Effect of Al2O3 on the morphological and gas sensing properties of SnO2 pellets

Alumina mixed tin oxide (SnO
₂
: Al
₂
O
₃
) powders were obtained by employing chemical and physical synthesis methods. The powders were prepared from tin chloride as Sn source, urea (R1) and ammonia (R2) as precipitant agents. The resultant SnO
₂
powders are milled in a planetary ball mill. Finally, Al
₂
O
₃
was added to the milled SnO
₂
powders manually in different ratios, and then pressed to manufacture thin pellets. After several experimental trials, stable SnO
₂
: Al
₂
O
₃
pellets were formed. Later, silver contacts were manufactured on the pellets surface by the thermal evaporation technique. The effect of Al
₂
O
₃
ratio and precipitation agent on the morphological properties are presented in this work. The morphological study was developed by using Scanning Electron Microscopy (SEM). Additionally, the sensing properties of these pellets as a function of the SnO
₂
: Al
₂
O
₃
ratio were measured in carbon monoxide (CO) atmosphere and a hypothesis model for an arrangement of SnO
₂
and Al
₂
O
₃
particles on the pellets surface for different mixing ratios is proposed.