Polar lattice vibrations and phase transition dynamics in Pb(Zr1–xTix)O3<

Abstract

Infrared (IR) reflectivity spectra of nominally pure Pb(Zr 1-x Ti x )O 3 ceramics with different Ti/Zr concentration (x = 0.42-0.58) were measured and evaluated, along with the time-domain terahertz transmittance spectra in the temperature range 10 K-900 K. The temperature dependence of the low-frequency vibrations, related to Pb atoms, was analyzed in terms of two overdamped modes-a soft mode and an anharmonic hopping central mode-in the cubic and high-temperature ferroelectric phase and three main vibrations in the low-temperature ferroelectric phase with the doubled unit cell: two E-symmetry modes (the soft mode and a mode corresponding to antiphase vibrations of neighboring Pb atoms in the terahertz range) and the antiferrodistortive mode producing the antiphase tilts of the oxygen octahedra. The last bare mode is not IR active, but it becomes activated by coupling with the soft mode. As predicted by theory, the intrinsic permittivity of Pb(Zr 1-x Ti x )O 3 has a maximum at the morphotropic phase boundary, although this represents just a small percentage of the total permittivity at lower frequencies. Its maximum is linked to the softening of the anharmonic vibrations of Pb ions, perpendicular to the polarization, and shifts from x = 0.48 at room temperature to x = 0.52 at 10 K.

Crystallization, phase evolution and ferroelectric properties of sol–gel-synthesized Ba(Ti0.8Zr0.2)O3–x(Ba0.7Ca0.3)TiO3thin films

“…The band around 250 cm À1 is a very weak and broad negative peak for the composition x ¼ 0.3-0.45, and begins to grow at x ¼ 0.5, then gets more and more pronounced to form a strong central peak at the terminal BCT composition. Such behavior is welldocumented in similar ferroelectric perovskites, 42,43 supporting the existence of a ferroelectric-ferroelectric (rhombohedraltetragonal) phase transition at about x ¼ 0.50 for BZT-xBCT.…”

“…For solution B, to suppress the hydrolysis of Ti(OC 4 H 9 ) 4 , an appropriate amount of glacial acetic acid was rst added to the accurately weighed Ti(OC 4 H 9 ) 4 , stirring for 20 min, followed by adding ZrO(NO 3 ) 2 $2H 2 O and absolute alcohol, and stirring at room temperature for 1 h to form Ti-Zr solution. Finally, solution A was added into solution B with stirring for 2.5 h at room temperature, and then maintained at [40][41][42][43][44][45][46][47][48][49][50] C for about 1 h to obtain a clear and homogeneous gel. Thin lms were prepared by spin-coating the above solution at 800 rpm for 9 s and at 3000 rpm for 30 s on clean platinumcoated silicon substrates.…”

The dielectric and ferroelectric properties of (Ba0.5Sr0.5)TiO3-doped (Bi0.5Na0.5)TiO3 lead-free ceramics

“…[1][2][3][4][5][6] However, in the past two or three decades, due to the health and environmental concerns, a variety of Pb-free perovskite ferroelectric materials have attracted a lot of positive attention. [7][8][9][10] Among them, (Bi 1=2 Na 1=2 TiO 3 ) (NBT), [11][12][13][14][15][16] BaTiO 3 (BT), [17][18][19][20][21][22] and (K 0:5 Na 0:5 )NbO 3 (KNN) [23][24][25][26] -based systems therefore have been widely investigated, especially focusing on the compositions near morphotropic phase boundary (MPB) or polymorphic phase transition (PPT) in order to achieve superior dielectric and piezoelectric properties.…”

The investigation of electrical properties and microstructure of ZnO-doped Ba0.9Sr0.1TiO3 ceramics

“…[1][2][3] During the past decades, lead-based ferroelectric materials dominated the application, and the representative systems were lead-based ferroelectric materials, such as Pb(Zr 1Àx Ti x ÞO 3 , and relaxorPbTiO 3 systems. [4][5][6][7] However, due to limitation of lead and other harmful elements used in electronic devices by the EU and other countries, developing lead-free ferroelectric materials becomes an urgent challenge from both fundamental and applying researches. [8][9][10][11] Among all lead-free ferroelectric materials, Ba x Sr 1Àx TiO 3 (BST) are frequently studied.…”