Characterisation of Generation II/III Piezoelectric Single Crystals for use in Sonar Transducers

用于声纳换能器的第二代/第三代压电单晶的表征

• 批准号: 2387826
• 金额: --
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2387826
• 关键词: Characterisation; Generation; II; III; Piezoelectric

Single crystal relaxor ferroelectrics have shown a strong temperature dependence to the piezoelectric coefficient as well as dynamics over an unprecedented frequency range. The main objective of this work is to understand the origin of the exceptional dielectric properties of these materials through studying the structural response in these systems as a function of both temperature and frequency. This project will aim to characterize these two aspects through the application of neutron scattering (through the University of Edinburgh) and dielectric measurements (University of Glasgow). The project will also investigate the application of negative muons for chemical and valence determination in bulk single crystalline materials.Neutron scattering is a bulk and non-destructive probe of materials resulting from the fact that neutrons interact with material via weak forces with the nuclei. This affords beam penetration depths on the order of centimeters and this has been exploited for characterization of industrial components for engineering. Neutrons are produced at reactors and accelerators with wavelengths and energy scales that match typical excitations of materials. In particular, lattice excitations (termed phonons) can be measured as a function of momentum and energy transfer distinguishing neutrons over other "Q=0" probes such as optical spectroscopy including Raman and infrared.This project will exploit recent developments in neutron instrumentation at large scale facilities to investigate the low-energy lattice fluctuations in relaxor ferroelectrics and compare them with dielectric measurements performed at the Universities of Glasgow and Edinburgh. The project will also explore the possibility of using negative muons to determine chemical composition in ferroelectrics and also to distinguish different valency of single ions such as iron, cobalt, and manganese. Initially, the project will involve the development of growth techniques of piezoelectric materials using the multizone furnace at the University of Edinburgh. In parallel, a new capacitance bridge setup will be tested on the current low-temperature equipment at the Centre for Science at Extreme Conditions (CSEC) using an available Quantum Design PPMS. This will be validated by measurements performed at Glasgow and also on standard known materials. The second part of the project will exploit new neutron spin echo spectrometers for the measurement of lattice fluctuations on the GHz frequency scale. These measurements will be compared and connected with measurements using current triple-axis spectrometers. These measurements will be done as a function of temperature and connected with capacitance measurements discussed above. Neutrons provide a direct momentum and energy resolved measure of the structural properties providing microscopic information that can be compared with lab based bulk probes.In the measurement of both capacitance and neutron spectroscopy, the project will also investigate the possibility of performing these measurements under hydrostatic pressure. Current large facilities have large pressure cells that can be used at cryogenic temperatures and pressure scales of up to at least several kbar. Measurements under applied electric fields will also be investigated.A final component of this project is the investigation of the use of negative muons for chemical composition determination. There is a current need to determine chemical composition in materials without destroying the material like is required for EXAFS or EDX. Negative muons may provide a spatially dependent probe that can be used to scan concentration. Initially, this part of the project will test standard materials with known valency. The second part of the project will then extend this to new relaxor materials. This work will be performed at the STFC-ISIS neutron and muon facility.

单晶松弛剂铁电气已经显示出对压电系数和空前频率范围内的压电系数以及动力学的强度依赖性。这项工作的主要目的是通过研究这些系统中的结构响应来了解这些材料的特殊介电特性的起源，这是温度和频率的函数。该项目的目的是通过应用中子散射（通过爱丁堡大学）和介电测量（格拉斯哥大学）来表征这两个方面。该项目还将调查负umon在散装单晶材料中的化学和价测定中的应用。内部散射是由于中子通过弱力与核与核与核的材料相互作用而导致的材料的批量和非破坏性探针。这为厘米的顺序提供了光束穿透深度，并且已经利用了工业组件来表征工程的工业组件。中子是在反应堆和带有波长和能量尺度的加速器上产生的，与材料的典型激发相匹配。特别是，可以根据动量和能量传递的函数来测量晶格激发（称为声子），以区分中子，而不是其他“ Q = 0”探针，例如包括拉曼和红外的光学光谱探针。该项目将利用大规模仪器的中子仪器的最新发展，从格拉斯哥大学和爱丁堡大学。该项目还将探索使用负雄臂来确定铁电的化学组成的可能性，并区分单个离子（例如铁，钴和锰）的不同价值。最初，该项目将涉及使用爱丁堡大学的Multizone熔炉开发压电材料的增长技术。同时，将使用可用的量子设计PPMS在极端条件下（CSEC）的当前低温设备上测试新的电容桥设置。这将通过在格拉斯哥和标准已知材料进行的测量来验证。该项目的第二部分将利用新的中子自旋回波光谱仪来测量GHz频率尺度上的晶格波动。这些测量值将被比较并与使用电流三轴光谱仪的测量值进行比较。这些测量将作为温度的函数进行，并与上面讨论的电容测量相关。中子提供了可以与基于实验室的散装探针进行比较的结构特性的直接动量和能量解析的度量。在测量电容和中子光谱学的测量中，该项目还将研究在静水压力下执行这些测量的可能性。当前的大型设施具有大型压力电池，可用于低温温度和至少几个KBAR的压力尺度。在应用电场下的测量值也将进行研究。该项目的最终组成部分是研究了使用负雄性化学成分确定的。当前需要确定材料中的化学成分而不破坏EXAFS或EDX所需的材料。负躯干可能会提供可用于扫描浓度的空间依赖探针。最初，项目的这一部分将以已知价值测试标准材料。然后，项目的第二部分将将其扩展到新的放松材料。这项工作将在STFC-ISIS中子和MUON设施中进行。