Defects in Yttria-Stabilized Zirconia Induced by Irradiation of Ultraviolet Photons

Abstract

When single-crystal yttria-stabilized zirconia samples are exposed to ultraviolet photons with an energy higher than 4.0 eV, three paramagnetic centers are observed at g ¼ 2:006, 1. 97 -1.95, and 1.91-1.86. With irradiation by ultraviolet photons, an absorption band and a photoluminescence (PL) band are also induced, showing respective peak energies at around 3.3 and 2.8 eV. The onset of the PL-excitation spectrum occurs around 4.0 eV. The induced absorption band and paramagnetic centers disappear with thermal annealing. By doing a numerical analysis on the experimentally obtained angular dependence of the signal at g ¼ 1:91{1:86, it is determined that signals at g ¼ 2:006 and 1.91-1.86 are due to the F þ center and the T center, respectively, and that the signal at g ¼ 1:97 {1:95 has some origin other than the two ESR centers. Since two ESR signals at g ¼ 2:006 and 1.97 -1.95, the 3.3-eV absorption, and the 2.8-eV PL have the same onset energy at around 4.0 eV, the reactions that induce them are triggered by electrons excited into the conduction band tail.

Roles of Point Defects in Thermally Enhanced Generation and Transfer of Electrons and Holes in LaAlO3

“…We have been carrying out research on point defects in many insulating materials mainly by measuring optical absorption, photoluminescence, and electron spin resonance (ESR) spectra or by doing quantum chemical calculations for many years. [6][7][8][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Especially in LaAlO 3 , we have reported the evidence of the presence of transition metal impurities such as Fe and Cr. 16,29) In LaAlO 3 , oxygen vacancies and vacancies of positive trivalent ions (La 3þ or Al 3þ ) are also present.…”

Electron spin resonance signature of the oxygen vacancy in HfO2

“…Stesmans 21 observed the P b center in HfO 2 on Si, but this was associated with the SiO 2 interlayer not the HfO 2 itself. Meanwhile, there were previous reports on paramagnetic defects in ZrO 2 and Y-stabilized ZrO 2 that were associated with Zr 3þ sites, [25][26][27] but these were in bulk or nanocrystalline material not of electronic grade.…”

Adsorption prospects of ultrafine, cubic 8 mol.% Y2O3‐stabilized ZrO2 nanoparticles

“…In the EPR plot, a signal appeared at g = 1.97 in Syn‐8YSZ nanoparticles. Various reports have been published on the assignment of the signal appearing at g = 1.97 44 . The origin of this signal consists of two possibilities: (i) the presence of F + ‐type centers (for singly ionized oxygen vacancies, $$V_{\mathrm{O}}^ \bullet $$) 44,45 and (ii) the presence of T centers (Zr 3+ at the trigonal symmetry site (C3v)) 46,47 .…”

“…Various reports have been published on the assignment of the signal appearing at g = 1.97 44 . The origin of this signal consists of two possibilities: (i) the presence of F + ‐type centers (for singly ionized oxygen vacancies, $$V_{\mathrm{O}}^ \bullet $$) 44,45 and (ii) the presence of T centers (Zr 3+ at the trigonal symmetry site (C3v)) 46,47 . Costantini et al 33 .…”