A one-step flash microwave synthesis of complex high dielectric nanoperovskites applied to microwave gas sensing of ammonia

Abstract

Ammonia is a major air pollutant whose industrial use is skyrocketing. It is therefore necessary to be able to selectively detect leaks of this pollutant into the atmosphere. This work proposes a microwave gas sensor for detecting ammonia in the 100–400 ppm range at room temperature and reflects on the sensitive material deposited on the sensor. Historically, the most widely used sensitive material for this microwave gas sensor has been TiO₂-P25, which is compared here with three different high dielectric nanoperovskites (BaTiO₃ (BT), Ba_0.6Sr_0.4TiO₃ (BST), and SrTiO₃ (ST)) synthesized using an innovative microwave process. These three compounds were characterized by XRD analysis, BET method and TEM before their use as a sensitive material on the microwave gas sensor. ST has been shown to be the best compound for detecting ammonia in the air (respose time of 100 seconds and recovery time of 1300 seconds). While BT can be used as a threshold device, the responses of BST and ST vary slightly with the amount of ammonia. The detection capacity of ST has been proven to be far superior to that of the reference titanium oxide.