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Structural Distortion-Modulated Magnetic and Dielectric Properties in Nonstoichiometric Yb2-Ti2O7-δ Pyrochlore
Ming-Yuan Yan1, Xiao-Yu Zhang1, Li-Huai Shu2
1National Laboratory of Solid State Microstructures, College of Engineering and Applied Science & Jiangsu Key Laboratory of Artificial Functional Materials & Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
Inorganic Chemistry
|June 29, 2022
Summary
Introducing nonstoichiometry into Ytterbium Titanate (Yb2Ti2O7) ceramics alters magnetic and dielectric properties. Increased oxygen vacancies and structural distortion lead to reduced ferromagnetism and enhanced dielectric relaxations.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid State Chemistry
Background:
- Rare-earth titanate pyrochlores, like Ytterbium Titanate (Yb2Ti2O7), are known for magnetic frustration.
- Yb2Ti2O7 is a quantum spin ice candidate, extensively studied for its magnetic properties.
- Dielectric properties and structure-property relationships in Yb2Ti2O7 remain less explored.
Purpose of the Study:
- To investigate the impact of nonstoichiometry on the structural, magnetic, and dielectric properties of Yb2Ti2O7 ceramics.
- To understand the structure-property relationship in nonstoichiometric Yb2Ti2O7.
- To explore the origin of dielectric relaxation in these materials.
Main Methods:
- Preparation of nonstoichiometric Yb2-xTi2O7-δ (x = 0-0.15) ceramics.
- Structural analysis to determine phase purity and identify distortions.
- Magnetic susceptibility measurements to determine magnetic ordering temperatures (Curie-Weiss temperature).
- Dielectric measurements to observe low-temperature dielectric relaxations and relaxor behavior.
Main Results:
- Samples with x ≤ 0.05 maintained a single-pyrochlore phase, but exhibited structural distortion and increased oxygen vacancies.
- Ferromagnetism, indicated by a positive Curie-Weiss temperature, decreased linearly with increasing nonstoichiometry (x).
- Composition-dependent low-temperature dielectric relaxations were observed, with enhanced relaxor behavior and altered dielectric curves due to nonstoichiometry.
Conclusions:
- Nonstoichiometry in Yb2Ti2O7 significantly influences its structural, magnetic, and dielectric properties.
- Dielectric relaxation is attributed to structural distortions arising from nonstoichiometry, not phase transitions in the studied temperature range.
- This study provides a comprehensive understanding of Yb2Ti2O7 properties, guiding future research on pyrochlores.
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