Chemical Pressure effect at the boundary of Mott insulator and itinerant   electron limit of Spinel Vanadates
  The chemical pressure effect on the structural, transport, magnetic and electronic properties (by measuring X-ray photoemission spectroscopy) of ZnV2O4 has been investigated by doping Mn and Co on the Zinc site of ZnV2O4. With Mn doping the V-V distance increases and with Co doping it decreases. The resistivity and thermoelectric power data indicate that as the V-V distance decreases the system moves towards Quantum Phase Transition. The transport data also indicate that the conduction is due to the small polaron hopping. The chemical pressure shows the non-monotonous behaviour of charge gap and activation energy. The XPS study also supports the observation that with decrease of the V-V separation the system moves towards Quantum Phase Transition. On the other hand when Ti is doped on the V-site of ZnV2O4 the metal-metal distance decreases and at the same time the TN also increases. 
P. Shahi, A. Kumar, Rahul Singh, Ripandeep Singh, P.U. Sastry, A. Das,   Amish G. Joshi, A. K. Ghosh, A. Banerjee and Sandip...
cond-mat.str-el cond-mat.mtrl-sci