Behavior of elastic constants, refractive index, and lattice parameter of cubic zirconia at high temperatures

Abstract

Acoustic mode frequency, lattice parameter, and refractive index measurements have been carried out on single crystals of cubic stabilized zirconia, ZrO2(xY2O3), in the temperature range 300 to 1450 K, using Brillouin scattering, x-ray diffraction, and interferometric methods, respectively. Elastic constants Cij and associated quantities such as the bulk modulus B=(C11+2C12)/3, the anisotropy ratio A=2C44/(C11−C12), and the Cauchy relation failure Δ=(C12−C44) have been determined from these measurements. The results show a linear reduction in C11 , C12 , and C44 until a characteristic transition temperature Tc, which depends on the dopant concentration x. The linear decrease is understood in terms of normal thermal expansion. Above Tc (1300 K for x=9.4 mol % and 1050 K for x=24 mol %) there are elastic anomalies; significant reductions in C11, (C11-C12)/2 and C44 occur, with an increase in C12 . These effects are considered to result from thermally generated disorder. Detailed examination of the temperature dependence of the Cij as well as B, A, and Δ show some similarities, but also significant differences in comparison with the anomalous elastic behavior corresponding to the high-temperature superionic state of fluorites. The thermally created defect structures formed at high temperatures in cubic zirconia are thus considered to be different from the anion Frenkel disorder formed in fluorites; this is in accord with recent results from computational simulations and high-temperature neutron scattering.

Near-infrared radiative properties of porous zirconia ceramics

“…(15) not only in the range 2.5 < k < 7 lm but also for 7 < k < 9 lm. One should remember that the error of this approach may be considerable in the last range.…”

“…It was shown that index of refraction decreases monotonically with yttria stabilizer concentration in the range between 10.9 and 32.4 mol.% Y 2 O 3 . Some additional data for temperature dependence of refractive index for zirconia with 9.4 and 24 mol.% of yttria were given in paper [15]. The measurements at wavelength k = 0.51 lm showed an increase in refractive index of about 6% in the temperature range 300 < T < 1450 K.…”

Experimental study of phase transformation and specific heat of ternary zirconia-based oxides using differential scanning calorimetry

“…Since only samples with trivalent dopant and co-dopant and substantial cphase (5ScYSZ and 5YbYSZ) exhibited the endothermic reaction, it is believed that this reaction may be associated with defect clustering/ordering during cooling. In fact, it has been observed in other research that the oxygen vacancies in c-phase preferentially locate on the next nearest neighbour to the substitutional dopant cations such as Y 3+ (Sc 3+ and Yb 3+ ) forming highly localized oxygen-cation clusters [28][29][30]. Upon reheating to a critical temperature, rapid diffusion of oxygen anions may occur producing a disordered structure [31].…”

Determination of global and local residual stresses in SOFC by X-ray diffraction

“…Calculation of the associated stress is made using elastic constants for an isotropic polycrystal of YSZ (Table 1). These constants are calculated from the elastic constants of the single crystal [8], using the Voigt model. The stress level obtained is in agreement with the literature [9] [10]: after manufacturing, the electrolyte is under strong bi-axial compressive stresses.…”