Zn-doped Fe 3 O 4 magnetic nanoparticles represented as Zn x Fe 3-x O 4 with different Zn contents of x varying from 0.0 to 1.0 were synthesized using a facile one-step solvothermal method. The Zn/Fe ratio in these particles could be accurately controlled using this facile synthesis technique. The ICP-OES and XRD measurements indicated that in the x range from 0 to 0.4 the doped Zn 2+ may replace the Fe 3+ at the A site and consequently the B-site Fe 2+ changed to Fe 3+ , while above 0.4 the Zn 2+ tends to replace the B-site Fe 2+ . The morphologies and size distributions of these samples characterized from the TEM showed that the nanoparticles appeared to aggregate into magnetic nanocrystal clusters with varying cluster sizes and different Zn doping contents. The magnetic measurement and Mossbauer spectra investigation revealed that the magnetic properties of the Zn x Fe 3-x O 4 would exhibit a sensitive dependence with the doped Zn variations. Most importantly, the heat capacity studies illuminated that, at low temperatures, the samples could have a ferromagnetic contribution with x = 0.0 and 0.2 and turn to an antiferromagnetic contribution with x = 0.5, 0.8, and 1.0.

Materials showing synergy of magnetic and dielectric transitions are promising candidates for future molecular devices. The challenge is how to realize synergy between spin and dielectric transitions with responses to external stimuli. Herein, we design a 2D spin crossover (SCO) complex, [Fe II (dpa)][(pzTp)Fe III -(CN) 3 ] 2 (1) (dpa = 1,2-bis(4-pyridyl)ethyne and pzTp = tetrakis(pyrazolyl)borate). The local structural changes about the Fe II ion were propagated to the whole crystal through the rigid bridging ligands (dpa), leading to elastic interactions to realize the abrupt SCO and rotational movements of polar apical pyrazolyl rings in the [(pzTp)Fe III (CN) 3 ] À units. Dielectric measurements confirmed a substantial dielectric change (Δɛ' = 2.3) upon the spin transition. This work provides a rational strategy to couple the spin transition and rotation of polar components, which is crucial for the synergetic switch of magnetism and dielectricity.

La-MOF shows excellent chemical stability and high fluorescence sensing. La-MOF electrode exhibits high specific capacity and good cycling stability.