  The Kagome material $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ ($A$ = K, Rb, Cs) with
geometry frustration hosts non-trivial topological electronic structures,
electronic nematicity, charge density wave (CDW) and superconductivity,
providing an ideal platform to study the interplay between these phases.
Specifically, in pressurized- or substituted-${\mathrm{CsV}}_3{\mathrm{Sb}}_5$,
the relationship between CDW and superconductivity is unusual and remains to be
fully understood. Recently, coexisting and competing 2 $\times$ 2 $\times$ 4
and 2 $\times$ 2 $\times$ 2 CDW phases were discovered in
${\mathrm{CsV}}_3{\mathrm{Sb}}_5$. To investigate the evolution of the CDW
phases with the substitution of V atoms, we performed x-ray diffraction (XRD)
experiments on
${\mathrm{Cs(V}}_{1-x}{\mathrm{Ta}}_{x}{\mathrm{)}}_3{\mathrm{Sb}}_5$ and
${\mathrm{Cs(V}}_{1-x}{\mathrm{Nb}}_{x}{\mathrm{)}}_3{\mathrm{Sb}}_5$. Our
results indicate that in all substituted samples, the discrete CDW reflection
points in pristine ${\mathrm{CsV}}_3{\mathrm{Sb}}_5$ change to rod-like
structures along the $c^\star$ direction. This suggests that the long-ranged
three-dimensional CDW becomes quasi-two-dimensional by the substitution of V by
Ta/Nb. Moreover, our temperature-dependent measurements show that there is no
hysteresis behavior of CDW signals, indicating that the 2 $\times$ 2 $\times$ 4
CDW phase is easily suppressed by even a slight substitution of V with Nb/Ta.
These findings uncover the CDW evolution upon substitution of V atoms in
CsV$_3$Sb$_5$, providing insights into the microscopic mechanism of CDW and
helping to understand the interplay between intertwined phases and
superconductivity.
