Synthesis and characterization of a new high-entropy oxide based on rare-earth elements (Dy,Y,Yb,Nd,Pr)O$_{1.5\pm\delta}$ prepared by citrate–nitrate combustion synthesis

Skalar, Tina (author), Levičar, Maks (author), Marinšek, Marjan (author), Genorio, Boštjan (author), Ptáček, Petr (author), Blahut, Jan (author), Sokola, Patrik (author)

High-entropy oxides represent a modern class of materials with broad applicability, in which the configurational entropy of multiple equimolar cations stabilises single-phase structures with unique defect chemistry and tunable functional properties. In the proposed work, a novel rare-earth high-entropy oxide with the composition (Dy,Y,Yb,Nd,Pr)O$_{1.5\pm\delta}$ was synthesized via citrate–nitrate combustion synthesis, followed by calcination in the temperature range 600-1100 °C. Thermogravimetry coupled with mass spectrometry revealed multi-stage decomposition and carbon removal, defining the temperatures required for complete oxidation of carbonaceous residues. High-temperature and ambient XRD analyses confirmed the formation of a single-phase cubic oxide with progressive crystallite growth from ∼10 to 40 nm upon calcination. Optical reflectance measurements showed a semiconducting band gap from 2.26 to 2.39 eV and Urbach energies that reflect changes in structural disorder during calcination. SEM/EDS analyses demonstrated the formation of homogeneous nanocrystals, with surface areas up to 31 m$^2$g$^{−1}$. The study provides a detailed description of phase evolution, defect chemistry, and disorder formation in a combustion-derived rare-earth high-entropy oxide with potential applications in the semiconductor industry.

• Language: English
• Keywords: high-entropy ceramics, combustion synthesis, thermal analysis, band gap
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 11 str.
• Numbering: Vol. , iss.
• PID: 20.500.12556/RUL-181380
• UDC: 620.1
• ISSN on article: 0272-8842
• DOI: 10.1016/j.ceramint.2026.03.405
• COBISS.SI-ID: 274021891
• Publication date in RUL: 03.04.2026

Record is a part of a journal

• Title: Ceramics international
• Shortened title: Ceram. int.
• Publisher: Elsevier
• ISSN: 0272-8842
• COBISS.SI-ID: 5822215

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: keramika z visoko entropijo, zgorevalna sinteza, termična analiza, pasovna vrzel

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P1-0175
• Name: Napredna anorganska kemija

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: I0-0022
• Name: Mreža raziskovalnih infrastrukturnih centrov Univerze v Ljubljani (MRIC UL)