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https://ptsldigital.ukm.my/jspui/handle/123456789/499704Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | Roslan Abd Shukor, Prof Dato. Dr. | - |
| dc.contributor.author | Ghazeian Maryam Ranjbar (P54229) | - |
| dc.date.accessioned | 2023-10-13T09:33:56Z | - |
| dc.date.available | 2023-10-13T09:33:56Z | - |
| dc.date.issued | 2015-06-20 | - |
| dc.identifier.other | ukmvital:81680 | - |
| dc.identifier.uri | https://ptsldigital.ukm.my/jspui/handle/123456789/499704 | - |
| dc.description | The study involves the effect of Cr substitution for Tl in TlSr2CaCu2O7-x (Tl-1212) and TlBa2Ca2Cu3O9-z (Tl-1223) superconductors. The samples investigated in this study were (Tl1-xCrx)Sr2CaCu2O7 for (x = 0-0.6), (Tl1-xCrx)Sr2CaCu2O7-z (with 50 nm CuO) for (x = 0- 0.7) and (Tl1-xCrx)Ba2Ca2Cu3O9-z for (x = 0.3-1.0). The (Tl1-xCrx)Sr2CaCu2O7 for x = 0.05 with 3, 7 and 8 min of flowing oxygen, (Tl1-xCrx)Sr2CaCu2O7 for x = 0.1 with 7, 10 and 18 min of flowing oxygen and (Tl1-xCrx)Sr2CaCu2O7 for x = 0.15 with 2, 5, 7, 9 and 10 min of flowing oxygen were also studied. Cr was chosen because it has the capability to promote the formation of superconducting phase and enhance critical temperature (Tc) in the Tl-1212 and Tl-1223 phase. The ionic radius of Cr 3+/4+/5+ (≤ 0.061 nm) is smaller than Tl 3+ (0.095 nm). It is interesting to investigate the effect of smaller ionic radius on the excess conductivity and superconductivity of the Tl-1223 and Tl-1212 phase. The samples were synthesis via the solid state reaction method. The volume fraction of Tl- 1223 phase for (Tl1-xCrx)Ba2Ca2Cu3O9 increased with increasing Cr substitution. X-ray diffraction patterns indicated a Tl-1223 phase with tetragonal unit cell with a few weak diffraction lines of the Tl-2212 phase. A single Tl-1223 phase was obtained for x = 0.6. The formation of pure Tl-1223 phase in this sample showed that Cr may have entered the lattice of the Tl-1223 phase. The (Tl1-xCrx)Ba2Ca2Cu3O9-z (x = 0.3-0.8) series showed the highest superconducting behaviour for x = 0.6, 0.7 and 0.8 with onset critical temperature (Tc onset ) of 124 K. The (Tl1-xCrx)Sr2CaCu2O7-z and (Tl1-xCrx)Sr2CaCu2O7-z (with nano CuO) series showed the highest superconducting transition at x = 0.5 (109 K) and x = 0.2 (110 K), respectively. For the (Tl,Cr)-Sr-Ca-Cu-O series for (x = 0.05, 0.1 and 0.15) the electrical resistance versus temperature curve showed semiconductor normal state behaviour except for (Tl,Cr)-Sr-Ca-Cu-O (x = 0.1) with 7 min oxygen flow that showed metallic normal state behaviour with Tc onset at 100 K. The AC susceptibility measurements were used to determine the transition temperature of (Tl0.095Cr0.05)Sr2CaCu2O7-z prepared with 3 min flowing oxygen and the Tc was 78 K. The superconducting fluctuation behaviour in (Tl1-xCrx)Sr2CaCu2O7-z (with nano CuO) for x = 0.2-0.5 and (Tl1-xCrx)Ba2Ca2Cu3O9-z for x = 0.4-0.8 series were analyzed by using Asmalazov Larkin theory. All samples showed characteristic cross over from 2D to 3D behaviour. For (Tl1-xCrx)Sr2CaCu2O7-z (with nano CuO), the x = 0.2-0.5 samples showed the shortest coherence length and weakest inter-plane coupling strength occurred when x = 0.4. For (Tl1-xCrx)Ba2Ca2Cu3O9-z (x = 0.4-0.8) series, excess conductivity analysis indicated that Cr substitution modified coherence length ξc(0), decreased the interlayer v coupling strength and increased the anisotropy of the samples. This work showed that optimal Tc can be achieved in the Tl-1212 and Tl-1223 phase although the interlayer CuO-CuO coupling was weak.,Kajian ini melibatkan kesan penggantian Cr pada Tl dalam superkonduktor TlSr2CaCu2O7-x (Tl-1212) dan TlBa2Ca2Cu3O9-z (Tl-1223). Sampel yang dikaji adalah (Tl1-xCrx)Sr2CaCu2O7 dengan x = 0-0.6, (Tl1-xCrx)Sr2CaCu2O7 (dengan 50 nm CuO) dengan x = 0-0.7 dan (Tl1-xCrx)Ba2Ca2Cu3O9 dengan x = 0.3-1.0. Sampel (Tl1- xCrx)Sr2CaCu2O7 untuk x = 0.05 dengan pengaliran oksigen 3, 7 dan 8 minit, (Tl1- xCrx)Sr2CaCu2O7 untuk x = 0.1 dengan pengaliran oksigen 7, 10 dan 18 minit dan (Tl1- xCrx)Sr2CaCu2O7 untuk x = 0.15 dengan pengaliran oksigen 2, 5, 7, 9 dan 10 minit juga telah dikaji. Cr dipilih kerana keupayaannya yang menggalakan pembentukan fasa kesuperkonduksian dan meningkatkan suhu genting (Tc) fasa Tl-1212 dan Tl-1223. Jejari ion Cr 3+/4+/5+ (≤ 0.061 nm) adalah lebih kecil daripada Tl 3+ (0.095 nm). Adalah menarik untuk mengkaji kesan ion yang berjejari lebih kecil ke atas kekonduksian lebihan dan pembentukan fasa Tl-1223 dan Tl-1212. Sampel telah disintesis melalui kaedah tindak balas keadaan pepejal. Pecahan isipadu Tl-1223 bagi (Tl1-xCrx)Ba2Ca2Cu3O9 meningkat dengan peningkatan penggantiaan Cr. Corak pembelauan sinar X menunjukkan fasa Tl- 1223 dengan unit sel tetragonal dengan beberapa garis pembelauan fasa Tl-1212 yang lemah. Fasa tunggal Tl-1223 telah diperoleh bagi sampel x = 0.6. Pembentukan fasa tulen Tl-1223 dalam sampel ini menunjukkan bahawa Cr mungkin telah memasuki kisi fasa Tl-1223. Siri (Tl1-xCrx)Ba2Ca2Cu3O9 (x = 0.3-0.8) menunjukkan sifat kesuperkonduksian yang paling tinggi pada x = 0.6, 0.7 and 0.8 dengan suhu genting mula (Tc mula) pada 124 K. Siri (Tl1-xCrx)Sr2CaCu2O7 dan (Tl1-xCrx)Sr2CaCu2O7 (dengan nano CuO) menunjukkan sifat kesuperkonduksian yang paling tinggi pada x = 0.5 (109 K) dan x = 0.2 (110 K), masing-masing. Semua sampel (Tl,Cr)-Sr-Ca-Cu-O dengan (x = 0.05, 0.1 and 0.15) menunjukkan lengkung rintangan elektrik lawan suhu yang bersifat semikonduktor kecuali (Tl,Cr)-Sr-Ca-Cu-O (x = 0.1) dengan pengaliran oksigen 7 minit menunjukkan sifat logam dengan Tc mula pada 100 K. Pengukuran kerentanan arus ulang-alik telah digunakan untuk menentukan suhu peralihan bagi (Tl0.095Cr0.05)Sr2CaCu2O7 yang disediakan dengan pengaliran oksigen selama 3 minit dan Tc adalah 78 K. Sifat turun naik kesuperkonduksian dalam siri (Tl1-xCrx)Sr2CaCu2O7 (dengan nano CuO) untuk x = 0.2-0.5 dan (Tl1-xCrx)Ba2Ca2Cu3O9 untuk x = 0.4 dan 0.8 telah dianalisis dengan menggunakan teori Asmalazov Larkin (AL). Kedua-dua siri menunjukkan ciri peralihan daripada sifat 2D ke 3D. Bagi (Tl1-xCrx)Sr2CaCu2O7 (dengan nano CuO), sampel x = 0.2-0.5 menunjukkan panjang koheren yang paling pendek dan kekuatan gandingan antara satah (J) yang paling lemah iaitu pada x = 0.2. Sampel ini juga menunjukkan Tc mula yang paling tinggi dan pecahan isipadu Tl-1212 yang maksimum (70%). Bagi siri (Tl1- xCrx)Ba2Ca2Cu3O9 (x = 0.4-0.8),analisis kekonduksian lebihan menunjukkan bahawa vii penggantian Cr mengubah panjang kepaduan ξc(0), mengurangkan kekuatan gandingan antara lapisan dan meningkatkan anisotropi sampel. Kajian ini menunjukkan Tc optimum boleh dicapai dalam fasa Tl-1212 dan Tl-1223 walaupun gandingan antara lapisan CuOCuO adalah lemah.,Ph.D | - |
| 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.subject | Superconductivity | - |
| dc.subject | Cr-substitution | - |
| dc.subject | Superconductivity. | - |
| dc.title | Phase formation and excess conductivity analysis of Cr-Substituted T1Sr2CaCu2O7-x and T1Ba2Ca2Cu3O9-z superconductors | - |
| dc.type | Theses | - |
| dc.format.pages | 131 | - |
| dc.identifier.callno | QC611.96 .G483 2015 | - |
| dc.identifier.barcode | 001457 | - |
| Appears in Collections: | Faculty of Science and Technology / Fakulti Sains dan Teknologi | |
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|---|---|---|---|---|
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