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https://ptsldigital.ukm.my/jspui/handle/123456789/499584Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | Roslan Abd Shukor, Prof. Dato. Dr. | - |
| dc.contributor.author | Annas Saeed Ahmad Al-Sharabi (P59483) | - |
| dc.date.accessioned | 2023-10-13T09:32:57Z | - |
| dc.date.available | 2023-10-13T09:32:57Z | - |
| dc.date.issued | 2014-07-24 | - |
| dc.identifier.other | ukmvital:80295 | - |
| dc.identifier.uri | https://ptsldigital.ukm.my/jspui/handle/123456789/499584 | - |
| dc.description | Kajian ini merangkumi tujuh penggantian berbeza dalam superkonduktor T1-1212. Ini merangkumi siri (Tl1-xMx)Sr2CaCu2O7-δ (M = Cr atau Re atau Rh) dan siri TlSr2(Ca1-xMx)Cu2O7-δ (M = Cr atau Re atau Hf atau Te) untuk siri (x = 0.05- 0.30). Tujuan kajian ini ialah untuk menentukan kesuperkonduksian dan pembentukan fasa Tl-1212. Semua sampel disediakan dengan menggunakan kaedah tindak balas keadaan pepejal. Corak pembelauan serbuk sinar-X menunjukkan fasa T1-1212 tunggal dengan unit sel tetragonal (kumpulan ruang, P4/mmm) yang dominan dengan beberapa garisan pembelauan T1-1201 yang lemah, dan fasa yang tidak diketahui untuk semua sampel. Pengukuran kerintangan elektrik melawan suhu untuk siri (Tl1-xCrx)Sr2CaCu2O7-δ (x = 0.05- 0.30) menunjukkan sifat superkonduktor yang terbaik pada x = 0.15 dengan suhu genting (Tc mula) 105 K. Fasa T1-1212 tunggal didapati untuk x ≤ 0.10. (Tl1-xRhx)Sr2CaCu2O7-δ menunjukkan perubahan pada kerintangan pada suhu bilik dan sampel x =0.20 menunjukkan Tc mula yang tertinggi (91 K). Pengukuran kerintangan elektrik pada siri TlSr2(Ca1-xCrx)Cu2O7-δ (x = 0.05- 0.30) menunjukkan peningkatan dalam Tc mula yang diikuti dengan peningkatan mendadak pada x =0.20. Peratus isipadu bagi fasa TlSr2(Ca1-xCrx)Cu2O7-δ kebanyakannya melebihi 82% untuk x = 0.05- 0.20. Bagi siri TlSr2(Ca1-xRex)Cu2O7-δ, sampel x = 0.20 menunjukkan fasa T1-1212 tunggal terbaik (96%). Bagi Hf dan Te yang menggantikan tapak Ca, sampel dengan x = 0.20 dan 0.25 menunjukkan Tc mula tertinggi iaitu masing-masing 47 K dan 61 K. Sifat fluktuasi kesuperkonduksian (SFB) pada siri (Tl1-xMx)Sr2CaCu2O7-δ (x = 0.05-0.30) (M = Cr atau Re) dan siri TlSr2(Ca1-xMx)Cu2O7-δ (M = Cr atau Re atau Hf atau Te) untuk siri (x = 0.05- 0.30) telah dianalisis menggunakan teori Asmalazov-Larkin (AL). Untuk siri (Tl1-xCrx)Sr2CaCu2O7-δ (x = 0.05 - 0.30) dan (Tl1-xRex)Sr2CaCu2O7-δ, analisis menunjukkan ciri-ciri lintasan daripada sifat 2D ke 3D apabila suhu berkurang. Penggantian T1 dalam siri ini memberi kesan pada panjang koheren paksi-c ξc(0) dan T2D-3D dengan peralihan tertinggi dipamerkan. Untuk siri TlSr2(Ca1-xCrx)Cu2O7-δ (x = 0.05- 0.30), nilai maksimum untuk ξc(0) ialah 1.011 Ǻ (x = 0.20) yang juga menunjukkan suhu peralihan 2D ke 3D tertinggi, T2D-3D (146 K) antara sampel. Untuk siri TlSr2(Ca1-xRex)Cu2O7-δ (x = 0.05- 0.30) keputusan menunjukkan semua penggantian Re telah mengubah ξc(0), mengurangkan kekuatan gandingan antara lapisan dan menyebabkan peningkatan anisotropi sampel. Malahan, penggantian Re mengubah T2D-3D; peralihan tertinggi ialah pada x = 0.15. Penggantian Hf pada tapak Ca telah mengubah ξc(0) dan menyebabkan peningkatan anisotropi sampel dan mengurangkan kekuatan gandingan antara lapisan. Peralihan daripada sifat 2D ke 3D telah diperhatikan memandangkan suhu menurun pada siri TlSr2(Ca1-xTex)Cu2O7-δ (x = 0.05- 0.30). Anisotropi tertinggi (γ) antara siri-siri tersebut ialah 10.24 pada x = 0.25. Sebagai kesimpulan, kajian ini menunjukkan bahawa penggantian ion multivalent pada tapak T1 atau Ca dalam TlSr2CaCu2O7-δ (x = 0.05-0.30) menghasilkan fasa superkonduktor 1212. Ciri-ciri skala pada lengkungan yang diperoleh daripada lebihan kekonduksian ln(Δσ/σo) melawan pengurangan suhu, ln(ε) untuk penggantian ion multivalent menunjukkan lintasan antara sifat dua ke tiga dimensi di sekitar kawasan genting.,This study involves seven different substitutions of the Tl-l2l2 superconductors; (Tl1-xMx)Sr2CaCu2O7-δ series (M = Cr or Re or Rh) and TlSr2(Ca1-xMx)Cu2O7-δ series (M = Cr or Re or Hf or Te) for (x = 0.05-0.30) series. The objectives are to determine the superconductivity and the formation of the Tl-1212 phase. All the samples were synthesized using the solid state reaction method. The X-ray powder diffraction patterns indicated that a single Tl-1212 phase with tetragonal unit cell (space group, P4/mmm) was dominant with few weak diffraction lines of the Tl-1201, and an unknown phase for all samples. The temperature dependent electrical resistance measurements on (Tl1-xCrx)Sr2CaCu2O7-δ (x = 0.05-0.30) showed the best superconducting behavior at x = 0.15 with critical temperature (Tc onset) of 105 K. A single Tl-1212 phase was obtained for x ≤ 0.10. The (Tl1-xRhx)Sr2CaCu2O7-δ showed changes in room-temperature resistivity and sample with x = 0.20 showed the highest Tc onset (91 K). The electrical resistance measurements on TlSr2(Ca1-xCrx)Cu2O7-δ (x = 0.05-0.30) series showed increase in Tc onset followed by an abrupt increase at x = 0.20. The volume fraction for TlSr2(Ca1-xCrx)Cu2O7-δ phase was mostly above 82% for x = 0.05–0.20. For TlSr2(Ca1-xRex)Cu2O7-δ (x = 0.05-0.30) samples, the x = 0.20 exhibited the highest single Tl-1212 phase (96 %). For Hf and Te substitution at the Ca site, samples with x = 0.20 and 0.25 showed the highest Tc onset 47 and 61 K, respectively. In addition, the superconducting fluctuation behavior (SFB) in (Tl1-xMx)Sr2CaCu2O7-δ series (M = Cr or Re) and TlSr2(Ca1-xMx)Cu2O7-δ series (M = Cr or Re or Hf or Te) for (x = 0.05-0.30) series was analyzed by using Asmalazov-Larkin (AL) theory as a framework. In the (Tl1-xCrx)Sr2CaCu2O7-δ (x = 0.05-0.30) and (Tl1-xRex)Sr2CaCu2O7-δ (x = 0.05-0.30) series, the analyses showed characteristic cross-over from 2D to 3D behavior with decreasing temperature. Substitutions of the Tl site in these series are suggested to affect the c-axis coherence length ξc(0) and T2D-3D with the highest transition observed. For TlSr2(Ca1-xCrx)Cu2O7-δ (x = 0.05-0.30) series, the maximum value of ξc(0), was 1.011 Å (x = 0.20) which also showed highest 2D to 3D transition temperature, T2D-3D (146 K) amongst the samples. For TlSr2(Ca1-xRex)Cu2O7-δ (x = 0.05-0.30) series, the results indicated that Re substitution modified ξc(0), decrease the interlayer coupling strength and increase the anisotropy of the samples. Moreover, Re substitution changed the T2D-3D; the highest transition was observed at x = 0.15. Hf substitution at the Ca site modified ξc(0) and consequently increased the anisotropy of the samples and reduced the interlayer coupling strength. A transition from 2D to 3D behavior was observed as the temperature was decreased for the TlSr2(Ca1-xTex)Cu2O7-δ series (x = 0.05-0.30). The highest anisotropy (γ) within the series was 10.24 at x = 0.25. In conclusion, this work showed that the substitution with multivalent ion at Tl or Ca sites in TlSr2CaCu2O7-δ (x = 0.05–0.30) formed the 1212 superconductor phase. The characteristic scaling of the curves obtained from excess conductivity ln(Δσ/σo) as a function of reduced temperature, ln(ε) for our multivalent ion substitution showed a crossover between two to three-dimensional behaviors around critical region.,PhD | - |
| dc.language.iso | eng | - |
| dc.publisher | UKM, Bangi | - |
| dc.relation | Faculty of Science and Technology / Fakulti Sains dan Teknologi | - |
| dc.rights | UKM | - |
| dc.subject | Superconductors | - |
| dc.title | Superconducting properties and excess conductivitiy analyses of Cr, Re, Rh, Hf and Te substitutions at TI and Ca sites of T1Sr2CaCu2O7-δ | - |
| dc.type | Theses | - |
| dc.format.pages | 188 | - |
| dc.identifier.callno | TK7872.S8A455 2014 tesis | - |
| dc.identifier.barcode | 001179 | - |
| Appears in Collections: | Faculty of Science and Technology / Fakulti Sains dan Teknologi | |
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|---|---|---|---|---|
| ukmvital_80295+SOURCE1+SOURCE1.0.PDF Restricted Access | 4.29 MB | Adobe PDF |  View/Open |
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