The discovery of 39 K superconductivity in MgB₂ and the recent observations of high-T _c superconductivity in the high-pressured hydrides motivate ones to search for new superconductors in the compounds containing H or B light element. In this article, we chose the heavier Ge to replace the Si in the ternary borides Mo₅SiB₂ with the Cr₅B₃ type tetragonal structure, a relative new group borosilicate superconductors, and prepared Mo₅GeB₂ polycrystalline sample. By the combination of resistivity, magnetization, and specific heat measurements and band calculations, we determine its superconducting parameters. It was found that Mo₅GeB₂ is a type II superconductor, with the critical temperature T _c = 5.4 K, and the Ginzburg–Landau (GL) parameter k _GL (0) = 4.2. The estimated electron-phonon coupling constant λ _ph (0.57) and the specific heat jump (1.33) demonstrate that Mo₅GeB₂ is a weak-coupling, single-gap phonon-mediated superconductor. Band calculations reveal that Mo₅GeB₂ has a similar density of state (DOS) near Fermi energy to that of Mo₅SiB₂ with the same T _c , but smaller than that Mo₅PB₂ with T _c = 9.2 K.

MgB ₂中39 K超导性的发现以及高压氢化物中高T _c超导性的最新发现促使人们在含H或B轻元素的化合物中寻找新的超导体。在本文中，我们选择了较重的Ge来用Cr ₅ B ₃型四方结构，相对较新的硼硅酸盐超导体代替三元硼化物Mo ₅ SiB _2中的Si ，并制备了Mo ₅ GeB ₂ 多晶样品。通过电阻率，磁化强度，比热测量和能带计算的组合，我们确定了它的超导参数。发现Mo ₅ GeB ₂是II型超导体，临界温度T _c = 5.4 K，Ginzburg-Landau（GL）参数k _GL（0）= 4.2。所估计的电子-声子耦合常数λ _ph值（0.57）和比热跳跃（1.33）表明，莫₅ GEB ₂是弱耦合，单间隙声子介导的超导体。能带计算显示Mo ₅ GeB ₂ 具有相同的T _c的Mo ₅ SiB ₂具有接近费米能量的态密度（DOS），但小于具有T _c = 9.2 K的Mo ₅ PB ₂。