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Journals / Niğde Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi / 2026 / Cilt: 15

Influence of chromium valence states on the structural, magnetic and magnetocaloric properties of La₀.₈Ba₀.₂Mn₁₋ₓCrₓO3

Krom valans durumlarının La₀.₈Ba₀.₂Mn₁₋ₓCrₓO3'ün yapısal, manyetik ve manyetokalorik özelliklerine etkisi

Cumhur Gökhan Ünlü(PAMUKKALE ÜNİVERSİTESİ)0000-0003-2554-5886
Pages
1–10
Publication Date
2026-01-15
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AI Summary & Key Takeaways

AI Insight
⚡ TL;DR(Too Long; Didn't Read)

X-ray photoelectron spectroscopy (XPS) results indicated that Mn³⁺ and Mn⁴⁺ ions in the La₀.₈Ba₀.₂MnO₃ compound play a crucial role in the double-exchange mechanism.

📌 3 Key Takeaways

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Objective & Hypothesis:Perovskite type lanthanum manganite and lanthanum chromate compounds have attracted considerable attention due to their remarkable colossal magnetoresistance and magnetocaloric properties.
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Key Findings & Data:In this study, the structural, microstructural, magnetic, and magnetocaloric properties of La₀.₈Ba₀.₂Mn₁₋ₓCrₓO₃ (x= 0, 0.1) compounds were investigated.
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Conclusion & Impact:X-ray photoelectron spectroscopy (XPS) results indicated that Mn³⁺ and Mn⁴⁺ ions in the La₀.₈Ba₀.₂MnO₃ compound play a crucial role in the double-exchange mechanism.
🔬Design:Araştırma Makalesi
📍Scope:Comprehensive Sample
⚙️Variables:Perovskit manganit · lantan kromat · manyetizma

Abstract

Perovskite type lanthanum manganite and lanthanum chromate compounds have attracted considerable attention due to their remarkable colossal magnetoresistance and magnetocaloric properties. In this study, the structural, microstructural, magnetic, and magnetocaloric properties of La₀.₈Ba₀.₂Mn₁₋ₓCrₓO₃ (x= 0, 0.1) compounds were investigated. The samples were synthesized via the sol–gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses revealed that the crystal structure transforms from orthorhombic to rhombohedral with increasing Cr content, while SEM images showed a homogeneous grain distribution with slightly increased grain boundaries upon Cr substitution. X-ray photoelectron spectroscopy (XPS) results indicated that Mn³⁺ and Mn⁴⁺ ions in the La₀.₈Ba₀.₂MnO₃ compound play a crucial role in the double-exchange mechanism. Upon Cr substitution, an increase in the Mn⁴⁺ ion concentration was observed, accompanied by the emergence of Cr³⁺ and Cr⁶⁺ ions. The magnetic measurements confirmed ferromagnetic–paramagnetic transitions near Tc≈ 300 K for the parent compound and Tc≈ 240 K for the Cr-doped sample. The saturation magnetization (Ms) decreased from 86 to 68 Am²kg⁻¹ with Cr substitution at the B-site of the perovskite lattice. The maximum magnetic entropy change (−ΔSM) reached 4.3 J kg⁻¹ K⁻¹ and 3.1 J kg⁻¹ K⁻¹ under a 5 T field for x= 0 and x= 0.1, respectively. These results indicate that Cr substitution weakens the double-exchange interaction and reduces the magnetocaloric efficiency.

Özet

Perovskit tipi lantan manganit ve lantan kromit bileşikleri, olağanüstü devasa manyetodirenç ve manyetokalorik özellikleri nedeniyle büyük ilgi görmüştür. Bu çalışmada, La₀.₈Ba₀.₂Mn₁₋ₓCrₓO₃ (x= 0, 0.1) bileşiklerinin yapısal, mikroyapısal, manyetik ve manyetokalorik özellikleri araştırılmıştır. Numuneler sol-jel yöntemiyle sentezlenmiştir. X-ışını kırınımı (XRD) ve taramalı elektron mikroskobu (SEM) analizleri, Cr içeriğinin artmasıyla kristal yapının ortorombikten rombohedral faza dönüştüğünü göstermiştir. SEM görüntüleri, Cr katkısıyla birlikte tane sınırlarında hafif bir artışla homojen bir tane dağılımı ortaya koymuştur. X-ışını fotoelektron spektroskopisi (XPS) sonuçları, La₀.₈Ba₀.₂MnO₃ bileşiğinde Mn³⁺ ve Mn⁴⁺ iyonlarının çift değişim mekanizmasında kritik rol oynadığını göstermiştir. Cr katkısıyla birlikte Mn⁴⁺ iyonu konsantrasyonunda artış gözlenmiş ve Cr³⁺ ile Cr⁶⁺ iyonlarının varlığı belirlenmiştir. Manyetik ölçümler, ana bileşik için Tc≈ 300 K ve Cr katkılı numune için Tc≈ 240 K civarında ferromanyetik-paramanyetik geçişleri doğrulamıştır. Doygunluk mıknatıslanması (Ms), perovskit kafesinin B-bölgesindeki Cr katkılamanması 86'dan 68 Am²kg⁻¹'ye düşmüştür. Maksimum manyetik entropi değişimi (−ΔSM), x= 0 ve x= 0,1 için 5 T alan altında sırasıyla 4,3 Jkg⁻¹K⁻¹ ve 3,1 Jkg⁻¹K⁻¹'ye ulaştı. Bu sonuçlar, Cr ikamesinin çift değişim etkileşimini zayıflattığını ve manyetokalorik verimliliği düşürdüğünü göstermektedir.

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Cite This Article

Ünlü, C. G. (2026). Influence of chromium valence states on the structural, magnetic and magnetocaloric properties of La₀.₈Ba₀.₂Mn₁₋ₓCrₓO3. Niğde Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi, Cilt: 15, 1–10. https://doi.org/10.28948/ngumuh.1805806

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