Crystal structure, morphotropic phase transition and luminescence in the new cyclosilicates Sr3R2(Si3O9)2, R=Y, Eu–Lu

2013 ◽  
Vol 197 ◽  
pp. 447-455 ◽  
Author(s):  
Alexander P. Tyutyunnik ◽  
Ivan I. Leonidov ◽  
Ludmila L. Surat ◽  
Ivan F. Berger ◽  
Vladimir G. Zubkov
ChemInform ◽  
2013 ◽  
Vol 44 (8) ◽  
pp. no-no
Author(s):  
Alexander P. Tyutyunnik ◽  
Ivan I. Leonidov ◽  
Ludmila L. Surat ◽  
Ivan F. Berger ◽  
Vladimir G. Zubkov

Author(s):  
David C. Martin ◽  
Jun Liao

By careful control of the electron beam it is possible to simultaneously induce and observe the phase transformation from monomer to polymer in certain solid-state polymcrizable diacetylenes. The continuous change in the crystal structure from DCHD diacetylene monomer (a=1.76 nm, b=1.36 nm, c=0.455 nm, γ=94 degrees, P2l/c) to polymer (a=1.74 nm, b=1.29 nm, c=0.49 nm, γ=108 degrees, P2l/c) occurs at a characteristic dose (10−4C/cm2) which is five orders of magnitude smaller than the critical end point dose (20 C/cm2). Previously we discussed the progress of this phase transition primarily as observed down the [001] zone (the chain axis direction). Here we report on the associated changes of the dark field (DF) images and selected area electron diffraction (SAED) patterns of the crystals as observed from the side (i.e., in the [hk0] zones).High resolution electron micrographs (HREM), DF images, and SAED patterns were obtained on a JEOL 4000 EX HREM operating at 400 kV.


2006 ◽  
Vol 31 (1) ◽  
pp. 39-48
Author(s):  
Najla Vix-Gurtel ◽  
Chaari Dentzer ◽  
Slaheddine Chaabouni ◽  
Jean-Michel Savariault ◽  
Abdelhamid ben Salah

2021 ◽  
pp. 102579
Author(s):  
Shilpa Singh ◽  
Yogesh Sonvane ◽  
K.A. Nekrasov ◽  
A.S. Boyarchenkov ◽  
A. Ya. Kupryazhkin ◽  
...  

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Qian Li ◽  
Yun Liu ◽  
Andrew Studer ◽  
Zhenrong Li ◽  
Ray Withers ◽  
...  

We characterized the temperature dependent (~25–200°C) electromechanical properties and crystal structure of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3single crystals usingin situelectrical measurement and neutron diffraction techniques. The results show that the poled crystal experiences an addition phase transition around 120°C whereas such a transition is absent in the unpoled crystal. It is also found that the polar order persists above the maximum dielectric permittivity temperature at which the crystal shows a well-defined antiferroelectric behavior. The changes in the electrical properties and underlying crystal structure are discussed in the paper.


1992 ◽  
Vol 47 (1-2) ◽  
pp. 177-181 ◽  
Author(s):  
Shi-Qi Dou ◽  
Alarich Weiss

AbstractThe two line 35Cl NQR spectrum of 4,5-dichloroimidazole was measured in the temperature range 77≦ T/K ≦ 389. The temperature dependence of the NQR frequencies conforms with the Bayer model and no phase transition is indicated in the curves v ( 35Cl)= f(T). Also the temperature coefficients of the 35Cl NQR frequencies are "normal". At 77 K the 35Cl NQR frequencies are 37.409 MHz and 36.172 MHz and at 389 K 35.758 MHz and 34.565 MHz. The compound crystallizes at room temperature with the tetragonal space group D44-P41212, Z = 8 molecules per unit cell; at 295 K : a = 684.2(5) pm, c = 2414.0(20) pm. The relations between the crystal structure and the NQR spectrum are discussed.


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