Is Pr_{1-x}Ca_xMnO_3 a ferroelectric of new mechanism?
  A new type of charge-ordering pattern for Pr1-xCaxMnO3: a hybridization of site- and bond-centred ordering (SBCO) was proposed by Efremov et al.. It was believed this discovery opened a new route to magnetic ferroelectrics. Here we argue that the possible ferroelectric of Pr1-xCaxMnO3 also originates from the cation displacement, similar to prototypical ferroelectric system. 
Shuai Dong and J.-M. Liu