PEKTROSKOPI RAMAN AURIVILLIUS LAPIS EMPAT ABi4Ti4O15 (A = Ba, Sr, Pb)

Aurivillius material have the general formula of An-1Bi2BnO3n+3 (n = 1, 2, 3, 4,…). Generally cations in A position are elements such as Ca2+, Sr2+, Ba2+, Pb2+, Bi3+, Na1+, or a mixtures of these elements, while the cations in B position is occupied by cations with the high charge suc...

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Bibliographic Details
Main Author: PRASETYO (NIM: 30511011) , ANTON
Format: Dissertations
Language:Indonesia
Online Access:https://digilib.itb.ac.id/gdl/view/19902
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Institution: Institut Teknologi Bandung
Language: Indonesia
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Summary:Aurivillius material have the general formula of An-1Bi2BnO3n+3 (n = 1, 2, 3, 4,…). Generally cations in A position are elements such as Ca2+, Sr2+, Ba2+, Pb2+, Bi3+, Na1+, or a mixtures of these elements, while the cations in B position is occupied by cations with the high charge such as Ti4+, Nb5+, Ta5+, W6+, or Mo6+. Aurivillius oxides show ferroelectric properties, with huge potential, especially for the electronics industry to be applied as a capacitor, or FRAMs (Ferroelectric Random Access Memorys). The origin of ferroelectricity in Aurivillius come from several mechanisms (a) the displacive mechanism, which involves A-site and/or B-site cationic displacements, (b) the rigid layer (RL) mode which involved displacements of the Bi2O2 fluorite-like planes relative to the perovskite-like blocks, and (c) the octahedral tilting in perovskite. Many studies showed that the Raman spectroscopy is an ideal tool for detecting local distortions in the crystal structure such as weak layer octahedron tilting, cation disorder in a small range, Jahn-Teller effect or a change in symmetry. The changes in Raman mode i.e Raman shifting, full width half at maximum (FWHMs) and intensities will be able to indicate even small local changes in the crystal structure. The aim of the present work is investigated the Raman spectrum of four-layer Aurivillius ABi4Ti4O15 (A = Ba, Sr, and Pb) dan Pb1-xBi4+xTi4xMnxO15 (x = 0,2 and 0,4) at 100-850 K. The spectra were temperature reduced to account for the Bose-Einstein occupation factor and fitted using a Lorentzian model to determine the peak wave numbers, FWHM, and integrated intensities of peaks. The temperature evolution of Raman spectra BaBi4Ti4O15 revealed the structural transformation at near (a) 300-350, (b) 380, and (c) 670 K. The structural transformation at 300 K involed (a) A-site Ba2+/Bi3+ displacements which mirrored by vibration modes 35, 90. 155 cm-1, and (b) the tilting octahedral which mirrored by vibration modes 225, 270, 460, 550 dan 886 cm-1. The structural transformation at 400 and 670 K involved (a) RL mode which mirrored by vibration mode 58 cm-1, and (b) Ba2+/Bi3+ or Ti4+ displacements which mirrored by vibration modes 155 cm-1. The structural transformation at 670 K relates to Ferroelectric-Paraelectric (FE-PE) transition. The temperature evolution of Raman spectra SrBi4Ti4O15 revealed the structural transformation at near (a) 300, (b) 380, and (c) 690 K. The structural transformation at 300 K are relates to (a) A-site Sr2+/Bi3+ displacements which mirrored by vibration modes at 90 cm-1, and (b) octahedral tilting which mirrored by vibration modes 225, 550, and 870 cm-1. The structural transformation at 380 K involved (a) RL mode which mirrored by vibration mode 58 cm-1, and (b) bending-streching TiO6 which mirrored by vibration mode 380 cm-1. The structural transformation at 690 K involved (a) Sr2+/Bi3+ displacements which mirrored by vibration modes 40 cm-1, and (b) bending TiO6 which mirrored by vibration mode 235 cm-1. The structural transformation at 800 relates to FE-PE transition is well mirrored by octahedral tilting modes 380, and 555 cm-1.The temperature evolution of Raman spectra PbBi4Ti4O15 revealed the structural transformation at near (a) 400, (b) 600, and (c) 800 K. The structural transformation at 400 K involved RL mode. The structural transformation at 600 K relates to minor polarization which involved (a) the A-site Pb2+/Bi3+ displacements which mirrored by vibration mode 40 cm-1, and (b) tilting octahedral which mirrored by vibration modes 225 cm-1. The structural transformation at 800 K involved RL mode which mirrored by vibration mode 58 cm-1 and relates to FE-PE transition.The temperature evolution of Raman spectra Pb0,8Bi4,2Ti3,8Mn0,2O15revealed the structural transformation at near (a) 400, (b) 570, and (c) 800 K. The structural transformation at 400 K involved RL mode. The structural transformation at 570 K involved (a) the A-site Pb2+/Bi3+ displacements which mirrored by vibration mode 40 cm-1, and (b) tilting octahedral which mirrored by vibration modes 225, 550 and 690 cm-1. The structural transformation at 800 K involved RL mode which mirrored by vibration mode 58 cm-1 and relates to FE-PE transition.The temperature evolution of Raman spectra Pb0,6Bi4,4Ti3,6Mn0,4O15 revealed the structural transformation at near (a) 400, and (b) 765 K. The structural transformation at 400 K (a) the A-site Pb2+/Bi3+ displacements which mirrored by vibration mode 40, 110 and 115 cm-1, and (b) RL mode which mirrored by vibration mode 58 cm-1. The structural transformation at 765 K involved RL mode which mirrored by vibration mode 58 cm-1 and relates to FE-PE transition.The ionic radii of A-site cation influenced to the new structural transformation (Ta) which involved the A-site cation displacement. The shorter ionic radii of Asite, Ta will be decreases. The influencing of A-site cation to tilting octahedral as showed that Ta which involved tilting octahedral have the same temperature Ta which involved the A-site cation displacement. The increases dopant Mn3+ in Bsite will increases the local thermal expansion of corresponding vibration unit. The substitution Ti4+ in B-site with Mn3+ cation will be affected the expansibility BO6 octahedra. The increases Mn3+ dopant will be increases the expansibility BO6 octahedra