Influence of divalent sr²ᶧ, zn²ᶧ and ca²ᶧ substitutions on ultrasonic velocity and elastic properties of dyba₂cu₃o₇₋ᵟ high temperature superconductors / Norashikin Abdul Rasih

Ultrasonic longitudinal velocity measurements between 80 K and 280 K and shear velocity measurements between 80 K and 220 K have been performed in polycrystalline superconducting DyBa2-jSrjCu307.s (x = 0, 0.3, 0.6), DyBa2Cu3_ xZn^07.j (x - 0.01 and 0.03) and Dyo.9Cao.1Ba2Cu3-jZnjO7.tf (x = 0.01) sam...

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Main Author:	Abdul Rasih, Norashikin
Format:	Thesis
Language:	English
Published:	2011
Subjects:	Physical and theoretical chemistry Analytical chemistry
Online Access:	https://ir.uitm.edu.my/id/eprint/39754/1/39754.pdf
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spelling	my-uitm-ir.397542022-04-21T03:28:04Z Influence of divalent sr²ᶧ, zn²ᶧ and ca²ᶧ substitutions on ultrasonic velocity and elastic properties of dyba₂cu₃o₇₋ᵟ high temperature superconductors / Norashikin Abdul Rasih 2011-01 Abdul Rasih, Norashikin Physical and theoretical chemistry Analytical chemistry Ultrasonic longitudinal velocity measurements between 80 K and 280 K and shear velocity measurements between 80 K and 220 K have been performed in polycrystalline superconducting DyBa2-jSrjCu307.s (x = 0, 0.3, 0.6), DyBa2Cu3_ xZn^07.j (x - 0.01 and 0.03) and Dyo.9Cao.1Ba2Cu3-jZnjO7.tf (x = 0.01) samples utilizing the pulsed-echo-overlap technique. A step-like longitudinal anomaly characterized by a step-like slope change was observed at 240 K for x = 0 and x = 0.3 and at 260 K for x = 0.6 in DyBa2-jSrjCu307.s samples. In addition, a longitudinal anomaly was also observed at around 240 K for DyBa2Cu3.jZni.x07.5 (x = 0) and at 230 K for x = 0.01 and 0.03. Substitution of Zn2+ which caused suppression of critical temperature, Tc however, did not suppress the step-like anomaly. On the other hand, substitution of Ca in Dyo.9Cao.iBa2Cu3.>,Zni.707.j (y = 0.01) caused the step-like anomaly to disappear. The step-like anomalies observed in samples were suggested due to oxygen ordering process in Cu-0 chains during a phase transition process at low temperatures. For DyBa2.jSrjCu3O7.tf (x = 0, 0.3, 0.6), the reduction in the slope change of the step-like anomalies indicates some degree of weakening of oxygen ordering due to the Sr substitution. Substitution of Zn2+ ions in place of Cu in Dyo.9Cao.1Ba2Cu3-jZnjO7.tf (x = 0.01 and x = 0.03) was suggested to go into Cu-0 planes and did not interfere with oxygen ordering in Cu-0 chains and cause nonsuppressed step-like anomalies in DyBa2Cu3.jZni.j07.§ (x = 0.01 and 0.03) samples. But, disappearance of the step-like anomaly due to Ca2+ substitution in Dyo.9Cao.1Ba2Cu3.jZnjO7.tf (x = 0.01) is probably related to reduction in oxygen content which depletes at Cu-0 chain sites. On the other hand, it was found that Sr substitution in DyBa2-jSrjCu307.g (x = 0, 0.3 and 0.6), Zn substitution in DyBa2Cu3_ jZn1.jO7.tf (x = 0.01 and 0.03) and Ca substitution in Dyo.9Cao.iBa2Cu3.>Zni-) ,07-tf (v = 0.01) has the effect of lowering the calculated Debye temperature and BCS electron-phonon coupling constant, signifying that the step-like anomaly may not be related to superconductivity. A comparison between experimental data and calculated lattice anharmonicity curve based on the model by Lakkad (1971) showed that the large deviation of the experimental velocity curves for DyBa2.jSrjCu3O7.tf (x = 0, 0.3) and DyBa2Cu3.jZn1.jO7.tf (x = 0, 0.01 and 0.03) from the calculated curves is strongly influenced by the existence of the step-like longitudinal anomalies. 2011-01 Thesis https://ir.uitm.edu.my/id/eprint/39754/ https://ir.uitm.edu.my/id/eprint/39754/1/39754.pdf text en public masters Universiti Teknologi MARA Faculty of Applied Sciences Hayati, Ahmad Kamal (Prof Dr.)
institution	Universiti Teknologi MARA
collection	UiTM Institutional Repository
language	English
advisor	Hayati, Ahmad Kamal (Prof Dr.)
topic	Physical and theoretical chemistry Analytical chemistry
spellingShingle	Physical and theoretical chemistry Analytical chemistry Abdul Rasih, Norashikin Influence of divalent sr²ᶧ, zn²ᶧ and ca²ᶧ substitutions on ultrasonic velocity and elastic properties of dyba₂cu₃o₇₋ᵟ high temperature superconductors / Norashikin Abdul Rasih
description	Ultrasonic longitudinal velocity measurements between 80 K and 280 K and shear velocity measurements between 80 K and 220 K have been performed in polycrystalline superconducting DyBa2-jSrjCu307.s (x = 0, 0.3, 0.6), DyBa2Cu3_ xZn^07.j (x - 0.01 and 0.03) and Dyo.9Cao.1Ba2Cu3-jZnjO7.tf (x = 0.01) samples utilizing the pulsed-echo-overlap technique. A step-like longitudinal anomaly characterized by a step-like slope change was observed at 240 K for x = 0 and x = 0.3 and at 260 K for x = 0.6 in DyBa2-jSrjCu307.s samples. In addition, a longitudinal anomaly was also observed at around 240 K for DyBa2Cu3.jZni.x07.5 (x = 0) and at 230 K for x = 0.01 and 0.03. Substitution of Zn2+ which caused suppression of critical temperature, Tc however, did not suppress the step-like anomaly. On the other hand, substitution of Ca in Dyo.9Cao.iBa2Cu3.>,Zni.707.j (y = 0.01) caused the step-like anomaly to disappear. The step-like anomalies observed in samples were suggested due to oxygen ordering process in Cu-0 chains during a phase transition process at low temperatures. For DyBa2.jSrjCu3O7.tf (x = 0, 0.3, 0.6), the reduction in the slope change of the step-like anomalies indicates some degree of weakening of oxygen ordering due to the Sr substitution. Substitution of Zn2+ ions in place of Cu in Dyo.9Cao.1Ba2Cu3-jZnjO7.tf (x = 0.01 and x = 0.03) was suggested to go into Cu-0 planes and did not interfere with oxygen ordering in Cu-0 chains and cause nonsuppressed step-like anomalies in DyBa2Cu3.jZni.j07.§ (x = 0.01 and 0.03) samples. But, disappearance of the step-like anomaly due to Ca2+ substitution in Dyo.9Cao.1Ba2Cu3.jZnjO7.tf (x = 0.01) is probably related to reduction in oxygen content which depletes at Cu-0 chain sites. On the other hand, it was found that Sr substitution in DyBa2-jSrjCu307.g (x = 0, 0.3 and 0.6), Zn substitution in DyBa2Cu3_ jZn1.jO7.tf (x = 0.01 and 0.03) and Ca substitution in Dyo.9Cao.iBa2Cu3.>Zni-) ,07-tf (v = 0.01) has the effect of lowering the calculated Debye temperature and BCS electron-phonon coupling constant, signifying that the step-like anomaly may not be related to superconductivity. A comparison between experimental data and calculated lattice anharmonicity curve based on the model by Lakkad (1971) showed that the large deviation of the experimental velocity curves for DyBa2.jSrjCu3O7.tf (x = 0, 0.3) and DyBa2Cu3.jZn1.jO7.tf (x = 0, 0.01 and 0.03) from the calculated curves is strongly influenced by the existence of the step-like longitudinal anomalies.
format	Thesis
qualification_level	Master's degree
author	Abdul Rasih, Norashikin
author_facet	Abdul Rasih, Norashikin
author_sort	Abdul Rasih, Norashikin
title	Influence of divalent sr²ᶧ, zn²ᶧ and ca²ᶧ substitutions on ultrasonic velocity and elastic properties of dyba₂cu₃o₇₋ᵟ high temperature superconductors / Norashikin Abdul Rasih
title_short	Influence of divalent sr²ᶧ, zn²ᶧ and ca²ᶧ substitutions on ultrasonic velocity and elastic properties of dyba₂cu₃o₇₋ᵟ high temperature superconductors / Norashikin Abdul Rasih
title_full	Influence of divalent sr²ᶧ, zn²ᶧ and ca²ᶧ substitutions on ultrasonic velocity and elastic properties of dyba₂cu₃o₇₋ᵟ high temperature superconductors / Norashikin Abdul Rasih
title_fullStr	Influence of divalent sr²ᶧ, zn²ᶧ and ca²ᶧ substitutions on ultrasonic velocity and elastic properties of dyba₂cu₃o₇₋ᵟ high temperature superconductors / Norashikin Abdul Rasih
title_full_unstemmed	Influence of divalent sr²ᶧ, zn²ᶧ and ca²ᶧ substitutions on ultrasonic velocity and elastic properties of dyba₂cu₃o₇₋ᵟ high temperature superconductors / Norashikin Abdul Rasih
title_sort	influence of divalent sr²ᶧ, zn²ᶧ and ca²ᶧ substitutions on ultrasonic velocity and elastic properties of dyba₂cu₃o₇₋ᵟ high temperature superconductors / norashikin abdul rasih
granting_institution	Universiti Teknologi MARA
granting_department	Faculty of Applied Sciences
publishDate	2011
url	https://ir.uitm.edu.my/id/eprint/39754/1/39754.pdf
_version_	1783734534708133888

Influence of divalent sr²ᶧ, zn²ᶧ and ca²ᶧ substitutions on ultrasonic velocity and elastic properties of dyba₂cu₃o₇₋ᵟ high temperature superconductors / Norashikin Abdul Rasih

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