SYNTHESIS AND CHARACTERIZATION OF LEADFREE PIEZOELECTRIC (K0.5Na0.5) NbO3 PRODUCED WITH IMPROVED CALCINATION TEMPERATURE

Potassium sodium niobate (KNN) is one of the lead free piezoelectric material that catch the attention of researchers and also those in the industrial field because of its stable piezoelectric responses and environmental friendly composition. The recent development of KNN shows that many methods have been used to synthesize the KNN but the stoichiometric Ka0.5Na0.5NbO3 composition is extremely difficult to consolidate. One of the ways to overcome the problem is to precisely pre-calcine and use milling process for proper homogenization followed by natural sintering process. In this paper, attempt has been made to synthesize the KNN produced at 750 oC calcination temperature. The results of 1060oC sintering temperature for 2 hours show a good composition of KNN with orthorhombic crystal structure where the final sintered pellet can reach to a relative density up to 87.13 %

Scienceploration 2023

The Scienceploration Camp is an initiative of the Centre for Pre-University Studies, UNIMAS (PPPU), which aims to increase the interest in science among secondary school students. It is also an effort taken by PPPU towards the achievement of Sustainable Development Goals 4 in providing equal quality education and promoting lifelong learning opportunities for all. On top of that, this camp supports Sarawak’s Digital Economy Strategy in nurturing an integrated ecosystem to foster inclusive digital society, by building the right foundations to grow our local digital economy

Single Step Growth of Vertically Oriented Zinc Oxide Nanowire Using Thermal Evaporation

Commonly, the synthesis of ZnO nanowires involves the use of metal catalyst via a nondirect step growth which contribute to the contamination on the final product. Thus, in this work we synthesized catalyst-free ZnO nanowires using a direct or single step growth of nanowires. Thermal evaporation method is used to synthesize ZnO nanowires on bare glass substrates with different distances between Zn powder and the substrates; on-top (1.2 cm), 16 cm and 18 cm. Field Emission Scanning Electron Microscopy images showed a vertically well-aligned with high density of ZnO nanowires were successfully synthesized via self-seeding process and the longest nanowires were produced at the shortest distance. Energy Dispersive X-ray and X-Ray Diffraction analyses confirmed that high purity of ZnO nanowires were obtained and ZnO (002) strongest and sharp peak was observed, indicating preferentially grown ZnO nanowires along the c-axis perpendicular to the substrates and leading towards single crystal structure. Four peaks were observed in visible range from Photoluminescence spectra (PL) which related to fundamental defects with the highest peak at 3.04 eV. The on-top sample with distance 1.2 cm from Zn powder has the lowest transmittance due to the high thickness of ZnO nanowires. The range of energy band gap for ZnO nanowires obtained from the extrapolation graph is in agreement with PL highest peak approximately 3.00 eV. Therefore, this direct or single step deposition method is of great interest since it has successfully produced ZnO nanowires with significant characteristics without employing the non-direct step growth

Influence of double calcination-milling route on the structural and microstructural properties of lead-free K0.5Na0.5NbO3 (KNN) ceramics.

Potassium sodium niobate (KNN) has always beenone of the most potential candidates to replace lead-based piezoelectric ceramics due to its strong piezoelectric properties and environmentally friendly composition. A strong piezoelectric property is constantly influenced by the sample's densification as well as its microstructural characteristics. One of the current main issues with this KNN lead-free piezoelectric material is the difficulty in creating high-density samples by conventional preparation and sintering. Thus, KNN lead-free ceramics were synthesised using an improved solid-state method by introducing the double calcination-milling route to this process. The outcome demonstrates that, despite the presence of additional KNN secondary phases, the double calcination-milling approach contributed to the early creation of the KNN phase. When sintered pellets are subjectedto adouble calcination milling process, the XRD pattern revealed that the main peaks of the sample are indexed to orthorhombic K0.5Na0.5NbO3.The double calcination KNN pellet havea relative density of 90% densificationwhich is slightly higher than that of single calcination KNN pellet which shows 88% densificatio