A series of oxygen-doped RE_2CuO_4 (RE=Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm) was synthesized using high-pressure/oxygen-doped technique. The structures and low temperature magnetic properties were investigated. The XRD ...A series of oxygen-doped RE_2CuO_4 (RE=Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm) was synthesized using high-pressure/oxygen-doped technique. The structures and low temperature magnetic properties were investigated. The XRD patterns indicate that the structures of high oxygen pressure RE_2CuO_4 (only for RE=Sm, Eu) samples are pure T′ phase, but when RE= Gd, Tb, Dy, Ho, Er, Tm, the structures turn to disorder. The magnetic anomalies that occurred at T^30 K are observed in high oxygen pressure RE_2CuO_4. It is found that the transition temperatures of weak ferromagnetic anomalies are nearly independent of the rare-earth components. Thus, the O-doping plays an important role in anomalous magnetic properties of RE_2CuO_(4+δ). The magnetic anomalies in RE_2CuO_4 are considered to be due to ferromagnetic clusters formed in the Cu-O plane after the oxygen doping.展开更多
The nearly single phase(R_(0.4)Pr_(0.6))_(0.5)Ca_(0.5)Ba_(2)Cu_(3)O_(7-δ)compounds(R=La,Pr,Nd,Sm,Eu,Gd and Y)with Tc about 100 K were prepared under high pressure and high temperature using the cubic anvil apparatus....The nearly single phase(R_(0.4)Pr_(0.6))_(0.5)Ca_(0.5)Ba_(2)Cu_(3)O_(7-δ)compounds(R=La,Pr,Nd,Sm,Eu,Gd and Y)with Tc about 100 K were prepared under high pressure and high temperature using the cubic anvil apparatus.The Tc is much higher than that of the traditional R-123 superconductors without doping Ca on the rare-earth site.For various rare earths with different ionic radius,the(R_(0.4)Pr_(0.6))_(0.5)Ca_(0.5)Ba_(2)Cu_(3)O_(7-δ)compounds have almost the same critical temperature.This is different from the result of the ion-size effect of rare-earth ions in R1-xPrxBa2Cu3O7-δcompounds.Our results show that Pr has the same properties as other rare earths in the 123-phase compounds due to the doping of Ca.展开更多
The structural transition process of the superconducting phase in Bi_(1-x)Pb_(x)SrCaCu_(2)O_(y)(x=0,0.2)samples has been investigated at temperatures ranging from-190℃ to 800℃ by means of electron diffraction.Two st...The structural transition process of the superconducting phase in Bi_(1-x)Pb_(x)SrCaCu_(2)O_(y)(x=0,0.2)samples has been investigated at temperatures ranging from-190℃ to 800℃ by means of electron diffraction.Two struc-tures about 310℃ and 490℃ respectively for the BiSrCaCu_(2)O_(y) sample,and about 310℃ and 470℃ for the Bi_(0.8)Pb_(0.2)SrCaCu_(2)O_(y) sample.After these transitions a new structural phase forms.展开更多
文摘A series of oxygen-doped RE_2CuO_4 (RE=Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm) was synthesized using high-pressure/oxygen-doped technique. The structures and low temperature magnetic properties were investigated. The XRD patterns indicate that the structures of high oxygen pressure RE_2CuO_4 (only for RE=Sm, Eu) samples are pure T′ phase, but when RE= Gd, Tb, Dy, Ho, Er, Tm, the structures turn to disorder. The magnetic anomalies that occurred at T^30 K are observed in high oxygen pressure RE_2CuO_4. It is found that the transition temperatures of weak ferromagnetic anomalies are nearly independent of the rare-earth components. Thus, the O-doping plays an important role in anomalous magnetic properties of RE_2CuO_(4+δ). The magnetic anomalies in RE_2CuO_4 are considered to be due to ferromagnetic clusters formed in the Cu-O plane after the oxygen doping.
基金Supported by the Ministry of Science and Technology of China(NKBRSF-G19990646).
文摘The nearly single phase(R_(0.4)Pr_(0.6))_(0.5)Ca_(0.5)Ba_(2)Cu_(3)O_(7-δ)compounds(R=La,Pr,Nd,Sm,Eu,Gd and Y)with Tc about 100 K were prepared under high pressure and high temperature using the cubic anvil apparatus.The Tc is much higher than that of the traditional R-123 superconductors without doping Ca on the rare-earth site.For various rare earths with different ionic radius,the(R_(0.4)Pr_(0.6))_(0.5)Ca_(0.5)Ba_(2)Cu_(3)O_(7-δ)compounds have almost the same critical temperature.This is different from the result of the ion-size effect of rare-earth ions in R1-xPrxBa2Cu3O7-δcompounds.Our results show that Pr has the same properties as other rare earths in the 123-phase compounds due to the doping of Ca.
文摘The structural transition process of the superconducting phase in Bi_(1-x)Pb_(x)SrCaCu_(2)O_(y)(x=0,0.2)samples has been investigated at temperatures ranging from-190℃ to 800℃ by means of electron diffraction.Two struc-tures about 310℃ and 490℃ respectively for the BiSrCaCu_(2)O_(y) sample,and about 310℃ and 470℃ for the Bi_(0.8)Pb_(0.2)SrCaCu_(2)O_(y) sample.After these transitions a new structural phase forms.
