of the orientation distribution coefficient σ).The coercivities of the magnets with different orientation degree are calculated based on the pinning,nucleation and starting field theory,respectively.The comparison of the calculated values with the experimental results shows that the theoretical results are deviating from the experiments seriously for both pinning mechanism and nucleation mechanism. In contrast with that,the calculated values based on the starting field theory are in good agreement with the experimental results.展开更多
The effects of the partial substitution of element M(M=Cr,V,Mn,x=0.05;Zr,Ga,x=0.017; Si,x=0.15;Co,x=0.10)for Fe in samarium-iron-nitride Sm_2(Fe_(1-x)M_x)_(17)N_y compounds on their stabilities and Curie temperatures ...The effects of the partial substitution of element M(M=Cr,V,Mn,x=0.05;Zr,Ga,x=0.017; Si,x=0.15;Co,x=0.10)for Fe in samarium-iron-nitride Sm_2(Fe_(1-x)M_x)_(17)N_y compounds on their stabilities and Curie temperatures have been studied.It is found that Co,Ga can raise the Curie temperature of the compounds.The initial decomposition temperatures cannot be raised significantly by all the studied elements except Co.The result contradicts the formation enthalpy consideration.The final decomposition tempera- tures can be raised by all of the substitution elements.The effects of atmospheres on their decomposition be- havior were also studied.The results show that oxidation is the major reason for magnetic deterioration of the powder heated in air.Compared with nitrogen atmosphere,argon or vacuum helps to delay the decompo- sition of the compounds.展开更多
Since the initial work done by Bednorz and Müller in 1986, four families of highT<sub>c</sub> oxide superconductor systems have been discovered. They are La<sub>2-x</sub>A<sub>x</...Since the initial work done by Bednorz and Müller in 1986, four families of highT<sub>c</sub> oxide superconductor systems have been discovered. They are La<sub>2-x</sub>A<sub>x</sub> Cu O<sub>4</sub>-j) （A= Ca, Sr, Ba）, LnBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-y</sub>,（Ln=Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu）,展开更多
Great attention has been paid to the RFe<sub>11</sub>（Ti, V） compounds with ThMn<sub>12</sub> type structure since 1987. Among them the SmFe<sub>11</sub>Ti compound seems to be th...Great attention has been paid to the RFe<sub>11</sub>（Ti, V） compounds with ThMn<sub>12</sub> type structure since 1987. Among them the SmFe<sub>11</sub>Ti compound seems to be the most promising candidate for permanent magnets（PMs）. However, the saturation magnetization of SmFe<sub>11</sub>Ti is much less than that of Nd<sub>2</sub>Fe<sub>14</sub>B although its Curie temperature T<sub>C</sub> is approximately the same as that of Nd<sub>2</sub>Fe<sub>14</sub>B; in addition, Sm is more expensive than Nd. All this makes SmFe<sub>11</sub>Ti uncompetitive from economic point of view.展开更多
文摘The experimental results show that the coercivity of Nd-Fe-B sintermagnet decreases with increasing of the grain alignment degree of the magnets (i.e. decreasing of the orientation distribution coefficient σ).The coercivities of the magnets with different orientation degree are calculated based on the pinning,nucleation and starting field theory,respectively.The comparison of the calculated values with the experimental results shows that the theoretical results are deviating from the experiments seriously for both pinning mechanism and nucleation mechanism. In contrast with that,the calculated values based on the starting field theory are in good agreement with the experimental results.
文摘The effects of the partial substitution of element M(M=Cr,V,Mn,x=0.05;Zr,Ga,x=0.017; Si,x=0.15;Co,x=0.10)for Fe in samarium-iron-nitride Sm_2(Fe_(1-x)M_x)_(17)N_y compounds on their stabilities and Curie temperatures have been studied.It is found that Co,Ga can raise the Curie temperature of the compounds.The initial decomposition temperatures cannot be raised significantly by all the studied elements except Co.The result contradicts the formation enthalpy consideration.The final decomposition tempera- tures can be raised by all of the substitution elements.The effects of atmospheres on their decomposition be- havior were also studied.The results show that oxidation is the major reason for magnetic deterioration of the powder heated in air.Compared with nitrogen atmosphere,argon or vacuum helps to delay the decompo- sition of the compounds.
文摘Since the initial work done by Bednorz and Müller in 1986, four families of highT<sub>c</sub> oxide superconductor systems have been discovered. They are La<sub>2-x</sub>A<sub>x</sub> Cu O<sub>4</sub>-j) （A= Ca, Sr, Ba）, LnBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-y</sub>,（Ln=Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu）,
文摘Great attention has been paid to the RFe<sub>11</sub>（Ti, V） compounds with ThMn<sub>12</sub> type structure since 1987. Among them the SmFe<sub>11</sub>Ti compound seems to be the most promising candidate for permanent magnets（PMs）. However, the saturation magnetization of SmFe<sub>11</sub>Ti is much less than that of Nd<sub>2</sub>Fe<sub>14</sub>B although its Curie temperature T<sub>C</sub> is approximately the same as that of Nd<sub>2</sub>Fe<sub>14</sub>B; in addition, Sm is more expensive than Nd. All this makes SmFe<sub>11</sub>Ti uncompetitive from economic point of view.
