The sixth Taniguchi Symposium on the Theory of Condensed Matter was held between 14-18 November 1983 at Kashikojima. Japan. During the Symposium, about twenty participants lived together and discussed the magnetic super conductors and related problems in an active and friendly atmosphere. This volume contains the papers presented at this Symposium. A strong impetus for organizing a Symposium of this subject is afforded by recent intense interest and accumulated information on magnetic and other novel superconductors newly discovered, and indeed the Symposium has pro duced many excellent contributions to this very exciting field of condensed matter theory, as reported in this volume. In order to give the readers a general outline of the subject, a brief sketch of the problem is made in the Introduction. Then the remainder of this volume is divided into four Parts and an Appendix. Part I is devoted to di scuss ions on several aspects of ferromagnetic superconductors includ ing superconductivity in heavy fermion systems. Part II treats problems on anti ferromagnetic superconductors. In Part III three papers on organic supercon ductors are presented. Part IV includes discussions on the exotic supercon ductors. The Appendix is concerned with the new research project towards high Tc superconductors in Japan. The last but not least remark is to mention the activity of the Taniguchi Foundation whose support makes this Symposium possible. For many years Mr."

viii The growing use of NTD silicon outside the U. S. A. motivated an interest in having the next NTD conference in Europe. Therefore, the Third International Conference on Neutron Transmutation-Doped Silicon was organized by Jens Guldberg and held in Copenhagen, Denmark on August 27-29, 1980. The papers presented at this conference reviewed the developments which occurred during the t'A'O years since the previous conference and included papers on irradiation technology, radiation-induced defects, characteriza tion of NTD silicon, and the use of NTD silicon for device appli cations. The proceedings of this conference were edited by Jens Guldberg and published by Plenum Press in 1981. Interest in, and commercial use of, NTD silicon continued to grow after the Third NTD Conference, and research into neutron trans mutation doping of nonsilicon semiconductors had begun to accel erate. The Fourth International Transmutation Doping Conference reported in this volume includes invited papers summarizing the present and anticipated future of NTD silicon, the processing and characterization of NTD silicon, and the use of NTD silicon in semiconductor power devices. In addition, four papers were pre sented on NTD of nonsilicon semiconductors, five papers on irra diation technology, three papers on practical utilization of NTD silicon, four papers on the characterization of NTD silicon, and five papers on neutron damage and annealing. These papers indi cate that irradiation technology for NTD silicon and its use by the power-device industry are approaching maturity."

Since the First International Symposium on Superconductivity (ISS '88) was held in Nagoya, Japan in 1988, significant advances have been achieved in a wide range of high temperature superconductivity research. Although the T c's of recently discovered oxide superconductors still do not exceed the record high value of 125K reported before that meeting, the enrichment in the variety of materials should prove useful to the investigation of the fundamental mechanism of superconductiv ity in these exotic materials. The discovery of the n-type superconducting oxides proved to oppose the previously held empirical fact that the charge carriers in all oxide superconductors were holes. In addition, optimization of the charge carrier density has been established as a technique to improve the superconducting proper ties of the previously known oxide materials. Many new experimental and theoreti cal advances have been made in understanding both the fundamental and the applied aspects of high temperature superconductivity. In this latter area, various new processing techniques have been investigated, and the critical current densities and other significant parameters of both bulk and thin film oxide superconductors are rapidly being improved. At this exciting stage of research in high temperature superconductivity, it is extremely important to provide an opportunity for researchers from industry, academia, government and other institutions around the world to freely exchange information and thus contribute to the further advancement of research."

The structural. electronic and lattice properties of superconducting ternary com pounds are the subject of this Topics volume. Its companion volume (Topics in Cur rent Physics. Volume 34) deals primarily with the mutual interaction of supercon ductivity and magnetism in ternary compounds. These two volumes are the culmination of a project. started nearly two years ago. that was inspired by the intense re search effort. both experimental and theoretical. then being expended to explore and develop an understanding of the remarkable physical properties of ternary super conductors. Research activity on this subject has increased in the meantime. The interest in ternary superconductors originated in 1972. when B.T. Matthias and his co-workers first discovered superconductivity in several ternary molybdenum sulfide compounds that had been synthesized in 1971 by R. Chevrel. M. Sergent. and J. Prigent. The superconducting critical temperature Tc of one of the compounds. PbMo S * was reported to be ~ 15 K. This value is sufficiently high that there was g 6 (and still is) reason to expect that other ternary compounds would be found with superconducting transition temperatures rivaling those of the A15 compounds. of which Nb Ge has the record high Tc of 23 K. The interest in ternary superconductors 3 received further impetus when several of the ternary molybdenum sulfides were found to have exceptionally high upper critical magnetic fields. some of them in the neighborhood of 50 Tesla or more. An immense amount of research on ternary molybdenum chalcogenides then followed.

The book provides an in-depth understanding of the fundamentals of superconducting electronics and the practical considerations for the fabrication of superconducting electronic structures. Additionally, it covers in detail the opportunities afforded by superconductivity for uniquely sensitive electronic devices and illustrates how these devices (in some cases employing high-temperature, ceramic superconductors) can be applied in analog and digital signal processing, laboratory instruments, biomagnetism, geophysics, nondestructive evaluation and radioastronomy. Improvements in cryocooler technology for application to cryoelectronics are also covered. This is the first book in several years to treat the fundamentals and applications of superconducting electronics in a comprehensive manner, and it is the very first book to consider the implications of high-temperature, ceramic superconductors for superconducting electronic devices. Not only does this new class of superconductors create new opportunities, but recently impressive milestones have been reached in superconducting analog and digital signal processing which promise to lead to a new generation of sensing, processing and computational systems. The 15 chapters are authored by acknowledged leaders in the fundamental science and in the applications of this increasingly active field, and many of the authors provide a timely assessment of the potential for devices and applications based upon ceramic-oxide superconductors or hybrid structures incorporating these new superconductors with other materials. The book takes the reader from a basic discussion of applicable (BCS and Ginzburg-Landau) theories and tunneling phenomena, through the structure and characteristics of Josephson devices and circuits, to applications that utilize the world's most sensitive magnetometer, most sensitive microwave detector, and fastest arithmetic logic unit.

This Topics in Current Physics (TCP) Volume 34 is concerned primarily with super- conductivity and magnetism, and the mutual interaction of these two phenomena in ternary rare earth compounds. It is the companion of TCP Volume 32 - Superconduc- tivity in Ternary Compounds: Structural, Electronic and Lattice Properties. The interplay between superconductivity and magnetism has intrigued theoreticians and experimentalists alike for more than two decades. V. L. Ginzburg first addressed the question of whether or not superconductivity and ferromagnetism could coexist in 1957, and B. T. Matthias and coworkers carried out the first experimental inves- tigations on this problem in 1959. The early experiments were made on systems that consisted of a superconducting element or compound into which small concentrations of rare earth impurities with partially-filled 4f electron shells had been intro- duced. These dilute impurity systems were chosen because the scattering of conduc- tion electrons by parama9. netic rare earth impurity ions usually has a strong de- structive "pa i r breaking" effect on superconducti vity, typi ca lly drivi ng the super- conducting transition temperature to zero at impurity concentrations of only a few atomic percent. Unfortunately, analysis of these early experiments was complicated by clustering and/or the formation of short range or "glassy" types of magnetic order so that definitive conclusions regarding the coexistence of superconductivity and magnetism could not be reached.

The recent discovery of high-temperature superconductivity in copper based oxides is an event of major importance not only with respect to the physical phenomenon itself but also because it definitely shows that solid state chemistry, and especially the crystal chemistry of oxides, has a crucial place in the synthesis and understanding of new materials for future appli cations. The numerous papers published in the field of high Tc supercon ductors in the last five years demonstrate that the great complexity of these materials necessitates a close collaboration between physicists and solid state chemists. This book is based to a large extent on our experience of the crystal chemistry of copper oxides, which we have been studying in the laboratory for more than twelve years, but it also summarizes the main results which have been obtained for these compounds in the last five years relating to their spectacular superconducting properties. We have focused on the struc ture, chemical bonding and nonstoichiometry of these materials, bearing in mind that redox reactions are the key to the optimization of their supercon ducting properties, owing to the importance of the mixed valence of copper and its Jahn-Teller effect. We have also drawn on studies of extended defects by high-resolution electron microscopy and on their creation by ir radiation effects."

Thermoelectric devices could play an important role in making efficient use of our energy resources but their efficiency would need to be increased for their wide scale application. There is a multidisciplinary search for materials with an enhanced thermoelectric responses for use in such devices. This volume covers the latest ideas and developments in this research field, covering topics ranging from the fabrication and characterization of new materials, particularly those with strong electron correlation, use of nanostructured, layered materials and composites, through to theoretical work to gain a deeper understanding of thermoelectric behavior. It should be a useful guide and stimulus to all working in this very topical field.

In this text experts review experimental studies that directly reveal the relationship between the atomic structure and physical behavior of high-Tc superconductors. The thorough discussion centers on twins, twin boundaries, the vortex lattice, and magnetic and mechanical properties in connection with structural imperfections. Particular attention is paid to the role of the oxygen atom in the Y-Ba-Cu-O and La-Cu-O species. The experimental methods evaluated include electron and X-ray diffraction, electron microscopy, and M-ssbauer spectroscopy. This book makes extraordinarily valuable data obtained at the Institute of Solid State Physics at Chernogolovka accessible to the wider international community of researchers in superconductivity.

During the past thirty years considerable efforts have been made to design the synthesis and the study of molecular semiconductors. Molecular semiconductors - and more generally molecular materials - involve interactions between individual subunits which can be separately synthesized. Organic and metallo-organic derivatives are the basis of most of the molecular materials. A survey of the literature on molecular semiconductors leaves one rather confused. It does seem to be very difficult to correlate the molecular structure of these semiconductors with their experimental electrical properties. For inorganic materials a simple definition delimits a fairly homogeneous family. If an inorganic material has a conductivity intermediate between that of an 12 1 1 3 1 1 insulator " 10- n- cm- ) and that of a metal (> 10 n- cm- ), then it is a semiconductor and will exhibit the characteristic properties of this family, such as junction formation, photoconductivity, and the photovoltaic effect. For molecular compounds, such simplicity is certainly not the case. A huge number of molecular and macromolecular systems have been described which possess an intermediate conductivity. However, the various attempts which have been made to rationalize their properties have, more often than not, failed. Even very basic electrical properties such as the mechanism of the charge carrier formation or the nature and the density ofthe dopants are not known in detail. The study of molecular semiconductor junctions is very probably the most powerful approach to shed light on these problems.

The characterization of epitaxial layers and their surfaces has benefitted a lot from the enormous progress of optical analysis techniques during the last decade. In particular, the dramatic improvement of the structural quality of semiconductor epilayers and heterostructures results to a great deal from the level of sophistication achieved with such analysis techniques. First of all, optical techniques are nondestructive and their sensitivity has been improved to such an extent that nowadays the epilayer analysis can be performed on layers with thicknesses on the atomic scale. Furthermore, the spatial and temporal resolution have been pushed to such limits that real time observation of surface processes during epitaxial growth is possible with techniques like reflectance difference spectroscopy. Of course, optical spectroscopies complement techniques based on the inter action of electrons with matter, but whereas the latter usually require high or ultrahigh vacuum conditions, the former ones can be applied in different environments as well. This advantage could turn out extremely important for a rather technological point of view, i.e. for the surveillance of modern semiconductor processes. Despite the large potential of techniques based on the interaction of electromagnetic waves with surfaces and epilayers, optical techniques are apparently moving only slowly into this area of technology. One reason for this might be that some prejudices still exist regarding their sensitivity."

For the last few years astrophysicists and elementary particle physicists have been working jointly on the following fascinating phenomena: 1. The solar neutrino puzzle and the question: What happens to the neutrinos on their way from the sun to the earth? 2. The growing evidence that our universe is filled with about 10 times more matter than is visible and the question: What is dark matter made of? 3. The supernovae explosions and the question: What do neutrinos tell us about such explosions and vice versa? The experimental investigation of these phenomena is difficult and involves unconventional techniques. These are presently under development, and bring together such seemingly disparate disciplines as astrophysics and elementary particle physics on the one hand and superconductivity and solid-state physics on the other. This book contains the proceedings of a workshop held in March 1987 at which the above subjects and their experimental investigation were discussed. The proposed experimental methods are very new. They involve frontier developments in low temperature and solid-state physics. The book should be useful to researchers and students who actively work on these subjects or plan to enter the field. It also offers the non-expert reader with some physics background a good survey of the activities in this field.

One of the most exciting developments in modern physics has been the discovery of the new class of oxide materials with high superconducting transition temperature. Systems with Tc well above liquid nitrogen temperature are already a reality and higher Tc's are anticipated. Indeed, the idea of a room-temperature superconductor, which just a short time ago was considered science fiction, appears to be a distinctly possible outcome of materials research. To address the need to train students and scientists for research in this exciting field, Jeffrey W. Lynn and colleagues at the University of Maryland, College Park, as well as other superconductivity experts from around the U.S., taught a graduate-level course in the fall of 1987, from which the chapters in this book were drawn. Subjects included are: Survey of superconductivity (J. Lynn).- The theory of type-II superconductivity (D. Belitz).- The Josephson effect (P. Ferrell).- Crystallography (A. Santoro).- Electronic structure (C.P. Wang).- Magnetic properties and interactions (J. Lynn).- Synthesis and diamagnetic properties (R. Shelton).- Electron pairing (P. Allen).- Superconducting devices (F. Bedard).- Superconducting properties (J. Crow, N.-P. Ong).

Single-electron tunneling (SET) and related phenomena have recently come to be considered as "hot topics." This also became apparent when we organized the 4th International Conference on Superconducting and Quantum Effect Devices and Their Applications, SQUID'91, which was held June 18-21, 1991, in Berlin, Germany. Impressed by the number of contributions dedicated to the new physics of ultrasmall devices, we deemed it appropriate to devote this volume of the Springer Series in Electronics and Photonics to these specialized proceedings. The other contributions presented at SQUID'91, which are more conventional in character but nevertheless contain excitingly innovative results, are published separately as Volume 64 of the series Springer Proceedings in Physics. At first glance it seems strange that a conference abbreviated SQUID'91 should attract so many papers on non-superconducting devices, and in fact the first SQUID'XX conferences dealt exclusively with the physics and technology of Josephson junctions, SQUIDs and other superconducting devices and their ap plications. However, many concepts developed for superconducting devices, like tunneling, flux quantization, and flux-charge conjugation, appeared to be suitable for ultrasmall non-superconducting structures as well, and many researchers in the field of superconducting devices extended their activities accordingly. Thus the extension of the conference programme evolved quite informally. Meanwhile, the meetings established themselves as well-known conference series tradition ally appreciated by the SQUID community for its balanced mixture of physics and technology, review and preview. SQUID'XX became a kind of a trademark."

Physics and Chemistry of Transition-Metal Oxides includes both theoretical and experimental approaches to the variety of phenomena found in the transition-metal oxides, including high-temperature superconductivity, colossal magnetoresistance, and metal-insulator transition. These are the central issues in materials science and condensed matter physics/chemistry, and readers can obtain up-to-date information on what is happening in this field of research.

Springer-Verlag, Berlin Heidelberg, in conjunction with Springer-Verlag New York, is pleased to announce a new series: CRYSTALS Growth, Properties, and Applications The series presents critical reviews of recent developments in the field of crystal growth, properties, and applications. A substantial portion of the new series will be devoted to the theory, mechanisms, and techniques of crystal growth. Occasionally, clear, concise, complete, and tested instructions for growing crystals will be published, particularly in the case of methods and procedures that promise to have general applicability. Responding to the ever-increasing need for crystal substances in research and industry, appropriate space will be devoted to methods of crystal characterization and analysis in the broadest sense, even though reproducible results may be expected only when structures, microstructures, and composition are really known. Relations among procedures, properties, and the morphology of crystals will also be treated with reference to specific aspects of their practical application. In this way the series will bridge the gaps between the needs of research and industry, the pos sibilities and limitations of crystal growth, and the properties of crystals. Reports on the broad spectrum of new applications - in electronics, laser tech nology, and nonlinear optics, to name only a few - will be of interest not only to industry and technology, but to wider areas of applied physics as well and to solid state physics in particular. In response to the growing interest in and importance of organic crystals and polymers, they will also be treated."

In less than two decades the concept of supercon In every field of science there are one or two ductivity has been transformed from a laboratory individuals whose dedication, combined with an innate curiosity to usable large-scale applications. In the understanding, permits them to be able to grasp, late 1960's the concept of filamentary stabilization condense, and explain to the rest of us what that released the usefulness of zero resistance into the field is all about. For the field of titanium alloy marketplace, and the economic forces that drive tech superconductivity, such an individual is Ted Collings. nology soon focused on niobium-titanium alloys. They His background as a metallurgist has perhaps given him are ductile and thus fabricable into practical super a distinct advantage in understanding superconduc conducting wires that have the critical currents and tivity in titanium alloys because the optimization of fields necessary for large-scale devices. More than superconducting parameters in these alloys has been 90% of all present-day applications of superconductors almost exclusively metallurgical. Advantages in use titanium alloys. The drive to optimize these training and innate abilities notwithstanding, it is alloys resulted in a flood of research that has been the author's dedication that is the essential com collected, condensed, and analyzed in this volume."

Recent experimental and theoretical progress has elucidated the tunable crossover, in ultracold Fermi gases, from BCS-type superconductors to BEC-type superfluids.

"The BCS-BEC Crossover and the Unitary Fermi Gas" is a collaborative effort by leading international experts to provide an up-to-date introduction and a comprehensive overview of current research in this fast-moving field.

It is now understood that the unitary regime that lies right in the middle of the crossover has remarkable universal properties, arising from scale invariance, and has connections with fields as diverse as nuclear physics and string theory.

This volume will serve as a first point of reference for active researchers in the field, and will benefit the many non-specialists and graduate students who require a self-contained, approachable exposition of the subject matter.

"

Polymer semiconductor is the only semiconductor that can be processed in solution. Electronics made by these flexible materials have many advantages such as large-area solution process, low cost, and high performance. Researchers and companies are increasingly dedicating time and money in polymer electronics. This book focuses on the fundamental materials and device physics of polymer electronics. It describes polymer light-emitting diodes, polymer field-effect transistors, organic vertical transistors, polymer solar cells, and many applications based on polymer electronics. The book also discusses and analyzes in detail preparation techniques and device properties of polymer electronics.

Various experimental techniques for point contact production are described. Examples of point-contact spectra are presented for pure metals, alloys and compounds, as well as for semimetals and semiconductors, heavy fermion systems, Kond-lattices, mixed valence compounds and more. Superconducting point contacts are considered in respect to Andreev reflection and Josephson effects. Special attention is paid to contact conductance fluctuation, and new trends of research are outlined.

Semiconductors have been used widely in signal-level or "brain" applications. Since their invention in 1948, transistors have revolutionized the electronics industry in computers, information processing, and communications. Now, however, semiconductors are being used more and more where consid erable "brawn" is required. Devices such as high-power bipolar junction tran sistors and power field-effect transistors, as well as SCRs, TRlACs, GTOs, and other semiconductor switching devices that use a p-n-p-n regenerative effect to achieve bistable action, are expanding the power-handling horizons of semicon ductors and finding increasing application in a wide range of products including regulated power supplies, lamp dimmers, motor drives, pulse modulators, and heat controls. HVDC and electric-vehicle propulsion are two additional areas of application which may have a very significant long range impact on the tech nology. The impact of solid-state devices capable of handling appreciable power levels has yet to be fully realized. Since it first became available in late 1957, the SCR or silicon-controlled rec tifier (also called the reverse blocking triode thyristor) has become the most popular member of the thyristor family. At present, SCRs are available from a large number of manufacturers in this country and abroad. SCR ratings range from less than one ampere to over three thousand amperes with voltage ratings in excess of three thousand volts."

This volume contains the proceedings of the ffiM Japan International Sympo sium on Strong Correlation and Superconductivity, which was held in Keidan ren Guest House at the foot of Mt. Fuji, May 21-25, 1989. The purpose of the Symposium was to provide an opportunity for discus sions on the problem of strong correlation of electrons in the context of high-Tc superconductivity. Sixty-eight scientists were invited from seven countries and forty-three papers were presented in the Symposium. Soon after the discovery ofhigh-Tc superconducting oxides, Professor P. W. Anderson proposed that the essence of high-Tc superconductivity lies in the strong correlation among the electrons in these materials. This proposal has stimulated a wide range of theoretical investigations on this profound and dif ficult problem, which are expected to lead eventually to new concepts describ ing strong electron correlation. In the Symposium, Anderson himself started lively discussions by his talk entitled "Myth and Reality in High-Tc Supercon ductivity," which was followed by various reports on theoretical studies and experimental results. Concise and thoughtful summaries of experiment and theory were given by Professors H. R. Ott and P. A. Lee, respectively. It is our hope that this volume reflects the present status of the research activity on this outstanding problem from the viewpoint of the basic physics and that it will further stimulate the effort to understand these fascinating systems, the high-Tc oxides."

While basic features of polarons were well recognized a long time ago and have been described in a number of review papers and textbooks, interest in the role of electron-phonon interactions and polaron dynamics in di?- ent materials has recently gone through a vigorous revival. Electron-phonon interactions have been shown to be relevant in many inorganic and organic semiconductors and polymers, colossal magnetoresistance oxides, and tra- port through nanowires and quantum dots also often depends on vibronic displacements of ions. These interactions presumably play a role in hi- temperature superconductors as well. The continued interest in polarons extends beyond the physical description of advanced materials. The ?eld has been a testing ground for analytical, semi-analytical, and numerical techniques, such as path integrals, strong-coupling perturbation expansion, advanced variational methods, exact diagonalization, Quantum Monte Carlo, and other techniques. This book reviews some recent developments in the ?eld of polarons, starting with the basics and covering a number of active directions of research. Single- and multipolaron theories have o?ered more insight into colossal magnetoresistance and in a broad spectrum of ph- ical properties of structures with reduced dimension and dimensionality such as transport, optical absorption, Raman scattering, photoluminescence, magneto-optics, etc. While nobody - at present - has a ?nal theory of hi- temperature superconductivity, we discuss one alternative (polaronic) route. We have bene?ted from discussions with many experts in the ?eld.

Spin wave theory of magnetism and BCS theory of superconductivity are typical theories of the time before renormalization group (RG) theory. The two theories consider atomistic interactions only and ignore the energy degrees of freedom of the continuous (infinite) solid. Since the pioneering work of Kenneth G. Wilson (Nobel Prize of physics in 1982) we know that the continuous solid is characterized by a particular symmetry: invariance with respect to transformations of the length scale. Associated with this symmetry are particular field particles with characteristic excitation spectra. In diamagnetic solids these are the well known Debye bosons. This book reviews experimental work on solid state physics of the last five decades and shows in a phenomenological way that the dynamics of ordered magnets and conventional superconductors is controlled by the field particles of the infinite solid and not by magnons and Cooper pairs, respectively. In the case of ordered magnets the relevant field particles are called GSW bosons after Goldstone, Salam and Weinberg and in the case of superconductors the relevant field particles are called SC bosons. One can imagine these bosons as magnetic density waves or charge density waves, respectively. Crossover from atomistic exchange interactions to the excitations of the infinite solid occurs because the GSW bosons have generally lower excitation energies than the atomistic magnons. According to the principle of relevance the dynamics is governed by the excitations with the lowest energy. The non relevant atomistic interactions with higher energy are practically unimportant for the dynamics.

The aim of this book is to acquaintthe reader with the phenomenon of sup- conductivity and the high temperature superconductors discovered in 1986 by Bednorz and Muller. Just after this discovery, a lot of research work was carried out by the scientists worldwide over for more than about 10 years. This book describes the superconductivity phenomenon (Chap. 1), the structureofhighT superconductors(Chap.2), thecriticalcurrents(Chap.3), c synthesis of high T superconductors (Chap. 3), the superconductivity in c cuprates (Chap. 4), proximity e?ect and SQUID devices, their design criteria and noise aspects (Chap. 6), theories (Chap. 7) and applications (Chap. 8). TheauthorisgratefultoProfessorO.N.Srivastava, BanarasHinduUniv- sity, VaranasiforvaluableguidanceanddiscussionsduringPh.D.tenureofthe author andalsothankful to Prof.R.S. Tiwari, Dr. K.Ramakrishna, Dr. Balak Das, Dr. K.K. Verma, Dr. G.D. Varma andDr. H.K. Singh, who workedalong with the author during researchat B.H.U., leading to his Ph.D. The author is thankful to Prof. D.P. Tiwari (Head, Physics Department, A.P.S. University, Rewa), Dr. A.P. Mishra and Dr. S.L. Agrawal, Physics Department, A.P.S. University, for boosting the morale. The author is thankful to scientists and researchers whose work/papers have been consulted for preparing the manuscript. Further I wish to express thanks to Mr. Dharmendra Saxena for preparing type-sc