Temperature dependence of the work function of Bi2Sr2CaCu2O8 single crystal cleaved at low temperature

2005 ◽  
Vol 252 (2) ◽  
pp. 379-384 ◽  
Author(s):  
S. Saito ◽  
T. Sutou ◽  
Y. Norimitsu ◽  
N. Yajima ◽  
Y. Uhara ◽  
...  
2014 ◽  
Vol 70 (a1) ◽  
pp. C195-C195
Author(s):  
Shinobu Aoyagi ◽  
Kunihisa Sugimoto ◽  
Hiroshi Okada ◽  
Norihisa Hoshino ◽  
Tomoyuki Akutagawa

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.


JETP Letters ◽  
1996 ◽  
Vol 64 (11) ◽  
pp. 832-838 ◽  
Author(s):  
M. R. Trunin ◽  
A. A. Zhukov ◽  
G. É. Tsydynzhapov ◽  
A. T. Sokolov ◽  
L. A. Klinkova ◽  
...  

2005 ◽  
Vol 886 ◽  
Author(s):  
Jian He ◽  
Kelvin Aaron ◽  
Edward Abbott ◽  
Joseph Kolis ◽  
Terry M. Tritt

ABSTRACTSingle crystal NaCo2O4 platelets with sizes up to 6mm were synthesized by the typical high temperature NaCl flux method. The in-plane thermopower α and in-plane resistivity ρ were measured to be ∼100µV/K and 0.3mΩ-cm at 300K, respectively. The in-plane thermal conductivity κ was measured by our custom-designed “PTC” system and found to be ∼5 W-m−1K−1 at 300K, which is 2-3 times larger than the polycrystalline NaCo2O4. The in-plane phonon mean free path lph was estimated to be ∼9.5Å, which is much smaller than the in-plane mean free path of conducting carriers (la∼51Å). A novel low temperature flux method where NaCl/NaOH was used as flux and metallic Co powders as Co source was developed to successfully synthesize Na-deficient NaxCo2O4 crystals with size up to 6mm at low temperature of 550°C. The different temperature dependence in resistivity reveals that two different types of crystals can exist, one is metallic and another is semiconducting. The temperature dependence of the measured k is like that of a disordered solid and the value is found to be ∼7 W-m−1K−1 at 300K.


Author(s):  
S. G. Ghonge ◽  
E. Goo ◽  
R. Ramesh ◽  
R. Haakenaasen ◽  
D. K. Fork

Microstructure of epitaxial ferroelectric/conductive oxide heterostructures on LaAIO3(LAO) and Si substrates have been studied by conventional and high resolution transmission electron microscopy. The epitaxial films have a wide range of potential applications in areas such as non-volatile memory devices, electro-optic devices and pyroelectric detectors. For applications such as electro-optic devices the films must be single crystal and for applications such as nonvolatile memory devices and pyroelectric devices single crystal films will enhance the performance of the devices. The ferroelectric films studied are Pb(Zr0.2Ti0.8)O3(PLZT), PbTiO3(PT), BiTiO3(BT) and Pb0.9La0.1(Zr0.2Ti0.8)0.975O3(PLZT).Electrical contact to ferroelectric films is commonly made with metals such as Pt. Metals generally have a large difference in work function compared to the work function of the ferroelectric oxides. This results in a Schottky barrier at the interface and the interfacial space charge is believed to responsible for domain pinning and degradation in the ferroelectric properties resulting in phenomenon such as fatigue.


2020 ◽  
Vol 96 (3s) ◽  
pp. 148-153
Author(s):  
С.Д. Федотов ◽  
А.В. Бабаев ◽  
В.Н. Стаценко ◽  
К.А. Царик ◽  
В.К. Неволин

Представлены результаты изучения морфологии поверхности и структуры слоев AlN, сформированных аммиачной МЛЭ на темплейтах 3C-SiC/Si(111) on-axis- и 4° off-axis-разориентации. Опробован технологический режим низкотемпературной эпитаксии зародышевого слоя AlN на поверхности 3C-SiC(111). Среднеквадратичная шероховатость поверхности (5 х 5 мкм) слоев AlN толщиной 150 ± 50 нм составила 2,5-3,5 нм на темплейтах 3C-SiC/Si(111) on-axis и 3,3-3,5 нм на 4° off-axis. Показано уменьшение шероховатости смачивающего слоя AlN при изменении скорости роста. Получены монокристаллические слои AlN(0002) со значениями FWHM (ω-геометрия) 1,4-1,6°. The paper presents the surface morphology and crystal structure of AlN layers formed by ammonia MBE on 3C-SiC/Si(111) on-axis and 4° off-axis disorientation. It offers the technological approach of low-temperature epitaxy of the AlN nucleation layer on the 3C-SiC (111) surface. Root mean square roughness (5 х 5 |xm) of AlN layers with thickness of 150 ± 50 nm was 2,5-3,5 nm onto on-axis templates and 3.3-3.5 nm onto 4° off-axis. It appears that the RMS roughness of the AlN surface is changing with the growth rate variation. Single-crystal AlN(0002) layers with FWHM values (ω-geometry) of 1.4-1.6° have been obtained.


2017 ◽  
Vol 122 (8) ◽  
pp. 084103 ◽  
Author(s):  
E. Smirnova ◽  
A. Sotnikov ◽  
S. Ktitorov ◽  
H. Schmidt

2021 ◽  
Author(s):  
Qi Zhao ◽  
Jin-Peng Xue ◽  
Zhi-Kun Liu ◽  
Zi-Shuo Yao ◽  
Jun Tao

A mononuclear complex with long alkyl chains, [FeII(H2Bpz2)2(C9bpy)] (1; H2Bpz2 = dihydrobis(1-pyrazolyl)borate, C9bpy = 4,4'-dinonyl-2,2'-bipyridine), was synthesized. Single-crystal X-ray crystallographic studies revealed that - and - forms of the complex...


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