Sc5Rh6Sn18 with a cage-type quasiskutterudite crystal lattice and type II superconductivity, with superconducting transition temperature Tc = 4.99 K, was investigated under hydrostatic high-pressure (HP) using electrical transport, synchrotron X-ray diffraction (XRD) and Raman spectroscopy. Our data show that HP enhance the metallic nature and Tc of the system. Tc is found to show a continuous increase reaching to 5.24 K at 2.5 GPa. Athough the system is metallic in nature, Raman spectroscopy investigations at ambient pressure revealed the presence of three weak modes at 165.97, 219.86 and 230.35 cm-1, mostly related to the rattling atom Sc. The HP-XRD data revealed that the cage structure was stable without any structural phase transition up to ~7 GPa. The lattice parameters and volume exhibited a smooth decrease without any anomalies as a function of pressure in this pressure range. In particular, a second order Birch-Murnaghan equation of state can describe the pressure dependence of the unit cell volume well, yielding a bulk modulus of ~ 97 GPa. HP Raman investigations revealed a linear shift of all the three Raman modes to higher wavenumbers with increasing pressure up to ~8 GPa. As the pressure enhances the bond overlap, thus inducing more electronic charges into the system, HP-XRD and Raman results may indciate the possibility of obtaining higher Tc with increasing pressures in this pressure range.

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Herein, the transport properties of Sr3Rh4Sn13, Ca3Rh4Sn13, and La3Rh4Sn13 quasi‐skutterudites are studied which show sharp superconducting (SC) transition with a transition temperature, Tc, ≈4.7, ≈8, and ≈2 K, respectively. In Sr3Rh4Sn13 system, electrical resistivity data evidence a pronounced anomaly before the SC transition at T* ≈136 K. No such anomalies are observed in the other two systems. Detailed structural investigations using synchrotron single‐crystal and powder diffraction reveal that these systems have cubic structure with Sr3Rh4Sn13 and Ca3Rh4Sn13 being in PmPmn space group setting. The La3Rh4Sn13 shows additional weak reflections which can be described by I4132 space group with almost doubled lattice parameters compared to Sr3Rh4Sn13 system. All three systems are found to show weak Raman modes below 240 cm−1. High‐pressure (HP) resistivity measurements up to 3.2‐GPa on Sr3Rh4Sn13 system reveal that the T* anomaly decreases almost linearly with pressure whereas the superconducting Tc almost linearly increases. HP structural investigations on Sr3Rh4Sn13 compound reveal that the structure remains in the cubic Pmn phase in 0–10 GPa range, following well a second‐order Birch–Murnaghan equation of state. The results provide interesting similarities and differences in the chemical and physical pressure effects on the quasi‐skutterudite X3Rh4Sn13 (x =  Sr, Ca, and La) system.

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