(北京有色金屬研究總院 先進(jìn)電子材料研究所，北京100088)
摘 要: 通過輥壓成型及隨后的可控結(jié)晶過程，制備Pb2Nb2O7 -NaNbO3-SiO2系納米復(fù)合材料。X射線衍射分析結(jié)果表明：溫度為750~900 ℃時，Pb2Nb2O7，NaNbO3和PbNb2O6晶相可在玻璃基體中析出；Pb2Nb2O7相在750 ℃結(jié)晶析出，850 ℃消失；NaNbO3為850 ℃時的主晶相；而PbNb2O6相的晶化溫度為850 ℃；由可控結(jié)晶技術(shù)制備的玻璃陶瓷介電性能受熱處理過程中所形成的相組成影響很大；試樣在850 ℃退火3 h，具有最高的介電常數(shù)(＞600)。微觀結(jié)構(gòu)分析結(jié)果表明，殘余玻璃相填充在納米晶粒的晶界處。電鏡分析進(jìn)一步發(fā)現(xiàn)，850 ℃退火3 h的試樣中不均勻地分布著納米NaNbO3和PbNb2O6顆粒，這是材料具有高介電常數(shù)的主要原因。
關(guān)鍵字: 玻璃陶瓷；鈮酸鹽；介電性能；顯微結(jié)構(gòu)；電介質(zhì)
（Advanced Electronic Materials Institute,General Research Institute for Nonferrous Metals, Beijing 100088, China）
Abstract:The glass-ceramics with nanometer-sized crystals grown in the glass phase in Pb2Nb2O7 -NaNbO3-SiO2 system were synthesized to produce bulk materials via roll-quenching followed by controlled crystallization. X-ray diffraction studies indicate that Pb2Nb2O7, NaNbO3 and PbNb2O6 phases are formed from the as-quenched glass at temperature ranging from 750 to 900 ℃. Pb2Nb2O7 crystallizes at 750 ℃ and disappears at 850 ℃, NaNbO3 is the primary phase at 850 ℃, while PbNb2O6 forms at a higher temperature of 850 ℃. The dielectric properties of the glass-ceramics formed through controlled crystallization have a strong dependence on the phase assemblages developed during heat treatment. The highest dielectric constants (＞600) are found in samples annealed at 850 ℃ for 3 h. Microstructural observation shows that randomly oriented, nanometer-sized crystalline are found with residual glass concentrated at crystallite boundaries. Further studies by scanning tunneling electron microscopy (STEM) in conjunction with energy dispersive spectroscopy (EDS) reveals inhomogeneous distribution of NaNbO3 and PbNb2O6 in the sample annealed at 850 ℃ for 3 h and these phases contribute to the high dielectric constant
Key words: glass-ceramic; niobate; dielectric properties; microstructure; dielectrics
