  A series of polycrystalline SmFeAs1-xOx bulks was prepared to systematically
investigate the influence of sample density on flux pinning properties.
Different sample densities were achieved by controlling the pelletizing
pressure. The superconducting volume fraction, the critical current densities
Jcm and the flux pinning force densities Fp were estimated from the
magnetization measurements. Experimental results manifest that: (1) the
superconducting volume fraction decreases with the decreasing of sample
density. (2) The Jcm values have the similar trend except for the sample with
very high density may due to different connectivity and pinning mechanism.
Moreover, The Jcm(B) curve develops a peak effect at approximately the same
field at which the high-density sample shows a kink. (3) The Fp(B) curve of the
high-density sample shows a low-field peak and a high-field peak at several
temperatures, which can be explained by improved intergranular current, while
only one peak can be observed in Fp(B) of the low-density samples. Based on the
scaling behaviour of flux pinning force densities, the main intragranular
pinning is normal point pinning.
