Heterogeneous composites with coexisting spin-crossover and long-range magnetic ordering

A facile precipitation transformation method at room temperature was employed to efficiently prepare the FeTrz@PB heterostructural composites containing both [Fe(Htrz)(2)(trz)](BF4) (Htrz=1H-1,2,4-triazole) and Prussian blue KFeIII[Fe-II(CN)(6)] with the coexistence of spin crossover (SCO) and long-range magnetic ordering (LRMO). The controllable growth process of these heterostructural composites was fully characterized by scanning electron microscope, transmission electron microscope, powder X-ray diffraction, FTIR, X-ray photoelectron spectroscopy, energy-dispersion X-ray analysis, thermogravimetric analysis, and magnetic studies. The size of the PB particles and the appearance of FeTrz@PB can be tuned by controlling the reaction time. Increasing the reaction time leads to the increased ratio of the PB phase in the FeTrz@PB composites. Remarkably, magnetic studies on FeTrz@PB revealed the coexistence of SCO above room temperature (362-392 K) and LRMO at low temperatures (ca. 5.6 K). The high spin (HS) fraction and ZFC/FC intensity gradually increased with the growth time, while the heights of the hysteresis loops decreased gradually.