Phase separation and oxygen diffusion in electrochemically oxidized La2CuO4+ delta : A static magnetic susceptibility study.
Phase separation and oxygen diffusion in electrochemically oxidized La2CuO4+ delta : A static magnetic susceptibility study.
复制标题
电化学氧化 La2CuO4 δ 中的相分离和氧扩散：静态磁化率研究。
DOI：
10.1103/physrevb.54.572
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Johnston
中科院分区：
文献类型：
--
作者：
Chou;Johnston
已知化合物La{sub 2}CuO{sub 4+{delta}}在温度{ital T}{sub ps}{大约}300 K以下以0.01{approx_lt}{delta}{approx_lt}0.06相分离为接近化学量的反铁磁化合物La{sub 2}CuO{sub 4.01{endash}4.02}，其N{急变e}温度{ital T}{sub {ital N}}{大约}250 K，和一个金属富氧相La{sub 2}CuO{sub {approx_=}4.06}，其超导转变温度{ital T}{sub {ital c}}{大约等于}34 K。本文报道了用电化学氧化或还原法制备的La{sub 2}CuO{sub 4+{delta}}样品的超导性和正态静态磁化率{chi}的研究，样品值为0{约x_lt}{delta}{le}0.11。在低{ital T}处，混相间隙的上限为{delta}{约x_lt}0.065，与前人的研究结果一致。采用热和磁场历史相关{chi}（{ital T},{ital T}）测量与温度{ital T}和时间{ital T}作为探针，研究了相分离过程中的间隙氧扩散。在{大约}100 K/s的温度下淬火可以抑制相分离，而在{大约}0.5 K/min的温度下缓慢冷却有利于相分离。对于在混相间隙内的La{sub 2}CuO{sub 4+{delta} more»（{delta}{近似等于}0.030,0.044）样品，在淬火至5 K后再加热得到的数据与在300 K后缓慢冷却得到的数据之间存在较大的正常态和超导态{chi}（{ital T}）的热滞后。淬火使{ital T}{sub {ital c}}相对于缓慢冷却后得到的值（34 K）降低{近似等于}5 K。La{sub 2}CuO{sub 4.065}不发生相分离，也有类似的减少，说明在这一单相中氧序效应的重要性。（摘要节选）«少
The compound La{sub 2}CuO{sub 4+{delta}} is known to phase separate for 0.01{approx_lt}{delta}{approx_lt}0.06 below a temperature {ital T}{sub ps}{approximately}300 K into the nearly stoichiometric antiferromagnetic compound La{sub 2}CuO{sub 4.01{endash}4.02} with N{acute e}el temperature {ital T}{sub {ital N}}{approximately}250 K, and a metallic oxygen-rich phase La{sub 2}CuO{sub {approx_equal}4.06} with superconducting transition temperature {ital T}{sub {ital c}}{approx_equal}34 K. We report studies of the superconducting and normal-state static magnetic susceptibility {chi} of La{sub 2}CuO{sub 4+{delta}} samples with 0{approx_lt}{delta}{le}0.11 prepared by electrochemical oxidation or reduction of conventionally synthesized ceramic La{sub 2}CuO{sub 4+{delta}}. The upper limit to the miscibility gap at low {ital T} is found be {delta}{approx_lt}0.065, in agreement with the previous work. The interstitial oxygen diffusion during the phase-separation process was studied using thermal- and magnetic-field history-dependent {chi}({ital T},{ital t}) measurements versus temperature {ital T} and time {ital t} as a probe. Phase separation is found to be suppressed by quenching at {approx_gt}100 K/s and favored by slow cooling at {approximately}0.5 K/min. A large thermal hysteresis of both the normal and superconducting state {chi}({ital T}) was observed between data obtained after quenching to 5 K and then warming, and data obtained while or after slowly cooling from 300 K, for samples of La{sub 2}CuO{sub 4+{delta}}more » ({delta}{approx_equal}0.030, 0.044) within the miscibility gap. Quenching reduces {ital T}{sub {ital c}} by {approx_equal}5 K relative to the value (34 K) obtained after slow cooling. A similar decrease is found for La{sub 2}CuO{sub 4.065} which does not phase separate, indicating the importance of oxygen-ordering effects within this single phase. (Abstract Truncated)« less