含铋层状结构陶瓷CaBi_2Nb_2O_9的A位掺杂改性研究

Study on A-site Cation Doping of CaBi_2Nb_2O_9 with Bismuth Layered Structure

利用固相反应法合成了Ca1-x(KLa)x/2Bi2Nb2O9(x=0～0.20)(xKLaCBNO)铋层状陶瓷,分析不同KLa掺杂量对CaBi2Nb2O9(CBNO)基陶瓷微观结构、介电、压电及电导性能的影响.XRD分析表明KLa的引入未改变CBNO陶瓷的单相结构.SEM和介电系数温度谱结果分别显示,KLa掺杂量的增加,细化尺寸趋于一致,而居里温度(Tc)从943℃降低至875℃,其峰值介电常数减小、峰值介电损耗增大.当掺杂量x=0.1时,样品的高温电阻率较纯CBNO显著升高,压电系数d33由5.2 pC/N提高到15.8 pC/N,居里温度高达870℃,说明A位(KLa)掺杂改性后的CBNO陶瓷在高温传感器等领域具有潜在的应用前景.

High curie temperature piezoelectric ceramics based on KLa-doped Ca1-x（KLa）x/2Bi2Nb2O9（x=0–0.20） were prepared by a conventional solid state reaction method.Crystal structure and microstructures of Ca1-x（KLa）x/2Bi2Nb2O9 ceramics were characterized by XRD and SEM.XRD patterns show that the crystal structures are a single phase of bismuth oxide layer structure having general formula（Bi2O2）2＋（Am-1BmO3m＋1）2-with m = 2.The grains of polished and thermally etched surfaces revealled a plate-liked morphology.The Curie point（Tc） decreases obviously whereas the piezoelectric activity of CBNO ceramics is significantly improved by the doping of potassium and lanthanum.The KLa-doped CBNO materials have an electrical conductivity value 1–2 orders of magnitude lower than undoped samples.The thermal depoling behavior of Ca1-x（KLa）x/2Bi2Nb2O9ceramics shows that all of them have a high Curie point（Tc≥850 ℃） and show good resistance to thermal depoling up to temperatures close to their Curie points.The results showed that the excellent properties is obtained in the ceramics with composition of x=0.1,i.e.d33=15.8 pC/N,Tc=870 ℃ and theDC conductivity is one order of magnitude smaller than that of undoped CBNO.All the results suggest that the doped CaBi2Nb2O9 is a potential material for high temperature sensor.