A study on the role of surfactant in the synthesis of cerate-zirconate ceramic powder / Nurul Asyikin Mazlan

In this study, the powder of BaCe0.54Zr0.36Y0.1O2.95 (BCZY) was synthesized via a modified sol-gel process assisted with a surfactant. Three different classes of surfactants were used which are; non-ionic (polyoxyethylene (10) oleyl ether, Brij97, polyoxyethyleneoctyl phenyl ether, Triton X-100, polyethylene glycol, PEG6000 and polyoxyethylene (20) sorbitan monooleate, Tween80), cationic (dimethyl dioctadecyl ammonium chloride, DiDAC, hexadecyltrimethylammonium bromide, HTAB and benzalkonium chloride, BKC) and anionic (aluminium lauryl sulfate, ALS and sodium dodecyl sulfate, SDS). The prepared samples were characterized using Thermogravimetric Analyzer (TGA), Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Diffractometer (XRD) and Scanning Electron Microscopy/Energy Dispersive X-ray (SEM/EDX). TGA results clearly showed that all samples prepared using surfactant exhibits lower thermal decomposition temperature (Ttd< 800 °C) compared to control sample (Ttd> 900 °C). The attachment of surfactant molecules onto the BCZY particle surface was confirmed by the presence of stretching band at ~2900 – 2800 cmˉ1 in the FTIR spectrum. In addition, the presence or absence of carbonate compound is proven by FTIR results with the appearance of the stretching band at ~1400 cmˉ1 and for metal-oxide (M-O) bond at 700 ̶ 400 cmˉ1 after the heating treatment. XRD results for the sample prepared with Brij97, Triton X-100 and DiDAC successfully formed single perovskite phase of BCZY at T= 1100 ºC. However, samples prepared with other surfactants consist of a mixture of secondary phases such as BaCO3, BaCeO3, BaZrO3, (Ce,Zr)O2, ZrO2 and CeO2 even after calcined at T= 1100 ºC. In addition, the lowest synthesizing temperature obtained for the formation of single BCZY perovskite phase was at T= 950 °C using Brij97 as a surfactant which lower than the control sample (T= 1100 °C). This might due to the presence of steric hindrance and repulsive forces between the chelating agent and Brij97 which could assist the formation of BCZY ceramic at a lower temperature. SEM analysis also revealed that the employment of Brij97, Triton X-100 and DiDAC produced homogeneous and fewer agglomerate particles with particle size ranging from 20 nm to 100 nm. The SEM micrograph showed all samples prepared with cationic surfactants exhibited cubic particles due to its hydrophilic head charges indicate that surfactant also affects the morphology of the final product. As a conclusion, the employment of surfactant in a modified sol-gel method able to reduce the synthesizing temperature of BCZY ceramic powder as well as its particle size. Therefore, a study on the behavior of surfactant on cerate-zirconate ceramic powder may contribute to a significant new knowledge in the synthesis of BCZY powder at a relatively lower temperature than a conventional sol-gel method.