  PrOFe0.9Co0.1As is known to be a superconductor with a TC of ~14 K. In an
attempt to induce charge transfer and also induce chemical pressure between the
FeAs and PrO layers we have synthesized for the first time oxypnictides of the
type PrOFe0.9Co0.1As1-xPx (P doping at As sites). All the compounds crystallize
in the tetragonal ZrCuSiAs type structure (space group = P4/nmm). The lattice
parameters (a and c) decrease as expected on substitution of smaller
phosphorous at the arsenic site in PrOFe0.9Co0.1As and a decrease in TC was
observed on substitution of P ions at a low rate of 0.13K/at. % of P for x >
0.1. The irreversibility field (Hirr) and critical current density (JC),
obtained using the AC susceptibility measurements was found to decrease
monotonically with increasing 'P' concentration. 'Hirr' is observed to be much
smaller than HC2, pointing to a very low pinning energy. The pinning potential
obtained using both in-field transport and AC susceptibility measurements
indicate a low value of ~40 meV and show no significant variation with P
substitution.
