The main objective of this work was to study the superconducting properties of
RE
BCO films with a mixture of rare-earth (
RE
) ions with large difference in ion size, in particular Sm
3+
and Yb
3+
. These Yb
1−
x
Sm
x
Ba
2
Cu
3
O
7−
δ
films have been successfully prepared for the first time by chemical solution deposition following the extremely low-fluorine route, which allows reducing the fluorine content by 93% with respect to standard full trifluoroacetate solutions. On the one hand, critical temperature
T
c
remains stable at approximately 90 K with Sm content up to
x
= 0.5 where
T
c
starts to increase towards the values of pure SmBCO films of approximately 95 K. On the other hand, the critical current densities
J
c
of the pure SmBCO films are the largest at 77 K, where the influence of a higher
T
c
is very relevant, while at lower temperatures and low fields, the mixed films reach larger values. This demonstrates that mixing rare-earth elements
RE
in
RE
Ba
2
Cu
3
O
7−
δ
causes a change in the pinning properties of the films and reveals the importance of selecting adequate
RE
BCO compounds according to the temperature and magnetic field region of a desired application.
Rapid Pyrolysis of SmBa2Cu3O7-δ Films in CSD-MOD Using Extremely-Low-Fluorine Solutions