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Ferroelectric Hysteresis Measurement & Analysis

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Ferroelectric Hysteresis Measurement & Analysis NPL Report CMMT(A) 152 Ferroelectric Hysteresis Measurement & Analysis M. Stewart & M. G. Cain National Physical Laboratory D. A. Hall University of Manchester May 1999 Ferroelectric Hysteresis Measurement & Analysis M. Stewart & M. G. Cain Centre for Materials Measurement and Technology National Physical Laboratory Teddington, Middlesex, TW11 0LW, UK. D. A. Hall Manchester Materials Science Centre University of Manchester and UMIST Manchester, M1 7HS, UK. Summary It has become increasingly important to characterise the performance of piezoelectric materials under conditions relevant to their application. Piezoelectric materials are being operated at ever increasing stresses, either for high power acoustic generation or high load/stress actuation, for example. Thus, measurements of properties such as, permittivity (capacitance), dielectric loss, and piezoelectric displacement at high driving voltages are required, which can be used either in device design or materials processing to enable the production of an enhanced, more competitive product. Techniques used to measure these properties have been developed during the DTI funded CAM7 programme and this report aims to enable a user to set up one of these facilities, namely a polarisation hysteresis loop measurement system. The report describes the technique, some example hardware implementations, and the software algorithms used to perform the measurements. A version of the software is included which, although does not allow control of experimental equipment, does include all the analysis features and will allow analysis of data captured independently. ã Crown copyright 1999 Reproduced by permission of the Controller of HMSO ISSN 1368-6550 May 1999 National Physical Laboratory Teddington, Middlesex, United Kingdom, TW11 0LW Extracts from this report may be reproduced provided the source is acknowledged. Approved on behalf of Managing Director, NPL, by Dr C Lea, Head, Centre for Materials Measurement and technology Ferroelectric Hysteresis Measurement and Analysis Contents 1. POLARISATION-FIELD (P-E LOOPS) AND STRAIN-FIELD (S-E) MEASUREMENTS FOR PIEZOELECTRIC CERAMICS................................................................................................................... 1 1.1 INTRODUCTION....................................................................................................................................... 1 1.2 PIEZOELECTRIC CHARACTERISATION........................................................................................................ 2 1.3 P-E LOOP MEASUREMENT........................................................................................................................ 4 2. HARDWARE FOR P-S-E LOOP MEASUREMENTS ............................................................................ 6 2.1 INTRODUCTION....................................................................................................................................... 6 2.2 HARDWARE SYSTEM................................................................................................................................ 6 2.3 CHOOSING HV AMPLIFIERS ..................................................................................................................... 7 2.4 CHOOSING DISPLACEMENT MEASUREMENT SYSTEMS FOR S-E MEASUREMENTS .......................................... 8 2.4.1 Fibre optic probe ........................................................................................................................... 8 2.4.2 Capacitance probe......................................................................................................................... 9 2.4.3 Laser interferometry ...................................................................................................................... 9 2.4.4 Strain gauges ............................................................................................................................... 10 2.5 CHARGE MEASUREMENT FOR P-E LOOP MEASUREMENTS......................................................................... 10 2.6 SUMMARY ............................................................................................................................................ 12 3. THEORETICAL BASIS FOR P-E LOOP ANALYSIS SOFTWARE................................................... 14 3.1 INTRODUCTION..................................................................................................................................... 14 3.2 MEASUREMENT ROUTINES..................................................................................................................... 14 3.3 CONSTRUCTION OF P-E AND S-E HYSTERESIS LOOPS............................................................................... 15 3.4 DETERMINATION OF EQUIVALENT HIGH FIELD DIELECTRIC COEFFICIENTS................................................. 17 3.5 RAYLEIGH LAW REPRESENTATION OF DIELECTRIC BEHAVIOUR IN PIEZOELECTRIC MATERIALS ................... 19 3.6 REPRESENTATION OF A LOSSY DIELECTRIC AS A PARALLEL CR NETWORK TO MODEL PE LOOPS................. 22 4. OVERVIEW OF THE SOFTWARE PACKAGE................................................................................... 23 4.1 GENERAL INFORMATION........................................................................................................................ 23 4.2 STARTUP AND MAIN PANEL................................................................................................................... 23 4.3 READ DATA FILES................................................................................................................................. 25 4.4 SHOW PLOTS ........................................................................................................................................ 26 4.4.1 Main Plot Window........................................................................................................................ 26 4.4.2 Plot Options................................................................................................................................. 27 4.5 P-E ANALYSIS...................................................................................................................................... 29 4.6 PROCESS DATA FILE ............................................................................................................................. 30 4.7 DATA ACQUISITION .............................................................................................................................. 31 4.7.1 Main Data Acquisition Window.................................................................................................... 31 4.7.2 Generator Setup** ........................................................................................................................ 32 4.7.3 Setup Inputs** ............................................................................................................................. 33 4.7.4 Ageing Measurements** .............................................................................................................. 35 4.8 ANALYSIS OPTIONS .............................................................................................................................. 36 4.9 RECALL / SAVE SETUP........................................................................................................................... 37 4.10 HARDWARE SUPPORT AND SETUP**..................................................................................................... 37 4.11 PRINTING ........................................................................................................................................... 38 5. REFERENCES......................................................................................................................................... 39 6. APPENDIX............................................................................................................................................... 40 6.1 INSTALLING THE SOFTWARE .................................................................................................................. 40 6.1.1 Requirements ............................................................................................................................... 40 6.1.2 Installing the PEHys software ...................................................................................................... 40 6.1.3 Running PEHys software.............................................................................................................. 40 6.1.4 Uninstalling the PEHys software.................................................................................................. 40 6.2 SOME EXAMPLE FILES ........................................................................................................................... 41 6.2.1 File: Capb.txt............................................................................................................................... 41 6.2.2 File: PC5H_13.hyz....................................................................................................................... 42 6.2.3 File: Rayleigh.txt ......................................................................................................................... 43 6.3 FILE FORMATS...................................................................................................................................... 43 6.3.1 Configuration File : Peconfig.txt.................................................................................................
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