Vacancy-driven magnetocaloric effect in Prussian blue analogues.

We experimentally show that the magnetocaloric properties of molecule-based Prussian blue analogues can be adjusted by controlling during the synthesis the amount of intrinsic vacancies. For CsxNi4II[Cr-III(CN)(6)]((8+x)/3), we find indeed that the ferromagnetic phase transition induces significantly large magnetic entropy changes, whose maxima shift from similar to 68 to similar to 95K by varying the number of [Cr-III(CN)(6)](3-) vacancies, offering a unique tunability of the magnetocaloric effect in this complex. (c) 2007 Elsevier B.V. All rights reserved.