Zhang Danlu, Sumption Michael D, Collings Edward W, Thong C J, Rindfleisch Matt A
Center for Superconducting and Magnetic Materials, Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210, United States.
Hyper Tech Research, Columbus, OH 43212, United States.
Physica C Supercond. 2020 Nov 15;578. doi: 10.1016/j.physc.2020.1353749. Epub 2021 Aug 19.
Three (MgB) (SnO) samples with ranging from 0 to 5 wt% were prepared by the route to study the effect of tin dioxide additions on the superconducting properties of MgB bulk materials. All of the reacted samples were slightly Mg deficient although the starting Mg:B precursor powder ratio was 1:2. A heat treatment (HT) temperature of 700 °C with a dwell time of 30 min was used. XRD results showed evidence of peak shifts for MgB phases with SnO addition. The magnitude of the -axis lattice constant change (0.361 ± 0.075 %) calculated for the 3 wt% doped samples is comparable in magnitude to that seen previously for the C-doped MgB bulks which exhibited enhanced . The upper critical fields ( ) and the irreversibility fields ( ) were measured resistively in fields up to 14 T at 5 K to . The best value at 20 K (15.2 T based on extrapolation) was seen for sample IS3 (x = 3 wt%), and was comparable to the best values (≈ 15 T at 20 K) seen for C-doped MgB bulks. IS3 had a corresponding = 10.8 T (20 K). The superconducting transition temperature ( ) appeared to increase slightly with doping, although within the range of error bars (37.4 K to 37.6 K for 1.6 T increase at 20 K), in contrast to C doping which is accompanied by a significant decrease in (39 K to 36 K for 3.8 % C doped MgB bulk). We attribute the observed increase in both and for SnO-additions to lattice strain caused by the introduction of precipitates within the grains.
通过该路线制备了三种二氧化锡添加量范围为0至5 wt%的(MgB)(SnO)样品，以研究添加二氧化锡对MgB块材超导性能的影响。尽管起始的Mg:B前驱体粉末比例为1:2，但所有反应后的样品都略有镁缺乏。使用了700 °C的热处理(HT)温度，保温时间为30分钟。XRD结果显示添加SnO后MgB相有峰位移动的证据。对于3 wt%掺杂样品计算得到的c轴晶格常数变化幅度(0.361 ± 0.075 %)与之前观察到的C掺杂MgB块材的幅度相当，后者表现出增强的c。在5 K至14 T的磁场中通过电阻测量了上临界场(Hc2)和不可逆场(Hirr)。样品IS3(x = 3 wt%)在20 K时的最佳Hc2值(基于外推为15.2 T)与C掺杂MgB块材的最佳Hc2值(20 K时≈15 T)相当。IS3对应的Hirr = 10.8 T(20 K)。超导转变温度(Tc)似乎随着掺杂略有增加，尽管在误差范围内(1.6 T时从37.4 K到37.6 K，20 K时增加)，这与C掺杂不同，C掺杂会伴随着Tc的显著降低(3.8 % C掺杂的MgB块材从39 K到36 K)。我们将观察到的SnO添加导致的Hc2和Hirr增加归因于晶粒内析出物引入引起的晶格应变。
