Abstract The transition metal pentatelluride ZrTe5 has been studied extensively due to high thermoelectric power factors for potential applications in low-temperature refrigeration devices. Recent studies reveal that the physical properties of ZrTe5 are strongly dependent on Te concentration. Here, we have synthesized the Te-rich ZrTe5+δ polycrystalline by direct solid-state reaction and systematically investigated the electrical, magneto-transport and thermoelectric properties. Temperature-dependent resistivity and magneto-transport characterizations substantiate that ZrTe5+δ is a p-type (hole-doped) semiconductor. Besides, Seebeck coefficient is positive and linearly increases with T when T is within 10–150 K, and saturated to 120 μV K−1. Remarkably, a significant figure of merit ZT is obtained (∼0.037 at T = 300 K), which is higher than those in polycrystalline ZrTe5 (∼0.026) and sister compound HfTe5 (∼0.016) measured at 300 K. The significant thermoelectric performance of ZrTe5+δ is attributed to its low electrical resistivity (∼5 mΩ·cm), relative low thermal conductivity (∼2.0 W·K−1·m−1) and moderate Seebeck coefficient (∼120 μV K−1) at 300 K. Our work demonstrates the defect engineering, through delicate synthesis method, is an effective way to improve the thermoelectric property of ZrTe5.

中文翻译：

---

富含 Te 的 ZrTe 5+δ 多晶的电、磁传输和显着的热电性能

摘要 过渡金属五碲化物 ZrTe5 具有较高的热电功率因数，因此在低温制冷装置中具有潜在的应用前景，因此得到了广泛的研究。最近的研究表明，ZrTe5 的物理性质强烈依赖于 Te 浓度。在这里，我们通过直接固态反应合成了富含 Te 的 ZrTe5+δ 多晶，并系统地研究了电、磁传输和热电性能。温度相关电阻率和磁传输特性证实 ZrTe5+δ 是 p 型（空穴掺杂）半导体。此外，当 T 在 10–150 K 范围内时，塞贝克系数为正且随 T 线性增加，并饱和至 120 μV K-1。值得注意的是，获得了显着的品质因数 ZT（在 T = 300 K 时~0.037），