Vyacheslav Solovyov

• Brookhaven National Laboratory

Coplanar (with the ground) 20 cm long waveguides are manufactured from the YBCO-on-Kapton material. We inves-tigate the effect of parasitic ground plane resonances on the per-formance of these waveguides. It is concluded that dense rows stitching vias are essential for isolating the lines to a level below 60 dB at 6 GHz. We demonstrate a metalized...

Coplanar (with the ground) and stripline 25 cm long waveguides are manufactured from the YBCO-Kapton material. The waveguides are intended as the key components of a scalable signal delivery for large quantum computing systems and detec-tors. The waveguide is coupled with an integrated power divider that replaces the standard attenuator. The divide...

Here, we report the performance of a coil wound from a defect-tolerant superconducting cable. The cable is comprised of a stack of four 2 mm wide filaments. The defect tolerance is achieved by continuous current sharing between the filaments. The current sharing is assisted by fusing the filament with a directed hot air stream during the winding pr...

The future compact fusion reactors, will feature very high, >16 tesla, magnetic fields, which can be only created by magnet coils wound with the second generation (2G) superconducting wire. The 2G wires are currently manufactured with a thin (1-2 μm) YBCO layer deposited on a ∼100 μm thick metal substrate. The substrate makes up a considerable port...

Development of practical quantum computers would require 1000's of qubits and equally large number of read-outs, bias and drive lines. New materials that combine low passive loss and good RF properties are needed. Here we report performance of signal interconnects comprised of high-temperature YBCO films that are exfoliated from a metal substrate a...

Particle accelerators use a variety of low field magnets. This paper describes a recently proposed, novel concept of using circular superconducting coils for multipole iron-dominated magnets. This type of magnet design is most suitable for the use in high temperature superconductors (HTS), as well as in react and wind magnet technology. The HTS qua...

The performance and reliability of magnets made from second generation (2G), exfoliated, YBCO conductors are highly improved by use of narrow, stacked, multifilamentary cable instead of a single wide tape. This paper reports on tests of five mini-coils wound from 2.4 mm wide ExoCable™, which is comprised of eight, stacked, exfoliated, YBCO filament...

Development of multifilament YBCO cables is an im-portant step towards the manufacture of practical superconducting magnets based on second generation high temperature supercon-ductor technology. Currently, magnets manufactured from wide 2G tapes suffer from high magnetization loss, and poor reliability. The presence of an insulation substrate is t...

The second-generation high temperature superconductor (2G HTS) wire is the most promising conductor for high-field magnets such as accelerator dipoles and compact fusion devices. The key element of the wire is a thin Y1Ba2Cu3O7 (YBCO) layer deposited on a flexible metal substrate. The substrate, which becomes incorporated in the 2G conductor, reduc...

Optical photonic structures driven by picosecond, GW-class lasers are emerging as promising novel sources of electron beams and high quality X-rays. Due to quadratic dependence on wavelength of the laser ponderomotive potential, the performance of such sources scales very favorably towards longer drive laser wavelengths. However, to take full advan...

Recent advances in second-generation (YBCO) high-temperature superconducting wire could potentially enable the design of super high performance energy storage devices that combine the high energy density of chemical storage with the high power of superconducting magnetic storage. However, the high aspect ratio and the considerable filament size of...

Superconducting fault current limiters (SFCLs) are increasingly implemented in the power grid as a protection of substation equipment from fault currents. Resistive SFCLs are compact and light, however they are passively triggered and thus may not be sufficiently sensitive to respond to faults in the distribution grid. Here, we explore the prospect...

This invention provides a method of making a fluorinated precursor of a superconducting ceramic. The method comprises providing a solution comprising a rare earth salt, an alkaline earth metal salt and a copper salt; spraying the solution onto a substrate to provide a film-covered substrate; and heating the film-covered substrate in an atmosphere c...

We discuss the feasibility of enhancement of the gap field in a short-period hybrid undulator by using pole inserts with the saturation inductance Bs, over that of iron, 2 T. Dysprosium metal, with the saturation inductance of 3.4 T below 90 K, and Gadolinium with Bs=2.7 T, appear as good candidates as the optimized pole material. However, due to t...

Reversible operation of a high current superconductor switch based on the quench of high-resistance second generation high temperature superconducting wire is demonstrated. The quench is induced by a burst of an ac field generated by an inductively coupled radio-frequency coil. The switch makes a superconducting-to-normal transition within 5 ms and...

The ex situ process has emerged as a popular technology for growing epitaxial YBa2Cu3O7 (YBCO) for the second generation of coated conductors. The process combines low cost, ease of scale-up, the possibility of achieving high critical currents in relatively thick YBCO layers, as well as high tolerances to substrate misalignment. All of these factor...

This work reports a detailed structural study by synchrotron x-ray diffraction of several sets of thick YBa2Cu3O7 layers. The samples represent recent advances in flux-pinning design, containing various concentrations of artificial pinning centers: (i) BaZrO3 nanorods, (ii) BaZrO3 nanoparticles, and (iii) Y2O3 nanoparticles. A statistical analysis...

Large-scale, high-rate epitaxial growth technology for the second-generation superconducting wire brings unique technological challenges for the thin-film coating industry. One of the most difficult steps of the process is controlling nucleation of a complex compound over a km-long low-cost oxide template. Here, we analyze early stages of industria...

The high upper critical field characteristic of the recently discovered iron-based superconducting chalcogenides opens the possibility of developing a new type of non-oxide high-field superconducting wires. In this work, we utilize a buffered metal template on which we grow a textured FeSe$_{0.5}$Te$_{0.5}$ layer, an approach developed originally f...

We report size-dependent strain in epitaxial gadolinium doped ceria nanoislands, which was determined by synchrotron x-ray diffraction. Reciprocal space sections of symmetric, (004) and asymmetric, (224) reflections are approximated by a model assuming size-dependent strain of the islands using real-space size distribution obtained by atomic force...

Catalysts are widely utilized to promote reactions in liquid and gaseous phases but are rarely encountered in solid state synthesis. Here we use catalytically active (001) ceria buffers to modify the structure of the epitaxial high temperature superconductor YBa2Cu3O7. The modification is achieved by catalytically-assisted synthesis of a previously...

We describe here the use of high-temperature oxidation and reduction to produce highly crystalline nanoparticles of Ni and NiO. Starting with an amorphous Ni powder, we demonstrate that oxidation at 900 °C produces faceted NiO nanocrystals with sizes ranging from 20 to 60 nm. High-resolution transmission electron microscopy measurements indicate ne...

The purpose of this study is to enhance properties of the second-generation wires by increasing the density of Y1Ba2Cu3O7 (YBCO) nucleation centers on the surface of the ceria buffer. To identify the nature of the nucleation centers, we compare nucleation kinetics and performance of YBCO layers deposited by the metal–organic process on a standard R...

X-ray reciprocal-space mapping and atomic force microscopy (AFM) are used to study kinetics and mechanisms of lateral grain growth in epitaxial (001) ceria (CeO{sub 2}) deposited by pulsed laser deposition on (001) yttria-stabilized zirconia (YSZ) and (12 lowbar 10) (r-cut) sapphire. Rate and character of the grain growth during postannealing at 10...

The prime goal of the second-generation superconducting wire technology is to grow high-quality epitaxial layers of YBa ₂ Cu ₃ O ₇ (YBCO) superconductor using high-rate deposition on low-cost, kilometer-long substrates. We analyze the influence of Ni–W RABiTS™ substrate grain misalignment on nucleation of epitaxial...

The present invention is a method for producing a crystalline end-product. The method comprising exposing a fluoride-containing precursor to a hydrogen fluoride absorber under conditions suitable for the conversion of the precursor into the crystalline end-product.

We correlate the critical current performance of thick film second-generation YBa2Cu3O7 (YBCO) coated conductors, made by metal–organic deposition, with specimen grain size. The transport critical current densities, JcT, of these conductors were observed to be inversely proportional to YBCO grain size in the 5–40 µm size range. Analysis of magnetic...

This invention provides a method of making a fluorinated precursor of a superconducting ceramic. The method comprises providing a solution comprising a rare earth salt, an alkaline earth metal salt and a copper salt; spraying the solution onto a substrate to provide a film-covered substrate; and heating the film-covered substrate in an atmosphere c...

Metallographic polishing was used for the rapid assessment of the texture quality of 2 μm thick YBa2Cu3O7 (YBCO) layers deposited on oxide buffered RABiTS™ metal substrates. The YBCO films were grown using the barium fluoride ex situ process. The method is based on partial removal of the YBCO layer by mechanical polishing, resulting in the formatio...

In this work, we used quantitative x-ray diffraction measurements and optical metallography to investigate the relationship between structural quality and critical current densities Jc for 3- and 4-μm-thick YBa2Cu3O7 (YBCO) films grown on CeO2-buffered Ni–W substrates by the BaF2 process. The Jc of the films was shown to be approximately: (1) propo...

The critical current densities J(c-w)( H) per unit width of the tape were measured at 75 K in applied magnetic fields H on a 3 mu m-thick YBa2Cu3O7 film on a metallic substrate fabricated using the BaF2 process. J(c-w)( H) was the highest reported for YBa2Cu3O7 conductors with H perpendicular to the tape, and was independent of the angle between H...

We report on the synthesis and performance of 3- and 4-mum-thick YBa2Cu3O7 films on buffered metallic tapes. The precursor films were deposited by vacuum coevaporation of BaF2, Y, and Cu on the substrates and converted to YBa2Cu3O7 by the BaF2 ex situ process at reduced processing gas pressures. The best value of critical-current density Jc for the...

SuperPower is focused on scaling up second-generation (2-G) high-temperature superconductor (HTS) technology to pilot-scale manufacturing. The emphasis of this program is to develop R&D solutions for scale-up issues in pilotscale operations to lay the foundation for a framework for large-scale manufacturing. Throughput continues to be increased in...

Magnetic flux front and induction contours in superconducting YBa2Cu3O7-d films with defect size s ~ l (superconducting coherence length) and s > l are studied by magneto-optical imaging. Robust self-affine spatial correlation was observed using scaling analysis in the small pinning-dominated (s ~ l) disorderd films. The roughness exponent was dete...

Coated-conductor applications of YBCO require YBCO layers with high J_c and a thickness of several micrometers. The barium fluoride process offers a convenient way of depositing crack-free fluorinated precursor layers up to 5 microns thick. However, converting thick precursor layers into c-axis-oriented YBCO films is challenging due to ex...

The BaF2 process is a very attractive fabrication process for YBCO conductors since it allows the deposition and the formation steps of YBCO films to be separately performed, and it has been demonstrated that the films with high critical current densities can be fabricated on the buffered metallic substrates. However, we still face one major challe...

We present experimental data on direct measurements of area densities of YBa2Cu3O7−x, YBCO, nuclei in fluorinated precursor films which are on CeO2 buffered metallic and single-crystalline SrTiO3 substrates. The area density of the YBCO nuclei was measured by polarized-light microscopy after the nuclei had grown to the surface of the film. The dens...

A new technique for the growth of epitaxial c-axis oriented YBa2Cu3O7 using spray pyrolysis at atmospheric pressure is described. The technique consists of three steps: the deposition of an oxide precursor by spray pyrolysis of a nitrate solution, fluorination of the oxide precursor in an atmosphere containing a fluorinated gas, and finally, growth...

We studied the fractal penetration of magnetic flux in YBa_2Cu_3O_7-δ (YBCO) thin films by using high resolution Magneto Optical Imaging (MOI) technique. The flux penetration pattern was found to be fractal with a dimension d=1.33 in a 1 μm thick YBCO film grown by BaF2 ex situ reaction method, which has large structural imhomogenity ( 5 μm). In a...

We present magneto optical studies of the critical state in YBa2Cu3O7-δ (YBCO) thick films prepared using BaF2ex-situ post reaction process. A distinctive fractal propagation pattern was observed as the magnetic flux entering the superconducting films, in a striking contrast to the behavior expected of a uniform type II superconducting film in the...

The removal of hydrogen fluoride gas (HF) is a significant problem for the ex situ processing of large area YBCO precursor coated conductors employed in the BaF2 process. We propose a new solution based on the in situ chemical absorption of HF. This approach allows the design of a simple ex situ reactor, which, in theory, has an extremely large cap...

The ac losses at 20 and 30 Hz were measured for two disk-shaped YBa ₂ Cu ₃ O ₇ films in perpendicular peak applied magnetic fields up to ∼0.2 T in liquid nitrogen. One of the films had a significantly higher critical-current density than the other as determined from the loss measurements. Also, it exhibited a more-u...

Some coated conductor applications require a YBCO layer at least 5 μm thick with high J_c. The growth of thick c-axis oriented epitaxial layers using the barium fluoride ex-situ technology is not always possible. Films over 3 μm thick have more undesirable a-oriented and random grains than thinner ones. We present an analysis of thick fil...

The mechanisms have been identified for the hetero-epitaxial nucleation of YBa2Cu3O ∼ 6.1 (YBCO) at the buried interface between a precursor film and SrTiO3 for the so-called BaF2 process which is a postdeposition reaction process for the synthesis of epitaxial YBCO films. It is shown that the preferential nucleation of YBCO at the interface is due...

The nucleation and growth of the c-axis-aligned Yba2Cu3Ox on SrTiO3 and CeO2, from precursor films, were studied by examining quenched and fully processed specimens using transmission electron microscopy techniques. The precursor films, a stoichiometric mixture of fine-grained Y, Cu, and BaF2, were deposited using physical vapor deposition methods....

Recently, considerable efforts have been made in growing bi-axially aligned thick Yba 2 cu 3 O 7 (YBCO) films on a flexible, textured metallic substrate for electrical power applications. The BaF 2 post-deposition annealing process is one of the most promising methods. to understand the nucleation and growth mechanism of YBCO in this process, exten...

YBa2Cu3O7 films were fabricated on SrTiO3 substrates using the BaF2 ex situ process. Precursor films 1, 3 and 5 μm thick were processed in an atmospheric pressure reactor using a gas mixture of oxygen, nitrogen and water vapor. The films were processed at different water vapor pressures and it was observed that the film growth rate was independent...

Ex-situ post-deposition reaction processing is considered a promising alternative to in-situ physical vapor deposition techniques for coated Y₁Ba₂Cu₃O₇ conductor development. It was reported recently that attempts at ex-situ processing of long Y₁Ba₂Cu₃O₇ precurs...

We present a study of superconducting and microstructural properties of [001] tilt YBa₂Cu₃O_7-δ (YBCO) thick film grain boundaries (GB) on SrTiO₃ bicrystal substrates prepared using a BaF₂ ex-situ post deposition reaction process. For a 15° tilt boundary, multiple microbridges were patterned ac...

The development of YBa 2 Cu 3 O 7 (YBCO) thick films on a flexible, textured, metallic substrate has recently attracted considerable scientific and technical interest. It is well known that the interfacial microstructure plays an important role on the formation and alignment of the YBCO films. Thus, understanding the evolution of the phases near th...

The ex situ growth of thick textured YBa2Cu3O7 films on SrTiO3 substrates was investigated in order to find the factors, which influence growth kinetics. It was found that the growth rate of YBa2Cu3O7 films remains constant during heat treatment and is proportional to the square root of the H2O partial pressure in the processing atmosphere. Using t...

We present a study of superconducting and microstructural properties of [001] tilt YBCO thick film grain boundaries on SrTiO3 bicrystal substrates and textured Ni substrates. The YBCO films with thickness ranging from 0.5 to 5 micrometer were prepared using BaF2 ex-situ post reaction process of the precursor by high rate e-beam deposition. The miso...

Transport critical current densities in single crystals of the strongly anisotropic high- superconductor were measured in a wide range of temperature, applied field and angles between field direction and c-axis of the crystals, above and below the decoupling line. In the low-field region, below the decoupling line, an analysis of the field and angl...

this paper we analyze the effect of variations of the post-annealing process as regards the growth kinetics and critical currents. In the first section we report on the results of in-situ resistivity measurements as a method for monitoring the growth kinetics of the films during the post-annealing process. Data on the film growth rate as a function...

High rate evaporation techniques were used to deposit Y, BaF2, and Cu precursor films onto SrTiO3 single crystal substrates at rates in excess of 10 nm/s. Y and Cu were deposited by electron beam (e-beam) heating and thermal heating was used for BaF2. Post deposition annealing was used to form 3 μm thick c-axis aligned YBa2Cu3O7 films on the SrTiO3...

Over the last few years, considerable efforts have been made in developing fabrication processes for thick superconducting YBa 2 Cu 3 O 7-δ film on a metallic substrate for electric power applications. Since these applications require the composite tape to be longer than 4-500m, any methods chosen need to be compatible with such length requirement....

Secondary phase evolution in the 12 wt.% Cr steel austenitized at 1100 and 1330°C and subsequently tempered at 750°C was investigated. To describe the microstructures and identify the secondary phases, methods of light microscopy and transmission electron microscopy including electron diffraction and microanalysis were used. It was found that oil q...

Bulk cylindrical blocks of YBCO, 30 mm in diameter and 17 mm in thickness, are prepared by a modified Melt Textured Growth batch process. Blocks are consisting of weak textured 1–2 cm3 grains. Samples with dimensions of about (8×8×5) mm3 are cutted from the blocks, encapsulated in ZrO2 and inserted in a recessed anvil-type high pressure apparatus a...

The present study demonstrates the possibility of preparing Bi-based SC-ceramics with almost theoretical density and high level of superconductive and mechanical properties in a short time by temperature treatment under high pressure conditions. It is shown that there is a P-T-τ-region where the 2223 phase content may be increased. The variation of...

The nucleation of the c-axis aligned and non-c-axis YBaâCuâO{sub â¼6.1} (YBCO) from precursor films on [001]-cut SrTiOâ was investigated for the so-called BaFâ process. Specimens with different thickness were quenched from 735 C, then studied by transmission electron microscopy and x-ray diffraction techniques. Preceding the formation of YBCO nucle...

The nucleation of the c-axis aligned and non-c-axis YBaâCuâO{sub â¼6.1} (YBCO) from precursor films on [001]-cut SrTiOâ was investigated for the so-called BaFâ process. Specimens with different thickness were quenched from 735 C, then studied by transmission electron microscopy and x-ray diffraction techniques. Preceding the formation of YBCO nucle...