Illustration of fit of XRD pattern for samples (a) and (b) .
The variation of lattice parameters with Ni additions (a) of all stoichiometric samples and (b) nonstoichiometric specimens.
The high resistances (by approximately four to five orders) of specimens 2 and 4 with and 0.07Ni, respectively, represent specimens sintered and annealed in Ar showing extremely high resistance, compared to specimens 3 and 5 with the same Ni content but annealed in O.
Resistance with and without field and MR of various samples. (a) Resistance with and without Ni doping; note the high resistance of the undoped sample. (b) Resistance of specimen 8; note the transition to the FM condition. (c) Comparison of MR of various Ni-doped specimens; only specimen 8 shows a transition to FM condition.
The derivative of resistivity with temperature vs for undoped specimen. CO transition is indicated at with and without field. The activation energy is .
Magnetization of (a) measured in magnetic field and (b) measured at 230 K vs .
Magnetization of (a) measured in magnetic field 100 Oe and (b) measured at 10 K vs .
Magnetization of (a) vs at 100 Oe, (b) vs magnetic field at different temperatures, and (c) vs magnetic field at ambient and 10.6 kbar pressure at 10 K.
XRD of samples 3 and 8. No shift of peaks can be detected. Based on the XRD analysis, it was assumed that in both cases the O content is about the same at an average level of 2.975 (the chemical analysis of sample 8). The peak shift of to the right occurred in O treated samples.
Temperature dependences of EMR spectra: (a) undoped sample , . (b) Ni-doped sample , .
Temperature dependences of EMR spectra for two samples with the same Ni-doping level : low temperature region, (a) sample 3, and (c) sample 8, ; high temperature region, (b) sample 3, , dotted ellipses mark the additional low-field EMR signals, and (d) sample 8, .
Temperature dependences of doubly integrated EMR spectra intensities: blue open triangles—sample , black open stars—sample , and red circles—sample . All intensities are normalized to the intensity value taken at (PM region). The lines are guides for eyes.
Temperature dependences of EMR spectra parameters: (a) line widths and (b) resonance field (manganitelike line only). Blue open triangles—sample , black open stars—sample , and red circles—sample . The lines are guides for eyes.
Lattice parameters for various specimens.
Activation energies for conduction at and .
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