Synthesis of NdAlO3 with good microwave dielectric properties by stearic acid method

Abstract

In this study, NdAlO3 with perovskite structure was synthesized by the stearic acid method at relatively low temperature. The structural characteristics of the as-synthesized product were identified by TG–DSC, XRD, FT–IR, SEM, and TEM techniques. Using the powders as starting materials, NdAlO3 bulk microwave ceramics were prepared, and the corresponding densification process, microstructural and dielectric properties were studied. The XRD and FI–IR results confirmed that single phase NdAlO3 could be prepared at low temperature by the stearic acid method. A unique two-dimensional platelike morphology with an unevenly dispersed bubble shape structure was observed in the calcined powder. However, the TEM result revealed that the powder calcined at 800 °C had a good dispersity accompanied with narrow particle size distribution within a range of 20–35 nm. The average particle size of 27.3 nm was in accordance with that calculated from the XRD data. Using the powder calcined at 800 °C as raw materials, the as-obtained NdAlO3 ceramics sintered at 1500 °C for 4 h possessed the highest density and favorable combined microwave dielectric properties (i.e., εr = 23.02, Q × f = 65320 GHz, and τf = −32.4 ppm/°C). The present work developed a fast, energy-efficient approach to synthesize NdAlO3 powder used as promising raw materials of microwave dielectric ceramics.