Top-seeded Infiltration Growth Process Research Articles

Enhanced trapped magnetic field in bulk (Gd, Y, Er) Ba2Cu3O7-y via varied liquid sources in top-seeded infiltration growth process

The practical applications of the bulk superconductors are determined by the trapped field (TF) and its overall performance. This study aims to demonstrate the effect of various compositions of liquid sources on the trapped field performance of bulk superconductors fabricated using the Top-Seeded Infiltration Growth process (TSIG) in air. We utilized a combination of different liquid sources, Ba3Cu5O8, Yb2O3: BaCuO2: CuO (1:10:6) and ErBa2Cu3Oy + Ba3Cu5O8 (1:1) to fabricate the ternary bulk (Gd, Y, Er) Ba2Cu3O7-y (Gd, Y, Er)-123. The use of these liquid sources demonstrated a pivotal role in fabricating single-domain bulks, showcasing significant variation in the trapped field performance. Specifically, the bulk fabricated using ErBa2Cu3Oy + Ba3Cu5O8 (1:1) as a liquid source exhibited the best-trapped field performance, showcasing an improvement of 42.92 % compared to the bulk obtained using conventional Ba3Cu5O8 as the liquid source. An enhancement in the critical current density below 77 K was observed in the bulk material produced utilizing Ba3Cu5O8 as the liquid source, with a Jc (3T, 50 K) value reaching 244 kA/cm2. The flux pinning force density (Fp) was analyzed for all samples to understand the pinning mechanisms in ternary (Gd, Y, Er)-123 bulk materials. Furthermore, the maximum trapped field for a 30 mm bulk sample fabricated using a mixture of ErBa2Cu3Oy + Ba3Cu5O8 (1:1) was measured at 0.336T. These results emphasize the potential for enhancing or controlling the trapped field performance of the TSIG-processed RE-123 bulks by optimizing the liquid source according to the intended applications of the bulk.

Influence of polyurethane skeleton on structural and superconducting properties of Y-123 foams

The physicochemical properties of Y-123 superconducting foams of various topologies prepared by the top-seeded infiltration-growth (TSIG) method are discussed. During the TSIG process, precursor foams (polyurethanes with various densities, flexibilities, and skeleton types) were infiltrated with a green phase (Y-211) and thermally converted to Y-123 superconductors using NdBCO single-crystal seeds oriented in the [100] direction. The occurrence of the desired superconducting phases were confirmed by X-ray diffraction, Raman and X-ray absorption spectroscopies as well as magnetometric and transport measurements. It was found that the growth of Y-123 foam preserves the crystallographic orientation of the NdBCO seed regardless of the initial alignment of the skeleton. The foams exhibit the critical temperature (Tc) similar to YBCO bulk. High-density and stiffness skeletons favor the Y-123 phase formation, while more flexible foam structures hamper transformation of the Y-211 phase into the Y-123 one.

Exploring the effects of liquid source on superconducting properties and microstructure in ternary bulk (Gd, Y, Er)−123 by infiltration growth process

Superconductors are used in a wide range of applications, each requiring specific magnetic field strengths to operate at their best. The optimal magnetic strength is determined by the superconducting properties, such as critical current density (Jc). In this study, we propose that by using different compositions of liquid source, the superconducting properties and microstructure of bulk superconductors can be optimized according to their intended application. Ba3Cu5O8, Yb2O3:BaCuO2:CuO (1:10:6) and Er123 + Ba3Cu5O8 (1:1) were tested as liquid sources, and ternary single-grain bulks (Gd, Y, Er) Ba2Cu3Oy were produced using the top-seeded infiltration growth process (TSIG) in the air. Microstructural analysis with a scanning electron microscope revealed that using Er123 +Ba3Cu5O8(1:1) as the liquid source resulted in a significant reduction in the 211 secondary phase particle size, with a mean particle size reduction of 43.13% compared to the conventional Ba3Cu5O8. Each composition of the liquid source had a significant impact on the superconducting properties, and the Er123 + Ba3Cu5O8 liquid source yielded the highest Jc of 81.91 kA/cm2 in self-field and 28.29 kA/cm2 at 1 T for (Gd, Y, Er)−123 ternary system. These results emphasize the importance of liquid sources in controlling the final microstructure, which ultimately determines the performance of the bulk ternary (Gd, Y, Er)−123 system produced by the IG process.

A New Method for Batch Production of Single Domain GdBCO Bulks of Different Growth Sectors Using One Seed by the RE+011 TSIG Process

A single domain REBCO bulk, fabricated with one seed whether by the top seeded melt growth method or top seeded infiltration growth (TSIG) process, consists of five growth sectors (GSs) generally. ...

Pulsed-field magnetisation of Y-Ba-Cu-O bulk superconductors fabricated by the infiltration growth technique

Bulk high temperature superconductors based on the rare-earth copper oxides can be used effectively as trapped field magnets capable of generating large magnetic fields. The top-seeded infiltration growth (TSIG) processing technique can provide a more homogeneous microstructure and therefore more uniform superconducting properties than samples grown using conventional melt growth processes. In the present investigation, the properties of bulk, single grain superconductors processed by TSIG and magnetised by the pulsed-field magnetisation technique using a copper-wound solenoid have been studied. A trapped field of ∼3 T has been achieved in a 2-step buffer-assisted TSIG-processed Y-Ba-Cu-O (YBCO) sample at 40 K by magnetising the bulk superconductor completely via a single-pulse magnetisation process. Samples were also subjected to pulsed-field magnetisation at 65 K and by conventional field-cooled magnetisation at 77 K for comparison. Good correlation was observed between the microstructures, critical current densities and trapped field performance of bulk samples fabricated by TSIG and magnetised by pulsed-field and field-cooled magnetisation. The homogeneous distribution of Y2BaCuO5 inclusions within the microstructure of bulk YBCO samples fabricated by the 2-step buffer-assisted TSIG process reduces inhomogeneous flux penetration into the interior of the sample. This, in turn, results in a lower temperature rise of the bulk superconductor during the pulsed-field magnetisation process and a more effective and reliable magnetisation process.

Production of Sharp-Edged and Surface-Damaged Y2BaCuO5 by Ultrasound: Significant Improvement of Superconducting Performance of Infiltration Growth-Processed YBa2Cu3O7-δ Bulk Superconductors.

Growth and physical properties of bulk REBa2Cu3O7−δ (REBCO) superconductors fabricated by the infiltration growth (IG) method strongly depend on the initial size and morphology of the RE2BaCuO5 (211) particles. The present work details the novel method we developed for producing sharp-edged and surface-damaged 211 particles to be added to the REBCO bulks. We employed high-energy ultrasonic irradiation for pretreating the 211 particles and fabricated high-performance bulk single-grain YBa2Cu3O7−δ (YBCO) superconductors via the top-seeded IG process. Increasing the ultrasound irradiation power and time duration mechanically damaged the surface of the 211 particles, producing more fine and sharp edges. Systematic investigations of the microstructural properties of the final YBCO bulks indicated that the size and content of the 211 particles gradually decreased without any additional chemical doping. The effective grain refinement and improved interfacial defect densities enhanced the critical current density by a factor of two at 77 K and self-field as compared to a YBCO sample fabricated without any pretreatment. A maximum trapped field of 0.48 T at 77 K was obtained for a sample (20 mm diameter) with 211 particles treated for 60 min and 300 W ultrasound radiation. The effectiveness of the novel method is demonstrated by the superior performance of the YBCO bulk samples prepared as compared to bulk samples fabricated with the addition of Pt and CeO2. This method is novel, cost effective, and very convenient, maintaining high sample homogeneity, and is free of chemical contaminants as compared to other methods which significantly affect the properties of all REBCO bulk products grown by sintering, melt growth, and IG methods.

A Practical Processing Method for the Fabrication of NdBCO Seed Crystals and High-Performance Single-Domain GdBCO Bulk Superconductors

NdBCO seed crystals and high-performance GdBCO bulk superconductors were prepared successfully by a modified top-seeded melt-textured growth (TSMG) process and by Gd + 011 top-seeded infiltration growth (TSIG) process. The modified TSMG process used a new composition powder (NCP, 0.9 Nd2O3 + 2.4 BaCuO2 + CuO) instead of the conventional composition powder (CCP, NdBa2Cu3O7-x + 0.4 Nd2BaCuO5), the GdBCO bulk superconductor seeded by the self-made NdBCO seed crystal. In the whole procedure above, only one precursor powder (BaCuO2) needs to be sintered, three kinds of powder and three pellets are required, so time and energy consumption were greatly reduced. The results of thermal analysis and X-ray diffraction (XRD) patterns revealed the reaction mechanism of the modified TSMG process. Superconductivity properties of the GdBCO sample were measured employing a levitation force measurement system and a vibrating-sample magnetometer (VSM); the maximum value of the levitation force of the GdBCO sample was 44.78 N (77 k, 0.5 T); the onset superconductivity transition temperature (Tc) was approximately 93.7 K; the transition width was 6.2 K, and the maximum value of critical current density (Jc) was 1.5 × 105 A∙cm−2 (0 T, 77 K). These results indicate that, by combing the modified TSMG process and Gd + 011 TSIG process, a practical processing method for preparing the NdBCO seed crystals and the high-performance single-domain GdBCO bulk superconductors was developed.

The effect of cooling rate on critical current density and microstructure of single grain bulk YBa2Cu3Oy superconductors grown by IG process

In the recent years, top-seeded infiltration-growth (TS-IG) process of YBa2Cu3Oy (YBCO) had shown crucial and promising strengths as compared to melt growth process. The IG process lucidly clarified that a supply of liquid phase is more than essential for further growing large grains. Further, this experimentation aimed to enhance the performance of bulk YBCO superconducting materials, which were processed by IG process. The homemade Yb-123 and Y-211 were utilized in order to produce YBa2Cu3Oy samples with the means of Yb-123+liquid (1:1) as a liquid source under a varied cooling rate. Moreover, single grain YBCO bulks were fabricated employing TS-IG process consisted of numerous varied cooling rates of 0.16 °C/h, 0.25 °C/h and 0.5 °C/h, respectively. In essence, all samples were oxygenated for 100 h with a constant pressure of 300 mL/min. Therefore, all samples’ texture was determined by means of X-ray diffraction measurements. Microstructure analysis was performed by scanning electron microscopy for correlation of critical current density of TS-IG processed single grain YBCO bulks.

Optimization of growth parameters for fabricating single grain (Gd, Dy)BCO bulk superconductors in top-seeded infiltration growth process

Fabrication of single grain bulk REBa2Cu3O7-δ (REBCO) superconductors with superior performance along with shape retaining is a recent topic. Mixed REBCO superconductors produced in melt growth (MG) technique had showed enhanced superconducting performance. However, this process offers many disadvantages such as macro-porosity, shrinkage in final products, inhomogeneous distribution of 211 secondary phase particles etc., which limit many practical applications. Infiltration growth (IG) process is advanced and superior to MG technique in several aspects. Recently, we fabricated (Gd, Dy)Ba2Cu3O7-δ ((Gd, Dy)BCO) bulk superconductors through systematic addition of Dy2BaCuO5 (Dy-211) content. The addition of 20 wt.% of Dy-211 in GdBCO was found to be optimum which resulted in enhanced superconducting performance. In the present work, in order to determine a suitable temperature window for fabrication of large single grain (Gd, Dy)BCO bulk superconductors, isothermal experiments were carried out at several constant temperatures in top-seeded IG process in air atmosphere. Systematic microstructural and magnetic properties were assessed and analysed. The 211 secondary phase particles are enlarged to as high as ∼ 25 µm when the sample assembly is dwelled at high temperatures and reduced to ∼ 2 µm – 4 µm in the samples dwelled at lower temperatures. Main emphasis will be given on the growth rate progress and difficulties involved in IG processing of mixed REBCO superconductors.

A novel method to fabricate single domain YBCO bulk superconductors without any residual liquid phase by Y+011 TSIG technique

Top-seeded infiltration growth (TSIG) technique is a very important way for the fabrication of single domain YBCO bulk superconductors. But there are still two problems because of the usage of Y-based composite (such as YBa2Cu3O7-δ+Ba3Cu5O8) as liquid phase sources. One is that there are still exist some residues of liquid phase sources after TSIG process, which is an excess waste of materials; the other is that the residual liquid phase sources is difficult and have to be cut off from the single domain YBCO bulk. In order to overcome these problems, we proposed a new method to completely eliminate residual liquid phase sources by use a new liquid phase of (3BaCuO2+2CuO) to replace the traditional liquid phase (YBa2Cu3O7-δ+Ba3Cu5O8) and new solid phase of (Y2O3+BaCuO2) to replace the traditional solid phase Y2BaCuO5 during the TSIG process. The effects of (3BaCuO2+2CuO) content on the morphology, levitation force, microstructure and trapped field of the YBCO bulks have been investigated. It is found that single domain YBCO bulks can be fabricated with reasonable amount of new liquid phase source by TSIG process. The trapped field and levitation force of the YBCO bulk samples are of 0.3520 T and 40.85 N, which are higher than that of 0.3190 T and 37.21 N of the samples fabricated with the conventional liquid phases respectively. It is also found that the residues of the liquid phase sources have been completely eliminated by using reasonable new liquid phase source (3BaCuO2+2CuO). This provides a new way to fabricate high-quality single domain YBCO bulk superconductors with low cost, higher levitation force and without any residual liquid phase by TSIG process.

A simplified infiltration growth technique for fabricating single-grain Y–Ba–Cu–O bulk superconductor by employing just one precursor powder: Y2BaCuO5

A simplified top-seeded infiltration growth (TSIG) technique is reported for fabricating single-grain Y–Ba–Cu–O (YBCO) bulk superconductor by employing just one precursor powder: Y2BaCuO5 (Y-211). The composition of Ba3Cu5O8+15wt% Y-211, while Ba3Cu5O8 was prepared using raw materials of BaO and CuO, was used as liquid source for the TSIG process of YBCO bulk, thus the BaCuO2 precursor powder could be avoided in the whole TSIG flow, which simplified the fabrication process and advanced the efficiency. Experimental results indicated that, the sample exhibited well single-grain morphology in top surface and homogeneous distribution of fine Y-211 inclusions in microstructure, as well as a satisfactory Jc performance of 5.11×104A/cm2 in self-field at 77K.

High-Efficient Method for Introducing Nanometer Y2Ba 4 CuNbO x Flux Pinning Centers in Single-Domain YBa2Cu3O7−δ Bulk Superconductors by TSIG Process

Single-domain YBa2Cu3O7−δ (YBCO) superconductors with different additions of Nb2O5 have been fabricated by a modified top seeded infiltration growth (TSIG) process. The growth morphology, microstructure and levitation force were investigated in details. The experimental results reveal that Nb2O5 can react with precursor powders in the TSIG process and finally form nanometer Y2Ba4CuNbO x (YNb2411) particles which can act as effective flux pinning centers. The content addition of Nb2O5 has sensitive effect on microstructure and superconductive property of YBCO bulks The levitation force increases firstly from 30 to 36 N and then reduces down to 21 N with the increasing of Nb2O5 additions from 0.1 to 0.9 wt% and 1.5 wt%. These results indicate a high-efficient method to improve the properties of YBCO bulks.