Študij priprave tankih plasti natrijevega niobata s sintezo v raztopini

Grižnik, Mojca (avtor), Malič, Barbara (mentor), Cerc Korošec, Romana (komentor)

V okviru magistrskega dela sem pripravila tanke plasti natrijevega niobata s sintezo v raztopini. Poleg prekurzorske raztopine v organskem topilu, ki je služila kot referenca, sem pripravila tudi vodno raztopino prekurzorja natrijevega niobata. Pripravila sem tudi prekurzorski raztopini z dodatkom 1 množinskega % Mn kot dopanta. Raziskala sem vpliv izbire prekurzorjev in pogojev toplotne obdelave na fazno sestavo, mikrostrukturo in funkcijski odziv tankih plasti. Alkoksidno prekurzorsko raztopino sem pripravila iz natrijevega acetata, niobijevega(V) etoksida ter dietanolamina, pri čemer sem kot topilo uporabila 2-metoksietanol. Plasti sem pripravila s petimi ponovitvami nanosa raztopine na podlago platiniziranega silicija z metodo vrtenja podlage, sušenja in pirolize, ter končnim segrevanjem pri 650 °C. Plasti so kristalizirale v perovskitni fazi. Debelina plasti je bila okrog 150 nm, velikost zrn na površini pa okrog 300 nm pri hitrosti segrevanja ≤ 12,5 K/s. Hitrost segrevanja je nekoliko vplivala na povprečno velikost zrn in njihovo velikostno porazdelitev. S piezoelektričnim modulom mikroskopa na atomsko silo smo potrdili, da plasti izkazujejo lokalni piezoelektrični in feroelektrični odziv. Vodno prekurzorsko raztopino sem pripravila iz natrijevega nitrata in amonijevega niobijevega oksalata hidrata ter ji dodala polivinil alkohol v 1 masnem odstotku za boljše omakanje podlage. Segrevanje plasti po petih nanosih raztopine na podlago je ne glede na hitrost segrevanja vodilo do kristalizacije faze Na2Nb4O11. Plasti so kristalizirale v perovskitni fazi samo, če smo jih pripravili tako, da smo jih segrevali po vsakem nanosu raztopine na podlago, torej v celoti petkrat pri 600 °C. Debelina plasti je bila okrog 100–140 nm, velikost zrn na površini plasti pa okrog 350 nm. Vzorci so izkazali šibek piezo- in feroelektrični odziv, ki se je nekoliko izboljšal z dodatkom mangana.

• Jezik: Slovenski jezik
• Ključne besede: tanke plasti, NaNbO3, sinteza v raztopini, mikrostruktura, lokalne električne lastnosti
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2021
• PID: 20.500.12556/RUL-127572
• COBISS.SI-ID: 68044291
• Datum objave v RUL: 15.06.2021

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Study of Chemical Solution Deposition of Sodium Niobate Thin Films

Izvleček

In the master thesis, sodium niobate thin films were prepared by chemical solution deposition. The precursor solution, which served as a reference, was synthesized in an organic solvent. In addition, the sodium niobate precursor was also synthesized in an aqueous solution. To both solutions, 1 mol% of manganese was added as a dopant and the influence of the choice of precursor and heat treatment conditions on the phase composition, microstructure and functional response of the sodium niobate thin film was investigated. The reference precursor solution was prepared from sodium acetate, niobium(V) ethoxide and diethanolamine in 2-methoxyethanol as solvent. The films were prepared by repeating the deposition of the solution on a platinized silicon substrate five times by spin-coating, drying and pyrolysis with the final heating at 650 °C. The films crystallized in the perovskite phase. The film thickness was about 150 nm and the surface grain size was about 300 nm at the heating rate ≤ 12.5 K/s. The heating rate slightly affected the average grain size and size distribution. Using a piezoelectric module of the atomic force microscope, we confirmed that the films showed local piezoelectric and ferroelectric responses. The aqueous precursor solution was prepared from sodium nitrate and ammonium niobium oxalate hydrate with the addition of 1 wt% polyvinyl alcohol to improve substrate wetting. Final annealing of the films after applying the solution five times resulted in crystallization of the Na2Nb4O11 phase, regardless of the heating rate. The films crystallized in the perovskite phase only when they were annealed after each deposition of the solution onto the substrate, followed by drying and pyrolysis steps, i.e., a total of five times at 600 °C. The thickness of the films was about 100–140 nm, and the surface grain size was about 350 nm. The samples exhibited weak piezoelectric and ferroelectric behaviour, which was slightly improved by the addition of manganese.

• Ključne besede: thin films, NaNbO3, chemical solution deposition, microstructure, local electrical properties