宽温域光声气体探测用高品质BIBO单晶的压电性能及振动耦合机理研究

Photoacoustic (PA) effect is very promising for trace gas detection. However, the sensitivity and serving temperature range of current piezoelectric transducers are hard to meet the requirements of PA gas detection over a wide-temperature-range. High performance piezoelectric crystal and new transducer are in pressing need. The bismuth triborate (α-BiB3O6, BIBO) piezoelectric crystals were found to possess higher Q value, higher piezoelectric voltage constant g, and better temperature stability of piezoelectric properties than the used PZT and LN piezoelectric materials, promising for wide-temperature-range PA gas detection. In this project, the electro-elastic properties as well as their temperature dependent behaviors will be studied using impedance, pulse-echo and interferometric methods. The formation of micro defects and their influences on piezoelectric properties will be discussed. In addition, piezoelectric vibration modes and the coupling mechanism of BIBO crystal will be investigated, for designing the optimum crystal cut with the merits of pure mode, high effective piezoelectric coefficient and good temperature stability of piezoelectric performance. Furthermore, trace gas PA detection experiments will be carried out at different temperatures, striving for optimizing the performance of the crystal cut and making a strong foundation of BIBO crystal in PA gas detections over a wide temperature range.

光声效应在痕量气体探测领域具有重要应用前景，目前探测用压电换能器件的灵敏度和服役温度难以适用宽温域光声气体探测的应用需求。为此，急需开发高性能压电晶体并研制新型换能器件。三硼酸铋（α-BiB3O6, BIBO）晶体具有比PZT和LN等现役压电材料更高的Q值、压电常数g及其性能温度稳定性，在宽温域光声气体探测领域中具有光明的应用前景。本项目拟采用阻抗法、超声法和干涉法研究晶体的电弹性能及其温度依赖性；研究晶体的微观缺陷及其对宏观电学性能的影响机制；研究分析该晶体的压电振动模态，阐明不同模态之间的耦合机理；设计压电常数较高、振动模态单一且温度稳定性优良的最佳晶体切型，试制压电换能器件，用于痕量气体的变温探测实验，不断优化晶体切型的综合性能，力争为该晶体在宽温域光声气体探测领域的应用开发奠定基础。

光声效应在痕量气体探测领域具有重要应用前景，目前探测用压电换能器的灵敏度和服役温度难以适用宽温域光声气体探测应用需求，有必要开发高性能压电晶体并研制新型换能器件。本项目以三硼酸铋（α-BiB3O6, BIBO）晶体为主要研究对象，探究晶体微观缺陷对宏观电学性能的影响；对比研究不同压电晶体的电弹性能及其温度依赖性；研究分析该晶体的压电振动模态，阐明不同模态之间的耦合规律；设计压电常数较高、振动模态单一且温度稳定性优良的最佳晶体切型，试制压电传感器件并完成痕量气体探测实验，力争为该晶体在宽温域光声气体探测领域的应用开发奠定基础。.在课题资助下，本项目取得的创新性研究成果主要有：（1）通过XPS表征，分析得到了BIBO晶体褐色呈色缺陷的成因与B元素的缺失有关。通过单晶生长工艺改进，补充足量的B元素，能够获得无色的高品质BIBO单晶；（2）设计了单斜晶系2点群晶体压电系数的测算方案并给出了最佳的切型设计方案，验证了阻抗法和激光干涉法联用验证压电系数的大小和正负符号的有效方法，得到了BIBO晶体电弹常数的可靠数值，为压电传感器件研制奠定了重要基础；（3）为高温压电传感器设计需要，对比研究了BIBO和LN等压电晶体电弹性能的温度依赖性，得出BIBO晶体在-150℃~150℃和20℃~600℃范围内均具有相对较高的压电活性，变化率低于±10%；（4）研究了BIBO等压电晶体的最佳敏感切型及尺寸效应对压电振动模态的影响，得到当直径和厚度之比为5:7时，可获得纯的纵向伸缩振动模式；（5）基于BIBO和LN晶体，设计了厚度压缩式和剪切式压电换能器件，通过Hsu–Nielsen实验，验证了室温至500℃范围内的传感特性，灵敏度变化率低于44%；（6）设计了法布里-珀罗谐振腔系统结构和压电晶体基音叉结构，采用千分之一浓度的甲烷混合气完成了光声气体的测试实验，成功观测到了电信号随甲烷气体浓度的变化。.项目成果有利于推动压电晶体传感器件研发，开拓其中气体传感技术领域中的应用。