Dopant Concentration Controls Quasi-Static Electrostrictive Strain Response of Ceria Ceramics

elastic moduli nanoindentation anelasticity Materials Engineering 02 engineering and technology 530 electrostriction 620 Physical sciences Engineering primary creep Chemical sciences Chemical Sciences point defects ultrasonic time of flight doped ceria Nanoscience & Nanotechnology 0210 nano-technology
DOI: 10.1021/acsami.0c07799 Publication Date: 2020-07-23T21:19:37Z
ABSTRACT
Electromechanically active ceramic materials, piezoelectrics and electrostrictors, provide the backbone of a variety of consumer technologies. Gd- and Sm-doped ceria are ion conducting ceramics, finding application in fuel cells, oxygen sensors, and, potentially, as memristor materials. While optimal design of ceria-based devices requires a thorough understanding of their mechanical and electromechanical properties, reports of systematic study of the effect of dopant concentration on the electromechanical behavior of ceria-based ceramics are lacking. Here we report the longitudinal electrostriction strain coefficient (M33) of dense RExCe1-xO2-x/2 (x ≤ 0.25) ceramic pellets, where RE = Gd or Sm, measured under ambient conditions as a function of dopant concentration within the frequency range f = 0.15-350 Hz and electric field amplitude E ≤ 0.5 MV/m. For >100 Hz, all ceramic pellets tested, independent of dopant concentration, exhibit longitudinal electrostriction strain coefficient with magnitude on the order of 10-18 m2/V2. The quasi-static (f < 1 Hz) electrostriction strain coefficient for undoped ceria is comparable in magnitude, while introducing 5 mol % Gd or 5 mol % Sm produces an increase in M33 by up to 2 orders of magnitude. For x ≤ 0.1 (Gd)-0.15 (Sm), the Debye-type relaxation time constant (τ) is in the range 60-300 ms. The inverse relationship between dopant concentration and quasi-static electrostrictive strain parallels the anelasticity and ionic conductivity of Gd- and Sm-doped ceria ceramics, indicating that electrostriction is partially governed by ordering of vacancies and changes in local symmetry.
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