In recent years, ferroelectric materials and thin films have attracted much attention and exhibited potential in many important applications such as dynamic random access memories (DRAMS), non-volatile ferroelectric random access memories micro-armours and infrared sensors. At present, the ferroelectric materials suitable for these devices are Pb(Zr,Ti)O3 (PZT) systems, SrBi2Ta2O9 (SBT) systems, Bi4Ti3O12 (BIT) systems and BaTiO3 (BT) systems that are studied with a great deal of interest.
In these ferroelectric materials, BaTi0.91(Hf0.5,Zr0.5)0.09O3 (BTHZ-9), one of the BT systems, which has several advantages such as an extremely low coercive field, a high remnant polarization, better mechanical strength and small deviation in composition, could have a strong potential application for ferroelectric thin film devices.
In previous reports, the remnant polarization (Pr) and coercive field (Ec) of these materials were determined to be 15 µC/cm2 and 0.65kV/cm respectively, showing a satisfactory piezoelectric property. Also, the BTHZ-9 was shown to have a quadratic characteristic in the strain as a function of electric field in AC field of above 1kV/cm, due to an extremely low coercive field and an excellent piezoelectric property.
Especially, the BTHZ-9 with rhombohedral phase at room temperature had a longer endurance against repetition of polarization reversal than that of the tetragonal. It may be due to its low coercive field, which is required for polarization reversal.
In addition, the BTHZ systems, lead and/or bismuth-free material, also present a great interest both for applications in the field of environmental protection and for fundamental studies. Therefore, the BTHZ system is expected to be one of the attractive materials suitable for ferroelectric thin film devices.
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Primary author: J. Thongrueng, K. Nishio, Y. Watanable, K. Nagata and T.Tsuchiya
Source: Abstracted from The Journal of the Australasian Ceramics Society, Vol. 37, No. 1, pp. 51-55 2001.
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