Analysis of TihxOy Films Produced by Physical Vapor Deposition Method

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Black carbon-doped TiO2 films: Synthesis, characterization and photocatalysis

This research is funded by the European Social Fund according to the activity ‘Improvement of researchers’ qualification by implementing world-class R&D projects’ of Measure No. 09.3.3-LMT- K-712, project „Investigation of the application of TiO2 and ZnO for the visible light assisted photocatalytical disinfection of the biologically contaminated water“ (09.3.3-LMT-K-712-01-0175). The authors express gratitude for the S. Tuckute, M. Urbonavicius, G. Laukaitis and K. Bockute for their valuable input in current work. © 2019. This work is licensed under a CC BY-NC-ND 4.0 license.Black colour TiO2 films were synthesized on amorphous fused silica substrates by DC magnetron sputtering technique with carbon powders placed at the working magnetron surface. Comprehensive sample analysis by X-ray diffraction, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy showed that the rutile/anatase heterostructure TiO2 films were successfully formed. Moreover, observation of Osingle bondTisingle bondC bonds confirmed that TiO2 phase was doped by carbon additives. Scanning electron microscopy, atomic force microscopy and X-ray diffraction were used to identify the effect of deposition time and TiO2 film thickness on the surface morphology, roughness and crystallite size. Results of electron spin resonance showed that oxygen vacancies were generated on the surface with trapped unpaired electrons. Optical analysis by UV–vis light spectrophotometer showed that TiO2 films with carbon additives improve its capability to absorb visible light. Accordingly, methylene blue bleaching experiments under UVsingle bondA and visible light irradiation showed that black colour TiO2 films are capable to decompose methylene blue solution at both UVsingle bondA and visible light irradiation.----/ / /---- This is the preprint of the following article: Sarunas Varnagiris, Arturs Medvids, Martynas Lelis, Darius Milcius, Andris Antuzevics, Black carbon-doped TiO2 films: Synthesis, characterization and photocatalysis, Journal of Photochemistry and Photobiology A: Chemistry Volume 382, 1 September 2019, 111941 (2019), DOI 10.1016/j.jphotochem.2019.111941, which has been published at https://www.sciencedirect.com/science/article/abs/pii/S1010603019303442. This article may be used for non-commercial purposes in accordance with Elsevier Terms and Conditions for Sharing and Self-Archiving. This work is licensed under a CC BY-NC-ND 4.0 license.European Social Fund 09.3.3-LMT-K-712-01-0175; Institute of Solid State Physics, University of Latvia as the 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

Investigation of substrate surface effects on kinetics of thin Mg-Ni, Mg and Mg-Ti films hydrogenation

Įprastai plonų metalų hidridų dangų tyrimuose didžiausias dėmesys skiriamas pačios dangos sudėčiai, storiui ir kt. savybėms, tuo tarpu padėkliukas, ant kurio garinama danga, laikomas laisvai pasirenkamu kintamuoju, kurio potenciali įtaka dangos hidrinimuisi yra visiškai nenagrinėjama. Todėl pagrindinis šio disertacinio darbo tikslas buvo eksperimentiškai ištirti, ar vien skirtingų padėkliukų bei skirtingo jų paruošimo metodų naudojimas yra pakankamas veiksnys siekiant modifikuoti pasirinktos medžiagos plonų dangų hidrinimosi savybes. Tikslui pasiekti darbe tiriama skirtingais plazmos režimai paveiktų silicio ir politetrafluoroeteno padėkliukų įtaka Mg-Ni, Mg ir Mg-Ti plonų dangų hidrinimo kinetikai, kristalinių fazių formavimuisi ir dangų mikrostruktūrai. Gautieji eksperimentiniai rezultatai parodė, kad skirtingų paviršinių savybių padėkliukų panaudojimas leidžia valdyti kokia kristalinė hidrido fazė yra suformuojama Mg-Ni plonų dangų hidrinimo metu. Darbe pateikti aiškinamieji modeliai, kurie susieja Mg-Ni dangų hidrinimosi ypatybes su padėkliukų chemine sudėtimi ir fizikinėmis savybėmis. Mg-Ni tyrimų metu pastebėti padėkliukų įtakos dėsningumai ir prielaidos buvo papildomai patikrinti panaudojant Mg ir Mg-Ti dangas. Tyrimai su papildomomis medžiagomis, taip pat parodė esant sąryšių tarp padėkliukų paviršinių savybių ir hidrinimo metu dangose vykstančių pokyčių.In thin metal hydrides research and applications most of the attention is paid to the hydrogen adsorbing material and modification of its properties, meanwhile the potential effect of substrate and its interaction with the film is not investigated. Therefore the main aim of this research work was to test experimentally if using dissimilar substrates and varying their pretreatment conditions alone could have significant effects to change hydrogenation properties of selected materials in thin film form. For this purpose it was tested how silicon and polytetrafluoroethylene substrates with different plasma pretreatment effects the hydrogenation properties of Mg-Ni, Mg and Mg-Ti thin films. The observed results revealed that differing properties of the substrates surfaces have significant effect on hydrogenation of Mg-Ni thin films and purposive selection of particular substrates can be used to control the formation of particular phase of Mg-Ni hydride. Experimental observations for Mg-Ni thin films were linked to the chemical composition and physical properties of the substrates. In order to test if the findings with Mg-Ni thin films can be applied to other hydrogen adsorbing films, additional research was made by using Mg and Mg-Ti thin films deposited on the same differing substrates. For later films the influence of substrate properties to the thin film behaviour during hydrogenation was also observed.Vytauto Didžiojo universiteta

Hydrinimo procesų indukuoti struktūriniai virsmai Mg-Ni dangose

We investigated thin film samples of Mg2NiH4 with two intentions. First of all, we wanted to ascertain if the same nanomaterial (Mg2NiH4) prepared by magnetron sputtering and ball milling can exhibit different hydrogen storage properties and to see possible advantages/disadvantages of employing of magnetron sputtering for synthesis of nanometerials for hydrogenstorage. Furthermore, we wanted to see if thin film samples of Mg2NiH4 could be used in a switchable mirror or window device by utilizing the high to low temperature transition at about 510 K. In powder samples, this transition, between a monoclinic conducting low temperature phase to an FCC non-conducting high temperature phase, have been demonstrated in a mechanical reversible conductor–insulator transition [Blomqvist and Nor��us, J. Appl. Phys 91(2002)5141]. The new thin film Mg2NiH4 samples were produced by reacting hydrogen with magnetron sputtered Mg2Ni films on quartz glass or CaF2 substrates. But we could not obtain the monoclinic low temperature phase upon cooling the samples. Instead a cubic phase, related but not identical to the cubic high temperature phase, was formed at temperatures both below and above 510 K. TEM pictures revealed the new cubic phase in the films to have the same cell parameter as the FCC high temperature phase. But the symmetry was lower with similar streaking patterns as observed for the monoclinic low temperature phase. IR-spectroscopy indicated an identical vibrational frequency for the allowed stretching mode of the tetrahedral NiH4-complex both in film and powder samples. Band gap measurements indicated a band gap of 2.3 eV for the films but 1.1 eV for monoclinic Mg2NiH4 powders. The films were transparent with a yellow colour that gradually deepened into red when heating up to 600 K in hydrogen. A typical first order phase transition from a low to high temperature phase could not be observed with DSC when heating through the low- to high temperature phase transition at 510 K. A severely strained film was revealed with optical microscopy in reflected light. This observed microstrain may reflect a prevailing intrinsic structural strain. We assume that strain in the film prevents the NiH4-complexes from fully relaxing back into an ordered arrangement as in the monoclinic structure. Concluding it can be said that magnetron sputtering gave somehow different results from those received for powder material and this “structure locking” can by typical artefact for the thin films not achievable by the ball milling technique.Tiriamojo darbo metu magnetroniniu garinimu suformuotos Mg-Ni dangos, kurios hidrintos esant aukštai temperatūrai ir vandenilio slėgiui. Hidrintos dangos ištirtos įvairiais analizės metodais, siekiant nustatyti magnetronio garinimo būdu suformuotos medžiagos (magnio nikelio hidrido) skirtumus nuo rutulinio trynimo metodu gautos analogiškos medžiagos. Darbe išanalizuoti duomenys ir pateiktas aiškinamasis modelis, kuris atskleidžia plonų dangų ypatybes, dėl kurių dangose pilnai neįvyksta dangos relaksacijos procesai. Nustatyta, kad dėl tų pačių priežasčių, dangų panaudojimo „įjungiamiesiems veidrodžiams“ galimybės yra ribotos.Vytauto Didžiojo universiteta

Investigation of Catalyst Development from Mg2NiH4 Hydride and Its Application for the CO2 Methanation Reaction

In current study various aspects of catalyst development for the Sabatier type methanation reaction were investigated. It was demonstrated that starting from 330–380 °C Mg2NiH4 hydride heating under CO2 and H2 gas flow initiates hydride decomposition, disproportionation and oxidation. These reactions empower catalytic properties of the material and promotes CO2 methanation reaction. Detailed structural, colorimetric and thermogravimetric analysis revealed that in order to have fast and full-scale development of the catalyst (formation of MgO decorated by nanocrystalline Ni) initial hydride has to be heated above 500 °C. Another considerable finding of the study was confirmation that potentially both high grade and low grade starting Mg2Ni alloy can be equally suitable for the hydride synthesis and its usage for the promotion of methanation reactions

Padėkliukų paviršiaus įtakos plonų Mg-Ni, Mg ir Mg-Ti dangų hidrinimo kinetikai tyrimas

In thin metal hydrides research and applications most of the attention is paid to the hydrogen adsorbing material and modification of its properties, meanwhile the potential effect of substrate and its interaction with the film is not investigated. Therefore the main aim of this research work was to test experimentally if using dissimilar substrates and varying their pretreatment conditions alone could have significant effects to change hydrogenation properties of selected materials in thin film form. For this purpose it was tested how silicon and polytetrafluoroethylene substrates with different plasma pretreatment effects the hydrogenation properties of Mg-Ni, Mg and Mg-Ti thin films. The observed results revealed that differing properties of the substrates surfaces have significant effect on hydrogenation of Mg-Ni thin films and purposive selection of particular substrates can be used to control the formation of particular phase of Mg-Ni hydride. Experimental observations for Mg-Ni thin films were linked to the chemical composition and physical properties of the substrates. In order to test if the findings with Mg-Ni thin films can be applied to other hydrogen adsorbing films, additional research was made by using Mg and Mg-Ti thin films deposited on the same differing substrates. For later films the influence of substrate properties to the thin film behaviour during hydrogenation was also observed.Įprastai plonų metalų hidridų dangų tyrimuose didžiausias dėmesys skiriamas pačios dangos sudėčiai, storiui ir kt. savybėms, tuo tarpu padėkliukas, ant kurio garinama danga, laikomas laisvai pasirenkamu kintamuoju, kurio potenciali įtaka dangos hidrinimuisi yra visiškai nenagrinėjama. Todėl pagrindinis šio disertacinio darbo tikslas buvo eksperimentiškai ištirti, ar vien skirtingų padėkliukų bei skirtingo jų paruošimo metodų naudojimas yra pakankamas veiksnys siekiant modifikuoti pasirinktos medžiagos plonų dangų hidrinimosi savybes. Tikslui pasiekti darbe tiriama skirtingais plazmos režimai paveiktų silicio ir politetrafluoroeteno padėkliukų įtaka Mg-Ni, Mg ir Mg-Ti plonų dangų hidrinimo kinetikai, kristalinių fazių formavimuisi ir dangų mikrostruktūrai. Gautieji eksperimentiniai rezultatai parodė, kad skirtingų paviršinių savybių padėkliukų panaudojimas leidžia valdyti kokia kristalinė hidrido fazė yra suformuojama Mg-Ni plonų dangų hidrinimo metu. Darbe pateikti aiškinamieji modeliai, kurie susieja Mg-Ni dangų hidrinimosi ypatybes su padėkliukų chemine sudėtimi ir fizikinėmis savybėmis. Mg-Ni tyrimų metu pastebėti padėkliukų įtakos dėsningumai ir prielaidos buvo papildomai patikrinti panaudojant Mg ir Mg-Ti dangas. Tyrimai su papildomomis medžiagomis, taip pat parodė esant sąryšių tarp padėkliukų paviršinių savybių ir hidrinimo metu dangose vykstančių pokyčių.Vytauto Didžiojo universiteta

Padėkliukų paviršiaus įtakos plonų MG-NI, MG ir MG-TI dangų hidrinimo kinetikai tyrimas : daktaro disertacija : fiziniai mokslai. fizika (02 P)

Disertacija rengta 2008-2012 metais Vytauto Didžiojo universiteto fizikos katedroje ir Lietuvos energetikos instituto Vandenilio energetikos technologijų centreBibliogr.: p. 156-168Gamtos mokslų fakultetasVytauto Didžiojo universiteta

Magnesium nickel hydride - presumable smart material for energy related applications

Magnesium nickel hydride Mg2NiH4 was discovery by Reilly and Wiswall in 1968 [1]. Since then it became a target of many fundamental and application (mainly hydrogen storage) driven studies. It was revealed that in powder form Mg2NiH4 has three crystal phases: LT-1 and LT-2 are both monoclinic low temperature (below 510 K) phases respectively without and with microtwinings [2-3], and HT is FCC non-conducting high temperature (above 510 K) phase. For Mg2NiH4 powders, phase transition between low temperature and high temperature phases is reversible [3]. Each of these phases has unique optical and electrical properties, therefore properly using these phase transitions could lead to the creation of smart material presumably suitable for smart windows devices, new generation of wide band gap solar cells or even metal hydride batteries. This presentation reviews main requirements and available fundamental prerequisites for Mg2NiH4 to be used as smart material for energy applicationsFizikos katedraVytauto Didžiojo universiteta

Hydrogen storage in Mg-based nanocrystalline metal hydrides

In this paper, attention in focused on the nanostructured magnesium films for hydrogen storage.It is shown that 2um thick Mg film is transformed into MgH2 film under highflux and fluence hydrogen plasma immersion ion implantation at 450K for 15min. All hydrogen desorbs around 530K temperature, which corresponds to the decomposition of MgH2 Mg+H2. The Mg-based hydrides compounds are too stable for practical applications and can be destabilized by adding small amount of transition metals (Ti, V, Ni).The results provide new aspects of hydriding of thin nanocrystalline film materials under highly nonequalibrium conditions on the surface and destabilization oh hydrides using additivesLietuvos energetikos instituta

Hydrogen storage in Mg-based nanocrystalline metal hydrides

In this paper, attention in focused on the nanostructured magnesium films for hydrogen storage.It is shown that 2um thick Mg film is transformed into MgH2 film under highflux and fluence hydrogen plasma immersion ion implantation at 450K for 15min. All hydrogen desorbs around 530K temperature, which corresponds to the decomposition of MgH2 Mg+H2. The Mg-based hydrides compounds are too stable for practical applications and can be destabilized by adding small amount of transition metals (Ti, V, Ni).The results provide new aspects of hydriding of thin nanocrystalline film materials under highly nonequalibrium conditions on the surface and destabilization oh hydrides using additivesLietuvos energetikos instituta