| Description |
viii, 80 leaves : illustrations, photographs ; 29 cm |
| Summary |
"Pure, accepton and Al doped NdCrO₃ were prepared by an organo-metallic process. The crystal structure and lattice parameters were determined by x-ray diffraction. All compositions were orthorhombic Pbnm. Pellets were pressed from powders of each composition and sintered to high density in a reducing atmosphere. When a small amount of Fe was substituted for Cr, the powder could be sintered in air. Electrical conductivity for acceptor doped NdCrO₃ varied from about 1 (ohm cm)⁻¹ at room temperature to about 10 (ohm cm)⁻¹ at 900°C, about two orders of magnitude higher than the electrical conductivity of the undoped NdCrO₃. The activation energy for conduction was lowered by acceptor doping (from 0.18 to 0.08 ev). The thermal expansion coefficient of NdCrO₃ was 7.5 x 10⁻⁶/°C. Doped and Al substituted material had higher thermal expansion coefficients, with no crystallographic transitions being observed in any composition with thermal expansion measurements to 900°C"--Abstract, leaf ii. |
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