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Synthesis of calcium copper titanate by mechanochemical route
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  1. 1. SYNTHESIS AND CHARACTERIZATION OF CALCIUM COPPER TITANATE BY MECHANOCHEMICAL ROUTE Master of Technology In Material Engineering PRESENTED by NANDAN KUMAR Exam Roll No- M4MAT1701 Class Roll No- 001511303001 Registration No- 13717 of 2015-16 Under the supervision of Dr. Sathi Banerjee Department of Metallurgical and Material Engineering Jadavpur University,Kolkata-700032 15TH JUNE
  2. 2. INTRODUCTION INSULATOR • An electrical insulator is a material whose internal electric charges do not flow freely, and due to which it does not conduct an electric current, by applying electric field. • Almost all insulators have large band gap because of the "valence" band consisting of the highest energy electrons is full, and the next band is separated from it by a large energy gap above it. • Breakdown voltage that will give the electrons enough energy to be excited into this band. Once the voltage i.e. the breakdown voltage is exceeded the material discontinue being an insulator, and charge starts passing through it.
  3. 3. DIELECTRIC • Dielectric is used to indicate the energy storing capacity of the material. • A dielectric is an electrical insulator that can be polarized only by applying an applied electric field. • Whenever a dielectric is placed in an electric field, electric charges stops flowing through the material but slight shift from their average equilibrium positions causes dielectric polarization. • Another term is the dielectric constant which describes the extent to which a substance concentrates the electrostatic lines of flux. • An important property of a dielectric is its ability to support an electrostatic field while dissipating minimum energy in the form of heat.
  4. 4. Calcium Copper Titanate (CCTO) • A novel electroceramic material • Possessing high and nearly constant (room temperature to 300° C) dielectric constant • For single crystal the value of dielectric constant is 100000 • For bulk material it is 10000 • CCTO shows moderate dielectric loss (tanδ ≈ 0.15) up to 106 Hz • It is being widely used in the electronic industries to manufacture electronic component such as multi-layer capacitor (MLCC), dynamic random access memory (DRAM), microwaves devices and devices for automobile and aircraft.
  6. 6. STRUCTURE OF CCTO Continue... • Calcium copper titanate, CaCu3Ti4O12 (CCTO) is a perovskite structure that has a body-centered cubic crystal structure with slightly tilted [TiO6] octahedra facing each other. • CCTO structure is derived from the cubic perovskite by an octahedral tilt distortion, this is caused due to the size mismatch and the nature of the A cations. • The structure of CaCu3Ti4O12 shown as TiO6 octahedra, Cu in square planar coordination (dark blue spheres), O ions at the centre of each face and edge (light blue spheres) and Ca at the origin and cube centre (red spheres).
  7. 7. IMPORTANCE OF CCTO • CCTO shows nonlinear current-voltage characteristics. This is due to schottky-type electrostatic barriers at the grain boundaries. • Usually large dielectric constants are found in ferroelectric materials. CCTO is non-ferroelectric and has no structural changes down to 35 K. • This material exhibits no crystallographic structural phase transition, associated with spontaneous polarization.
  8. 8. DIELECTRIC PROPERTIES OF CCTO • The perovskite-related body-centered cubic materials CaCu3Ti4O12 (CCTO) exhibited in giant dielectric constant at room temperature and also the dielectric constant between 100 and 400 K. • These properties are very important for device implementation and microelectronic application. • From the structural studies we found that CCTO maintains a cubic structure without phase transitions.
  9. 9. STATEMENT OF PROBLEM!!!!! • It is known from literature study that CCTO can act as a good dielectric material for electronic industries. It is also widely used in automobile and aircraft industries. • Synthesis of CCTO by Mechanochemical Route will be tried to process high purity and close control of powder morphology, which result in desired microstructure and dielectric behaviour.
  11. 11. RESULTS & DISCUSSION • XRD Analysis • SEM Analysis • FTIR Analysis • FE SEM Analysis • UV-VIS Analysis • HR-TEM Analysis • Dielectric Analysis
  13. 13. XRD ANALYSIS OF CCTO Continue... Standard 2θ Value Obtained 2θ Value Planes Phases 29.533 29.539 (211) CCTO 34.329 34.345 (220) CCTO 42.367 42.361 (222) CCTO 49.316 49.315 (400) CCTO 61.444 61.445 (422) CCTO 72.292 72.291 (440) CCTO 82.450 82.450 ( 620) CCTO
  14. 14. XRD ANALYSIS OF CCTO Continue... • The XRD patterns confirm the single phase ABO3 structure. • At the composition we get sharp peaks in the 2θ range at 34.26°, 49.25°, 61.39° and 82.45°. • Small peaks can also be seen around 29.53°, 42.29° and 72.29° respectively. • At 1000°C the maximum peak is achieved at 34.26°. • The peaks are indexed as per the (hkl) values reported in the JCPDS file (75-2188).
  15. 15. SEM ANALYSIS OF CCTO 18 hours heat treated at 1000° C
  16. 16. SEM ANALYSIS OF CCTO 26 Hours heat treated at 1000° C
  17. 17. FE SEM ANALYSIS OF CCTO 26 Hours heat treated at 1000° C
  18. 18. FESEM ANALYSIS OF CCTO Continue...
  20. 20. FTIR ANALYSIS OF CCTO Continue... Wavenumber (cm-1) Assignment 463 cm-1 Vibration mode of (Ti-O-Ti) band appeared [1] 525 cm-1 Cu-O bonding observed [2] 606 cm-1 Ca-O bonding observed [3] 380cm-1 - 700cm-1 Absorbtion band arising from mixed vibration of CuO4 and TiO6 group[4]
  22. 22. UV-VIS ANALYSIS OF CCTO Continue... • The band gap of the samples were calculated using (αhν)2 versus hν plot, where α is the absorbance of the sample and hν is the incident energy. • The band gap of the pure sample annealed at 1000°C was calculated to be 2.44eV, which falls in the visible region of the electromagnetic spectrum.
  24. 24. HR TEM ANALYSIS OF CCTO Continue...
  26. 26. HR TEM ANALYSIS OF CCTO Continue... • TEM images confirm the agglomerated nature of the synthesized particles with particles sizes in good accordance with that determined from the Scherrer’s formula. Some over growth can also be seen in the images. • Selected Area Electron Diffraction (SAED) pattern is given in figure 5.6.2 which reveals the polycrystalline nature and the rings in the SAED pattern corresponds to (422), (400), (013), (220) and (200) crystal planes of cubic pseudo- perovskite phase of CCTO.
  27. 27. DIELECTRIC PROPERTY ANALYSIS OF CCTO Dielectric Constant vs Frequency
  28. 28. Continue..
  29. 29. Dielectric Loss vs Frequency
  30. 30. Continue...
  31. 31. CONCLUSION  Calcium Copper Titanate (CCTO) is successfully synthesized by Mechanochemical route.  XRD results reveals peaks corresponding to cubic perovskite structure. The disordering in samples decreased with increasing heat treatment time. Moreover, XRD results show the formation of single phase.  The SEM and FESEM images show formation of well defined grain. The grain sizes increases with increasing sintering temperature with higher porosity.  The SAED pattern of TEM imaging proved the polycrystalline nature of CCTO.  Dielectric studies sample reveals that the dielectric constant is quite large, which gradually decreased on increasing the frequency and finally attained a constant value at higher frequencies.
  32. 32. REFERENCE • [1] Almeida AFL, de Oliveira RS, Goes JC, et al. Mater Sci Eng B 2002;96:275. • [2] Sahaya Shajan X, Mahadevan C. Cryst Res Technol 2005;40:598. • [3] Sahaya Shajan X, Mahadevan C. Cryst Res Technol 2005;40:598. • [4] Thomas P, Dwarakanath K, Varma KBR, et al. J Phys Chem Solids 2008;69:2594. •
  33. 33. ACKNOWLEDGEMENT • I am greatly indebted to my department for giving me the opportunity to take up this interesting project work. I am thankful to Prof P. C. Chakraborti, Head Of the Department of Metallurgical and Material Engineering for allowing me to do this project. • It is my privilege to convey my heartiest thanks to my thesis supervisor Dr. Sathi Banerjee, Dept. of Metallurgical and Material Engineering, Jadavpur University,Kolkata. I owe to her for her sincere help and constructive guidance rendered to me during thesis work • I am especially thankful to Dr. Soumya Mukherjee, Amity University, Kolkata. His close guidance helped me to do my work more efficiently. • I would like to convey my thanks to all the faculty and staff members for their valuable guidance and support during the implementation of the project. • I thank to Mr Sudhir Ghosh for their constant support in laboratory testing. • I thank to Srinath Ranjan Ghosh and Subhabrata Chakraborty, Research Scholors, Dept. of Metallurgical and Material Engineering and of course all of my friends for their close assistance throughout my project work.