Metal-insulator transition in NdNi1-xFexO3-delta

We report a systematic study of the electrical resistivity, electron tunnel ing, thermoelectric power and magnetoresistance of NdNi1-xFexO3-delta (x = 0.0-0.4). NdNiO3-delta undergoes an incomplete M-I transition at TM-I appro ximate to 200K. When 10% of Ni is replaced by Fe some unexpected features a re observed in the electrical resistivity; instead of becoming more resisti ve the material becomes more conducting. For 20% doping of Fe the material becomes highly resistive but is still metallic. For higher dopings of Fe th e sample becomes fully insulating. The sample with x = 0.3 shows variable r ange hopping while the sample with x = 0.4 exhibits activated conduction. ( C) 1999 Elsevier Science Ltd. All rights reserved.