Phase relations in the Bi[sub]2O[sub]3–Mn[sub]2O[sub]3–M[sub]2O[sub]3 (M=Fe, Al, and Ga) pseudoternary systems

Srečo D. Škapin (Author), Amalija Golobič (Author), Matjaž Spreitzer (Author), Danilo Suvorov (Author)

Abstract

This study establishes the subsolidus phase relations in the Bi₂O₃–Mn₂O₃–M₂O₃ (M = Fe, Al, and Ga) systems at 770°C in an oxidizing air environment, with a specific focus on identifying of phase stability and extension of solid solubility of new solid solutions. The pseudoternary nature of these systems is influenced by the presence of both Mn3⁺ and Mn⁴⁺ oxidation states in mullite Bi2Mn4O10-based phases and Mn4+ in sillenite Bi12MnO20-based phases. Our findings reveal that the addition of M₂O₃ (where M = Fe, Al, and Ga) in small amounts (up to 1.5 mol%) to Bi₂O₃ promotes the formation of the γ-Bi₂O₃ phase. However, with increased M₂O₃ addition (up to 7 mol%), isomorphous sillenite compounds Bi₂₅MO₃₉ are formed. These findings clearly show differences between the two phases, γ-Bi2O3 and sillenite Bi₂₅MO₃₉ which have been largely incorrectly defined in the past. In contrast, in the binary system Bi2O3–Mn2O3 the γ-Bi2O3 was not identified. The sillenite compounds Bi12MnO20 and Bi25MO39 exhibit solid solubility in all three systems M = Fe, Al, and Ga over the entire composition range. Additionally, the perovskite phase BiFeO₃ exhibits an extended solid solubility, incorporating up to 32 at% of Mn as a substitution for Fe however the perovskite-type BiGaO3 and BiAlO3 were not confirmed in the investigated systems. In the investigated systems, the mullite-type Bi2Mn4O10 and Bi2M4O9 (M = Fe, Al, and Ga) form solid solutions with various compositional extensions, which depends on the difference of ionic size of M atoms (Fe, Al, and Ga) in comparison of Mn size. Based on experimental results, the three phase diagrams of the Bi₂O₃–Mn₂O₃–M₂O₃ (M = Fe, Al, and Ga) systems were constructed.

Keywords

elektronska keramika;electronic ceramics;phase relations;phase diagram;fazni diagram;

Data

Language:	English
Year of publishing:	2024
Typology:	1.01 - Original Scientific Article
Organization:	IJS - Jožef Stefan Institute
UDC:	54
COBISS:	224011011
ISSN:	1551-2916
Views:	50
Downloads:	31
Average score:	0 (0 votes)
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Other data

Secondary language:	Slovenian
Secondary keywords:	Bizmutov oksid;
Type (COBISS):	Article
Pages:	str. 1-13
Volume:	ǂVol. ǂ
Issue:	ǂiss. ǂ, [article no.] e20323
Chronology:	2024
DOI:	10.1111/jace.20323
ID:	26017353