Priprava SrTiO3 keramičnih kompozitov z nizkotemperaturnim postopkom zgoščevanja

Terbovšek, Eva (author), Spreitzer, Matjaž (mentor), Krajnc, Matjaž (co-mentor)

Keramika na osnovi stroncijevega titanata (SrTiO3, krajše ST) je primer sodobne keramike, ki se v veliki meri uporablja na področju elektronike. Običajno se ga pripravlja z visokotemperaturnim procesom (sintranje), ki je energetsko in časovno zelo potraten. Zaradi tega potekajo raziskave v smeri razvoja novih postopkov za pripravo elektronskim elementov na osnovi keramike pri nižjih temperaturah. Eden takšnih je postopek zgoščevanja materialov pri sobni temperaturi. V magistrski nalogi sem ta postopek uporabila za pripravo 0-3 kompozitov na osnovi ST keramike. Osredotočila sem se na iskanje veziva, ki bi uspešno povezalo delce keramike, kar bi rezultiralo v visoki dielektrični konstanti in nizkih dielektričnih izgubah pripravljenih kompozitov. V preteklih študijah je bila že optimizirana priprava kompozitov pri sobni temperaturi na osnovi ST skupaj z Li2MoO4 vezivom. Usmerila sem se v iskanje novih veziv, ki bi jih lahko uporabili v nizkotemperaturnem postopku zgoščevanja. V ta namen sem sintetizirala in nato uporabila v pripravi kompozitov tri nova veziva; Na2MoO4, Na2WO4 in Na2SiO3. Rezultati FTIR in XRD analize so pokazali, da med pripravo kompozitov ni prišlo do tvorbe kemijskih vezi. Za primerjavo razporeditve delcev in mikrostrukture kompozitov z različnimi vezivi sem uporabila elektronski vrstični mikroskop skupaj z EDS »mapping« analizo. Glede na primerjavo dielektričnih lastnosti pripravljenih kompozitov so se uporabljena veziva izkazala kot odlična alternativa vezivu Li2MoO4. Postopek priprave kompozitov z zgoščevanjem pri sobni temperaturi in dodatnim korakom sušenja pri 110°C sem primerjala s postopkom, pri katerem sem kompozite stisnila pri povišani temperaturi; 130°C. Kompoziti pripravljeni s postopkom pri povišani temperaturi so imeli višjo dielektrično konstanto. V obeh primerih je imel najboljše dielektrične lastnosti kompozit z vezivom Na2SiO3. Pri postopku zgoščevanja pri sobni temperaturi je dielektrična konstanta omenjenega kompozita pri 1 MHz znašala 111, pri povišani temperaturi pa 134; dielektrične izgube so bile v obeh primerih 0,005.

• Language: Slovenian
• Keywords: stroncijev titanat, nizkotemperaturni postopek zgoščevanja, 0-3 kompozit, dielektrične lastnosti
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2023
• PID: 20.500.12556/RUL-146437
• COBISS.SI-ID: 158648835
• Publication date in RUL: 01.06.2023

Secondary language

• Language: English
• Title: Fabrication of SrTiO3 ceramic composites with low temperature densification method

Abstract

Ceramic based on strontium titanate (SrTiO3, abbreviated ST) is an example of modern ceramics that are widely used in the field of electronics. It is usually prepared by a high-temperature process (sintering), which is very energy- and time-consuming. Therefore, researchers are trying to develop fabrication procedures for electronic elements that are based on ceramic at lower temperatures. An example of this is room-temperature densification method. In my master thesis I used this process to prepare 0-3 composites based on ST ceramics. My focus was on finding such a binder that would successfully bind particles of ceramics together, resulting in a high relative permittivity and low dielectric losses of prepared composite. In previous studies, the fabrication process of composite at room temperature, based on ST with Li2MoO4 as a binder, has already been optimized. I focused on finding new binders that could be used in low-temperature densification process. For this purpose, I synthesized and then used in the preparation of composites three new binders: Na2MoO4, Na2WO4 in Na2SiO3. The results of FTIR and XRD analysis showed that no chemical bonds were formed during the fabrication of composites. For comparison of particles arrangement in composite and microstructure analysis, scanning electron microscope was used, combined with EDS mapping analysis. According to the comparison of dielectric properties of prepared composites, used binders proved to be an excellent alternative to the Li2MoO4 binder. Fabrication of composites with low-temperature densification method and an additional drying step at 110°C was compared with the process of composite pressing at elevated temperature; 130°C. Composites prepared at elevated temperature had higher value of dielectric constant. In both cases the composite with Na2SiO3 binder was shown to have the best dielectric properties. The relative permittivity of aforementioned composite obtained at 1 MHz was 111 for composite fabricated at room temperature and 134, respectively for composite fabricated at elevated temperature. Dielectric losses were 0.005 in both cases.

• Keywords: Strontium titanate, low-temperature densification method, 0-3 composite, dielectric properties