新铌酸盐Sr_5NdTi_3Nb_7O_(30)的合成与介电特性

Synthesis and Dielectric Properties of A New Niobate r_5NdTi_3Nb_7O_(30)

一些铁电铌酸盐具有优良的电光性能和非线性光学性能,因此该类化合物的人工合成、结构与性能的研究受到了重视,其中钨青铜结构的系列晶体(例如SBN、KNSBN、SCNN)在材料的制备和器件的设计方面都取得了很大进展,它们在实时全息存储、集成光学与光信号处理等领域具有广泛的应用前景[1].

A new niobate Sr5NdTi3Nb7O30 was synthesized in the SrO-Nd2O3-TiO2-Nb2O5 system by solid state reaction at 1350degreesC for 48h. The structure and dielectric properties of Sr5NdTi3Nb7O30 were determined by X-ray powder diffraction, scanning electron microscope and dielectric measurements. The results show that Sr5NdTi3Nb7O30 belongs to ferroelectric, phase of filled tetragonal tungsten bronze structure at room temperature with unit cell parameters: a = 1.23084(4) nm, c = 0.38794(2) nm, space group P4 bm, calculated density 5.245g (.) cm(-3). Sr5NdTi3Nb7O30 belongs to relaxor ferroelectrics. The phase transition temperature (T-c) of Sr5NdTi3Nb7O30 from ferroelectric to paraelectric is found to shift toward higher temperature side at higher frequency, and T-c is 180degreesC at 1 kHz. At room temperature, the dielectric constant (epsilon(r)) Sr5NdTi3Nb7O30 is nearly independent of frequency, and Sr5NdTi3Nb7O30 ceramic has high dielectric constant 288 at 1 MHz and low dielectric loss of 0.0022.