Superconductivity above 150 K in HgBa2Ca2Cu3O8+δ at high pressures

Chu, C. W.; Gao, Li; Chen, F.; Huang, Z. J.; Meng, R. L.; Xue, Y. Y.

doi:10.1038/365323a0

Cited by 587 publications

(205 citation statements)

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“…Here, T c0 denotes the superconducting transition temperature defined by the occurrence of zero resistivity. Note that T c0 is slightly lower than previous results, 2,3) suggesting that the present sample is slightly underdoped. The magnitude of resistivity is less than 1 m cm at room temperature, which is more than 10 times smaller than those in previous reports, indicating high density.…”

contrasting

confidence: 72%

“…As stated, T c0 of the present sample is 130 K, which is slightly lower than the optimal value of 135 K, [2][3][4]10) implying that the present sample is slightly underdoped. The systematic investigation of the doping dependence of T c0 at high pressures is an intriguing issue.…”

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confidence: 76%

“…6) To the best of our knowledge, the highest record of the zero resistivity temperature is, at most, 140 K even today. [2][3][4] In order to definitively prove the occurrence of superconductivity and to accurately determine T c from the resistivity measurements, one must to demonstrate that (1) the resistivity drop is sharp enough and that (2) zero resistivity is realized below the transition. To fulfill the requirement, it is necessary to carry out the measurements using high-quality samples.…”

mentioning

confidence: 99%

“…Below 5 GPa, T c increases linearly with P. The slope, dT c0 =dP, is +2.5 K/GPa, which is one of the largest values among the existing copper-oxide superconductors 10) and is consistent with the previous results. 3,4,10,11) (For comparison, the results from the magnetization measurements of the Hg-1223 polycrystal 11) are also plotted as red triangles.) At higher pressures (P > 10 GPa), T c continues to increase with the dT c0 =dP ratio of 1 K/GPa.…”

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Zero Resistivity above 150 K in HgBa₂Ca₂Cu₃O_8+δat High Pressure

et al. 2013

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We measured the electrical resistivity of a HgBa 2 Ca 2 Cu 3 O 8þ (Hg-1223) polycrystalline sample under high pressure. Owing to the improved sample quality and the nearly hydrostatic pressure, we successfully observed zero resistivity, which is the unambiguous signature of superconductivity, up to the unprecedented temperature of 153.0 K at 15 GPa. This temperature surpasses the previous records by more than 10 K. Referring to the experimental results, we established the exact pressure (P) vs superconducting transition temperature (T c ) relationship. T c increases with P up to 15 GPa, suggesting the possibility of further enhancement of T c at higher pressures.

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confidence: 76%

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confidence: 99%

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Zero Resistivity above 150 K in HgBa₂Ca₂Cu₃O_8+δat High Pressure

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“…Estes materiais possuem temperaturas de transição para o estado supercondutor consideravelmente mais altas que as dos supercondutores metálicos convencionais como o nióbio, alumínio, o estanho, o chumbo, o índio e algumas ligas intermetá-licas. Atualmente, consegue-se o recorde para a temperatura crítica de transição supercondutora T c~1 53 K num composto do sistema Hg-Ba-Ca-Cu-O [3] quando submetido a pressão de 150 kbar.…”

Section: Introductionunclassified

Roteiro para a experiência de levitação de um imã repelido por um supercondutor no ensino de Física

Rocha¹,

Fraquelli²

2004

Rev. Bras. Ens. Fis.

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Propõe-se um roteiro para a demonstração do fenômeno da supercondutividade através da experiência de levitação de um ímã repelido por uma amostra de YBa 2 Cu 3 O 7 . A experiência é baseada na manifestação do efeito Meissner, característico de um material no estado supercondutor sob a ação de um campo magnético. A demonstração não requer grande investimento contribuindo com a introdução de tópicos de Física contemporânea na atualização dos currículos. Discute-se a base dos conceitos físicos da supercondutividade envolvidos na levitação do magneto. Ao final é apresentado no apêndice a descrição dos processos envolvidos na fabricação e tratamento térmico de uma amostra do material cerâmico supercondutor de alta temperatura crítica YBa 2 Cu 3 O 7 (T c~9 2 K). Palavras-chave: ensino de Física, experimentação, levitação magnética, supercondutividade.The aim of this paper is to propose an outline to demonstrate the phenomenon of superconductivity by means of a levitation experiment of a magnet, repelled by a sample of YBa 2 Cu 3 O 7 . The experiment is based on the evidence of the Meissner effect, a characteristic property of a superconducting material under the action of magnetic fields. This demonstration of the levitation phenomenon does not imply large expenditures. It helps to introduce contents of the contemporary physics that leads to update curriculum. The main physical concepts involved in the levitation of a magnet and the phenomenon of superconductivity are both discussed here. Finally, the appendix describes the procedures involved in the preparation and thermal treatment of a sample of the ceramic high critical temperature superconducting material YBa 2 Cu 3 O 7 (T c~9 2 K). Keywords: Physics teaching, experimentation, magnetic levitation, superconductivity. IntroduçãoO fenômeno da supercondutividade foi descoberto [1] em 1911 pelo físico holandês Heike Kammerlingh Onnes, três anos após sua façanha de liquefação do gás hélio que ocorre na temperatura de 4,2 K. Onnes observou que a resistência elétrica de uma amostra de mercúrio desaparecia completamente em temperaturas inferiores a 4 K. Desde sua descoberta, a supercondutividade despertou grande interesse no mundo científico acadêmico e tecnológico. Essa importância pode ser medida pelo número de quatro prêmios Nobel concedidos aos pesquisadores que atuaram brilhantemente na área. Num material supercondutor as cargas elétricas negativas podem fluir livremente sem haver perdas de energia por calor, caracterizando a ausência do efeito Joule. Outra manifestação característica de um supercondutor é o efeito Meissner que consiste na exclusão do fluxo magnético de dentro do material.O problema com o desenvolvimento tecnológico da supercondutividade tem sido sempre as baixas temperaturas necessárias para mantê-la. Contudo, a partir de 1986, novos materiais cerâmicos supercondutores [2], baseados em óxidos de cobre, foram descobertos. Estes materiais possuem temperaturas de transição para o estado supercondutor consideravelmente mais altas que as dos superconduto...

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Role of oxygen content in electronic structures of Ba _0.6 K _0.4 BiO _3–δ

Li¹

1997

Int. J. Quantum Chem.

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The band structure calculations on the K-doped superconductor Ba K BiO were carried out, and the effect of the oxygen content on its electronic 0.6 0.4 3᎐␦ structures was studied in the present work. The results show that the variation in the oxygen content caused by the partial substitution of K for Ba has a great effect on its electronic structure. The oxygen vacancies cause the saddle point singularity to be displaced gradually as the oxygen content is decreased, whereas the band structure is only translated a little and remains unchanged in shape, which reflects the non-rigidbandlike behavior of Ba K BiO in the presence of the oxygen vacancies. When the 0.6 0.4 3᎐␦ saddle point singularity is displaced and lies at the Fermi level E , the total density of f Ž . states at E , N E , has the highest value which is twice as large as that of the f f Ba K BiO compound without the oxygen vacancies. These results reveal the important 0.6 0.4 3 role of the oxygen content in the Ba᎐K᎐Bi᎐O superconducting system.

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Superconductivity above 150 K in HgBa2Ca2Cu3O8+δ at high pressures

Cited by 587 publications

References 4 publications

Zero Resistivity above 150 K in HgBa₂Ca₂Cu₃O_8+δat High Pressure

Zero Resistivity above 150 K in HgBa₂Ca₂Cu₃O_8+δat High Pressure

Roteiro para a experiência de levitação de um imã repelido por um supercondutor no ensino de Física

Role of oxygen content in electronic structures of Ba _0.6 K _0.4 BiO _3–δ

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Superconductivity above 150 K in HgBa2Ca2Cu3O8+δ at high pressures

Cited by 587 publications

References 4 publications

Zero Resistivity above 150 K in HgBa2Ca2Cu3O8+δat High Pressure

Zero Resistivity above 150 K in HgBa2Ca2Cu3O8+δat High Pressure

Roteiro para a experiência de levitação de um imã repelido por um supercondutor no ensino de Física

Role of oxygen content in electronic structures of Ba 0.6 K 0.4 BiO 3–δ

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Zero Resistivity above 150 K in HgBa₂Ca₂Cu₃O_8+δat High Pressure

Zero Resistivity above 150 K in HgBa₂Ca₂Cu₃O_8+δat High Pressure

Role of oxygen content in electronic structures of Ba _0.6 K _0.4 BiO _3–δ