Nghiên cứu tăng mật độ dòng tới hạn siêu dẫn Bi-Pb-Sr-Ca-Cu-O bằng tâm ghim nano

VIETNAM NATIONAL UNIVERSITY UNIVERSITY OF SCIENCE _______________________ Pham The An IMPROVEMENTS OF CRITICAL CURRENT DENSITY OF Bi-Pb-Sr-Ca-Cu-O HIGH-Tc SUPERCONDUCTOR BY ADDITIONS OF NANO-STRUCTURED PINNING CENTERS Major: Thermophysics Code: 9440130.07 DISSERTATION FOR DOCTOR OF PHILOSOPHY IN PHYSICS SUPERVISORS : 1. Luu Tuan Tai Professor of Physics 2. Tran Hai Duc Associate Professor of Physics Ha Noi - 2023 DECLARATION I hereby declare that this is my own research work. The results written in collaboration with other authors have been approved by the co-authors prior to being included in the thesis.

The results presented in the thesis are truthful and have not been published in any other works. Author Pham The An 1 ACKNOWLEDGMENTS Time as a doctoral student is the first step on our academic long journey. A challenging period that demanded great effort and perseverance, but was extremely rewarding, has enabled me to develop the necessary mindset, skills, and character to conduct independent research and contribute to scientific advancement. The achievements that I have attained today have greatly benefited from the contribution and support of my supervisors, lab-mates, colleagues, friends, and family.

Although these words can never fully express my gratitude and love, I would like to send my sincerest thanks to those who have accompanied me throughout this journey. First and foremost, I would like to express my highest reverent gratitude to my supervisors – Asso. Tran Hai Duc and Prof. Luu Tuan Tai, for their supervision, guidance, and invaluable feedback throughout the journey.

Their insightful comments and constructive criticisms were instrumental in shaping and refining my research work. I am truly grateful for the time and effort they have devoted to helping me achieve my academic goals. I am also grateful to the members of my dissertation committee, for their precise feedback. Their constructive comments and suggestions have immensely improved the quality of my work.

I would like to express my appreciation to my lab-mates, colleagues, and friends, who have provided enthusiasm and valuable support to me during the research. I extend my gratitude to the professors and staffs at my faculty and functional departments, especially, Dr. Nguyen Duy Thien, Dr. Sai Cong Doanh, Dr.

Nguyen Quang Hoa at Faculty of Physics, Asso. Nguyen Hoang Nam at Nano and Energy Center, and Dr. Nguyen Thanh Binh, University of Science, Vietnam National University; Dr. Nguyen Khac Man at International Training Institute for Materials Science, Hanoi University of 2 Science and Technology, who have provided me with administrative and technical support.

I also would like to express my appreciation for the collaboration with the research groups of Dr. Le Minh Tien, Msc. Tran Tien Dzung at Sungkyunkwan University (Korea), Dr. Wantana Klysubun at Synchrotron Light Resource Institute (Thailand), and Prof.

Takafumi Miyanaga at Hirosaki University (Japan). Their assistance has been crucial in facilitating the completion of my doctoral course. I would like to thank PhD Scholarship Programme of Vingroup Innovation Foundation, the Institute of Big Data and The Development Foundation of Vietnam National University, Hanoi for sponsoring my research. Lastly, I would like to express my sincere gratitude to my family and my girlfriend, for their support, encouragement, and spiritual strength during all of this challenging period.

Their love has been my great motivation to achieve every goal. I am most sincerely grateful for their sacrifices and unwavering belief in me. Ha Noi, August 2023 Pham The An 3 CONTENTS DECLARATION. 4 LIST OF NOTATIONS AND ABBREVIATIONS.

7 LIST OF TABLES. 10 LIST OF FIGURES. History of Superconductivity. Critical parameters of a superconductor.

Vortex state in type-II superconductors. VORTEX DYNAMICS IN TYPE-II SUPERCONDUCTORS. The collective pinning theory. Flux pinning mechanism in type-II superconductor.

RECENT STUDIES ON THE FIRST GENERATION SUPERCONDUCTING WIRE. Bi-Sr-Ca-Cu-O superconductor. Recent studies on the BSCCO superconductor. MOTIVATION OF THE DISSERTATION .1 Fabrication of Bi-Pb-Sr-Ca-Cu-O polycrystalline samples.

Fabrication of nanoparticles. Introductions of pinning centers into Bi-Pb-Sr-Ca-Cu-O polycrystalline samples. Crystal structure analyses. Superconducting property analyses.

56 CHAPTER 3 : IMPROVEMENTS OF CRITICAL CURRENT DENSITY IN HIGH-Tc Bi1.4Sr2Ca2Cu3O10+ OF SUPERCONDUCTOR BY USING SODIUM SUBSTITUTION EFFECT. FORMATION OF THE SUPERCONDUCTING PHASES. IMPROVEMENTS OF Jc. FLUX PINNING PROPERTIES.

Improvements of pinning force density. Identification of flux pinning type. Flux pinning mechanism. CONCLUSION OF CHAPTER 3.

75 CHAPTER 4 : IMPROVEMENTS OF CRITICAL CURRENT DENSITY IN HIGH-Tc Bi1.4Sr2Ca2Cu3O10+ SUPERCONDUCTOR BY ADDITION OF NON-MAGNETIC TiO2 NANOPARTICLE. FORMATION OF THE SUPERCONDUCTING PHASES. THE CORRELATION BETWEEN LOCAL STRUCTURE VARIATIONS AND CRITICAL TEMPERATURE. Fluctuation of mean field region.

Local structure variations. IMPROVEMENTS OF Jc. FLUX PINNING PROPERTIES. Flux pinning mechanism.

Improvements of pinning force density. Identification of flux pinning center. CONCLUSION OF CHAPTER 4. 106 5 CHAPTER 5 : IMPROVEMENTS OF CRITICAL CURRENT DENSITY IN HIGH-Tc Bi1.4Sr2Ca2Cu3O10+ SUPERCONDUCTOR BY ADDITION OF MAGNETIC Fe3O4 NANOPARTICLE.

FORMATION OF THE SUPERCONDUCTING PHASES. IMPROVEMENTS OF Jc. FLUX PINNING PROPERTIES. Identification of pinning center.

Improvements of pinning potential. COMPARISON OF SUBSTITUTION EFFECT, ADDITIONS OF NON-MAGNETIC AND MAGNETIC NANOPARTICLE ON THE CRITICAL CURRENT DENSITY OF Bi1.4Sr2Ca2Cu3O10+δ CERAMIC SUPERCONDUCTOR. 125 6 LIST OF NOTATIONS AND ABBREVIATIONS Notations Explain %Bi-2212 volume fraction of Bi-2212 phase %Bi-2223 volume fraction of Bi-2223 phase APC artifial pinning center b normalized field (b = B/Birr) Bc1 lower critical field Bc2 upper critical field BCS Bardeen-Cooper-Schrieffer Birr irreversibility field Blb large bundle field bpeak reduced field at maximum of flux pinning force density BPSCCO Bi-Pb-Sr-Ca-Cu-O Bsb small bundle field BSCCO Bi-Sr-Ca-Cu-O d effective inter-layering spacing dϕ inter-flux-line spacing e electron charge FL Lorentz force density Fp pinning force density fp normalized pinning force density (fp = Fp/Fp,max) Fp,max maximum value of pinning force density FWHM full width at half maximum ħ Planck constant I electric current I2212 X-ray diffraction intensity of Bi-2212 phase I2223 X-ray diffraction intensity of Bi-2223 phase 7 j normalized critical current density (j = Jc/Jc(0) ) J interlayer coupling strength Jc critical current density Jsv critical current density in single vortex regime k Gaussian critical exponent kB Boltzmann's constant R resistance SEM scanning electron microscopy T temperature t normalized temperature (t = T/Tc) Tc critical temperature TEM transmission electron microscopy TLD Lawrence–Doniach temperature U voltage difference U0 pinning potential v hole concentration V valence XANES X-ray absorption near edge structure XAS X-ray absorption spectrocopy XRD X-ray diffraction ΔM magnetization hysteresis width Δσ excess conductivity ε reduced temperature (ε = (T – Tc)/Tc ) λ coherence length λCu-Kα Cu-Kα radiation wavelength ξ penetration depth ξc c-axis coherence length 8 ρ resistivity ρ0 residual resistivity τ crystallite size Φ0 magnetic flux quantum 9 LIST OF TABLES Table 1. Details of types of pinning properties in type II superconductors.

Variations of volume fractions and lattice parameters for Bi-2223 phase of Bi1.4Sr2Ca2-xNaxCu3O10+ samples. Flux pinning centers properties with modified Dew-Hughes model scaling of the samples at 65 K, 55 K, 45 K, and 35 K. The volume fraction, average crystallite size, lattice constants for Bi- 2223 phase, Tc and ρ0 values of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0. Excess conductivity analysis calculated parameters of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0.

Bsb and Blb values of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0. Flux pinning centers properties with modified Dew-Hughes model scaling of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0. Characteristic fields and Dew–Hughes model fitting parameters of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(Fe3O4)x samples. 117 10 LIST OF FIGURES Figure 1.

History of Superconductivity. Three states of conductivity in a superconductor: zero resistance (inside the innermost surface), transition state (outer surface), and normal conductance (beyond the outer surface). Phase diagram of Type-I and Type-II superconductors. Vortices pinning in type-II superconductor.

Schematic of collective pinning regimes with increasing magnetic field. The Jc(B) pinning regimes as collective pinning theory. Balance of forces acting on vortices. Schematic of different types of nano-sized pinning centers in type- II superconductors.

Classification of types of pinning centers. Illustration of crystal structures of three phases of BSCCO system. BSCCO 1st generation HTS wire. Fabrication process of sample series illustration.

Bragg's Law reflection. The photoelectric effect, in which an x-ray is absorbed and a core level electron is promoted out of the atom. Illustration of estimation of ΔM from a hysteresis loop of a BPSCCO sample measured at 65 K. XRD patterns of Bi1.4Sr2Ca2-xNaxCu3O10+δ samples.

Field dependence of Jc at 65 K for Bi1.4Sr2Ca2-xNaxCu3O10+ samples in which enhancements of Jc were observed. Field dependence of Jc of the Na000 and Na006 samples at different temperatures. Descriptions of the field dependence of Jc of all samples by using the collective pinning theory at (a) 65 K, (b) 45K and (c) 25 K. The solid lines are the fitting curves using Eq.

(a) Field dependence of -ln(Jc(B)/Jc(0)) of Na000 and Na006 samples at 65K. (b) The temperature dependence of Birr of all samples at different temperatures. The solid lines are the fitting curves using Eq. (c) The B-T phase diagram of Na000 sample.

(d) The B-T phase diagram of Na006 sample. Pinning force density (Fp) versus reduced field (b) of the samples at (a) 65K, (b) 55K, (c) 45K, (d) 35K and (e) 25K. The relation between the pinning force density maximum Fp,max and irreversible field Birr with Na content as the hidden variable. Data are shown in double-logarithmic plots.

Scaling behaviors of the normalized pinning force density (fp) versus (b) at all measured temperatures of (a) Na000, (b) Na002, (c) Na004, (d) Na006, (e) Na008 and (f) Na010 samples. The solid lines are the fitting curves using Eq. (a) Normalized critical current density Jc(t)/Jc(0) versus normalized temperature t of all the samples; (b) Crossover field (Bsb) versus normalized temperature of all the samples. The solid lines are the fitting curves using Eq.

(a) TEM images and (b) histogram of TiO2 nanoparticles. XRD patterns of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0. SEM images of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0. The temperature dependence of resistivity of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0.

Double logarithmic plot of excess conductivity as a function of reduced temperature of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples (a) x = 0, (b) x = 0. The red, green, and blue solid lines correspond to the critical region, 3D and 2D region, respectively. The Cu-O, Cu-Ca and Cu-Sr bond distances of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0. (a) Cu K-edge XANES spectra of (Bi1.4Sr2Ca2Cu3O10+δ)1- x(TiO2)x samples, with x = 0, 0.

(b) Copper valence of all samples. (a) Cu L2,3-edge XANES spectra of (Bi1.4Sr2Ca2Cu3O10+δ)1- x(TiO2)x samples, with x = 0, 0. Ti L2,3-edge spectra of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0. The field dependence of Jc of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0.010 with small bundle regimes description using collective pinning theory at (a) 65 K, (b) 55 K, (c) 45 K, and (d) 35 K.

Dash-dot lines are fitting curves using Equation (1. (a) The normalized temperature dependence of normalized Jc and (b) normalized Bsb of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0. Solid lines are fitting curves in terms of the δl pinning and δTc pinning mechanisms using Eqs. The normalized field dependence of flux pinning force density of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(TiO2)x samples, with x = 0, 0.

The normalized field dependence of (Bi1.4Sr2Ca2Cu3O10+δ)1- x(TiO2)x samples, with x = 0, 0.010 with modified Dew-Hughes model scaling at (a) 65 K, (b) 55 K, (c) 45 K ,and (d) 35 K. Solid lines are fitting curves using Eq. (a) TEM images and (b) histogram of Fe3O4 nanoparticles. (a) XRD patterns and (b) Volume fractions and average crystalline size of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(Fe3O4)x samples, with x = 0, 0.

SEM images of (Bi1.4Sr2Ca2Cu3O10+δ)1-x(Fe3O4)x samples, with x = 0, 0. (a) Field dependence of Jc at 65 K with small-bundle regime fitting in double-logarithmic scale, (b) field dependence of –ln[Jc(B)/Jc(0)] of the x = 0 and 0.