Publication Date:
2014-07-25
Description:
Three composition groups in the BaTiO 3 – CaTiO 3 – BaHfO 3 ternary system, (1 − x ) Ba ( Hf y Ti 1− y ) O 3 – x ( Ba 1− z Ca z ) TiO 3 (abbreviated as BH y T – x BC z T with x = 0–1.0, y = 0.16, z = 0.20; x = 0–1.0, y = 0.16, z = 0.30; x = 0–1.0, y = 0.20, z = 0.30, respectively), have been designed for investigating the variation of the intermediate O-phase region and its effect on the electrical properties. The temperature-composition phase diagram of each group has been proposed based on the X-ray diffraction patterns and the temperature-dependent dielectric behaviors. The enhanced piezoelectric properties are achieved in the O–T phase boundary compositions of the three groups, which are BH 0.16 T –0.58 BC 0.20 T , BH 0.16 T –0.48 BC 0.30 T and BH 0.20 T –0.53 BC 0.30 T , respectively. Piezoelectric coefficient d 33 of 448 pC/N is obtained in BH 0.20 T –0.53 BC 0.30 T , which is higher than those of the other two phase boundary compositions. The O-phase zone in BH 0.20 T – x BC 0.30 T is narrower than those in the BH 0.16 T – x BC 0.20 T and BH 0.16 T – x BC 0.30 T . In spite of its small O-phase volume occupancy, the O-phase plays a key role in the properties of the system. Our work confirms that the enhancement in piezoelectric properties is not only related to the O–T phase boundary near room temperature (RT), but also related to the shift of T R-O toward RT. In addition, a quantitative relation between the phase boundary composition and atomic mole ratio of Hf to Ca ( R m ) is proposed, which the R m value corresponding to the phase boundary is about 0.58. The results clearly demonstrate that in this system high piezoelectric properties are achieved by tuning the specific R m value. Such a work may provide new clues for designing lead-free piezoelectric materials with enhanced piezoelectric property.
Print ISSN:
0002-7820
Electronic ISSN:
1551-2916
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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