Effect of Zr Doping on the Magnetic and Phase Transition Properties of VO₂ Powder

In this work, V_1-xZr_xO₂ powder (x = 0, 0.01, 0.02, 0.04) was synthesized by two step hydrothermal method. The micro-topography, magnetic and phase transition properties have been investigated using various measurement techniques. All prepared V_1-xZr_xO₂ powder samples exhibit monoclinic structure at room temperature. With the Zr⁴⁺ ions doping concentration increased, the shapes of VO₂ particles change from spherical to rectangular slice. Besides, the saturation magnetic moment of the samples decrease with the increase of doped Zr⁴⁺ ions concentration, while their phase transition temperature increase gradually with Zr ions doping at a rate of around 2 °C/at% on average. We investigated the Zr doping effects on V-V dimers and confirmed the role of V-V dimers in phase transition. We speculate that more V-V dimers form with Zr doping by magnetic measurements, which result in the monoclinic phase of Zr-doped VO₂ sample is more stable than rutile phase. Therefore the phase transition temperature is elevated by Zr doping in our experiment. We further consider that the VO₂ phase transition should be ascribed to Peierls transition caused by the changing of V-V dimers.