Research In Properties Of YSZ Buffer Layer And REBCO Superconducting Layer Prepared By PLD

In today’s society,severe energy crisis is attracting more and more attention.Economic and clean energy must be found to main the normal development and progress of our society.It has been a hundred years since superconducting phenomenon has been found,and there is huge application prospective in electrical power,electronics industry,healthcare,magnetism and so on.Taking electrical power industry for example,the superconducting tape made by superconducting material could effectively decrease the heat loss during electricity transportation,and thus to increase economic returns.Among different kinds of superconducting materials,YBCO attracts lots of attention due to its nice electronic and magnetic properties.These days,researchers from institutions worldwide have studied its properties from nearly all perspectives.Our research group has mainly focused on how to prepare kilometer-long superconducting tape with large current.And my work mainly covers three points:1.Yittria-Stabilized-Zircon（YSZ）buffer layers and YBCO(YBa₂Cu₃O_7-σ)superconducting layers are deposited on CeO₂ buffered RABiTS NiW substrates by pulsed laser deposition（PLD）,and the influence of oxygen partial pressure,pulsed laser frequency and target type on surface morphology of YSZ thin films is studied.By adjusting experiment parameters,YSZ films with clean and smooth surface are successfully deposited,and YBCO film deposited on smooth YSZ layer has less particles and outgrowths with superconducting current density of around 5MA/cm².2.Y_0.5Gd_0.5Ba₂Cu₃O_7-σand Ho_0.5Gd_0.5Ba₂Cu₃O_7-σthin films are deposited on CeO₂ substrate by PLD.The similarity and difference of REBCO(REBa₂Cu₃O_7-σ,RE=Y,Gd,Ho)thin films substituted by different element are studied,and the effect of laser energy density on deposited film’s properties is researched by changing laser lens of different focal lengths.We found that HGBCO film has better electrical transporting properties with the largest current density of 1.8 MA/cm²,and its lowest inner and outer plane texture are 3.49°and 1.614°respectively,and the largest current density is 1.8 MA/cm².3.Y_0.6Gd_0.6Ba₂Cu₃O_7-σtargets of different density are prepared by solid-state reaction method by adjusting the sintering temperature,and then are used to prepare thin film samples by PLD to study the effect of target density on thin films’properties.It is found Y_0.6Gd_0.6Ba₂Cu₃O_7-σthin films deposited using the target with density of 3.9 g/cm³ have nice structure,quite smooth surface morphology and high critical current of 136A/cm,and quality of thin film decreases with increasing target density.In a nutshell,we successfully prepared high-quality YSZ buffer layer,YGBCO and HGBCO superconducting layer,and studied the effect of different experiment parameters on thin films’properties.The prepared YSZ layer is of nice c-axis oriented structure and quite smooth surface,and the REBCO layer deposited on it has largest critical current of above130 A/cm and critical current density of around 5MA/cm².This is among the best samples that can be achieved in this field.