  We have sympathetically cooled and crystallized ${}^{113}\mathrm{{Cd}}^{+}$
ions with laser-cooled ${}^{40}\mathrm{{Ca}}^{+}$ ions, and directly observed
the complete large bicrystal structure in a linear Paul trap. The large
two-component crystal contains up to $3.5\times10^3$ ${}^{40}\mathrm{{Ca}}^{+}$
ions and $6.8\times10^3$ ${}^{113}\mathrm{{Cd}}^{+}$ ions. The temperature of
the crystallized ${}^{113}\mathrm{{Cd}}^{+}$ ions was measured to be as low as
41 mK with a large mass ratio. Moreover, we have studied several properties and
structures of the ultracold sample. The factors affecting the sympathetic
cooling effect were studied, including the electrical parameters and the number
ratio between laser-cooled ions and sympathetically-cooled ions. The results of
this paper enrich the experimental research of large two-component ion
crystals, and the ultracold sample of ${}^{113}\mathrm{{Cd}}^{+}$ ions makes it
possible to further improve the accuracy of the cadmium-ion microwave frequency
standard.
