Ni掺杂对Bi系超导氧化物微结构和物性的影响
发布时间：2018-08-20 17:42
【摘要】：本文主要是通过Pechini溶胶-凝胶法制备不同Ni掺杂量的Bi系氧化物超导粉体。研究了制备样品的前驱粉时候进行水浴和不同的烧结温度对Bi系氧化物超导粉体质量的影响,改进了Pechini溶胶-凝胶制备Bi系粉体的工艺。并在此基础上研究对Sr位进行不同量的Ni掺杂的Bi-2212粉体的微结构和物理性能。本文的具体研究内容可以分为以下几点：采用Pechini溶胶-凝胶法制备Bi2Sr2-xCaCu2NixO8+δ超导粉体。在制备样品的前驱粉时分别采用先水浴再石蜡浴和不经水浴直接石蜡浴的两种工艺。我们发现在当其他工艺条件相同时,经过水浴加热的样品质量更好。同时我们在烧结前驱粉时,采用835℃、850℃和855℃三个不同的温度,保温时间都是5h进行烧结。通过对X射线衍射图谱的分析发现烧结温度为850℃时,得到的样品相纯度最好。在850℃、保温5h条件下制备Sr位掺Ni的Bi-2212(Nii掺杂量为x=0.05-0.25)超导粉体样品。通过对衍射峰位变化的分析发现,随着Ni的掺杂量的不同,我们可以发现(002),(008)和(0010)这三个面的衍射峰在x=0.15时向大角的偏移量最大,而衍射峰(113),(115),(117)和(020)却正好相反。表明Ni进入Bi-2212的晶格当中,并使得晶格参数发生变化。我们还可以看到所有样品XRD图谱中有NiO相的峰存在,说明Ni并未全部进入到晶格当中去,剩余的部分Ni以NiO的形式存在。本文通过四引线法测量了不同Ni掺杂量样品的电阻随温度的变化规律,详细研究了Ni掺杂量的不同对样品电运输能力的影响。我们发现x=0.15样品的Tc,onset最小,而其他x值样品的Tc,onset相差不大,这表明x=0.15时Ni掺进晶格结构中的数量最大。x=0.25时减小的幅度最大,这是由于NiO相的作用,使温度降低到一定范围时电阻首先升高而后才降低,在一定程度上推迟了超导的转变。通过MPMS磁性测量系统分别在10K和20K温度下测量了不同x值的样品的磁滞回线,发现在10K时样品表现出较大的磁滞回线(AM值较大),表现出良好和均匀的超导性。在测得的磁滞回线的基础上,利用Bean模型可以计算出不同Ni掺杂量的样品的临界电流密度值Jc。可以看出不同Ni掺杂量的Bi2Sr2-xCaCu2NixO8+δ(x=0.05-0.25)超导粉体的临界电流密度随磁场的变化规律。即随着外加磁场向着正方向加大时临界电流减小。同样我们发现Ni掺杂量为x=0.25时所获得的临界电流密度最大。这于前面提到的x=0.25时样品具有最大的钉扎强度有关,而钉扎强度与MR成正比,所以x=0.25时可以获得更大的临界电流密度值。在相同的磁场条件下,随着x从最小值0.05增加到最大值0.25,Bi2Sr2-xCaCu2NiXO8+δ超导粉体的临界电流密度呈现出逐渐增大的基本趋势。产生这种结果的原因是NiO相在粉体中的钉扎作用,随着Ni掺杂量的增大而增大。
[Abstract]:In this paper, Bi oxide superconducting powder with different Ni doping content was prepared by Pechini sol-gel method. The effects of water bath and different sintering temperature on the quality of Bi system superconducting powder were studied. The process of preparing Bi based superconducting powder by Pechini sol gel was improved. On this basis, the microstructure and physical properties of Ni doped Bi-2212 powders with different Sr sites were investigated. The main contents of this paper are as follows: Bi2Sr2-xCaCu2NixO8 未 superconducting powder was prepared by Pechini sol-gel method. In the preparation of the precursor powder, two kinds of processes, water bath and paraffin bath and direct paraffin bath without water bath, were adopted respectively. We found that the quality of the samples heated by water bath was better when other process conditions were the same. At the same time, three different temperatures (835 鈩，
本文编号：2194472
[Abstract]:In this paper, Bi oxide superconducting powder with different Ni doping content was prepared by Pechini sol-gel method. The effects of water bath and different sintering temperature on the quality of Bi system superconducting powder were studied. The process of preparing Bi based superconducting powder by Pechini sol gel was improved. On this basis, the microstructure and physical properties of Ni doped Bi-2212 powders with different Sr sites were investigated. The main contents of this paper are as follows: Bi2Sr2-xCaCu2NixO8 未 superconducting powder was prepared by Pechini sol-gel method. In the preparation of the precursor powder, two kinds of processes, water bath and paraffin bath and direct paraffin bath without water bath, were adopted respectively. We found that the quality of the samples heated by water bath was better when other process conditions were the same. At the same time, three different temperatures (835 鈩，
本文编号：2194472
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