HEAT-CAPACITY AND NEUTRON-DIFFRACTION OF LOW DOPED FE3-XZNXO4

We report on the heat capacity and neutron diffraction studies of Fe3- xZnxO4 (x<0.04) series. Adiabatic heat capacity measurements, performe d on single crystals, confirm our earlier observations that in the ran ge x<0.012 the Verwey transition is of first order, whereas for 0.012< x<0.035 the transition character changes to second order. nle change o f transition order is accompanied by the clear difference in heat capa city baselines below Verwey transition temperature T-v. The time-of-fl ight neutron diffraction data were collected at the High Resolution Fo wder Diffractometer in ISIS in the T range 4-240 K for two Fe3-xZnxO4 samples with x falling within first and second order regime. The compa rison of spectra for both samples shows that second order sample under goes much smaller structure change than that observed for first order sample what was suggested by our heat capacity measurements results.