Temperature dependence of the low-frequency reflectance spectrum of a sodium nitrate single crystal: Effect of the phase transition on the lattice modes parameters

1981 ◽  
Vol 2 (2) ◽  
pp. 333-345 ◽  
Author(s):  
F. Brehat ◽  
B. Wyncke ◽  
A. Hadni
Keyword(s):  
Phase Transition ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Sodium Nitrate ◽  
Reflectance Spectrum ◽  
Low Frequency ◽  
Lattice Modes

Dynamic shock wave induced order-disorder type phase transition of sodium nitrate single crystal

2021 ◽  
pp. 114625
Author(s):  
A. Sivakumar ◽  
P. Eniya ◽  
S. Sahaya Jude Dhas ◽  
S. Joreme Dhas ◽  
J. Kalyana Sundar ◽  
...  
Keyword(s):  
Phase Transition ◽  
Shock Wave ◽  
Single Crystal ◽  
Sodium Nitrate ◽  
Type Phase ◽  
Wave Induced ◽  
Disorder Type

scholarly journals Crystal Structure and Dielectric Property of Endohedral Lithium Fullerene

2014 ◽  
Vol 70 (a1) ◽  
pp. C195-C195
Author(s):  
Shinobu Aoyagi ◽  
Kunihisa Sugimoto ◽  
Hiroshi Okada ◽  
Norihisa Hoshino ◽  
Tomoyuki Akutagawa
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Dielectric Property ◽  
Low Temperature ◽  
Dielectric Permittivity ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Structure Analysis ◽  
X Ray ◽  
Dielectric Phase

Endohedral lithium fullerene Li+@C60 can have a dielectric polarization by the off-centered location of the Li+ cation inside the C60 cage. The x-ray structure analysis of the PF6– salt [Li@C60](PF6) revealed that the Li+ cation occupies two off-centered equivalent positions at 20 K and hence the crystal is non-polar [1]. The disordered structure at low temperature is explained by a static orientation disorder of polar Li+@C60 cations and/or a dynamic tunneling of the Li+ cation inside the C60 cage. The Li+ tunneling would be suppressed by an intermolecular interaction at lower temperature and a dielectric phase transition might be induced. We reveal the dielectric property and crystal structure of [Li@C60](PF6) below 20 K in this study. The temperature dependence of the dielectric permittivity was measured for the single crystal down to 9 K. The dielectric permittivity increases with decreasing temperature according to the Curie-Weiss law. Such a behavior was also observed in H2O@C60 crystal but not in empty C60 crystal [2]. No dielectric phase transition was observed in H2O@C60 down to 8 K. In contrast, a dielectric anomaly suggesting a phase transition was observed in [Li@C60](PF6) around 18 K. The single-crystal x-ray diffraction experiment below 20 K was also performed at SPring-8 BL02B1. The crystal has a cubic structure at 20 K [1]. The temperature dependence of the cubic lattice constant shows no anomaly around 18 K. However, diffraction peaks that are forbidden for the given structure appear below 18 K. Thus the crystal symmetry is lowered by the dielectric phase transition. We present the result of the crystal structure analysis of the newly discovered low-temperature phase.

Permittivity and Microstructure of (Ba,Sr)TiO3 Films: Temperature and Electric Field Response

1999 ◽  
Vol 603 ◽  
Author(s):  
Yu.A. Boikov ◽  
T. Claeson ◽  
Z. Ivanov ◽  
E. Olsson
Keyword(s):  
Phase Transition ◽  
Dielectric Permittivity ◽  
Electric Field ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Transition Point ◽  
Phase Transition Point ◽  
Bulk Single Crystal ◽  
Temperature Range ◽  
Field Response

AbstractEpitaxial heterostructures (001)(Y,Nd)Ba2Cu3O7-δ∥(100)SrTiO3∥(001)(Nd,Y)Ba2Cu3O7-δ,(100)SrRuO3∥(100)Ba0.8Sr0.2TiO3∥(100)SrRuO3, (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 and (100)SrTiO3∥(001)YBa2Cu3O7-δ have been grown by laser ablation. There was only a small difference of the dielectric permittivity, in the temperature range 180-300K, between a bulk single crystal and an epitaxial (100)SrTiO3 layer inserted between either high-Tc superconducting or SrRuO3 electrodes. At T<1 50K, on the other hand, the response of the dielectric permittivity of the SrTiO3 layer on temperature or electric field depended to a large extent upon the materials used as bottom and top electrodes in the heterostructures. The temperature dependence of the dielectric permittivity for the SrTiO3 layer in (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 was well extrapolated by a Curie-Weiss relation in the range of T=80-300K, with about the same Curie constant (C0=7.5 × 104 K) and Curie temperature (TCurie=21K) as in a bulk single crystal. At temperatures higher the phase transition point (65 K), the electric field response of the permittivity of the SrTiO3 layer between high-TC superconducting or metallic oxide electrodes was well extrapolated by the same relation used for a bulk single crystal. The smallest loss factor, tanδ, was measured for the capacitance (100)SrRuO3∥(100)SrTiO3∥(100)SrRuO3 (T ≈ 50-300K, f=100kHz). The measured conductance G for the SrTiO3 layer in the (001)(Y,Nd)Ba2Cu3O7-δ heterostructure fitted well the relation InG∼-(ED/kT), with ED=0.08-0.09 eV in a temperature range close to 300K. Pronounced hysteresis was observed in the temperature dependence of the dielectric permittivity for the (100)Ba0.8Sr0.2TiO3 layer at temperatures close to the phase transition point, like in the case of a bulk single crystal. The permittivity of the (100)Ba0.8Sr0.2TiO3 layer decreased more than 50% when an electric field of 2.5×106V/m (T ≈ 300K, f=100 kHz ) was applied.

scholarly journals Reversibility in a Plastically Flexible Coordination Polymer Crystal: A High-Pressure Study

2020 ◽  
Author(s):  
Xiaojiao Liu ◽  
Adam Michalchuk ◽  
Biswajit Bhattacharya ◽  
Franziska Emmerling ◽  
Colin R. Pulham
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Coordination Polymer ◽  
Single Crystal ◽  
Structural Phase ◽  
Low Frequency ◽  
Hydrostatic Compression ◽  
Three Point Bending ◽  
Flexible Material ◽  
Plastic Materials

<p>Single crystals which exhibit mechanical flexibility are promising materials for advanced technological applications. Before such materials can be used, detailed understanding of the mechanisms and structural effects of bending are needed. Coordination polymer single crystal represent a fascinating class of mechanically flexible material; their bending contradicts existing models. Using single crystal X-ray diffraction and microfocus Raman spectroscopy, we study in atomic detail the high-pressure response of the plastically flexible coordination polymer [Zn(μ‐Cl)<sub>2</sub>(3,5‐dichloropyridine)<sub>2</sub>]<i><sub>n</sub>.</i> In stark contrast to three-point bending, the quasi-hydrostatic compression of the single crystal is completely reversible, even following compression to over 9 GPa. A structural phase transition is observed at <i>ca. </i>5 GPa. <i>Ab initio</i> DFT calculations show this transition to result from the pressure-induced softening of low frequency vibrations. This phase transition is not observed during three-point bending. Our combined experimental and theoretical high-pressure investigation propose slight compression at low levels of bending. However, our studies provide the first indication of overall disparate mechanical responses of bulk flexibility and quasi-hydrostatic compression. We suspect this to be a general feature of mechanically plastic materials. <b></b></p>

Temperature Dependence of Reflectance Spectrum of (SN)x Single Crystal

1977 ◽  
Vol 43 (3) ◽  
pp. 1013-1015 ◽  
Author(s):  
Keiichi Kaneto ◽  
Katsumi Yoshino ◽  
Yoshio Inuishi
Keyword(s):  
Single Crystal ◽  
Temperature Dependence ◽  
Reflectance Spectrum
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