Gd＿（1－x）Ca＿xBa＿2Cu＿3O＿（7－y）高温超导体压力效应的研究

HIGH-PRESSURE STUDIES OF THE Gd_(1-x)Ca_xBa_2Cu_3O_(7-y)HIGH-T_c SUPERCONDUCTORS

研究了Ｇｄ＿（１－ｘ）Ｃａ＿ｘＢａ＿２Ｃｕ＿３Ｏ＿（７－ｙ）（０．０≤Ｘ≤０．２０）高温超导体在常压和高压下的超导电性在１－３００Ｋ温度范围内，利用Ｂｒｉｄｇｍａｎ对顶砧获得压力达９．０ＧＰａ，测量了（Ｘ＝０．１０，０．１５，０．２０）样品的ｄＴ＿ｃ／ｄｐ分别为７．６８，７．８和４．４６Ｋ／ＧＰａ。发现Ｔ＿ｃ的压力导数随着ｃａ￣（２＋）含量的增加而下降，分析了氧含量对Ｔ＿ｃ和ｄＴ＿ｃ／ｄＰ的影响．利用常压下晶格参数精修值和阳离子与氧离子间距随压力的改变，说明ＣｕＯ＿２面在超导电性上的作用，用ＣｕＯ＿２面之间耦合解释Ｔ＿ｃ（Ｐ）曲线的非线性关系。

We have investigated the superconductivity of Ca￣2+-dopped Gd_(1-x)Ca_xBa_2Cu_3O_(7-y)compounds under both ambient and high pressure. Using a Bridgman-anvil cell, thehigh pressure up to 9.0GPa, in temperature range of 1-300K, have been obtained.The superconducting transition temperature T. (onset) initially increases with pres-sure at a rate of dT_c/dP = 7.68, 7.8 and 4.46K/GPa for x = 0.10, 0.15, 0.20 samp-les at OGPa < P≤ 2.0-3.0GPa, respectively. The effect of oxygen content on T_chas been investigated. By using the data of the structural parameters of samples atambient pressure and the changes of the distances between cation and oxygen withthe pressure, the role of the CuO_2 plane on superconductivity is demonstrated. Thecoupling between the CuO_2 planes may be used to explain the nonlinear dependenceof T_c(P).