Crystallographic Structure and Ferroelectricity of (A_xLa_1−x)₂Ti₂O₇ (A = Sm and Eu) Solid Solutions with High T_c

Abstract

The solubility and ferroelectric properties of (A x La 1x ) 2 Ti 2 O 7 (A = Sm and Eu) solid solutions were investigated. The crystallographic structure of the solid solutions was studied using X-ray diffraction and Raman spectroscopy. The solubility limits of Eu and Sm in (A x La 1x ) 2 Ti 2 O 7 were found to be greater than x = 0.5 and 0.8, respectively. The solid solutions had a monoclinic perovskite-like layered structure (PLS), similar to that of the pure La 2 Ti 2 O 7 , when x was less than the solubility limit. When x was above the solubility limit the materials were biphase. The biphases of (Sm x La 1x )Ti 2 O 7 (x = 0.9) consisted of (Sm x La 1x ) 2 Ti 2 O 7 with PLS and pure Sm 2 Ti 2 O 7 with pyrochlore structure, and the biphases of (Eu x La 1x )Ti 2 O 7 (x = 0.6, 0.7, and 0.8) consisted of (Eu x La 1x) 2 Ti 2 O 7 with PLS structure and La 3+ doped Eu 2 Ti 2 O 7 with pyrochlore structure. The effect of A-site substitution on the properties of La 2 Ti 2 O 7 was investigated by measuring the dielectric permittivity and loss at different frequencies and temperatures. The highest piezoelectric constant d 33 was 2.8 pC/N for (Sm 0.1 La 0.9 )Ti 2 O 7 . M. P. Paranthama-contributing editor Manuscript No. 36896.

The effect of Li/Ce co‐doping on structural and electrical properties of Sr2−x(Li, Ce)x/2Nb2O7 piezoelectric ceramics

“…The d 33 of the SLCNO‐0.04 ceramic has a slight decrease from 3.1 to 3.0 pC/N before 1200°C, suggesting that the SLCNO‐0.04 ceramic has excellent temperature stability. Figure 3D lists the T C values and d 33 values of some reported PLS ceramics 6,12,13,17,29,40–42 . It can be seen that the d 33 of Sr 2− x (Li, Ce) x /2 Nb 2 O 7 ceramics in this work have a significant improvement, while they ensure a high T C .…”

“…Figure 3D lists the T C values and d 33 values of some reported PLS ceramics. 6,12,13,17,29,[40][41][42] It can be seen that the d 33 of Sr 2−x (Li, Ce) x/2 Nb 2 O 7 ceramics in this work have a significant improvement, while they ensure a high T C .…”

Thermally enhanced piezoelectricityviathe superstructure in Ca2Nb2O7single-crystals with ultra-high Curie temperature

“…[6][7][8][9][10] The Aurivillius phase and perovskite-like layered structure (PLS) together with LiNbO 3 and LiTaO 3 are potential candidates for ultra-high-T c piezoelectric applications. [11][12][13][14] In particular, PLS ferroelectric materials can potentially operate above 1273 K. 15 Recently, researchers have focused on enhancing the piezoelectric properties of PLS materials. The piezoelectric coefficients of Sr 2 Nb 2 O 7 and La 2 Ti 2 O 7 ceramics, outstanding representatives of the PLS family, have been optimized to 2.8 and 4.8 pC N À1 , respectively, which are still lower than required for high-performance detector applications.…”

Теплоемкость и термодинамические функции GdGaTi-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- в области 320-1000 K

“…x R ′′ 1−x ) 2 Ti 2 O 7 [4], а так же частичной замены редкоземельных элементов на другие металлы с образованием соединений RMTi 2 O 7 [5]. Последние титанаты являются наименее исследованными.…”