摘要
以新型溶胶–凝胶法制备的平均晶粒尺寸为30 nm的铌酸钾钠粉体为原料,采用放电等离子体烧结工艺,在烧结温度为900℃,压力30 MPa,烧结时间1 min的条件下,制备得到纯正交相,相对密度高达99%以上,平均晶粒尺寸为40 nm的纳米铌酸钾钠陶瓷,并对该陶瓷的相结构、微观形貌、介电性能和铁电性能进行了研究。结果表明,与普通微米晶陶瓷不同,纳米铌酸钾钠陶瓷的室温介电常数仅为341,并且随温度变化不明显,表现出明显的介电弛豫现象,弥散因子γ为1.60,并具有明显的电滞回线,矫顽场强度为13.5 k V/cm,剩余极化为1.5μC/cm2。尺寸降低所引起的纳米铌酸钾钠陶瓷中晶界相所占的比例增大是其性能变化的主要原因,并且可以推断,如果铌酸钾钠陶瓷具有"临界尺寸",那么其值应该在40 nm以下。
Using average 30 nm grain sized potassium sodium niobate powders obtained by a novel Sol-Gel method as starting materials, nanocrystalline potassium sodium niobate ceramics with pure orthorhombic phase, relative density of above 99% and grain size of 40 nm were prepared by spark plasma sintering method under sintering temperature of 900 ℃, sintering pressure of 30 MPa and sintering time of 1 rain. The phase structure, micro-morphology, dielectric properties and ferroelectric properties of the ceramics were investigated. The results show that, differently from common micro-grain ceramics, dielectric constant of nanoerystalline potassium sodium niobate ceramics decreases to 341, which changes ＇little with the temperature, and the ceramics have obvious dielectric relaxation （dispersion factor 7 is 1.60）, and a well saturated ferroelectric hysteresis loop with coercive field of 13.5 kV/cm and remanent polarization of 1.5 μC/cm2. The abnormal properties can be attributed to the significant increasing content of grain boundary in nanocrystalline potassium sodium niobate ceramics, and it can be expected that if potassium sodium niobate ceramic has the critical size at room temperature, it would be less than 40 nm.
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2015年第1期59-64,共6页
Journal of Inorganic Materials
基金
国家自然科学基金(31101337)~~
关键词
铌酸钾钠
纳米陶瓷
介电弛豫
电滞回线
potassium sodium niobate
nanocrystalline ceramic
dielectric relaxation
ferroelectric hysteresis loop
