Environment-friendly lead-free piezoelectric materials with excellent piezoelectric properties are needed for high-frequency ultrasonic transducer applications. Recently, lead-free 0.915(K _0.45 Na _0.5 Li _0.05 )NbO ₃ -0.075BaZrO 3-0.01(Bi _0.5 Na _0.5 )TiO ₃ (KNLN-BZ-BNT) textured piezo- electric ceramics have high piezoelectric response, superior thermal stability, and excellent fatigue resistance, which are promising for devices applications. In this work, the KNLN-BZ-BNT textured ceramics were prepared by the tape-casting method. Microstructural morphology, phase transition, and electrical properties of KNLN-BZ-BNT textured ceramics were investigated. High-frequency needle-type ultrasonic transducers were designed and fabricated with these textured ceramics. The tightly focused transducers have a center frequency higher than 80 MHz and a −6-dB fractional bandwidth of 52%. Such transducers were built for an ${f}$ -number close to 1, and the desired focal depth was achieved by press-focusing technology associated with a set of customer design fixture. Its lateral resolution was better than $90~\mu \text{m}$ by scanning a 15- $\mu \text{m}$ tungsten wire target. These promising results demonstrate that the lead-free KNLN-BZ-BNT textured ceramic is a good candidate for high-frequency ultrasonic transducer applications.

中文翻译：

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适用于高频超声换能器的无铅KNN基纹理陶瓷

高频超声换能器应用需要具有优异压电性能的环保无铅压电材料。最近，无铅0.915（K _0.45 Na _0.5 Li _0.05 ）NbO ₃ -0.075BaZrO 3-0.01（Bi _0.5 Na _0.5 ）TiO ₃（KNLN-BZ-BNT）质感压电陶瓷具有高压电响应，出色的热稳定性和出色的抗疲劳性，这对于器件应用是有前途的。在这项工作中，通过流延法制备了KNLN-BZ-BNT网纹陶瓷。研究了KNLN-BZ-BNT织构陶瓷的微观结构，相变和电性能。高频针型超声换能器是用这些纹理陶瓷设计和制造的。紧密聚焦的换能器具有高于80 MHz的中心频率和-6dB的分数带宽，为52％。这样的传感器是专为 $ {f} $ 数接近1，并且通过与一组客户设计装置相关联的压力聚焦技术实现了所需的聚焦深度。其横向分辨率优于 $ 90〜\ mu \ text {m} $ 通过扫描15- $ \ mu \ text {m} $ 钨丝靶。这些有希望的结果表明，无铅KNLN-BZ-BNT质感陶瓷是高频超声换能器应用的理想选择。