We report the enhanced superconducting properties of double-chain based superconductor Pr${}_2$Ba${}_4$Cu${}_7$O${}_{15-\delta }$ synthesized by the citrate pyrolysis technique. The reduction heat treatment in vacuum results in the appearance of superconducting state with $T_{\mathrm{c}}$=22-24 K, accompanied by the higher residual resistivity ratios. The superconducting volume fractions are estimated from the ZFC data to be $50\sim 55\%$, indicating the bulk superconductivity. We evaluate from the magneto-transport data the temperature dependence of the superconducting critical field, to establish the superconducting phase diagram. The upper critical magnetic field is estimated to be about 35 T at low temperatures from the resistive transition data using the Werthamer-Helfand-Hohenberg formula. The Hall coefficient $R_H$ of the 48-h-reduced superconducting sample is determined to be $-0.5\times {10}^{-3}$ ${\text{cm}}^3\text{/C}$ at 30 K, suggesting higher electron concentration. These findings have a close relationship with homogeneous distributions of the superconducting grains and improved weak links between their superconducting grains in the present synthesis process.

我们报告了基于双链的超导体 Pr 的增强超导特性${}_2$巴${}_4$铜${}_7$哦${}_{15-\delta }$由柠檬酸盐热解技术合成。真空还原热处理导致超导态的出现${吨}_{\mathrm{C}}$=22-24 K，伴随着较高的残余电阻率。根据 ZFC 数据估计超导体积分数为$50～55\%$，表明体超导性。我们从磁传输数据评估超导临界场的温度依赖性，以建立超导相图。根据使用 Werthamer-Helfand-Hohenberg 公式的电阻转变数据，在低温下估计上临界磁场约为 35 T。霍尔系数${\mathrm{电阻}}_H$ 48 小时还原超导样品的 $-0.5\times {10}^{-3}$ ${\text{厘米}}^3\text{/C}$在 30 K，表明更高的电子浓度。这些发现与超导晶粒的均匀分布以及在目前的合成过程中超导晶粒之间的弱联系得到改善有密切的关系。