Sains Malaysiana 39(4)(2010): 621–626

Kelakuan Pengesanan Tekanan Bagi Seramik Natrium Bismut Titanat

(Pressure Sensing Behaviour of Sodium Bismuth Titanate Ceramics)

Mohammad Hafizuddin Haji Jumali*, Mohd Riduan Mt Said, Ngoi Yung Wee & Muhammad Yahaya

Pusat Pengajian Fizik Gunaan, Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E., Malaysia

Muhammad Mat Salleh

Institut Kejuruteraan Mikro dan Nanoelektronik (IMEN)

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E., Malaysia

Received: 16 September 2009 / Accepted: 5 January 2010

ABSTRAK

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 ^oC, 1200 ^oC dan 130 0^oC selama 12 jam. Selepas disinter, serbuk NBT dikisar dan dimampatkan menjadi pelet berdiameter 13 mm diikuti pemanasan selama 2 jam pada 700 oC. 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.

Kata kunci: Natrium bismut titanat; perovskit; piezoelektrik; sensor tekanan

ABSTRACT

A study to determine the microstructure and pressure sensing behaviour of Na0.45Bi0.55TiO3 (NBT) as lead-free ceramics has been conducted. NBT ceramics were prepared using the solid state reaction technique from stoichiometric mixture of Na2CO3, Bi2O3 and TiO2 powders. The mixture was sintered at three different temperatures namely 1100 oC, 1200 oC, 1300 oC for 12 hours. After sintering, the NBT powders were ground and pressed into pellet with 13 mm diameter and subsequently heated at 700 oC for 2 hours. Microstructure and morphology of the samples were determined using XRD and SEM, respectively. Customized pressure chamber using pneumatic load was employed for pressure sensing behaviour of the samples. X-ray diffraction analysis revealed that all samples consist of more than 70% of polycrystalline, rhombohedral NBT phase, with bismuth titanate, Bi2Ti2O7 (BTO) as the secondary phase. The increment in sintering temperature has resulted in the formation of higher NBT content in the sample. SEM micrographs showed that grain size and bulk density of the samples increased with the increment of sintering temperature. Pressure sensing test showed that all samples were responsive toward pressure variations only when initial voltage was applied to the ceramics. Based on density, stability and repeatability in pressure sensing behavior, NBT ceramic sintered at 1200 oC was the best ceramic with great potential as lead free pressure sensing material.

Keyword: Piezoelectric; pressure sensor; perovskite; sodium bismuth titanate

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*Corresponding author; email: hafizhj@ukm.my