Priprava (Ni$_{0,2}$Mg$_{0,2}$Co$_{0,2}$Cu$_{0,2}$Zn$_{0,2}$)O visoko entropijskega oksida z uporabo citratno-nitratne zgorevalne sinteze

Borovšak, Filip (avtor), Marinšek, Marjan (mentor)

Visoko entropijske keramike so bile odkrite na podlagi implementacije principov, poznanih iz visoko entropijskih zlitin na keramične materiale, in predstavljajo pomembno smer razvoja novih materialov znotraj ved o materialih. Njihove edinstvene lastnosti, ki izhajajo iz visoko entropijske narave teh materialov, jih delajo primerne za uporabo na najrazličnejših področjih, kot so kataliza, elektronika, termomehanika, optika in magnetizem. Prav zaradi širokega spektra uporabe teh materialov se je pojavila težnja po razvoju novih metod sinteze, ki bi omogočale pripravo takšnih materialov. V tem magistrskem delu smo sintetizirali visoko entropijsko keramiko (Ni$_{0,2}$Mg$_{0,2}$Co$_{0,2}$Cu$_{0,2}$Zn$_{0,2}$)O z uporabo citratno-nitratne zgorevalne sinteze. Ta metoda je preprosta in uporablja le osnovno laboratorijsko opremo, zato predstavlja dobro alternativo obstoječim metodam sinteze. Pri njej smo iz vodne raztopine nitratov petih kovin in citronske kisline po sušenju pridobili citratno-nitratni gel, ki smo ga stisnili v tabletko. To smo nato prižgali in izvedli zgorevalno sintezo. Nastali oksidni prah smo nato kalcinirali v laboratorijski peči in s tem pridobili produkt. V začetku eksperimentalnega dela smo po tej metodi postopoma sintetizirali produkte mono-, dvo- in trokomponentnih oksidov. Pri sintezi zadnjih smo prav tako preverjali vpliv temperature kalciniranja na končni vzorec, pri čemer smo za optimum izbrali 900 °C. Sledila je uspešna sinteza (Ni$_{0,2}$Mg$_{0,2}$Co$_{0,2}$Cu$_{0,2}$Zn$_{0,2}$)O, kjer smo izbrali začetno citratno-nitratno razmerje 0,2 in vzorec kalcinirali 1 h pri 900 °C. V nadaljevanju smo metodo skušali optimizirati s preverjanjem vpliva začetnega citratno-nitratnega razmerja v vzorcu in časa kalcinacije na sestavo končnega vzorca. Pri tem smo ugotovili, da ima citratno-nitratno razmerje največji vpliv na sestavo vzorca pred kalcinacijo, pri čemer so bili vzorci z razmerjem 0,18 najčistejši. Po enourni kalcinaciji pri 900 °C so razlike v sestavi vzorcev z različnimi začetnimi citratno-nitratnimi razmerji zanemarljive. V drugem delu optimizacije smo preverjali, ali lahko pol ure daljša kalcinacija pri 800 °C proizvede podoben produkt kot enourna kalcinacija pri 900 °C. Pri tem smo ugotovili, da z daljšo kalcinacijo pri nižji temperaturi še vedno ne dosežemo enako kakovostnega produkta. Zaključili smo torej, da so optimalni parametri za pripravo (Ni$_{0,2}$Mg$_{0,2}$Co$_{0,2}$Cu$_{0,2}$Zn$_{0,2}$)O s citratno-nitratno zgorevalno sintezo citratno-nitratno razmerje v območju med 0,18 in 0,22 s kalcinacijo 1 h pri 900 °C. Na koncu smo rezultate primerjali še z literaturo.

• Jezik: Slovenski jezik
• Ključne besede: visoko entropijski oksid, zgorevalna sinteza, HEO, HEC
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2025
• PID: 20.500.12556/RUL-171847
• COBISS.SI-ID: 253688835
• Datum objave v RUL: 03.09.2025

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Preparation of (Ni$_{0,2}$Mg$_{0,2}$Co$_{0,2}$Cu$_{0,2}$Zn$_{0,2}$)O high-entropy oxide using citrate-nitrate combustion synthesis

Izvleček

High-entropy ceramics were discovered by implementing the principles, known from high-entropy alloys to ceramic materials and represent an important direction of development of new materials in the field of material sciences. The unique properties that result from the high-entropy nature of these materials make them useful in a large spectrum of fields, such as catalysis, electronics, thermomechanics, optics and magnetism. Precisely because of their large spectrum of applications a need for new synthesis methods of obtaining them has arisen. In the present master’s thesis, we prepared a high-entropy ceramic (Ni$_{0,2}$Mg$_{0,2}$Co$_{0,2}$Cu$_{0,2}$Zn$_{0,2}$)O using citrate-nitrate combustion synthesis. This method is simple and uses only basic laboratory equipment and as such represents a good alternative to other synthesis methods. Using it, we prepared a citrate-nitrate gel by drying an aqueous solution of five metal nitrates and citric acid. The obtained gel was then pressed in a tablet and ignited to produce an oxide mixture by combustion synthesis. Afterward the oxide mixture was calcined in a laboratory furnace to obtain the product. In the beginning of the experimental work, we firstly synthesised one-, two- and three-component oxides. During the synthesis of the latter, we also tested the impact of calcination temperature on the structure of the sample. The optimum temperature of calcination was 900 °C. Following was a successful synthesis of (Ni$_{0,2}$Mg$_{0,2}$Co$_{0,2}$Cu$_{0,2}$Zn$_{0,2}$)O, where a starting citrate-nitrate ratio was 0,2 and the sample was calcined for 1 h at 900 °C. Following this, we tried to optimise the method by testing the effect of starting citrate-nitrate ratio in the gel and the effect of the time of calcination on the compsition of the final sample. We discovered that the gel with starting citrate-nitrate ratio of 0,18 produced the purest sample before calcination. However, the effect of the starting citrate-nitrate ratio on the composition of the samples after calcination at 900 °C is negligible. In the second part of optimisation we tested if half an hour longer calcination at 800 °C resulted in a similar product as one hour calcination at 900 °C. We discovered that a longer calcination at lower temperature doesn’t produce the final product of the same quality. With that, we concluded that the optimal parameters for the preparation of (Ni$_{0,2}$Mg$_{0,2}$Co$_{0,2}$Cu$_{0,2}$Zn$_{0,2}$)O using citrate-nitrate synthesis were citrate-nitrate ratio of 0,18 to 0,22 and 1 h calcination at 900 °C. In the end we also compered our findings with the literature.

• Ključne besede: high-entropy oxide, combustion synthesis, HEO, HEC