Nonmagnetic Phase Transition in La${}_3$TiSb${}_5$ Observed in ${}^{121}$Sb Nuclear Quadrupole Resonance

We measured the electrical resistivity and the ${}^{121}$Sb nuclear quadrupole resonance (NQR) spectra of La${}_3$TiSb${}_5$, which is a nonmagnetic reference system for a locally noncentrosymmetric antiferromagnet Ce${}_3$TiSb${}_5$, in order to determine its physical properties. The resistivity exhibited a hump anomaly at 120 K, suggesting a phase transition. The NQR spectra split below 110 K, whereas the nuclear spin-lattice relaxation exhibited no anomalies. These results can be explained by the incommensurate charge-density-wave (CDW) transition. This finding suggests the importance of quasi-one-dimensional characteristics and CDW instability in these systems.