Application of high-pressure techniques: stabilization and oxidation-state control of novel superconductive and related multi-layered copper oxides
Application of high-pressure techniques: stabilization and oxidation-state control of novel superconductive and related multi-layered copper oxides
复制标题
高压技术的应用：新型超导及相关多层铜氧化物的稳定化和氧化态控制
DOI：
10.1088/0953-2048/13/4/202
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发表时间：
2000
影响因子：
3.6
通讯作者：
M. Karppinen
中科院分区：
文献类型：
--
作者：
H. Yamauchi;M. Karppinen
铜氧化物超导体具有多层结构，沿c轴的层序为-CuO 2-（Q-CuO 2）n-1-AO-（MO 1 ±）m-AO-或-CuO 2-B-（O 2-B）s-1-CuO 2-AO-（MO 1 ±）m-AO-。根据这一层序，已知的氧化铜结构被分类为同源系列的成员，Mm Ar Qn-1 Cun Om +r +2n ±（M-mr（n-1）n ; A类）或Mm A2 k Bs Cu 1 +k Om +4k +2s ±（M-m（2k）s（1+k）; B类）。已经证明，在高压和/或强氧化条件下，这种结构的稳定化，特别是在n /s参数的高值的情况下，即同系的较高成员，明显地得到促进。因此，用于施加高氧气压力（10-2000大气压）和超高固体介质压力（2-8 GPa）的技术已有利地用于合成各种铜氧化物相。特别是在所谓的顶砧/带式装置中进行的超高固体介质压力合成已被证明在合成新的非晶相方面非常成功。为了在固体介质环境中获得高的氧分压，通常将“外部”产生氧的氧化物如KClO 4、KClO 3和Ag 2 O2加入到前体混合物中。需要强调的是，在某些情况下，可以单独使用“内部”氧化剂，即高度氧化的前体，例如仅含有与所需氧化铜相共有的金属成分的BaCuO 2+和Ba 2 Cu 3 O 5+。在本文中，高压技术在合成多层铜氧化物和相关结构的潜力和应用进行了审查和讨论，重点是重要的“历史”发现的新相和控制生产的高品质样品的现状，这样的阶段。
Copper oxide superconductors possess multi-layered structures with a layer sequence of -CuO2 -(Q-CuO2 )n -1 -AO-(MO1± )m -AO- or -CuO2 -B-(O2 -B)s -1 -CuO2 -AO-(MO1± )m -AO- along the elongated c axis. Based on this layer sequence, the known copper oxide structures are categorized as members of the homologous series, Mm Ar Qn -1 Cun Om +r +2n ± (M-mr (n -1)n ; category A) or Mm A2k Bs Cu1+k Om +4k +2s ± (M-m (2k )s (1+k ); category B). Stabilization of such structures especially in the case of high values of the n /s parameter, i.e. the higher members of the homologous series, has been demonstrated to be apparently promoted under high pressures and/or strongly oxidizing conditions. Consequently, techniques for applying both high oxygen gas pressures (10-2000 atm) and ultra-high solid-medium pressures (2-8 GPa) have been advantageously utilized in synthesizing various superconductive copper oxide phases. Especially the ultra-high solid-medium pressure synthesis carried out in the so-called cubic-anvil/belt-type apparatus has proven to be extremely successful in synthesizing novel superconductive phases. In order to achieve high partial pressures of oxygen in the solid-medium environment, `external' oxygen-generating oxides such as KClO4 , KClO3 and Ag2 O2 are commonly added to the precursor mixtures. It is emphasized that in some cases it is possible to utilize `internal' oxidizing agents alone, i.e. highly oxidized precursors such as BaCuO2+ and Ba2 Cu3 O5+ containing metal constituents common with the desired copper oxide phase only. In the present paper, the potential and applications of high-pressure techniques in synthesizing multi-layered copper oxides and related structures are reviewed and discussed with emphasis on the important `historical' discoveries of novel phases and the present status of controlled production of high-quality samples of such phases.