钽铌酸钾多组分复合热释电薄膜的设计、制备与性能研究

Potassium-tantalate-niobate (KTa1-xNbxO3 or KTN) is a compatible solid solution of the two peroskites potassium tantalite (KTaO3) and potassium niobate (KNbO3) with attractive quadratic (Kerr effect) and linear (Pockels effect) electro-optic properties, as well as a high dielectric permittivity and large piezoelectric and pyroelectric coefficients. In different form such materials find extensive applications as pyroelectric detectors, electro-optic modulators and efficient second-harmonic generation devices. With the development of integrated ferroelectrics and optics, the study of preparation of KTN thin films is very active. KTN singe crystals have been shown to have a large spontaneous polarization and pyroelectric response. In particular, relative permittivity of KTN thin films decrease because of small grain size, so their pyroelectric coefficient, roperties, and detecting sensitivity are improved. For example, KTa0.55Nb0.45O3 thin film has a pyroelectric coefficient of 2.2×10-6C/cm2.k at Curie temperature of 35℃，it reach the order of single crystal. However, its temperature region where thin film shows high pyroelectric coefficient is very small (35℃±1). It is obviously inconventient for pyroelectric device to use a thermistat. But the Curie temperature of KTN can be adjusted from approximately 13K(x=0) to 108K(x=1) by variation of the tantalum to niobium ratio. Key ferroelectric properties are therefore composition-dependent. Multicomposition composite thin films have a wider phase transition temperature region. In our works,thin films of multicomposition composite KTa1-xNbxO3(x=0.40,0.425，0.50，0.525,0.55) for high pyroelectric coefficient and with wider temperature were prepared by sol-gel method on BT/Pt/Ti/SiO2/Si substrates. The relative permittivity of KTN thin film was reduced by small size effect, and the phase transition temperature region of KTN thin film was broadened by multicomposition. Therefore,this kind of multicomposition composite KTa1-xNbxO3 thin film was a kind of new and excellent pyroelectric material.

设计、制备钽铌酸钾多组分复合薄膜，研究其热释电性能。利用小尺寸效应降低薄膜的相对介电常数，提供电压响应优值和探测度优值。利用多组分复合宽化铁电相变温区，使薄膜以高的热释电系数出现在较宽的温区范围。分析小尺寸效应降低相对介电常数机理。开发新型性能更优的热释电薄膜材料，为其在小型化、集成化热释电探测器等方面应用打集成。