Fabrication of Nano-LaCrO₃ Receptor by Polymeric Precursor Method and Its Impedancemetric NO_x Sensing Properties

Abstract

LaCrO3 was prepared by using the polymeric precursor method for use as a receptor material and its NOx sensing characteristics were investigated. Nano-LaCrO3 powders were synthesized at the optimum compositions of the mole ratio of [La-, Cr-source]:[EG]:[AcAc] = [a, a]:[160 a]:[8 a] with 1 wt% polyvinylpyrrolidone (PVP) using ethylene glycol (EG) as a solvent, acetyl acetone (AcAc) as a chelating agent, and PVP as a polymer additive. The thermal decomposition behavior, crystal structure, morphology, and particle sizes of nano powders were characterized by a thermal analysis (TG-DTA), X-ray diffraction (XRD), a field emission scanning electron microscopy (FE-SEM), and a particle size analyzer, respectively LaCrO3 powders were mainly orthorhombic in structure and the primary particle size was 30 nm according to the XRD results. All solid-state compact impedancemetric-type sensor devices composed of Li1.5Al0.5Ti1.5(PO4)3 (LATP) as a transducer and a perovskite-type LaCrO3 nano powder as a receptor, have been investigated for their ability to detect NOx (NO and NO2) in the range of 1-250 ppm at 400 degrees C. The sensor device showed high gas sensitivities at NO gas, but relatively low gas sensitivities for NO2 gas.