PROPERTY UNIFORMITY AND POLING BEHAVIOR OF PMN-PT CRYSTAL GROWN BY VERTICAL GRADIENT FREEZE METHOD
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- 英文论文题名：PROPERTY UNIFORMITY AND POLING BEHAVIOR OF PMN-PT CRYSTAL GROWN BY VERTICAL GRADIENT FREEZE METHOD
- 论文作者：Zi-bo JIANG
- 英文论文作者：Zi-bo JIANG ; Innovia Materials (Shanghai) Co. ; Ltd
- 年：2016
- 作者机构：Innovia Materials (Shanghai) Co., Ltd;
- 英文论文关键词：Piezoelectric crystal ; PMN-PT ; Over-poling ; Phase transition
- 会议召开时间：2016-10-21
- 会议录名称：2016年全国压电和声波理论及器件应用研讨会论文摘要集
- 英文会议录名称：Abstract Book of 2016 Symposium on Piezoelectricity, Acoustic Waves and Device Applications
- 语种：英文
- 分类号：O782
- 学会代码：AGLU
- 会议名称：2016年全国压电和声波理论及器件应用研讨会
- 会议地点：中国陕西西安
- 主办单位：中国力学学会、中国声学学会、IEEE UFFC分会
- 学会名称：中国力学学会
- 页数：2
- 文件大小：91k
- 原文格式：D
- 会议级别：全国
摘要
Background, Motivation and Objective As PMN-PT crystal is more widely used in medical ultrasound and SONAR applications, it is important for transducer designers to understand property characteristics and implementation limits of PMN-PT crystals. Vertical Gradient Freeze(VGF) method is an efficient melt-grown method to produce giant PMN-PT crystals. As a result, 3-inch PMN-PT crystal ingot was produced with special growth conditions and controllable orientation. In this paper, the piezoelectric and dielectric properties will be fully explored for crystals grown with this method. Further, how these key properties correlates with poling conditions as well as over-poling scenarios will also be studied. Statement of Contribution/Methods 72-mm diameter PMN-PT ingots were grown along [001] direction using VGF method. Wafers are sliced, sequentially numbered and tested for the study of composition segregation along the ingot, and samples from the same wafer were tested for the study of in-wafer uniformity. Coupling coefficient, dielectric constant and dielectric loss were recorded. Further, zero-field heating is used to determine phase transition temperature for crystals poled at different DC field. When over-poling occurs, furnace annealing is used to determine whether damages caused by over-poling could be reversed. Results In terms of in-wafer uniformity, variation coefficients of dielectric constant, electromechanical coupling coefficient and loss tangent are 0.02, 0.01 and 0.008, respectively. However, dielectric constant, electromechanical coupling coefficient k33 and Curie temperature change monotonically from one end of ingot to the other end, due to PT segregation. Upon poling, PMN-0.29 PT and PMN-0.31 PT behave differently: PMN-0.29 PT is fully poled around 350 V/mm and PMN-0.31 PT is fully poled around 250 V/mm. Both PMN-0.29 PT and PMN-0.31 PT are resistant to over poling up to DC 1300 V/mm at room temperature; beyond such limit, both crystals could be over-poled, with PMN-0.31 PT being more susceptible to phase transition due to closer vicinity to MBP. Such transition could be validated by the disappearance of TR-T in zero-field heating experiment and could be reversed by annealing at elevated temperatures. Discussion and Conclusions Vertical Gradient Freeze(VGF) method has proved to be an efficient method to produce giant piezoelectric crystals. The combined effect of controlled orientation growth and in-wafer uniformity is an advantage in transducer design. However, PT segregation is still apparent in VGF method, resulting in monotonic change in key piezoelectric and dielectric properties along the ingot. Hence, transducer designers should carefully select PMN-PT crystal grades while paying attention to their poling behaviors. It is advised to always avoid poling or driving the crystal beyond 1000 V/mm, and if over-poling occurs, furnace annealing at elevated temperature should be carefully implemented to reverse phase transition.
Background, Motivation and Objective As PMN-PT crystal is more widely used in medical ultrasound and SONAR applications, it is important for transducer designers to understand property characteristics and implementation limits of PMN-PT crystals. Vertical Gradient Freeze(VGF) method is an efficient melt-grown method to produce giant PMN-PT crystals. As a result, 3-inch PMN-PT crystal ingot was produced with special growth conditions and controllable orientation. In this paper, the piezoelectric and dielectric properties will be fully explored for crystals grown with this method. Further, how these key properties correlates with poling conditions as well as over-poling scenarios will also be studied. Statement of Contribution/Methods 72-mm diameter PMN-PT ingots were grown along [001] direction using VGF method. Wafers are sliced, sequentially numbered and tested for the study of composition segregation along the ingot, and samples from the same wafer were tested for the study of in-wafer uniformity. Coupling coefficient, dielectric constant and dielectric loss were recorded. Further, zero-field heating is used to determine phase transition temperature for crystals poled at different DC field. When over-poling occurs, furnace annealing is used to determine whether damages caused by over-poling could be reversed. Results In terms of in-wafer uniformity, variation coefficients of dielectric constant, electromechanical coupling coefficient and loss tangent are 0.02, 0.01 and 0.008, respectively. However, dielectric constant, electromechanical coupling coefficient k33 and Curie temperature change monotonically from one end of ingot to the other end, due to PT segregation. Upon poling, PMN-0.29 PT and PMN-0.31 PT behave differently: PMN-0.29 PT is fully poled around 350 V/mm and PMN-0.31 PT is fully poled around 250 V/mm. Both PMN-0.29 PT and PMN-0.31 PT are resistant to over poling up to DC 1300 V/mm at room temperature; beyond such limit, both crystals could be over-poled, with PMN-0.31 PT being more susceptible to phase transition due to closer vicinity to MBP. Such transition could be validated by the disappearance of TR-T in zero-field heating experiment and could be reversed by annealing at elevated temperatures. Discussion and Conclusions Vertical Gradient Freeze(VGF) method has proved to be an efficient method to produce giant piezoelectric crystals. The combined effect of controlled orientation growth and in-wafer uniformity is an advantage in transducer design. However, PT segregation is still apparent in VGF method, resulting in monotonic change in key piezoelectric and dielectric properties along the ingot. Hence, transducer designers should carefully select PMN-PT crystal grades while paying attention to their poling behaviors. It is advised to always avoid poling or driving the crystal beyond 1000 V/mm, and if over-poling occurs, furnace annealing at elevated temperature should be carefully implemented to reverse phase transition.
Background, Motivation and Objective As PMN-PT crystal is more widely used in medical ultrasound and SONAR applications, it is important for transducer designers to understand property characteristics and implementation limits of PMN-PT crystals. Vertical Gradient Freeze(VGF) method is an efficient melt-grown method to produce giant PMN-PT crystals. As a result, 3-inch PMN-PT crystal ingot was produced with special growth conditions and controllable orientation. In this paper, the piezoelectric and dielectric properties will be fully explored for crystals grown with this method. Further, how these key properties correlates with poling conditions as well as over-poling scenarios will also be studied. Statement of Contribution/Methods 72-mm diameter PMN-PT ingots were grown along [001] direction using VGF method. Wafers are sliced, sequentially numbered and tested for the study of composition segregation along the ingot, and samples from the same wafer were tested for the study of in-wafer uniformity. Coupling coefficient, dielectric constant and dielectric loss were recorded. Further, zero-field heating is used to determine phase transition temperature for crystals poled at different DC field. When over-poling occurs, furnace annealing is used to determine whether damages caused by over-poling could be reversed. Results In terms of in-wafer uniformity, variation coefficients of dielectric constant, electromechanical coupling coefficient and loss tangent are 0.02, 0.01 and 0.008, respectively. However, dielectric constant, electromechanical coupling coefficient k33 and Curie temperature change monotonically from one end of ingot to the other end, due to PT segregation. Upon poling, PMN-0.29 PT and PMN-0.31 PT behave differently: PMN-0.29 PT is fully poled around 350 V/mm and PMN-0.31 PT is fully poled around 250 V/mm. Both PMN-0.29 PT and PMN-0.31 PT are resistant to over poling up to DC 1300 V/mm at room temperature; beyond such limit, both crystals could be over-poled, with PMN-0.31 PT being more susceptible to phase transition due to closer vicinity to MBP. Such transition could be validated by the disappearance of TR-T in zero-field heating experiment and could be reversed by annealing at elevated temperatures. Discussion and Conclusions Vertical Gradient Freeze(VGF) method has proved to be an efficient method to produce giant piezoelectric crystals. The combined effect of controlled orientation growth and in-wafer uniformity is an advantage in transducer design. However, PT segregation is still apparent in VGF method, resulting in monotonic change in key piezoelectric and dielectric properties along the ingot. Hence, transducer designers should carefully select PMN-PT crystal grades while paying attention to their poling behaviors. It is advised to always avoid poling or driving the crystal beyond 1000 V/mm, and if over-poling occurs, furnace annealing at elevated temperature should be carefully implemented to reverse phase transition.
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