Abstract:
Solid derivatives Ni$_{1-x}$Li$_x$O $\cdot$ (0 $\le x\le$ 0.1) were produced by the thermolysis of formate precursor complexes Ni$_{1-x}$Li$_x$(HCOO)$_2$$\cdot$ 2H$_2$O at 700$^\circ$C in air. There are two regions of single phase compositions banded by 4 at.% Li one. X-ray structure is Face Centered Cubic (FCC, Fm$\bar3$m) for both regions. Experimental molar mass was calculated using a pycnometric density and X-ray data results, taking into consideration chemical composition, determined by isotope method. Structural defects are discussed and application of Raman spectroscopy is pointed to be necessary. Two laser sources (633 and 532 nm) were applied in a temperature region from room temperature up to 700$^\circ$C. True Stokes lines are distinguished from other Raman lines and they are referred to photoluminescence. After consideration both X-ray and Raman spectroscopy results we concluded that materials structure is fluoride-like (CaF$_2$) with high defect concentration. This structure is stable for compositions with Li concentration more than 4%. Derivatives with Li concentration less than 4% are undergo the transition into the rock salt structure during a high temperature treatment. In contrast with pure cubic NiO its derivatives Ni(Li)O have orthorhombic structure at room temperature.
Fulltext:
PDF file (804 kB)