  Within perturbative QCD approach based on $k_T$ factorization, we analyze the
scalar mesons $f_0(980)$ and $f_0(1500)$ productions in B decays. By
identifying $f_0(980)$ as the composition of $\bar ss$ and $\bar nn=(\bar
uu+\bar dd)/\sqrt2$, we calculate the exclusive decays $B\to f_0(980) K$. We
find that the non-factorization $f_0$-emission diagrams can give larger
contribution to the branching ratio, than the previous PQCD calculation. Our
new results can explain the current experimental data well. Under the
assumption of quarkonium dominance, we study the branching ratio of decays
$B\to f_0(1500) K$. The results show that in the two-quark picture of $f_0$
meson the contribution from $\bar s s$ component is at the similar size as that
from the $\bar n n$ component. Comparing with the data, our results show the
preference of $f_0(1500)$ as a member of the ground state of scalar $\bar qq$
nonet. Similar results can also apply to $f_0(1370)$ and $f_0(1710)$, if these
mesons are dominated by the quarkonium content. With more experimental data in
future, these studies will help us understand the intrinsic characters of these
scalar mesons.
