  We study the quantum phases of one-dimensional Bose-Fermi mixtures in optical
lattices. Assuming repulsive interparticle interactions, equal mass, and unit
total filling, we calculate the ground-state phase diagram by means of both
Tomonaga-Luttinger liquid theory and time-evolving block decimation method. We
demonstrate the existence of a counterflow superfluid (CFSF) phase of polaron
pairs, which are composite particles consisting of two fermions and two bosonic
holes, in a broad range of the parameter space. We find that this phase
naturally emerges in $^{174}$Yb-$^{173}$Yb mixtures, realized in recent
experiments, at low temperatures.
