Muhammad Mumtaz, who gave us this golden opportunity to work on this project, ... General, Khan Research Laboratories (KRL), who helped us for our samples ...
Dielectric properties of (Zn)x/CuTl-1223 nano-superconductor composites
Muhammad Waqas Ur Rehman (70-FBAS/BSPHY/S11)
Shoaib Azeem (73-FBAS/BSPHY/S11)
Saad Ullah (74-FBAS/BSPHY/S11)
Syed Ahsan Akhtar (90-FBAS/BSPHY/S11)
Supervised by Dr. Muhammad Mumtaz Assistance Prof. (TTS)
Department of Physics Faculty of Basis and Applied Sciences International Islamic University, Islamabad
(2015) i
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First of All Thanks To Allah Almighty This report is dedicated to our beloved parents and our great teachers.
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ACCEPTANCE BY THE VIVA VOCE COMMITTEE
Title of Thesis:
“Dielectric properties of (Zn)x/CuTl-1223 superconductor composites”.
Name of Student:
Muhammad Waqas Ur Rehman
Registration No:
70-FBAS/BSPHY/S11
Name of Student:
Shoaib Azeem
Registration No:
73-FBAS/BSPHY/S11
Name of Student:
Saad Ullah
Registration No:
74-FBAS/BSPHY/S11
Name of Student:
Syed Ahsan Akhtar
Registration No:
90-FBAS/BSPHY/S11
Accepted by the Department of Physics, Faculty of Basic & Applied Sciences, INTERNATIONAL ISLAMIC UNIVERSITY ISLAMABAD, in partial fulfillment of the requirements for the BS in Physics with specialization in Nanotechnology.
VIVA VOCE COMMITTEE
______________________ Chairman
______________________ Examiner
______________________ Supervisor
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DECLARATION We Muhammad Waqas Ur Rehman (Registration # 70-FBAS/BSPHY/S11), Shoaib Azeem (Registration # 73-FBAS/BSPHY/S11), Saad Ullah (Registration # 74-FBAS/BSPHY/S11), and Syed Ahsan Akhtar (Registration # 90-FBAS/BSPHY/S11) students of BS in Physics (session 2011-2015), hereby declare that the matter printed in the research project entitled “Dielectric properties of (Zn)x/CuTl-1223 superconductor composites is our own work and has not been published or submitted as research work or project/thesis in any form in any other university or institute in Pakistan or abroad.
Muhammad Waqas Ur Rehman (70-FBAS/BSPHY/S11)
Shoaib Azeem (73-FBAS/BSPHY/S11)
Saad Ullah (74-FBAS/BSPHY/S11)
Syed Ahsan Akhtar (90-FBAS/BSPHY/S11) Dated: _________________
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FORWARDING SHEET BY RESEARCH SUPERVISOR The research project entitled “Dielectric properties of (Zn) x/CuTl-1223 superconductor composites” submitted by Muhammad Waqas Ur Rehman, Shoaib Azeem, Saad Ullah, and Syed Ahsan Akhtar in partial fulfillment of BS (Physics) has been completed under my guidance and supervision. I am satisfied with the quality of student’s research work and allow them to submit this thesis for further process to complete their BS degree from Department of Physics, as per IIUI rules and regulations.
_____________________ Dr. Muhammad Mumtaz, (Supervisor) Assistant Professor Department of Physics, International Islamic University, Islamabad.
Date: ______________
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ACKNOWLEDGMENT First, we owe our deepest gratitude to Allah Almighty for all of his countless blessings. We offer our humblest words of thanks to his most noble messenger Prophet Muhammad ﷺ who is forever a torch of guidance and knowledge for all humanity. By virtue of HIS blessings today, we are able to carry out our research work and present it. We would like to express our special thanks of gratitude to our teacher, supervisor Dr. Muhammad Mumtaz, who gave us this golden opportunity to work on this project, who guided and supported us during our research work. Moreover, under his supervision from the preliminary to the concluding level enabled us to understand the field. His wide and deep knowledge have been a great value for us. May Allah Almighty bless him in every part of his life. We would also like to express our heartiest thanks to Dr. K. M. Aurangzeb, Director General, Khan Research Laboratories (KRL), who helped us for our samples characterizations. We will express our heartiest thanks to our seniors Abdul Jabbar, Waqee-Ur-Rehman and Ghulam Hussain for being very supportive and co-operative throughout our research work. At last, but not the least, we are forever indebted to our parents and family members Mother, Father, Brothers and Sisters for their prayers, continuous support, love, understanding, endless patience, encouragement and their all possible help throughout the time of research work, without their help and understanding this work could not have been completed.
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Table of Contents I.
Introduction ......................................................................................................................................... 1 1.1.Superconductors and Superconductivity ................................................................................ 1 1.1.1. Applications of Superconductors ................................................................................. 3 1.1.2. Classification of Superconductors................................................................................ 3 1.1.2.1. Type I and Type II Superconductors .............................................................. 3 1.1.3. Critical parameters of Superconductors ....................................................................... 4 1.1.3.1. Critical temperature (Tc) ................................................................................. 4 1.1.3.2. Critical field (Hc) ............................................................................................. 5 1.1.3.3. Critical current (Ic) ........................................................................................... 5 1.1.3.4. Relationship between three parameters .......................................................... 5 1.2. High temperature Superconductors ........................................................................................ 6 1.3. Copper Thallium based Superconductors .............................................................................. 7 1.4. Nanoscience and nanotechnology .......................................................................................... 8 1.4.1. Nano-materials ............................................................................................................. 8 1.4.2. Classification of Nano-materials .................................................................................. 8 1.4.2.1. Zero dimensional nano-materials ................................................................... 9 1.4.2.2. One dimensional nano-materials .................................................................... 9 1.4.2.3. Two dimensional nano-materials .................................................................... 9 1.4.2.4. Three dimensional nano-materials.................................................................. 9 1.5. Dielectrics ................................................................................................................................ 9 1.5.1. Mathematical formulas ............................................................................................... 12 1.6.Polarization ............................................................................................................................. 12
II.
Literature Review ..................................................................................... 14
III.
Experimental Details ............................................................................... 15 3.1. Nano-materials synthesis approaches .................................................................................. 15 3.1.1. Bottom up approach .................................................................................................... 15
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3.1.2. Top down approach ..................................................................................................... 15 3.2. Nanoparticles synthesis strategies ........................................................................................ 16 3.2.1. Vapor-phase synthesis ................................................................................................ 16 3.2.2. Liquid-phase synthesis ................................................................................................ 16 3.2.3. Solid-phase synthesis .................................................................................................. 16 3.2.4. Lithography ................................................................................................................. 16 3.3. Solid state reaction method................................................................................................... 16 3.3.1. Conventional routes .................................................................................................... 17 3.3.1.1. Steps in conventional solid state method ..................................................... 17 3.3.2. Nonconventional routes .............................................................................................. 17 3.4. Synthesis of Zinc doped superconductor ............................................................................. 18 3.4.1. Preparation of (Zn) x/CuTl-1223 nano-superconductor composites ........................ 18
IV.
Results and Discussions ............................................................................ 20 4.1. X-Ray Diffraction (XRD) ..................................................................................................... 20 4.1.1. XRD Analysis of Zinc nanoparticles ......................................................................... 20 4.1.2. XRD Analysis of nano-superconductor composites ................................................. 21 4.2. Scanning Electron Microcopy (SEM) .................................................................................. 22 4.3. Energy dispersive X-Ray Analysis (EDX) .......................................................................... 24 4.4. Resistance measurements ..................................................................................................... 25 4.5.Dielectric measurements ........................................................................................................ 26 4.5.1. Dielectric constant () ................................................................................................. 26 4.5.2. Real part of dielectric constant (´) ............................................................................ 27 4.5.3. Imaginary part of dielectric constant (´´) ................................................................. 28 4.5.4. Dielectric loss tangent (Tan) .................................................................................... 29 4.5.5. AC-Conductivity (ac) ................................................................................................ 31
V.
Conclusion ................................................................................................. 32 References ........................................................................................ 33
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Table of Figures Fig 1: The development of superconducting materials ..................................................................... 1 Fig 2: Type I and Type II superconductors ........................................................................................ 4 Fig 3: Phase diagram showing relationship between critical parameters ......................................... 5 Fig 4: History of high temperature superconductors .......................................................................... 6 Fig 5: Unit cell of CuTl-based HTSC’s .............................................................................................. 7 Fig 6: Classification of nano-materials ............................................................................................... 9 Fig 7: a) polar and b) nonpolar dielectrics in absence and presence of external electric field ...... 10 Fig 8: Polarization caused due to the presence of an electric field ................................................ 12 Fig 9: Classification of polarization .................................................................................................. 13 Fig 10: Top down approach vs bottom up approach ........................................................................ 15 Fig 11: Flow chart for the preparation of precursor material .......................................................... 19 Fig 12: Flow chart for the synthesis of (Zn) x/CuTl-1223 nano-superconductor composites ........ 19 Fig 13: XRD spectra of (Zn) nanoparticles ..................................................................................... 21 Fig 14: XRD spectra of (Zn) x/CuTl-1223 x=0%, 1%, 2%, 3%, 4% ............................................... 22 Fig 15: SEM images of (Zn) x/CuTl-1223 nano-superconductor composites with (a) x = 0, (b) x=2 wt.% ............................................................................................................................................. 23 Fig 16: EDX analysis of (Zn) x/CuTl-1223 composites with (a) x=2.0 wt.%, (b) x = 4 wt.% ....... 24 Fig 17: Resistance versus temperature measurements of (Zn) x/CuTl-1223 composite superconductor with x=0, 1.0, 3.0 wt. % ......................................................................................... 25 Fig 18: Variation of dielectric constant of (Zn) x/CuTl-1223 nano-superconductor composites versus log of frequency for x = 0, 1.0, 2.0, 3.0, 4.0 wt. %. The inset shows the variation of max. ɛ versus (Zn) nanoparticles content ...................................................................................................... 27 Fig 19: Variation of real part of the dielectric constant of (Zn) x/CuTl-1223 nano-superconductor composites versus log of frequency for x = 0, 1.0, 2.0, 3.0, 4.0 wt. %. The inset shows the variation of max. ɛ´ versus (Zn) nanoparticles content .................................................................... 28
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Fig 20: Variation of imaginary part of dielectric constant of (Zn) x/CuTl-1223 nanosuperconductor composites versus log of frequency for x = 0, 1.0, 2.0, 3.0, 4.0 wt. %. The inset shows the variation of max. ɛ´´ versus (Zn) nanoparticles content ................................................. 29 Fig 21: Variation of dielectric loss factor of (Zn) x/CuTl-1223 nano-superconductor composites with log of frequency for x = 0, 1.0, 2.0, 3.0, 4.0 wt. %. The inset shows the variation of resonance frequency and Tan δ versus (Zn) nanoparticles content ................................................. 30 Fig 22: Variation of ac-conductivity (σac) of (Zn) x/CuTl-1223 nano-superconductor composites with log of frequency for x = 0, 1.0, 2.0, 3.0, 4.0 wt. %. The inset shows the variation of max σac versus Zn nanoparticles content ......................................................................................................... 31
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Abstract Zinc (Zn) nanoparticles and (Cu0.5Tl0.5)Ba2Ca2Cu3O10-δ superconducting material were prepared separately by sol-gel and solid-state reaction method, respectively. These Zn nanoparticles were mixed in appropriate ratio to CuTl-1223 matrix at the final stage of (Zn) x/CuTl-1223; x = 0, 1, 2, 3, and 4 wt.%
nano-superconductor composites synthesis.
Structure and phase purity of Zn nanoparticles and (Zn) x/CuTl-1223 nano-superconductor composites were investigated by XRD, SEM and EDX techniques. There was no change in crystal structure of parent CuTl-1223 phase was observed after the addition of Zn nanoparticles, which provide a clue about the occupancy of these nanoparticles at the grain-boundaries. The morphology was examined by SEM images, which shows the presence of spherical and irregular shaped Zn nanoparticles at the grain-boundaries of CuTl-1223 matrix. The presence of Zn nanoparticles has reduced the voids and has improved the inter-grains connectivity. The mass percentage of different elements in the composition was determined by EDX spectroscopy. The dc-resistance vs temperature measurements of these samples were measured by four-probe technique. The zero resistance critical temperature T c (0) of these samples has been increased by increasing the weight percentage addition of Zn nanoparticles in the CuTl-1223 matrix, which can be attributed to improved inter-grains connectivity due to the metallic nature of these nanoparticles. The dielectric properties of these samples (i.e. dielectric constant, dielectric loss and ac-conductivity) were determined by experimentally measured capacitance (C) and conductance (G) as a function of frequency at different temperatures. The addition of Zn nanoparticles in CuTl-1223 matrix has randomly decreased the values of dielectric parameters. So, we can tune the dielectric properties of CuTl-1223 matrix by the addition of Zn nanoparticles with different wt. %.
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introduction
I. Introduction 1.1. Superconductors and Superconductivity Low temperature research was started with the liquefaction of natural gases in late 1800. French scientist Caillettet did successful liquefaction of O2 in 1877. In 1911, Dutch physicist Heike Kamerlingh Onnes discovered superconductivity in Mercury (Hg) at liquid Helium temperature below 4.2 K at which resistivity of Hg vanishes [1]. Most important properties of superconducting materials were discovered in the following years as a result of an intensive research on this area. Since its discovery, superconductivity is an important area of research in solid state physics and the emergence of nanotechnology in it is creating revolutionized materials and devices with amazing applications.
Fig. 1. The development of superconducting materials
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introduction
The sudden drop of electrical resistance to zero and approach of conductance to infinity at certain temperature in some materials is known as superconductivity. Once the electrical current is supplied, it will flow forever in a closed loop of superconducting material due to its zero resistivity [1, 2].
The resistivity of superconducting materials is zero ( under the condition T
