Heat capacity, entropy, dielectric properties and T-p phase diagram of (NH4)3TiF7

被引：19

作者：

Pogoreltsev, E. I. ^{[1
,2
]}

Flerov, I. N. ^{[1
,2
]}

Kartashev, A. V. ^{[1
]}

Bogdanov, E. V. ^{[1
,3
]}

Laptash, N. M. ^{[4
]}

机构：

[1] RAS, Siberian Dept, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia

[2] Siberian Fed Univ, Krasnoyarsk 660074, Russia

[3] Krasnoyarsk State Agr Univ, Krasnoyarsk 660049, Russia

[4] Russian Acad Sci, Far Eastern Dept, Inst Chem, Vladivostok 690022, Russia

来源：

JOURNAL OF FLUORINE CHEMISTRY | 2014年 / 168卷

基金：

俄罗斯基础研究基金会;

关键词：

Cubic fluorides; Phase transitions; Dielectric; Phase diagram; Calorimetry; CRYSTAL-STRUCTURE; TRANSITIONS; FLUORIDES; NH4F;

D O I：

10.1016/j.jfluchem.2014.10.016

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

Successive phase transitions G1 --> G2 --> G3 in the double salt (NH4)(3)TiF7 have been studied by detailed calorimetric, DTA under hydrostatic pressure and dielectric measurements. Rather large entropy jumps at phase transition points were found to be followed by large additional contributions associated with the temperature dependence of the excess heat capacity. The permittivity behaviour and the tangent of the dielectric losses proved the nonferroelectric nature of both transformations. Two triple-points were found on the temperature-pressure phase diagram, suggesting the existence of a hypothetical parent G0 = Pm-3m cubic phase. A direct transformation between high (G0) and low (G3) temperature cubic phases takes place at p > 0.41 GPa with a baric coefficient dT(G0) --> (G3)/dp = -40 K/GPa. (C) 2014 Elsevier B.V. All rights reserved.

引用

页码：247 / 250

页数：4

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