Phase transitions and properties of perovskite ferroelectric ceramics and films for certain applications

10.1007/s11451-008-3014-8

“…We note, however, that the investigation of ∆T ad in PST and PZT [3,4] was performed in markedly higher fields.…”

“…The researchers, who were more optimistically inclined, continued the search, first, for ways to improve the corresponding properties of the already known ferroelectric compounds, second, for new promising materials, and third, for novel schemes of operation of electrocaloric refrigerators [2]. To date, the range of ferroelectrics exhibiting reasonably high intensive ( ∆ T ad ) and extensive ( ∆ S ) caloric effects in the temperature interval 250-290 K is narrow and includes primarily compounds with a perovskite-related structure [3].…”

“…It is for these reasons that the search for promising materials is limited by the scope of lead-containing perovskites and their solid solutions, such as PbSc 1/2 Ta 1/2 O 3 (PST), PbSc 1/2 Nb 1/2 O 3 (PSN), and PbZr 0.95 Ti 0.05 O 3 (PZT), in which phase transitions give rise to ordering of lead atoms that are disordered in the cubic phase [3]; at the same time, one is looking for optimum ways to reduce the linear dimensions of samples down to the thickness of thin films [4,5]. Viewed from the ecological standpoint, however, the use of lead in the elements is certainly anything but an unfavorable factor.…”

“…On the one hand, the experimental value ∆ S 1 = 0.2 R turned out to be much smaller than ∆ S 2 = 0.8 R > R ln2, while on the other, model considerations suggest that the transition between the ferroelectric and antiferroelectric phases should involve a substantially larger entropy, i.e., ∆ S 2 = 1.4 R = R ln4. could realize a change in entropy that occurs in perovskite-like oxides ( ∆ S = R ln4) [7], i.e., that ammonium hydrosulfate near the phase transition at T 2 can turn out to become a material not inferior in electrocaloric parameters to solid-state cooling agents, which are presently used in the development of refrigerators [2][3][4]. That is what would justify interest in the studies of the electrocaloric effect in this crystal.…”

Synthesis, sintering and characterization of PLZST perovskite prepared by a lactate precursor route

“…[1][2][3][4][5][6][7] Since the discovery of the maximum 0.85% longitudinal strain in lanthanum-doped lead zirconate titanate stannate (PLZST) ceramics by Cross and coworkers, 7 these ceramics have been investigated by various groups, for the purpose of improving their properties. [8][9][10][11][12][13][14][15] It is well known that the properties of materials are strongly related to their preparation method and the starting materials.…”