Paramagnetic centers induced in cubic zirconia by 2.5-MeV electron and 2.6-GeV uranium ion irradiations

Charging kinetics in virgin and 1MeV-electron irradiated yttria-stabilized zirconia in the 300–1000K range

“…In particular, two paramagnetic centers were identified by EPR: a trigonal Zr 3+ electron center (T-center) with an axial (1 1 1) symmetry and an F + -type center associated with a singly ionized oxygen vacancy with an axial (1 0 0) symmetry [6]. Under the irradiation dose used in the present experiments (10 18 e/cm 2 ) the concentration of the Ttype center is about 100 times higher than that of the F + -center [6][7][8][9] and the thermal recovery of these two defects lies in the temperature range 480-550: 480 K for the F + -center, 550 K for the T-center [7,9].…”

“…The origin of this residual field has to be found in the nature of the defects created by irradiation. EPR has detected several types of defects after similar high-energy electron irradiations of YSZ [6][7][8][9]. In particular, two paramagnetic centers were identified by EPR: a trigonal Zr 3+ electron center (T-center) with an axial (1 1 1) symmetry and an F + -type center associated with a singly ionized oxygen vacancy with an axial (1 0 0) symmetry [6].…”

“…For example, it was shown that, under heavy ion irradiation, defects produced by ballistic or electronic excitation processes do not lead to full amorphization [5]. In the particular case of high-energy electron irradiation, point defects, especially color centers, are known to be generated in YSZ [6][7][8][9]. They are also known to be stable at room temperature but their influence on the electric state of the irradiated material is not well understood.…”

Influence of mechanical activation on the structure of ultrafine BaTiO3 powders

“…On the other hand, since we performed mechanical activation in a zirconia agate jar with zirconia agate balls, it also should be mentioned that the detected value of g = 1.901 is very close to the g-factor which is characteristic of trigonal Zr 3+ centers (T centers, with g = 1.89). It is known that in structures like cubic yttria stabilized zirconia, Zr 3+ ions occur due to the chargecompensating effect and are positioned at the center of the unit cell surrounded by six oxygen atoms and two oxygen vacancies [31]. Regarding the circumstance that Zr 3+ paramagnetic centers occur in a six-fold coordination, someone might assume the possibility of zirconium substitution for titanium ion in oxygen octahedron during the mechanical activation of BaTiO 3 powders in zirconia jars.…”

Defect production in ion-implanted yttria-stabilized zirconia investigated by positron depth profiling

“…Electron dispersive wave length X-ray analyses indicated a concentration of 9.5 mole % Y 2 O 3 and a natural impurity content of 1.4 wt.% Hf. All samples were optically polished (Ra ≈ 1.3 nm) and, prior to any measurement or irradiation, they underwent a heat treatment at 1473 K in air during 14 h. In this latter state, hereafter called "virgin", the single crystals remained colorless and transparent [10].…”