The effect of ZrO2 addition on the microstructure, morphology and pressure sensing behaviour of Pb(ZrxTi1-x)O3 ceramics was studied in five different compositions of ZrO2, namely x = 0.48, 0.50, 0.52, 0.54 and 0.56. The samples were prepared through the solid-state reaction method using high purity metal oxides powders. In order to control the PbO losses due to high temperature sintering, a novel approach were explored whereby the samples were sintered in Al2O3 environment. Structural investigation using X-ray diffraction (XRD) method revealed that all samples exhibited a tetragonal crystal structure. However the c/a lattice parameters ratios exhibited a decreasing trend as the ZrO2 content was increased, indicating that PZT crystals gradually evolved towards pseudocubic structure. SEM micrographs showed different morphology of each composition with the grain size varies in the range of 1.5 μm to 3.15 μm. The performance of pressure sensing behaviour showed that sample with composition x = 0.52 exhibited the best piezoelectric properties with high sensitivity. However, all samples failed to show good stability and repeatability due to slow recovery after severe lattice strain.
The aim of this research was to investigate the ability of organometallic titanium-PANi hybrid materials as gas sensor at room temperature. To form the hybrid materials, commercially available polyaniline (PANi) powder were directly added into organometallic titanium sols which was synthesized using the sol gel method. The composite films were prepared via spin coating technique followed by electrode deposition for sensors fabrication. Five different organometallic titanium:PANi ratios namely 1 wt% to 5 wt% of PANi were prepared for this experiment. For gas sensing test, all samples were exposed to ethanol vapour. The sensing mode is based on the variation in the electrical conductivity due to the
interaction between the gas molecules and the film. It was observed that the composite sensors required appropriate ratio to exhibit optimum sensing properties. This finding proved that the hybridization process is successful and offered much cheaper and easier method for fabrication of room temperature gas sensor.
Satu kajian bagi menentukan kesan suhu ke atas mikrostruktur dan kelakuan pengesanan tekanan seramik Na0.45Bi0.55TiO3 (NBT) sebagai bahan piezoelektrik bebas plumbum telah dilakukan. Seramik NBT disediakan secara tindak balas keadaan pepejal daripada campuran serbuk Na2CO3, Bi2O3 dan TiO2. Campuran serbuk disinter pada tiga suhu yang berlainan iaitu 1100°C, 1200°C dan 1300°C selama 12 jam. Selepas disinter, serbuk NBT dikisar dan dimampatkan menjadi pelet berdiameter 13 mm diikuti pemanasan selama 2 jam pada 700oC. Mikrostruktur dan morfologi sampel masing-masing dikaji dengan menggunakan XRD dan SEM. Sifat pengesanan tekanan NBT diuji dengan menggunakan kebuk tekanan pneumatik. Analisis pembelauan sinar-X menunjukkan semua sampel mengandungi lebih 70% NBT berstruktur rombohedral sebagai fasa utama dan bakinya merupakan fasa sekunder Bi2Ti2O7 (BTO). Kenaikan suhu sinteran didapati meningkatkan kandungan fasa NBT di dalam sampel. Mikrograf SEM menunjukkan saiz butiran dan ketumpatan sampel semakin meningkat dengan pertambahan suhu sinteran. Ujian sifat pengesanan tekanan menunjukkan kesemua sampel memberi sambutan apabila voltan pemula diberikan. Berdasarkan faktor ketumpatan, kestabilan dan kebolehulangan sifat pengesanan tekanan, seramik NBT yang disinter pada suhu 1200oC merupakan seramik yang terbaik dan berpotensi digunakan sebagai sensor tekanan.
The influence of PANI additions on methanol sensing properties of ZnO thin films at room temperature had been investigated. Commercial polyaniline powder (PANI) was mixed into 3 mL ZnO solution in five different weight percentages namely 1.25, 2.50, 3.75, 5.00 and 6.25% to obtain ZnO/PANI composite solutions. These solutions were spin coated onto glass substrate to form thin films. Microstructural studies by FESEM indicated that ZnO/PANI films showed porous structures with nanosize grains. The thickness of the film increased from 55 to 256 nm, proportionate to increment of PANI. The presence of 2 adsorption peaks at ~310 nm and ~610 nm in UV-Vis spectrum proved that addition of PANI has modified the adsorption peak of ZnO film. Methanol vapour detection showed that addition of PANI into ZnO dramatically improved the sensing properties of the sensor. The sensors also exhibited good repeatability and reversibility. Sensor with the amount of PANI of 3.75 wt% exhibited the highest sensitivity with response and recovery time was about 10 and 80 s, respectively. The possible sensing mechanism of the sensor was also discussed in this article.