Oxygen diffusion in pure and doped ZnO

Abstract

Oxygen diffusion coefficients in pure and doped ZnO polycrystals were determined by means of the gas-solid isotope exchange method using the isotope 18O as oxygen tracer. The diffusion experiments were performed from 900 to 1000 °C, under an oxygen pressure of 10(5) Pa. After the diffusion annealings, the 18O diffusion profiles were determined by secondary ion mass spectrometry. The results of the experiments show that oxygen diffusion in Li-doped ZnO is similar to the oxygen diffusion in pure ZnO, while in Al-doped ZnO the oxygen diffusion is enhanced in relation to that observed in pure ZnO, in the same experimental conditions. Based on these results is proposed an interstitial mechanism for oxygen diffusion in ZnO. Moreover, it was found that oxygen grain-boundary diffusion is ca. 3 to 4 orders of magnitude greater than oxygen volume diffusion in pure and doped ZnO, which means that the grain-boundary is a fast path for oxygen diffusion in ZnO

Investigation of native defects and property of bulk ZnO single crystal grown by a closed chemical vapor transport method

“…Since our ZnO samples are grown under a Zn-rich condition by CVT, it is reasonable that the Zn I and O V defects exist in our asgrown ZnO sample. On the other hand, according to the published diffusion experimental results [35,36], the diffusion coefficient of O atom and Zn atom in ZnO is around 10 À15 and 10 À6 cm 2 /s, respectively. The excess Zn must be removed and Zn I is annihilated from the ZnO sample through out-diffusion in the annealing process.…”

Chemical Vapor Synthesis of Size‐Selected Zinc Oxide Nanoparticles

“…The grainboundary diffusion coefficient of zinc was used for calculation because of the much higher diffusivity value of zinc compared to that of oxygen. [58,61] Figure 7 a shows the dependence of the primary-particle diameter (D pi = 2r i ) on t GB as a function of temperature. The experimental residence times in the sintering furnace at 25 8C (4.6 s) and 1000 8C (1.1 s) are also shown in Figure 7 a and it should be noted that the residence time decreases with an increase in sintering temperature.…”

First-principles study of migration mechanisms and diffusion of oxygen in zinc oxide

“…4 The interpretation of diffusion experiments is, however, often difficult and evidence for defect properties is indirect. In the past several experimental studies have been concerned with the determination of selfdiffusion coefficients, [5][6][7][8][9][10] but the data scatter is large and no consensus on activation energies, exponential prefactors, or migration mechanisms has been achieved. Therefore, a systematic theoretical investigation is highly desirable in order to obtain more fundamental insights on the subject.…”