Effect of Yb3+ doping level on the structure and spectroscopic properties of ZnO optical ceramics

This work was partly supported by the RFBR (Grant 19-03-00855).Zinc oxide optical ceramics with hexagonal structure doped with 0.6 –5.0 wt% Yb were fabricated by uniaxial hot pressing of commercial oxide powders at 1180 °C in vacuum. The ceramics were characterized by X-ray diffraction, SEM, EDX, X-ray and optical spectroscopy. It is shown that Yb3+ ions are distributed between C-type Yb2O3 sesquioxide crystals and ZnO grain boundaries. The Yb3+ doping of ZnO ceramics enhances the near-band-edge emission of zinc oxide. ZnO:Yb optical ceramics are promising for optoelectronic applications. © 2021 Institute of Physics Publishing. All rights reserved.RFBR (Grant 19-03-00855); The Institute of Solid State Physics, University of Latvia (Latvia), as the Centre of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase2 under grant agreement No. 739508, project CAMART2

A stability study of transparent conducting WO3/Cu/WO3 coatings with antimicrobial properties

This study was financially supported by ERDF project No. 1.1.1.1/21/A/050 “Large area deposition technologies of multifunctional antibacterial and antiviral nanocoatings”. The Institute of Solid State Physics, University of Latvia, as a Center of Excellence, has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART².WO3/Cu/WO3 coatings are transparent electrodes, but conductivity and transmittance have been observed to decrease with time. This paper reports the improved stability of WO3/Cu/WO3 coatings deposited by magnetron sputtering on glass and polyethylene terephthalate substrates. The stability issues due to Cu oxidation and migration can be addressed by adjusting the deposition parameters. Lowering the sputtering pressure results in denser WO3 films, confirmed by spectroscopic ellipsometry, and thus more stable coatings. The coatings retain their properties in an inert atmosphere, indicating that Cu oxidation is the main reason for the decrease in conductivity, rather than its migration observed by X-ray photoelectron spectroscopy. Optical property modeling is used to optimize the thickness of the three-layer coatings to obtain the highest figure-of-merit for a transparent electrode. A structure of glass/WO3 (70 nm)/Cu (10 nm)/WO3 (45 nm) gives a sheet resistance of 14 Ω/sq. and a light transmittance of 65% at 600 nm. In addition, the antimicrobial properties of these coatings are revealed. A decrease up to 105 of the gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacterial colony formation units is found for several WO3/Cu/WO3-based coatings. In the case of the MS2 (Emesvirus zinderi) bacteriophage, a decrease in infectious particles for up to 104 plaque-forming units is obtained. The results indicate that more stable samples also had higher antimicrobial activity. --//-- This is an open access article M. Zubkins, V. Vibornijs, E. Strods, I. Aulika, A. Zajakina, A. Sarakovskis, K. Kundzins, K. Korotkaja, Z. Rudevica, E. Letko, J. Purans, A stability study of transparent conducting WO3/Cu/WO3 coatings with antimicrobial properties, Surfaces and Interfaces, Volume 41, 2023, 103259, ISSN 2468-0230, https://doi.org/10.1016/j.surfin.2023.103259 published under the CC BY licence.ERDF project No. 1.1.1.1/21/A/050. The Institute of Solid State Physics, University of Latvia, as a Center of Excellence, has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

Comparative Study on Micromechanical Properties of ZnO:Ga and ZnO:In Luminiscent Ceramics

Indium (0.038 at.%) and gallium (0.042 at.%) doped ZnO ceramics were prepared by hot pressing. Ceramics were investigated to determine their structural and mechanical characteristics for the prospective use in scintillators. Based on results of nanoindentation, atom force and scanning electron microscopy as well as energy dispersive X-ray spectra measurements, locations of gallium within grain, indium at grain boundaries (GBs) and their different effect on the mechanical properties of ZnO ceramics were detected. Doping of gallium led to the increased modulus of elasticity in grain, decreased hardness near GBs, stabilization of micropores and brittle intercrystalline fracture mode. ZnO:In ceramic has modulus of elasticity and hardness values close to ZnO characteristics, the increased fracture toughness and some plasticity near GBs. Differences in the micromechanical properties of the ceramics correlate with the location of dopants. Results demonstrate that the ZnO:In ceramic has a greater stress relaxation potential than the ZnO:Ga

Impact of crystallisation processes on depth profile formation in sol-gel PbZr(0.52)Ti(0.48)O3 thin films

This study revealed the influence of crystallisation processes on the homogeneity of the sol‐gel PbZr0·52Ti0·48O3 thin films, allowing identification and further optimisation of thin film performance. Crystallisation processes determine the optical gradient appearance, irrespective of the chemical solvents used in this work. X-ray diffraction analysis showed that a refractive index gradient was apparent in the samples which had dominant (001)/(100) orientation and significant change of lattice parameters with thickness