LOW TEMPERATURE MELT PROCESS OF SmBa 2 Cu 3 O 7 y USING A LIQUID INFILTRATION TECHNIQUE CHAN-JOONG KIM*{, YOUNG A. JEE$, KYU-WON LEE%, TAE-HYUN SUNG}, SANG-CHUL HAN}, IL-HYUN KUK$ and GYE-WON HONG$ $Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon, 305-600, Korea %Superconductivity Laboratory, Korea Research Institute of Standards and Science, P.O. Box 3, Taeduk Science Town, Taejon, 305-606, Korea }Center for Advanced Studies in Energy and Environment, Korea Electric Power Research Institute, 103-16, Munjidong, Easing, Taejon, 305-380, Korea (Received 9 February 1998; accepted 5 March 1998) AbstractÐSmBa 2 Cu 3 O 7y (Sm123) was made by a liquid in®ltration technique using isothermal peritec- tic reaction below the peritectic temperature (T p =10608C) of SmBaCuO. By heating and isothermal holding, the coupled Ba 3 Cu 5 O 8 /Sm 2 BaCuO 5 (Sm211) powder compacts in the temperature range of 9008C±10508C in air, the Ba 3 Cu 5 O 8 powder melts and is then in®ltrated into the Sm211 compacted powder. The in®ltrated liquid phase reacts with the Sm211 phase to form a textured Sm123 structure. The microstructure and the superconducting properties of the samples are reported. # 1998 Elsevier Science Ltd. All rights reserved INTRODUCTION Melt processing which utilizes the peritectic reaction between RE 2 BaCuO 5 (RE: rare-earth elements) and Ba 3 Cu 5 O 8 liquid phase is known to be the most eective way to produce high critical current density (J c ) RE 2 BaCuO (REBCO) superconductors [1±5]. The magnetic J c of the melt-processed REBCO superconductors is as high as 10 4 A/cm 2 at 77 K and even at high mag- netic ®elds of several T, while the transport J c of the multi-domain sample is very low due to the weak link behavior of the grain boundary. Thus, their applications are limited to special ®elds such as a high speed motor and the bearing parts of a ¯ywheel energy storage system which utilizes the magnetic levitation properties [6±10]. Another obstacle for the high transport current applications of the REBCO materials is the high processing temperature of melt-processed REBCO which is higher than the melting point of metallic silver. The high reactivity of barium with other metallic elements [11, 12] makes it dicult to fabricate a superconducting wire using metal claddings or substrates. Furthermore, the heating cycles are complicated and time-consuming, since conventional melt processing involves slow cooling [1±3] through the peritectic temperature (T p ) or undercooling with sub- sequent prolonged holding below T p [13±15]. The possibility of the fabrication of the textured REBCO superconductors at low temperature below T p was proposed by Jee et al. in the YBCO system [16], which uses the in®ltration of a Ba 3 Cu 5 O 8 melt into a Y211 compact. The formation of the textured microstructure was enabled by the isothermal holding of the coupled Ba 3 Cu 5 O 8 /Y211 compact at about 9508C and the transport J c of the sample was about 1500 A/cm 2 [16]. The key points of this technique are the melting of the liquid-forming powder compact below T p and the ®lling of the open porosity of the Y211 compact with the melt. The process is a cost-eective method, because of the simple and shorter heating cycles compared to that of conventional melt processing. In this work, we applied the isothermal peritectic reaction using the liquid in®ltration tech- nique to the fabrication of Sm123 samples. The parameters of the low-temperature peritectic reaction method, the microstructure developed and the superconducting properties are reported. Applied Superconductivity Vol. 6, Nos. 2±5, pp. 149±156, 1998 # 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0964-1807/98 $ - see front matter PII: S0964-1807(98)00095-7 {Corresponding author. 149