Studv On Preparation And Properties Of YBCO And Ti_xO_y Superconducting Thin Films

Superconducting materials are a very popular direction in the field of materials research due to their unique zero resistance and complete diamagnetism.In particular,the discovery of high-temperature superconductor YBCO has broken through the dilemma that superconducting materials can only be applied at extremely low temperatures.In this article,we have prepared YBCO thin films with a thickness of about 3 00nm and a superconducting transition temperature Tconset of 91.09K on a SrTiO3(001)substrate by pulsed laser deposition.By changing the film thickness,we found that the thicker the film,the more uniform the deposition,and the higher the superconducting transition temperature Tc.By comparing the YBCO film samples prepared on the three substrates STO/LAO/MgO,we found that with the lattice mismatch becomes lager,the crystallographic quality of the film becomes worse,and the in-plane lattice mosaic phenomenon becomes more serious.Relatively speaking,the lattice of the STO substrate and the YBCO film are more suitable.We measured the YBCO film with a transmission type double mutual inductance coil device.The curve of the penetration depth of the magnetic field with temperature.The λ(T)of the sample with a film thickness of 35 nm in the low temperature section is very smooth,and theλ(0)is about 200 nm.This result is very close to the result measured in YBa2Cu3O7.0 powder material using the μSR method in the reference.On the other hand,finding new superconducting materials is also an important direction in the field of superconductivity research.The study of superconductivity in titanium oxides is of great significance to reveal the complex superconducting mechanism.In this paper,the pulsed laser deposition method was used to successfully fabricate a TixOysuperconducting films on α-Al2O3(0001)substrates,using a TiO2 target and a Ti2O3 target respectively.The sample of Ti4O7 and TiO2 eutectic superconducting thin films prepared from TiO2 have a film thickness of 301 nm and poor crystalline quality.The initial superconducting transition temperature Tconset is 6.0K,containing Ti4O7(1-31)phase and TiO2(200)phase.The thickness of the Ti7O13 superconducting thin film prepared from Ti2O3 is 162 nm,the surface flatness is relatively higher,the crystal quality is relatively higher,and the initial superconducting transition temperature Tconset is 7.6K,which is Ti7O13(020)phase.There are mainly five elements Al、Ti、O、N and C on the surface of the two films,and the distribution of each element is uniform,but the content of Ti element in the Ti7O13 superconducting film sample is relatively higher.By comparing the structures of the samples prepared by the two targets at different growth temperatures,we found that the slight difference in the oxygen content in the titanium suboxide films does have a great influence on the structure.