Zhenbao Li, Guoqing Liu, Gaofeng Jiao, Xiaoyan Xu, Qingbin Hao, Kai Yao, Jianfeng Li
{"title":"Sr/Ca对Bi-2212导线相演化机制、相纯度及临界电流密度的影响","authors":"Zhenbao Li, Guoqing Liu, Gaofeng Jiao, Xiaoyan Xu, Qingbin Hao, Kai Yao, Jianfeng Li","doi":"10.1016/j.supcon.2024.100136","DOIUrl":null,"url":null,"abstract":"<div><div>Two batches of Bi-2212 precursor powder with Sr/Ca = 2.24, 2.33 were prepared by the spray pyrolysis technology. Then two Bi-2212 superconducting wires marked as Line4 and Line8-2 were prepared by the above powders. Line4 with Sr/Ca = 2.24 showed much higher phase purity, higher texture and its critical current density(<em>J<sub>c</sub></em>) was 1.5 times that of Line8-2 with Sr/Ca = 2.33. Their micro-structure evolution was scrutinized by quenching each wire at 7 instantaneous moments during the partial melting process(PMP). Bi-2212 was found to decompose into (Sr,Ca)<sub>14</sub>Cu<sub>24</sub>O<sub>x</sub>(14:24AEC), Bi<sub>9</sub>Sr<sub>11</sub>Ca<sub>5</sub>O<sub>x</sub>(9:16CF), Bi-rich liquid Bi-2212 and Bi-rich solid Bi-2212 at the initial stage of PMP. When Bi-2212 began to solidify, the above four phases reacted to generate Bi-2212. By analyzing the particle size, the content and the composition variation for 14:24AEC, 9:16CF as well as the composition variation for Bi-2212 matrix in above 7 moments of PMP, the phase evolution’s difference between two wires was finally confirmed. The formation energy of 14:24AEC was smaller compared with 9:16CF, while 9:16CF was faster on dynamics. 14:24AEC determined the whole synthetic reaction’s rate of Bi-2212, and Sr/Ca as well as its value fluctuation in Bi-2212 precursor powder can decide both the timeline and the driving force of PMP. A larger Sr/Ca in Line8-2 made it melt earlier compared with Line4, which led to its earlier timeline during the melting stage of PMP. While the more consistent phase evolution’s pace between 14:24AEC and 9:16CF in Line4 finally contributed a larger Sr/Ca after solidification. Both the larger Sr/Ca and its larger fluctuation in Line4 finally contributed to its faster phase evolution’s pace, higher phase purity, better texture and higher <em>J<sub>c</sub></em>. The deep logic driving the phase evolution mechanism in Bi-2212 wires was disclosed for the first time, which will be very helpful to the future improvement of <em>J<sub>c</sub></em> for Bi-2212 wires.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"12 ","pages":"Article 100136"},"PeriodicalIF":5.6000,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Influence of Sr/Ca on the phase evolution mechanism, phase purity and critical current density of Bi-2212 wires\",\"authors\":\"Zhenbao Li, Guoqing Liu, Gaofeng Jiao, Xiaoyan Xu, Qingbin Hao, Kai Yao, Jianfeng Li\",\"doi\":\"10.1016/j.supcon.2024.100136\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Two batches of Bi-2212 precursor powder with Sr/Ca = 2.24, 2.33 were prepared by the spray pyrolysis technology. Then two Bi-2212 superconducting wires marked as Line4 and Line8-2 were prepared by the above powders. Line4 with Sr/Ca = 2.24 showed much higher phase purity, higher texture and its critical current density(<em>J<sub>c</sub></em>) was 1.5 times that of Line8-2 with Sr/Ca = 2.33. Their micro-structure evolution was scrutinized by quenching each wire at 7 instantaneous moments during the partial melting process(PMP). Bi-2212 was found to decompose into (Sr,Ca)<sub>14</sub>Cu<sub>24</sub>O<sub>x</sub>(14:24AEC), Bi<sub>9</sub>Sr<sub>11</sub>Ca<sub>5</sub>O<sub>x</sub>(9:16CF), Bi-rich liquid Bi-2212 and Bi-rich solid Bi-2212 at the initial stage of PMP. When Bi-2212 began to solidify, the above four phases reacted to generate Bi-2212. By analyzing the particle size, the content and the composition variation for 14:24AEC, 9:16CF as well as the composition variation for Bi-2212 matrix in above 7 moments of PMP, the phase evolution’s difference between two wires was finally confirmed. The formation energy of 14:24AEC was smaller compared with 9:16CF, while 9:16CF was faster on dynamics. 14:24AEC determined the whole synthetic reaction’s rate of Bi-2212, and Sr/Ca as well as its value fluctuation in Bi-2212 precursor powder can decide both the timeline and the driving force of PMP. A larger Sr/Ca in Line8-2 made it melt earlier compared with Line4, which led to its earlier timeline during the melting stage of PMP. While the more consistent phase evolution’s pace between 14:24AEC and 9:16CF in Line4 finally contributed a larger Sr/Ca after solidification. Both the larger Sr/Ca and its larger fluctuation in Line4 finally contributed to its faster phase evolution’s pace, higher phase purity, better texture and higher <em>J<sub>c</sub></em>. The deep logic driving the phase evolution mechanism in Bi-2212 wires was disclosed for the first time, which will be very helpful to the future improvement of <em>J<sub>c</sub></em> for Bi-2212 wires.</div></div>\",\"PeriodicalId\":101185,\"journal\":{\"name\":\"Superconductivity\",\"volume\":\"12 \",\"pages\":\"Article 100136\"},\"PeriodicalIF\":5.6000,\"publicationDate\":\"2024-12-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Superconductivity\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S277283072400053X\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ENGINEERING, ELECTRICAL & ELECTRONIC\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Superconductivity","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S277283072400053X","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, ELECTRICAL & ELECTRONIC","Score":null,"Total":0}
Influence of Sr/Ca on the phase evolution mechanism, phase purity and critical current density of Bi-2212 wires
Two batches of Bi-2212 precursor powder with Sr/Ca = 2.24, 2.33 were prepared by the spray pyrolysis technology. Then two Bi-2212 superconducting wires marked as Line4 and Line8-2 were prepared by the above powders. Line4 with Sr/Ca = 2.24 showed much higher phase purity, higher texture and its critical current density(Jc) was 1.5 times that of Line8-2 with Sr/Ca = 2.33. Their micro-structure evolution was scrutinized by quenching each wire at 7 instantaneous moments during the partial melting process(PMP). Bi-2212 was found to decompose into (Sr,Ca)14Cu24Ox(14:24AEC), Bi9Sr11Ca5Ox(9:16CF), Bi-rich liquid Bi-2212 and Bi-rich solid Bi-2212 at the initial stage of PMP. When Bi-2212 began to solidify, the above four phases reacted to generate Bi-2212. By analyzing the particle size, the content and the composition variation for 14:24AEC, 9:16CF as well as the composition variation for Bi-2212 matrix in above 7 moments of PMP, the phase evolution’s difference between two wires was finally confirmed. The formation energy of 14:24AEC was smaller compared with 9:16CF, while 9:16CF was faster on dynamics. 14:24AEC determined the whole synthetic reaction’s rate of Bi-2212, and Sr/Ca as well as its value fluctuation in Bi-2212 precursor powder can decide both the timeline and the driving force of PMP. A larger Sr/Ca in Line8-2 made it melt earlier compared with Line4, which led to its earlier timeline during the melting stage of PMP. While the more consistent phase evolution’s pace between 14:24AEC and 9:16CF in Line4 finally contributed a larger Sr/Ca after solidification. Both the larger Sr/Ca and its larger fluctuation in Line4 finally contributed to its faster phase evolution’s pace, higher phase purity, better texture and higher Jc. The deep logic driving the phase evolution mechanism in Bi-2212 wires was disclosed for the first time, which will be very helpful to the future improvement of Jc for Bi-2212 wires.
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