Electrostriction measurements on low permittivity dielectrics

A single-beam interferometer with sub- ngstr m displacement resolution for electrostriction measurements

“…This was previously reported to have an influence on the accuracy of the measurement [13,16,19,26]. Even though the conventional sample holder used in previous studies possessed several fundamental problems (non-uniform electric fields in the small cubic sample [19], sample clamping effects [9,16], mechanical loading from a lead-in filament [23], and the 'back-motion' problem caused by deformations of the brass disc and the conductive epoxy [16]), it was chosen for this current study because the nature of its working principle was understood [16,19].…”

“…In our case, the term 'single' means that only one sample surface is exposed to the laser beam. Details on the basic principle of the interferometer are readily available elsewhere [1,16,19,22,25]. Therefore this section will only discuss necessary interferometry equations.…”

“…The direct electrostrictive effect is defined as x i j = M i jmn E m E n or Q i jmn P m P n , where x i j is the induced strain, M i jmn and Q i jmn are respectively the field-related and polarization-related electrostrictive coefficients, E m is the applied electric field, and P m is the polarization. The magnitudes of electrostrictive coefficients depend largely upon the type of material [1]. Electrostrictive deformation of dielectric materials can be exploited in such devices as transducers, actuators, and sensors [2][3][4].…”

“…Measurements of the direct effect electrostrictive coefficients require the ability to accurately measure very small strains or displacements. Generally the electrostrictive displacements vary from sub-ångström in non-ferroelectrics to sub-micron in ferroelectrics [13]. In ferroelectric ceramics and elastomers, the electrostrictive properties have been extensively studied [14,15], but there are very few reliable experimental data for most low-permittivity dielectrics [9,16].…”

“…Problems associated with the system which include disturbances from the vibration of electrical wires, the effects of sample dimensions, and deleterious effects associated with high electric field are discussed. More importantly, this paper presents for the first time procedures designed to eliminate or minimize these problems [1]. Finally, representative measurements of electrostrictive coefficients in low-permittivity dielectrics are presented.…”