Kuscer Danjela, Kmet Brigita, Drnovšek Silvo, Bustillo Julien, Levassort Franck
Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia.
GREMAN UMR 7347, Université de Tours, CNRS, INSA CVL, 16 rue Pierre et Marie Curie, CEDEX 2, 37071 Tours, France.
Sensors (Basel). 2022 Apr 22;22(9):3223. doi: 10.3390/s22093223.
Thick films with nominal composition (K.Na.).Sr.NbO (KNNSr) on porous ceramics with identical nominal composition were investigated as potential candidates for environmentally benign ultrasonic transducers composed entirely of inorganic materials. In this paper, the processing of the multilayer structure, namely, the thick film by screen printing and the porous ceramic by sacrificial template method, is related to their phase composition, microstructure, electromechanical, and acoustic properties to understand the performance of the devices. The ceramic with a homogeneous distribution of 8 μm pores had a sufficiently high attenuation coefficient of 0.5 dB/mm/MHz and served as an effective backing. The KNNSr thick films sintered at 1100 °C exhibited a homogeneous microstructure and a relative density of 97%, contributing to a large dielectric permittivity and elastic constant and yielding a thickness coupling factor of ~30%. The electroacoustic response of the multilayer structure in water provides a centre frequency of 15 MHz and a very large fractional bandwidth (BW) of 127% at -6 dB. The multilayer structure is a candidate for imaging applications operating above 15 MHz, especially by realising focused-beam structure through lenses to further increase the sensitivity in the focal zone.
对具有相同标称成分（K.Na）.Sr.NbO（KNNSr）的多孔陶瓷上的标称成分厚膜进行了研究，它们是完全由无机材料组成的环境友好型超声换能器的潜在候选材料。在本文中，多层结构的加工，即通过丝网印刷制备厚膜以及通过牺牲模板法制备多孔陶瓷，与它们的相组成、微观结构、机电和声学性能相关，以了解器件的性能。具有8μm孔隙均匀分布的陶瓷具有足够高的衰减系数0.5dB/mm/MHz，并用作有效的背衬。在1100°C烧结的KNNSr厚膜呈现出均匀的微观结构和97%的相对密度，有助于产生大的介电常数和弹性常数，并产生约30%的厚度耦合因子。多层结构在水中的电声响应提供了15MHz的中心频率和在-6dB时127%的非常大的分数带宽（BW）。多层结构是工作在15MHz以上的成像应用的候选材料，特别是通过透镜实现聚焦束结构以进一步提高焦区内的灵敏度。
