Defect-fluorite Gd2Zr2O7 ceramics under helium irradiation: Amorphization,cell volume expansion,and multi-stage bubble formation

Here, we report a study on the radiation resistance enhancement of Gd₂Zr₂O₇ nanograin ceramics, in which amorphization, cell volume expansion, and multi-stage helium (He) bubble formation are investigated and discussed. Gd₂Zr₂O₇ ceramics with a series of grain sizes (55-221 nm) were synthesized and irradiated by 190 keV He ion beam up to a fluence of 5 × 10¹⁷ ions/cm². Both the degree of post irradiation cell volume expansion and the amorphization fraction appear to be size-dependent. As the average grain size evolves from 55 to 221 nm, the degree of post irradiation cell volume expansion increases from 0.56% to 1.02%, and the amorphization fraction increases from 6.8% to 11.1%. Additionally, the threshold He concentrations (at.%) of bubbles at different formation stages and locations, including (a) bubbles at grain boundary, (b) bubble-chains, and (c) ribbon-like bubbles within the grain, are all found to be much higher in the nanograin ceramic (55 nm) compared with that of the submicron sample (221 nm). We conclude that grain boundary plays a critical role in minimizing the structural defects, and inhibiting the multi-stage He bubble formation process.     

Preparation of Gd2Zr2O7 nanoceramics from two-step thermal treatment and the aqueous durability analysis

Gd₂Zr₂O₇ ceramics demonstrate important prospect in the immobilization of high-level radioactive wastes (HLWs). In this study, Gd₂Zr₂O₇ nanoceramics were fabricated using two-step method, where Gd₂Zr₂O₇ nanopowder was firstly synthesized by solvothermal method and Gd₂Zr₂O₇ nanoceramics were subsequently sintered via self-propagating chemical furnace plus quick pressing (SCF/QP). The characterization results display that the Gd₂Zr₂O₇ nanocrystalline ceramics with average grain size of 78 nm and bulk density of 5.53 g cm⁻³ were successfully prepared. The results of MCC-1 static leaching experiments show that the normalized release rate (LR_i) of Gd is 2.2 × 10⁻² g m⁻²•d⁻¹ on the first day and converges to 1.2 × 10⁻³ g m⁻²•d⁻¹ after 42 days. Zr shows superior chemical stability as the 21 days LR_Zr value is as low as 2.7 × 10⁻⁶ g m⁻²•d⁻¹, which becomes constant as the leaching duration prolongs.     

Helium irradiation effects on MgO-Nd2Zr2O7 composite ceramics prepared by one-step method used for inert matrix fuel

In this work, the helium irradiation effects were systematically investigated on MgO-Nd₂Zr₂O₇ (hereafter M-NZO) composite ceramics used for inert matrix fuel, in which the ion fluences range from 5 × 10¹⁶ to 3 × 10¹⁷ ions/cm² at room temperature. It was demonstrated that M-NZO composite ceramic shows superior radiation tolerance after He implantation. Specifically, MgO had almost no phase transition and extensive amorphization. And Nd₂Zr₂O₇ phase possessed slightly pyrochlore-fluorite-amorphization structural transformation, while part of Nd₂Zr₂O₇ maintained the ordered pyrochlore structure and co-existed with the irradiation-induced disordered fluorite structure. Importantly, GIXRD results indicated that MgO phase presents higher resistance to radiated damage than Nd₂Zr₂O₇ phase. Besides, SEM images illustrated that MgO particles have substantially less fragmentation than Nd₂Zr₂O₇ particles due to the higher thermal conductivity of MgO. It reconfirmed that MgO phase resists irradiation damage better than Nd₂Zr₂O₇ phase in post-irradiated M-NZO composite ceramics.     

Rapid preparation of Gd2Zr2−xCexO7 waste forms by flash sintering and their chemical durability

A simple and low-energy-consuming approach for preparing ceramic nuclear waste forms is greatly preferred for disposal of ever-increasing amounts of radioactive nuclear wastes. Herein, simulated radionuclide Ce could be rapidly incorporated into Gd₂Zr₂O₇ ceramic via flash sintering technique. Under an electric field of 250 V/cm, Gd₂Zr_2−xCe_xO₇ (0.0 ≤x ≤ 1.2) waste forms with a single phase of defect-fluorite were flash sintered at relatively low temperatures of 889–997 °C in 60 s. The onset temperature of flash sintering was decreased with the enhancement of Ce content. Furthermore, the density and grain size of Gd₂Zr_2−xCe_xO₇ waste forms were increased with the increase of the current limit. The nearly full dense Gd₂Zr_2−xCe_xO₇ waste forms were flash sintered at a current limit of 200 mA. The normalized leaching rates of Gd, Ce, and Zr in Gd₂Zr_0.8Ce_1.2O₇ after 28 d were 6.5475 × 10⁻⁵, 1.1624 × 10⁻⁷, and 1.1613 × 10⁻⁷ g·m⁻²·d⁻¹, respectively, which exhibited a good chemical durability.     

Effects of heavy-ion irradiation on Gd2Zr2O7 bearing simulated TRPO waste

Considering the urgent demand of nuclear waste disposal, a comprehensive study on the irradiation performance of nuclear waste forms is extremely necessary, especially on those containing multiple-nuclides with multiple-valence. The irradiation effects of Gd₂Zr₂O₇ pyrochlore bearing simulated trialkyl phosphine oxides (TRPO) waste (consisting of ZrO₂, MoO₃, RuO₂ and PdO) were studied in this work. Gd_10.685Mo_4.734Zr_28.924Ru_1.000Pd_1.745O_91.825 and Gd_8.883Mo_9.901Zr_33.760Ru_2.089Pd_3.644O_118.368 were irradiated by 1.5?MeV Xe²⁰⁺ to fluences from 1?×?10¹² to 1?×?10¹⁵ ions/cm² at room temperature. The results showed an irradiation induced disordering with slight micro-swelling. In addition, the ion irradiation tolerance of the solid solutions decreased as the TRPO waste content increased. The decrease and shift of Raman peaks indicated the structural disordering and inner stress after irradiation. The micromorphology and element distribution of the irradiated surface remained almost unchanged. The structural evolution from pyrochlore to fluorite and even amorphous structure were disclosed in this study.     

Role of structural ordering on the radiation response of Gd2Zr2O7 pyrochlore

Complex oxides with pyrochlore and fluorite phases offer several advantages for the Immobilization of actinides or high-level radioactive wastes. In this report, we present the different behavior of structural ordering/crystallinity of Gd₂Zr₂O₇ (GZO) ceramics upon sintering at two different temperatures (1400°C–1500 °C). XRD and Raman spectroscopy studies revealed the enhancement of structural ordering/crystallinity with the increase of sintering temperature. Further, the ion irradiation experiments using 100 MeV iodine at the fluence of 1.0 × 10¹⁴ ions/cm² were performed to investigate the radiation effects on both GZO ceramics. The irradiation studies insinuate that the GZO ceramic sintered at 1500 °C possesses relatively better radiation resistance than GZO ceramic sintered at 1400 °C. The variation in the radiation resistance response of GZO ceramics seems associated with the different degrees of structural ordering. These results suggest the role of structural ordering in the radiation resistance response of GZO ceramics. The relatively better radiation tolerance of GZO15 ceramic with some extant pyrochlore phase ordering may be suitable for applications in harsh environments.     

Free occupying mechanism of simulated tetravalent waste ions in Gd2Zr2O7 and performance evaluation of the waste forms

To extend the practicability of ceramics in immobilizing nuclear waste with fluctuant composition, structural design should be abandoned. The simulated tetravalent actinide waste An⁴⁺ (Ce⁴⁺) was directly doped into prepared Gd₂Zr₂O₇, and the waste forms were synthesized by high-temperature solid-state reaction. It has been shown that the maximum loading of CeO₂ in Gd₂Zr₂O₇ lies between 20 and 30 wt.%, and Ce elements are uniformly distributed in the matrix. Existing in Ce³⁺ and Ce⁴⁺, cerium ions automatically occupied both the Gd and Zr sites in Gd₂Zr₂O₇ according to valence equilibrium. This occupation causes the change of r(A³⁺)/r(B⁴⁺) and eventually leads to the structure transition from pyrochlore to fluorite. In addition, the normalized leaching rate of the sample with 60 wt.% of dopant was about 2.5 × 10⁻⁷ g m⁻² d⁻¹ on the 35th day. In this study, a free occupation of simulated waste ions in ceramics was proposed.     

Response of structure and mechanical properties of high entropy pyrochlore to heavy ion irradiation

Material with superior damage tolerance, chemical durability, and structure stability is of increasing interest in high-level radioactive waste management and structural components for advanced nuclear systems. In this paper, high-entropy (La_0.2Ce_0.2Nd_0.2Sm_0.2Gd_0.2)₂Zr₂O₇ with pyrochlore-type structure was synthesized through conventional solid-state method. The as-synthesized high-entropy oxide maintained crystalline after being irradiated by using Au³⁺ with 9.0 MeV energy at the fluence of 4.5 × 10¹⁵ ions·cm^-2, indicating its high tolerance to heavy-ion irradiation. The irradiation-induced order-disorder transition from pyrochlore structure to defective fluorite structure occurred in high-entropy (La_0.2Ce_0.2Nd_0.2Sm_0.2Gd_0.2)₂Zr₂O₇. After irradiation, no irradiation-induced segregation was observed at grain boundary. Moreover, the mechanical properties of high-entropy pyrochlore were improved. The heavy-ion irradiation resistance mechanisms of high-entropy pyrochlore were discussed in detail. Our work identified high-entropy (La_0.2Ce_0.2Nd_0.2Sm_0.2Gd_0.2)₂Zr₂O₇ can be a promising candidate for immobilization of high-level radioactive waste as well as advanced nuclear reactor system from the perspective of irradiation resistance.     

Effect of CaO doping on densification and microstructure control of highly transparent La0.4Gd1.6Zr2O7 ceramics

Calcium oxide (CaO) as sintering additive was first used to fabricate La_0.4Gd_1.6Zr₂O₇ transparent ceramics by a simple solid-state reaction and one-step vacuum sintering method. The effects of CaO dopant amount on the densification, as well as sintering behaviors and microstructure evolution of the as-fabricated La_0.4Gd_1.6Zr₂O₇ ceramics, were systematically investigated. Under the different sintering temperatures, the relationships during the sintering process between grain growth and zpore elimination were analyzed as well. It was found that 0.1 wt% CaO doping can effectively control the rate of grain growth and promote densification dominated by surface diffusion. Furthermore, Ca²⁺ entered the lattice of La_0.4Gd_1.6Zr₂O₇ ceramics to accelerate ion diffusion and suppress grain boundary migration. With the introduction of 0.1 wt% CaO doping, the highly transparent La_0.4Gd_1.6Zr₂O₇ ceramics (T = 80.4% at 1100 nm) were successfully fabricated at the traditional sintering temperature (1850°C).     

Elucidating the degradation mechanism of 0.5Gd2Zr2O7·0.5TRPO under multi-energy He ion irradiation

Gd₂Zr₂O₇ has long been considered as one of the most promising waste forms and has attracted broad interest in the field of nuclear waste immobilization. This work utilizes multi-energy He-irradiation to study the microstructural and helium bubble evolution of Gd₂Zr₂O₇ immobilizing with the final waste after partitioning high-level liquid waste by using the trialkyl phosphide (TRPO waste, the waste load is 50 wt%) in an experimentally feasible time frame. Interestingly, at less than 40 nm below the He-irradiated surface (Region I), there are a significant number of well-aligned large spherical He bubbles with diameters ranging from 5 to 25 nm and a severely amorphous structure. The mechanism of these novel phenomena may be related to enhanced migration rate of vacancies by high electronic energy loss, promoting the combination of vacancies with relatively high-density He atoms, suppressing the recombination-annihilation of vacancies and interstitial atoms, thus accelerating the irradiation amorphization.     

Structural integrity and damage of glass-ceramics after He ion irradiation: Insights from ZrO2-SiO2 nanocrystalline glass-ceramics

Developing new radiation-resistant materials and understanding the structural damages caused by radiation are persistent goals of material scientists. Here, we report on the structural integrity and damage to ZrO₂-SiO₂ nanocrystalline glass-ceramics after radiation with 1.4 MeV He ions at three different fluences: 1.0 × 10¹⁶ ions/cm² (low), 5.0 × 10¹⁶ ions/cm² (moderate), and 1.0 × 10¹⁷ ions/cm² (high) at 500 °C. Grazing incident X-ray diffraction shows the tetragonal-ZrO₂ to monoclinic-ZrO₂ phase transformation induced by microstrain from the irradiation. The addition of yttrium indicated tetragonal-ZrO₂ stabilization effect during irradiation. The irradiated glass-ceramics show a Raman signal-enhancement effect probably related to the electronic structure changes of the amorphous SiO₂ component in the glass-ceramics. The formation of microcracks and lattice defects within ZrO₂ nanocrystallites is the main structural damage caused by irradiation. There was no observable amorphization of ZrO₂ nanocrystallites due to irradiation. No obvious He bubbles were detected, either. The formation of microcracks results in a decrease of in the nanohardness of the glass-ceramics. The results provide fundamental experimental data to understand the structural integrity and damage caused by radiation, which could be useful to design radiation‐resistant nanocrystalline glass-ceramics for extremely radioactive environments.     

Alpha-particle irradiation effects on uranium-bearing Gd2Zr2O7 ceramics for nuclear waste forms

It is necessary to study the self-irradiation effects of nuclear waste forms under α-decay in the long term storage. In the present work, accelerated irradiation experiments were performed on (Gd_1-4xU_2x)₂(Zr_1-xU_x)₂O₇ (x = 0, 0.10, 0.14) samples using 0.5 MeV alpha-particle irradiation at fluences ranging from 1 × 10¹⁴ to 1 × 10¹⁷ ions/cm² at room temperature. Irradiation induced microstructural evolution was examined by grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy and Field-emission scanning electron microscopy (FESEM). The results show that the main crystal structure is kept, however, weaker structural ordering is leaded as a result of intensified irradiation. And the radiation resistance is enhanced by the growing uranium content in the discussed range. Moreover, the irradiation effects as a function of depth have been discussed. Raman spectra reveal that the vibration intensity of atomic bonds are changed due to increased irradiation. In addition, the microtopography and element distribution have been kept after irradiation.     

Irradiation-induced large bubble formation and grain growth in super nano-grained ceramic

In this work, 0.5TRPO•0.5Gd₂Zr₂O₇ ceramic with an average grain size of only ∼15 nm was prepared by a high pressure (5 GPa/520 °C) sintering method. Phase evolutions and microstructure changes of the as-fabricated super nano and micron-grained ceramics under a high-dose displacement damage induced by 300 keV Kr²⁺ ions were investigated. The results show that the super nano-grained ceramic has low degree of amorphization, obvious grain growth (2–3 times in grain size) and big Kr bubbles (10–68 nm) formation after irradiation. The micron-grained ceramic was severely amorphized after irradiation and many microcracks were formed parallel to its surface. The formation mechanism of Kr bubbles in the super nano-grained ceramic is on account of grain boundary diffusion and migration induced by the accumulation of the injecting Kr ions and irradiation defects. Nevertheless, microcracks formed in the micron-grained sample are caused by the accumulation of Kr atoms.     

Atomic order-disorder engineering in the La2Zr2O7 pyrochlore under low energy ion irradiation

Cation and anion disordering affect the structural and electronic properties of the isometric A₂B₂O₇ pyrochlore materials. Here, we report a study on the structural response of La₂Zr₂O₇ at two different temperatures (300 K and ~88 K) as a function of ion fluence (1 × 10¹³, 5 × 10¹³, and 1 × 10¹⁴ ions/cm²). The effect of ion fluence and irradiation temperature on the structural properties have been investigated using the grazing angle x-ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy. GIXRD results confirmed that the weakening/broadening of the diffraction peaks and lattice volume expansion increases monotonically as a function of ion fluence at both the temperatures and are more pronounced at ~88 K. The cation and anion disordering appear to be ion fluence and irradiation temperature-dependent. Raman spectroscopy shows that the atomic disordering is more pronounced with enhanced ion fluence and revealed the involvement of the X_48f parameter in the enhancement of disordering in the system. The HRTEM analysis revealed that the deterioration in the atomic ordering (amorphization) is significantly more pronounced at ~88 K. The qualitative analysis of cation/anion disordering and structural deformation revealed that irradiation parameters play a crucial role in developing and altering the properties of the pyrochlore materials for the technological applications.     

Structural evolution of Lu2-xCexTi2O7 pyrochlores under 400 keV Ne irradiation

Lu_2-xCe_xTi₂O₇ (LCTO) pyrochlores were irradiated by 400 keV Ne²⁺ with fluences (dose) of up to 5 × 10¹⁵ ions/cm² (1.875 dpa). The detailed damage process was investigated by combining grazing incident angle X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). Subsequent to the 2% volume swelling at a fluence of 1 × 10¹⁴ ions/cm² (0.037 dpa), the initially swollen LCTO pyrochlore formed both a disordered fluorite phase and a nanocrystalline pyrochlore phase at a fluence of 5 × 10¹⁴ ions/cm² (0.185 dpa). At higher fluences, the fluorite phase diminished as amorphous domains increased in volume when the dose reached a fluence of 1 × 10¹⁵ ions/cm² (0.371 dpa), while the nanocrystalline pyrochlore phase persisted. At the highest fluence of 5 × 10¹⁵ ions/cm² (1.854 dpa), the amorphous fraction decreased, meanwhile the degree of crystallinity of nanocrystalline pyrochlore phase was enhanced, as evidenced by the increased intensity of superlattice diffraction maxima. The phase transformation and recrystallization can be explained by the release of strain in irradiation-induced swollen pyrochlore crystallites. The evolution of the damage process is mainly driven by the differences in the Gibb's free energies of fluorite phase as compared with the pyrochlore phase as a function of grain size. We have demonstrated that ion beam techniques can be used to manipulate the phase stability and crystallite size of pyrochlore. These results provide the basis for tailoring the mechanical strength and response of pyrochlores to extreme radiation environments.     

Marked reduction in the thermal conductivity of (La0.2Gd0.2Y0.2Yb0.2Er0.2)2Zr2O7 high-entropy ceramics by substituting Zr4+ with Ti4+

The (La_0.2Gd_0.2Y_0.2Yb_0.2Er_0.2)₂(Zr_1-xTi_x)₂O₇ (x = 0–0.5) high-entropy ceramics were successfully prepared by a solid state reaction method and their structures and thermo-physical properties were investigated. It was found that the high-entropy ceramics demonstrate pure pyrochlore phase with the composition of x = 0.1–0.5, while (La_0.2Gd_0.2Y_0.2Yb_0.2Er_0.2)₂Zr₂O₇ shows the defective fluorite structure. The sintered high-entropy ceramics are dense and the grain boundaries are clean. The grain size of high-entropy ceramics increases with the Ti⁴⁺ content. The average thermal expansion coefficients of the (La_0.2Gd_0.2Y_0.2Yb_0.2Er_0.2)₂(Zr_1-xTi_x)₂O₇ high-entropy ceramics range from 10.65 × 10^?6 K^?1 to 10.84 × 10^?6 K^?1. Importantly, the substitution of Zr⁴⁺ with Ti⁴⁺ resulted in a remarkable decrease in thermal conductivity of (La_0.2Gd_0.2Y_0.2Yb_0.2Er_0.2)₂(Zr_1-xTi_x)₂O₇ high-entropy ceramics. It reduced from 1.66 W m^?1 K^?1 to 1.20 W m^?1 K^?1, which should be ascribed to the synergistic effects of mass disorder, size disorder, mixed configuration entropy value and rattlers.     

Effects of Gd3+ substitution on the structure,photoluminescence, scintillation,and thermometric features of Pr3+:Lu2Zr2O7 phosphors

In this study, it is shown how the photoluminescence, scintillation, and optical thermometric properties are managed via the introduction of Gd³⁺ ions into Pr³⁺:Lu₂Zr₂O₇. Raman spectra validate that partial replacement of Lu³⁺ with Gd³⁺ can promote the phase transition of Lu₂Zr₂O₇ host from the defective fluorite structure to the ordered pyrochlore one. Upon 289 nm excitation, all the samples emit the 483 (³P₀ → ³H₄), 581 (¹D₂ → ³H₄), 611 (³P₀ → ³H₆), 636 (³P₀ → ³F₂), and 714 nm (³P₀ → ³F₄) emissions from Pr³⁺ ions, which are enhanced with the addition of Gd³⁺ ions due to the modification of crystal structure. Dissimilarly, the X-ray excited luminescence spectra consist of a strong emission located at 314 nm from Gd³⁺ ions (⁶P_7/2 → ⁸S_7/2), together with the typical emissions from Pr³⁺ ions, which exhibit different dependences on the Gd³⁺ concentration. When the luminescence intensity ratio between the ³P₀ → ³H₆ (611 nm) and ¹D₂ → ³H₄ (581 nm) transitions is selected for temperature sensing, Pr³⁺:(Lu_0.75Gd_0.25)₂Zr₂O₇ shows the optimal relative sensing sensitivity of 0.78% K⁻¹ at 303 K, which is higher than that of the Gd³⁺-free sample. Therefore, the developed Pr³⁺:(Lu, Gd)₂Zr₂O₇ phosphors have the applicative potential for optical thermometry, X-ray detection, and photodynamic therapy.     

Irradiation response of Al2O3-ZrO2 ceramic composite under He ion irradiation

The dense Al₂O₃-ZrO₂ ceramic composite prepared by spark plasma sintering was irradiated by 500 keV He ions with different fluences and temperatures. The microstructural evolution and mechanical properties were investigated. The results showed that peak broadening and shifts at RT revealed by GIXRD and Raman are associated with damage induced microstrain and formation of point defects. The recovery at 500 °C suggested the reduction of irradiation induced damage. Compared with α-Al₂O₃, t-ZrO₂ exhibited a reverse trend in lattice parameters change and lattice expansion. Many helium bubbles with oblate and ribbon-like shape were mainly formed in α-Al₂O₃ grains at He concentration peak at 1.0 × 10¹⁷ ions/cm². With increasing of fluence at RT, ribbon-like helium bubbles developed into microcracks at 4.0 × 10¹⁷ ions/cm². Though evident structural changes, no full amorphization was observed at 4.0 × 10¹⁷ ions/cm². Formation of ribbon-like bubbles and microcracks is the main mechanism for degradation of mechanical properties of irradiated Al₂O₃-ZrO₂ composite.     

Impact of ionizing radiation on structural,dielectric, and piezoelectric properties of Sr modified PZT

Ion irradiation effects on piezoceramic (Pb_0.94 Sr_0.04) (Zr_0.52 Ti_0.48)O₃ (PSZT) are investigated by using 4 MeV carbon (C), 9 MeV copper (Cu), and 20 MeV gold (Au) ions. The energies of incident ions are selected in order to target the same range of all incident ions in the material, while producing different amounts of vacancies. The ion irradiation is performed with fluences of 1×10¹³, 1×10¹⁴, and 1×10¹⁵ ions/cm² using Tandem Pelletron accelerator (5UDH-2). Post irradiation changes in PSZT are investigated via various structural, dielectric, and piezoelectric measurement techniques. Results divulge that the irradiation process disturbs the crystallinity along with reduction in X-ray diffraction (XRD) peak intensities owing to strain induced structural defects. A small decrease in dielectric constant is observed due to trapped charges, which screen the depolarization after irradiation. However, a significant decrease is detected in piezoelectric charge coefficients (d₃₃) and piezoelectric voltage coefficients (g₃₃) due to switching of micro domains of PSZT as a result of energy observed during irradiation process. These results indicate that ion irradiation has damaging effects on the properties of PSZT. The discussed information may be utilized to assess performance of PSZT based devices under radiation rich environments such as space.     

Highly transparent Yb:Y2O3 ceramics obtained by solid-state reaction and combined sintering procedures

(Y_0.87-xLa_0.1Zr_0.03Yb_x)₂O₃ (x?=?0.02, 0.04, 0.05) transparent ceramics were obtained by solid-state reaction and combined sintering procedures with La₂O₃ and ZrO₂ as sintering additives. A method based on two-step intermediate sintering in air followed by vacuum sintering was applied in order to control the densification and grain growth of the samples during the final sintering process. The results indicate that La₂O₃ and ZrO₂ co-additives can improve the microstructure and optical properties of Yb:Y₂O₃ ceramics at relatively low sintering temperature. On the other hand, the addition of Zr⁴⁺ ions leads to the formation of dispersed scattering volumes in the ceramic bodies. Transmittance of 78.8% was measured for the 2.0?at% Yb:Y₂O₃ ceramic sample at the wavelength of 1100?nm. The spectroscopic properties of Yb:Y₂O₃ ceramics were investigated at room temperature. The obtained results show that the absorption cross-section at 978?nm is in the range of 2.08?×?10^–20 to 2.36?×?10^–20 cm², whereas the emission cross-section at 1032?nm is ~1.0?×?10^–20 cm².