[1] [1] JAFFE B, COOK W R, JAFFE H. Piezoelectric ceramics. Academic Press, New York. 1971.

[5] [5] SUBBARAO E C, SHIRANE G, JONA F. X-ray dielectric, and optical study of ferroelectric lead metatantalate and related compounds[J]. Acta Cryst, 1960, 13(3): 226-231.

[6] [6] FRANCOMBE M H. The relation between structure and ferroelectricity in lead Barium and Barium strontium niobates[J]. Acta Cryst, 1960, 13(2): 131-140.

[7] [7] SHROUT T R, CROSS L E, HUKIN D A. Ferroelectric properties of tungsten bronze lead Barium niobate (PBN) single crystals[J]. Ferroelectr Lett Sect, 1983, 44(11): 325-330.

[8] [8] OLIVER J R, NEURGAONKAR R R, CROSS L E. ChemInform abstract: ferroelectric properties of tungsten bronze morphotropic phase boundary (MPB) systems[J]. ChemInform, 1989, 20(20): 202-211.

[9] [9] RAO K S, YOON K H. Review: review of electrooptic and ferroelectric properties of Barium sodium niobate single crystals[J]. J Mater Sci, 2003, 38(3): 391-400.

[10] [10] LIU L L, GAO F, HU G X, et al. Fabrication of KSr2Nb5O15 particles with high aspect ratio by two-step molten salt synthesis[J]. Adv Powder Technol, 2014, 25(1): 219-225.

[11] [11] KHACHANE M, MOURE A, ELAATMANI M, et al. Processing by both classical and mechanosynthesis routes and characterization of a new solid solution of tungsten-bronze structure ceramics[J]. Mater Res Bull, 2006, 41(10): 1798-1805.

[12] [12] MANOLIKAS C. Electron microscopic study of the commensurate-incommensurate phase transition in Ba2NaNb5O15 and Sr2KNb5O15[J]. Phys Stat Sol (a), 1981, 68(2): 653-660.

[13] [13] PARIDA B N, DAS P R. Synthesis and characterization of a new ferroelectric oxide Li2Pb2Pr2W2Ti4Ta4O30[J]. J Alloys Compd, 2014, 585: 234-239.

[14] [14] TIAN Y, CHAO X L, WEI L L, et al. Phase transition behavior and electrical properties of lead-free (Ba1-xCax)(Zr0.1Ti0.9)O3 piezoelectric ceramics[J]. J Appl Phys, 2013, 113(18): 184107.