| The novel layered superconductor Bi4O4S3was discovered in2012and itssuperconducting transition temperature is4.5K. It is the first superconductor of thenovel BiS2-based superconducting family. The synthesized Bi4O4S3is crystallized intetragonal structure with space group I4/mmm. Bi4O4S3is a conventional s-wave typeand multi-band exotic superconductor. The charge carriers are mainly electron-type inBi4O4S3, it is a type-II superconductor. Then other BiS2superconductor La(O,F)BiS2、Nd(O,F)BiS2、Ce(O,F)BiS2、Pr(O,F)BiS2was found in succession. The emergence ofthe novel layered superconductor of BiS2based superconductor has caused wideattention and interest of researchers in condensed matter physics. Because that not butthe structure of the BiS2based superconductors is similar to the copper oxide hightemperature superconductors and iron-based superconductors, but also it has aferroelectric soft phonon, a charge density wave, the electric phonon coupling, and acoexistence between magnetic and superconducting and so on unique characteristics.This opens up a new stage on modern layered superconductors, it has very importantvalue of the studies of superconducting principle and matching mechanism.This paper main research the effects of Bi4O4S3structure and superconductivityby the3d magnetic ions(Fe,Co,Mn) substitution for Bi of Bi4O4S3. Expect thatthrough3d magnetic ions’ alternative better understand Bi4O4S3superconductivitymechanism.The corresponding results are listed as follows:In chapter one: we introduced the structure and related research of the BiS2basednovel layered superconductors, introduced the development profile ofsuperconductors and the application of high temperature superconductors, andsummarized the high field Paramagnetic Meissner effect of superconductors.In chapter two: we introduced the experimental methods and the theoreticalfoundation in this thesis, including sample preparation, X-ray powder diffraction(XRD) analysis, structure and physical property measurement system, etc. In chapter three: we introduced the preparation of the3d magnetic ions X (Fe,Co, Mn) doped Bi3.975X0.025O4S3polycrystalline samples, and study the changes ofthe structure, electrical and magnetic. The experimental results show that: the dopingof the Co ion result a increases of the lattice constant a, a decreases of the latticeconstant c and the volume, and superconducting transition temperature is constant, butthe superconducting transition width is reduced. The doping of the Fe, Mn ion result adecreases of the lattice constant a, a increases of the lattice constant c and the volumeand the superconducting transition temperature, but the superconducting transitionwidth is reduced. The superconducting transition temperature slightly increases withthe decreasing of the dopant ionic radius，and the superconducting transition width() decreases with the decreasing of the dopant ionic radius. So the ion radius sizeof doping of the3d magnetic ions affects Bi4O4S3superconductivity. Part of the3dmagnetic ions doping can improve the superconductivity of Bi4O4S3.In chapter four: we introduced the preparation of the different Mn dopantBi4-xMnxO4S3(x=0,0.025,0.075,0.1,0.125) polycrystalline samples, and study thechanges of the structure, electrical and magnetic. The experimental results show that:the structure is unchanged nearly after doping, the lattice constant a are nearlyconstant, but there are a increases of the lattice constant c. The normal resistivity isincreases and the critical magnetic field is changed with the increase of x. Because ofthe Mn ions doping, there are a thin magnetic Kondo effect at low temperature stagewith the decrease of the temperature. When x=0and0.075, there are a weakmagnetic resistance effect. When x=0.1and0.125, the variation magnetic ofBi4-xMnxO4S3is very rich; at125K, we found a transition of paramagnetic toantiferromagnetic; at47K, we found a transition of antiferromagnetic toferromagnetic. At nearly5K, a superconducting transition occurs, and there are acoexistence between ferromagnetic and superconducting, and there are thermalhysteresis in samples.In chapter five: A series of Y1-xCaxBa2Cu3O7-δ(x=0.05,0.125,0.2) superconductorfilms with different Ca doping were prepared by pulsed laser deposition (PLD) technique. The structure and high field Paramagnetic Meissner effect properties weresystematically investigated. The results show that their oxygen contents were reduced,and their lattice parameters a and c were increased, the lattice parameter b andorthogonal distortion e were decreased, and there had a variation tendency fromorthogonal phase to tetragonal phase, and their high field Paramagnetic Meissnereffect were weakened with the increasing of Ca contents. |
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