We report on the structural and superconducting properties of the intermetallic compound BaGaGe. We find that this material undergoes a structural second-order phase transition from a distorted ${\mathrm{AlB}}_2$-type structure [1H, $a=4.3254\left(2\right)$ Å, $c=5.1078\left(3\right)$ Å, $P6/mmm$] into a ${\mathrm{CaIn}}_2$-type structure [2H, $a=4.3087\left(3\right)$ Å, $c=10.2117\left(6\right)$ Å, $P{6}_3/mmc$] at a transition temperature of $T_{\mathrm{S}}=253\mathrm{K}$. We find that the structural phase transition corresponds to a coherent buckling of the honeycomb layers, which we can interpret as a disorder-to-order transition of the atoms located within this layer. We show that the 2H-BaGaGe phase becomes superconducting at a critical temperature of $T_{\mathrm{c}}=2.1\mathrm{K}$. The bulk nature of the superconductivity in 2H-BaGaGe is confirmed by means of specific-heat measurements, where we determine a value of $\mathrm{\Delta }C/\gamma T_{\mathrm{c}}=1.59$, which is close to the expected BCS value in the weak-coupling limit.

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• Superconductivity
• Crystal structures
• Magnetization measurements
• Resistivity measurements
• Specific heat measurements
• X-ray diffraction