硅酸盐学报

二氧化锰改性对K_0.5Na_0.5NbO₃陶瓷结构与介电性能的影响

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杨文虎 ¹^,² , 张豪杰 ¹ , 刘木华 ¹ , 陈智勇 ¹ , 何敏 ¹ , 郑明军 ¹

硅酸盐学报 | 研究论文 2026,54(6): 2007-2016

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硅酸盐学报 |研究论文 2026 , 54 (6) : 2007 -2016

二氧化锰改性对K_0.5Na_0.5NbO₃陶瓷结构与介电性能的影响

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杨文虎¹^,², 张豪杰¹, 刘木华¹, 陈智勇¹, 何敏¹, 郑明军¹

作者信息

^1．广东海洋大学电子与信息工程学院，广东湛江 524088

^2．广东海洋大学深圳研究院，广东深圳 518105

作者简介:

杨文虎（1979—），男，博士，副教授。

Effect of MnO₂ Modification on Structure and Dielectric Properties of K_0.5Na_0.5NbO₃ Ceramics

Wenhu YANG¹^,², Haojie ZHANG¹, Muhua LIU¹, Zhiyong CHEN¹, Min HE¹, Mingjun ZHENG¹

Affiliations

^1.School of Electronic and Information Engineering, Guangdong Ocean University, Zhanjiang 524088, Guangdong, China

^2.Shenzhen Institute of Guangdong Ocean University, Shenzhen 518116, Guangdong, China

YANG Wenhu (1979-), male, Ph.D., Associate Professor. E-mail: dellon9960@163.com

出版时间: 2026-05-12 doi: 10.14062/j.issn.0454-5648.20250538

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摘要

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研究了二氧化锰（MnO₂）掺杂对铌酸钾钠（K_0.5Na_0.5NbO₃）基陶瓷介电性能的影响。采用固相法制备了不同掺杂量的KNN陶瓷，并对其介电性能进行了全面表征和分析。结果表明，所有掺杂MnO₂的KNN陶瓷样品均呈现出典型的四方钙钛矿结构，适量的MnO₂掺杂显著提高了KNN陶瓷的介电性能。然而，过量掺杂会导致性能下降，但仍优于纯KNN陶瓷。在最佳的MnO₂掺杂条件下，介电常数逐渐升高，表明极化强度和介电性能得到增强。此外，MnO₂掺杂降低了KNN陶瓷的介电损耗。在低频下，由于掺杂引起的结构变化，所有KNN陶瓷样品的介电常数均随温度升高而增大；然而，超过某一温度阈值后，其介电常数开始下降，这一发现对于在特定温度范围内工作的电子设备至关重要。

关键词

铌酸钾钠 / 掺杂 / 介电常数 / 阻抗 / 耐压强度

Abstract

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Introdution

In recent years, lead titanate (PZT) based ceramics are used in the electronic ceramics due to their excellent piezoelectric and dielectric properties. However, PZT contains a high proportion of toxic heavy metal lead, which poses a serious threat to the environment and human-being health during production, use, and disposal. With increasingly strict global environmental regulations, the development of high-performance lead-free piezoelectric-based materials becomes an urgent task and consensus in the field of materials science. Among these ceramic materials, K_0.5Na_0.5NbO₃ (KNN) ceramics have attracted much attention as a lead-free alternative to conventional piezoelectric materials due to their excellent electromechanical properties and environmental compatibility. This study was to address these limitations via implementing a manganese dioxide (MnO₂) doping strategy. The primary objectives were to establish structure-property relationships and optimize dielectric performance for high-temperature/high-frequency electronic applications, while elucidating the underlying defect-mediated mechanisms governing the performance enhancement.

Methods

The KNN ceramics with controlled MnO₂ doping concentrations (i.e., x = 0, 0.010%, 0.020%, 0.035%, 0.060%, and 0.095%) were synthesized via conventional solid-state reaction. High-purity precursors (i.e., Na₂CO₃, K₂CO₃, Nb₂O₅, MnO₂) were stoichiometrically weighed, ground in a planetary mill with ethanol, calcined (at 800-900 ℃), re-ground, and pressed into pellets with a polyvinyl alcohol binder. The sintering was conducted at 1050-1070 ℃ for 3 h. The poling was performed at 2 kV/mm for electrical characterization. The phase purity and crystal structure were analyzed by X-ray diffraction (XRD). The microstructure and elemental distribution were characterized by scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS). The dielectric permittivity and loss tangent were determined at 40 Hz-10 MHz and varied temperatures using an LCR meter. The electrical conductivity, nonlinear "J-E" characteristics, and impedance spectroscopy were systematically evaluated.

Results and discussion

The XRD patterns confirm that all the compositions retain a pure tetragonal perovskite structures (space group P4mm). As 0.060% as an optimal doping concentration, Mn²⁺/Mn³⁺/Mn⁴⁺ substitution for Nb⁵⁺ induces lattice expansion and forms defect dipoles. The SEM images reveal a substantial grain growth from 1.2 μm (undoped) to 3.5 μm (doped at 0.060%), due to liquid-phase sintering and lattice strain. The doping concentration of 0.060% can achieve a synergistic enhancement of dielectrical property, i.e., ε_r increases significantly, while tanδ decreases dramatically at low frequencies, governed by grain homogenization suppressing electron-hopping conduction. Conversely, the doping concentration of 0.095% has anomalous high-frequency losses due to the intensified grain-boundary polarization and skin effects. The temperature-dependent studies demonstrate a reduced dielectric maximum temperature from 240 ℃ (undoped) to 200 ℃ (doped), with a superior stability in tan δ at10⁴-10⁶ Hz. The impedance spectra reveal an accelerated ion mobility at > 200 ℃. The optimal operational window is identified at 200-240 ℃ and 10⁴-10⁶ Hz. The excessive doping concentration (i.e., 0.095%) degrades the performance due to the secondary phase formation, reduces relative density, and increases porosity. The moderate improvements in DC conductivity (attributed to defect-assisted hopping) and nonlinear coefficient α are obtained.

Conclusions

In this study, a series of K_0.5Na_0.5NbO₃ (KNN) ceramics with different manganese oxide (MnO₂) concentrations were synthesized. The results showed that the optimal doping concentration of MnO₂ was 0.060%. At this optimal concentration, manganese ions in multiple oxidation states replaced Nb⁵⁺, causing the lattice expansion and the formation of beneficial defect dipoles. This doping strategy simultaneously improved the microstructure, promoted a significant grain growth from 1.2 µm to 3.5 µm, and enhanced dielectric properties, achieving a significant synergistic enhancement effect. This improvement could be mainly attributed to the uniformity of the microstructure, which inhibited a harmful electron hopping conduction. The study also clarified that the optimal window for stability performance could be 200 -240 ℃ and 10⁴-10⁶ Hz. Beyond the optimal doping level, the excessive doping concentration (i.e., 0.095%) led to a performance degradation due to the formation of secondary phases, increased porosity, and increased losses at high frequencies due to grain boundary polarization and surface effects. This study could provide a basic framework for developing manganese-doped potassium sodium nickel oxide ceramics for specific electronic applications.

Key words

potassium sodium niobate / doping / dielectric constant / impedance / withstand voltage strength

引用本文

杨文虎, 张豪杰, 刘木华, 陈智勇, 何敏, 郑明军. 二氧化锰改性对K_0.5Na_0.5NbO₃陶瓷结构与介电性能的影响. 硅酸盐学报, 2026 , 54 (6) : 2007 -2016 . DOI: 10.14062/j.issn.0454-5648.20250538

Wenhu YANG, Haojie ZHANG, Muhua LIU, Zhiyong CHEN, Min HE, Mingjun ZHENG. Effect of MnO₂ Modification on Structure and Dielectric Properties of K_0.5Na_0.5NbO₃ Ceramics[J]. Journal of the Chinese Ceramic Society, 2026 , 54 (6) : 2007 -2016 . DOI: 10.14062/j.issn.0454-5648.20250538

基金

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国家自然科学基金(62575121)

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2026年第54卷第6期

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文章信息

doi: 10.14062/j.issn.0454-5648.20250538

接收时间：2025-07-08
首发时间：2026-10-22
出版时间：2026-05-12

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收稿日期：2025-07-08
修回日期：2025-08-25

基金

国家自然科学基金(62575121)

作者信息

^1．广东海洋大学电子与信息工程学院，广东湛江 524088

^2．广东海洋大学深圳研究院，广东深圳 518105

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20250538

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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