Possibility of Nd:YAG-PLD Method for Fabricating REBCO Coated Conductors

Abstract

A Nd:YAG (neodymium-doped yttrium aluminum garnet) laser is environmentally safe, due to the absence of any poisonous or hazardous gases, and also economical, without the need for expensive gases. We can thus expect a safe and low cost <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm REBa}_{2}{\rm Cu}_{3}{\rm O}_{y}$</tex> </formula> (REBCO)-coated conductor fabrication process by using an Nd:YAG laser. We investigated the fabrication of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{y}$</tex></formula> (YBCO) films using a PLD method with a fourth harmonic Nd:YAG laser. The YBCO films showed good superconducting properties; for example, on <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${\rm SrTiO}_{3}$</tex></formula> single crystalline substrates, <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$T_{\rm c}$</tex></formula> and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$J_{\rm c}$</tex></formula> were about 90 K and 2.5 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm MA/cm}^{2}$</tex></formula> , respectively, at 77 K. In order to enhance <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$J_{\rm c}$</tex></formula> in magnetic fields, <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm BaSnO}_{3}$</tex> </formula> was doped into YBCO films by means of a combinatorial Nd:YAG-PLD method. The combinatorial method enabled the growth and study of a library of samples ranging from pure-YBCO to BSO-doped-YBCO. We demonstrated rapid optimization of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm BaSnO}_{3}$</tex> </formula> content by the combinatorial method and concluded that the optimal BSO content was around 3.6 wt%. In addition, in order to enhance material yield of the Nd:YAG-PLD method, we optimized the oxygen pressure and distance between the target and substrate. On a substrate with dimensions of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$10\times 10\ {\rm mm}^{2}$</tex> </formula> , the material yield of a YBCO film reached about 19.0%. These results suggest that the Nd:YAG-PLD method is promising for forming YBCO-coated conductors.