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Title:KRISTALIZACIJA IN RAZVOJ MIKROSTRUKTURE TANKIH PLASTI K 0.5 Na 0.5 NbO 3 -SrTiO 3 PRIPRAVLJENIH S SINTEZO IZ RAZTOPIN
Authors:ID Pečnik, Tanja (Author)
ID Goršek, Andreja (Mentor) More about this mentor... New window
Files:.pdf UNI_Pecnik_Tanja_2012.pdf (3,29 MB)
MD5: 39553E0BC8BEA7405CFB126436CE0520
PID: 20.500.12556/dkum/ce8bf0b9-a5dd-4d3f-acfd-51b872c8806c
 
Language:Slovenian
Work type:Undergraduate thesis (m5)
Typology:2.11 - Undergraduate Thesis
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:V delu opisujemo študij kristalizacije in razvoja mikrostrukture tankih plasti na osnovi trdne raztopine 0,85 K0.5Na0.5NbO3 – 0,15 SrTiO3 (KNN-STO), pripravljenih s sintezo iz raztopin, na platiniziranih silicijevih podlagah. Raztopino KNN-STO smo pripravili iz kalijevega acetata KO2C2H3, natrijevega acetata NaO2C2H3, niobijevega etoksida Nb(OEt)5, titanovega propoksida Ti(OC2H4CH3)4 in stroncijevega nitrata Sr(NO3)2. Kot topilo smo uporabili 2-metoksietanol CH3OCH2CH2OH. Plasti smo segrevali po dvostopenjskem in štiristopenjskem postopku segrevanja, kar pomeni, da smo jih po stopnji pirolize segrevali do končne temperature po vsakem drugem, oziroma po vsakem nanosu raztopine s koncentracijo cM = 0,4 M na podlago. Plasti, pripravljene iz raztopin različnih koncentracij (0,1 M, 0,2 M, 0,4 M), smo segrevali do končne temperature po vsakem nanosu raztopine na podlago. Rentgenski difraktogrami plasti kažejo, da vse plasti, ki smo jih segrevali po opisanih postopkih do temperatur med 500 °C in 700 °C, kristalizirajo v perovskitni fazi s psevdo-kubično osnovno celico brez izrazite kristalografske usmerjenosti. Mikrostruktura plasti je odvisna od pogojev priprave. Plasti, pripravljene iz raztopine KNN-STO s koncentracijo 0,4 M z dvostopenjskim segrevanjem, imajo enakomerno mikrostrukturo z enakoosnimi zrni, velikimi ~20 nm, medtem ko je mikrostruktura plasti, pripravljenih s štiristopenjskim segrevanjem, heterogena z zrni velikosti od ~20 nm do ~100 nm. Mikrostruktura plasti, ki smo jih pripravili iz raztopin KNN-STO z različnimi koncentracijami in segrevali po vsakem nanosu, je heterogena, z zrni velikosti od ~50 nm do ~150 nm. Pogoji priprave tankih plasti KNN-STO vplivajo tudi na njihove dielektrične lastnosti. Plasti, pripravljene z dvostopenjskim segrevanjem, imajo večjo vrednost dielektrične konstante kot plasti, pripravljene s štiristopenjskim segrevanjem. Vrednost dielektričnosti se povečuje z naraščajočo temperaturo in časom segrevanja. Plast KNN-STO, pripravljena z dvostopenjskim segrevanjem pri temperaturi T=700 °C in času t=15 min ima največjo dielektričnost in nizke dielektrične izgube, in sicer 700 in 0,04 pri sobni temperaturi in pri frekvenci 100 kHz. Izmerili smo temperaturno in frekvenčno odvisnost dielektričnosti in dielektričnih izgub omenjenega vzorca in ugotovili, da kaže značilen relaksorski odziv, podobno kot volumenska keramika z enako kemijsko sestavo.
Keywords:Tanke plasti, K0.5Na0.5NbO3 – SrTiO3, sinteza iz raztopin, mikrostruktura, kristalizacija, dielektričnost.
Year of publishing:2012
Publisher:[T. Pečnik]
Source:Maribor
PID:20.500.12556/DKUM-36997 New window
UDC:620.1/.2:666
COBISS.SI-ID:26082599 New window
NUK URN:URN:SI:UM:DK:SYLOX99S
Publication date in DKUM:23.07.2012
Views:2045
Downloads:183
Metadata:XML RDF-CHPDL DC-XML DC-RDF
Categories:KTFMB - FKKT
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Secondary language

Language:English
Title:CRYSTALLIZATION AND EVOLUTION OF MICROSTRUCTURE OF K 0.5 Na 0.5 NbO 3 -SrTiO 3 THIN FILMS PREPARED BY CHEMICAL SOLUTION DEPOSITION
Abstract:The work describes the study of crystallization and evolution of microstructure of the 0,85 K0.5Na0.5NbO3 – 0,15 SrTiO3 solid solution based thin films, prepared by Chemical Solution Deposition, on platinized silicon substrates. The solution was synthesized from potassium acetate KO2C2H3, sodium acetate NaO2C2H3, niobium-pentaethoxide Nb(OEt)5, titanium-n-propoxide Ti(OC2H4CH3)4, strontium nitrate Sr(NO3)2, and the solvent 2-methoxyethanol CH3OCH2CH2OH. The films, deposited from the solution with the 0˙4 M concentration by spin-coating, were heated at different temperatures and times by the two-step and four-step rapid thermal annealing. Furthermore, we prepared the films from the solutions with different concentrations, namely 0,1 M, 0,2 M, and 0,4 M, and annealing after each deposition . According to X-ray diffraction analysis, the films crystallized in perovskite phase with a pseudo-cubic unit cell upon heating to temperatures between 500 °C and 700 °C. We observed no preferential orientation of the perovskite phase. The films, prepared by the two-step annealing have got granular and homogeneous microstructures with the grain size of ~20 nm, while the microstructures of the films, prepared by the four-step annealing, are quite heterogeneous with equiaxed grains ranging from ~20 nm to ~100 nm. The films, prepared from the solutions with different concentrations and annealing after each deposition, have got heterogeneous microstructures with the grain size from ~50 nm to ~150 nm. The dielectric permittivity of the KNN-STO films depends on the heating profile. The films, processed by the two-step annealing have got higher values of dielectric permittivity than the films prepared by the four-step annealing. In both cases, the permittivity increases with longer annealing time and higher annealing temperature. The highest dielectric permittivity was obtained for the films, prepared by the two-step annealing at 700 °C for 15 min, namely 700 at room temperature and 100 kHz. The temperature and frequency dependent dielectric measurements revealed the relaxor-like behaviour of the KNN-STO film, similar as the bulk ceramic with the same chemical composition.
Keywords:Thin films, K0.5Na0.5NbO3 – SrTiO3, chemical solution deposition, microstructure, crystallization, dielectric permittivity.


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