Naslov
Permanganometric determination of oxygen nonstoichiometry in manganites

Autori
Žužić, Andreja ; Macan, Jelena

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
27HSKIKI Book of Abstracts / - , 2021

Skup
27. hrvatski skup kemičara i kemijskih inženjera (27HSKIKI)

Mjesto i datum
Veli Lošinj, Hrvatska, 05.10.2021. - 08.10.2021

Vrsta sudjelovanja
Poster

Vrsta recenzije
Recenziran

Ključne riječi
perovskites ; lanthanum manganite ; permanganate titration ; oxygen nonstoichiometry

Sažetak
Lanthanum strontium manganite, La1-xSrxMnO3, belongs to an extensive group of rare-earth manganites with the general formula Re1-xAxMnO3, where Re is the rare-earth ion (La) and A is a divalent ion (Sr). The rare-earth manganites are nowadays the subject of extensive research because of their promising electrical and magnetic properties [1]. These properties are strongly affected by oxygen nonstoichiometry and Mn3+/Mn4+ ratio, so the aim of this study was to examine the application of permanganate back titration on the determination of oxygen content in manganites [2, 3]. In our study, SrMnO3 was successfully prepared by citrate-nitrate autocombustion (CNA) and by the coprecipitation method. These methods were then applied to the synthesis of La1-xSrxMnO3 (x = 0, 0.1, 0.2 and 0.3). The optimal phase formation conditions were determined by thermogravimetry and differential scanning calorimetry. Crystallization of precursors and calcined powders was studied by X-ray diffraction. Powders in which pure manganite phase was obtained, were analyzed by permanganate titration with Mohr's salt to determine oxygen nonstoichiometry. Oxygen stoichiometry was achieved in SrMnO3 powders obtained by the CNA method and calcined at 1000 °C as well as in powders obtained by the coprecipitation method and calcined at 1200 °C. The La1-xSrxMnO3 phase was oxygen stoichiometric for x = 0.3 and 0.18 while the decreasing of x resulted in cation deficiency, i.e. oxygen excess. Oxygen deficit was achieved for x = 0.09 upon calcination at 1200 °C. The obtained results were confirmed by thermogravimetry.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo

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