Synthesis of the $Ba_{1-x}Na_{x}Ti_{2}Sb_{2}O_{z}$ system with x= 0.00, 0.15, 0.25 and 1.00, by solid-state reaction method

The present study of this system is a superconductor without Cu-O planes using solid-state reaction synthesis with slow cooling. The samples used were considered with an initial weight of 1 g after the losses to $CO_2$ owing to the reaction. Used ThermoGravimetric Analysis, we determined the reaction temperatures. The samples were characterized using X-Ray powder Diffraction and Scanning Electron Microscopy, expose the formation to secondary and ternary compounds, also the changes in the oxidation numbers of some initial reagents in each reaction temperature. A new contribution of this work is obtain the conditions of the monophase, $NaSbO_3$ with PDF 42-0223 in x=1.00 at 550 $^\circ$C/62 h 50 min. not reported in the literature.We observed in XRD an amorphous phase at the same temperature, which not observed at 700 $^\circ$C. By SEM we distinguish that the amorphous phase continue exist, but using XRD is not perceptible because it is in less proportion and showing a grains grow in the samples. We determine the thermodynamic conditions to obtain a $NaSbO_3$ monophase at x= 1.00, different that was be reported. This system exhibit an amorphous phase between 550 - 700 $^\circ$C. To optimize the connection between polycrystals grain pellets were manufactured at 800 $^\circ$C.