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J. M. Igartua G. Aguirre-Zamalloa I. Ruiz-Larrea M. Couzi A. López-Echarri T. Breczewski 《Journal of Thermal Analysis and Calorimetry》1994,41(6):1211-1215
The specific heat of N(CH3)4CdBr3 from 50 to 300 K has been measured by adiabatic calorimetry, using both static and dynamic methods. The obtained results have permitted a careful study of the ferro-paraelectric phase transition the crystal shows at 160 K. The available spectroscopic data have been used to generate a reliable baseline which accounts for the normal lattice contribution to the specific heat. These results allow for an accurate estimation of the phase transition thermodynamic functions: ΔH=2620 J·mol?1 and ΔS=18.04 J·(mol°C)?1. These high values are in agreement with the predictions of the 6 well potential Frenkel model. 相似文献
3.
H. Schmid 《Phase Transitions》2013,86(1-4):205-214
A short overview is given on recent polarized light microscopy studies of the orthorhombic ferroelastic domains and domain structures of YBa2Cu3O7-x . The optical characteristics of large domains and lamellar domains with a high density of twin walls are pointed out, both for reflected and transmitted light. The polarizing microscope has allowed to observe the ferroelastic detwinning in situ and to determine the activation energy of the ferroelastic wall movements. The question of a potential ferroelectric phase transition is also discussed. 相似文献
4.
Shiro Matsumoto Yasuyuki Sugiyama Seizou Sakata Takayoshi Hayashi 《Liquid crystals》2013,40(5):649-655
Polymers containing droplets of liquid crystal smaller than 100 nm, which have good transparency and easily form films, were prepared under various conditions to evaluate their potential as electro-optic materials for waveguide-type devices. By varying the liquid crystal concentration and the strength of the UV irradiation causing photo-induced phase separation of the droplets, we were able to control the droplet size and density. We have clarified how the birefringence generated in an applied electric field, switching speed, and optical loss of light propagating in the film depend on droplet size and density. Polymer materials having a large electro-optic effect (δn = 0.001 at 8 V μm-1), low propagation loss (~2.5 dB cm-1), and fast response time (~10 μs) have been developed. 相似文献
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Back Cover: Chemical Preparation of Ferroelectric Mesoporous Barium Titanate Thin Films: Drastic Enhancement of Curie Temperature Induced by Mesopore‐Derived Strain (Chem. Eur. J. 36/2014)
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7.
通过高温固相反应法制备了Ba0.85Ca0.15Ti0.90Zr0.10O3∶xSm3+(BCTZ∶xSm3+,x=0.0%、0.2%、0.4%、0.6%、0.8%、1.0%,物质的量分数)陶瓷,系统研究了其微观形貌、铁电性能、储能性能和光致发光性能。研究表明,Sm3+掺入后,陶瓷平均晶粒大小明显下降,致密度显著提高。所有陶瓷均表现出典型的铁电性。BCTZ∶xSm3+陶瓷放电储能密度得到了极大的提高,BCTZ∶1.0% Sm3+陶瓷放电储能密度较纯BCTZ陶瓷可提高约49.0%。此外,在408 nm光的激发下,BCTZ∶xSm3+陶瓷在596 nm左右表现出强烈的橙红色发光,且发光强度相对可调性可达449%。 相似文献
8.
铁电材料拥有自发电极化, 不同的极化方向会对异质结的电子结构产生可逆的和非易失性的影响. 本工作采用分子束外延技术在二维铁电材料α-In2Se3 衬底上成功制备了 Pb 纳米岛构建 Pb/α-In2Se3 超导铁电异质结,并通过扫描隧道显微镜表征了其表面原子结构与电子结构. 进一步的扫描隧道谱测量显示不同层厚 Pb 岛的量子阱态消失, 并且我们在4.5 K 的温度下没有观察到超导能隙, 表明铁电衬底会影响 Pb 岛的电子结构, 甚至其超导特性. 这些发现为理解铁电衬底对超导性的影响提供了参考, 并为调控低维量子材料中的电子结构及超导性提供了新的思路. 相似文献
9.
This supplement contains 222 (angel number) further papers on false or unconfirmed ferroelectric properties in single crystals, ceramics and polymers and only concerns bulk materials. Thus, the number of such papers has reached huge value 727. The papers marked in red have drastically broken the principles of symmetry because they reported the existence of ferroelectricity in crystals without the polar axis. 相似文献
10.
The first-principles study of ferroelectric behaviours of PbTiO3/SrTiO3 and BaTiOn/SrTiO3 superlattices
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We have performed the first-principles calculation to investigate the origins of ferroelectricities and different po- larization behaviours of superlattices BaTiO3/SrTiO3 and PbTiO3/SrTiO3. The density of state (DOS) and electronic charge profiles show that there are strong hybridizations between atoms Ti and O and between atoms Pb and O which play very important roles in producing the ferroelectricities of superlattices BaTiO3/SrTiO3 and PbTiO3/SrTiO3. Ow- ing to the decline of internal electric field in SrTiO3 (ST) layer, the tetragonality and polarizations of superlattices decrease with increasing the fraction of SrTiO3 in the superlattices. We find that the polarization of PbTiO3/SrTiO3 is largerthan that of BaTiO3/SrTiO3 at the same ratio of components, because the polarization mismatch between PbTiO3 and SrTiO3 is larger than that between BaTiO3 and SrTiO3. The polarization and tetragonality are en- hanced with respect to those of bulk tetragonal BaTiO3 in the superlattices BaTiO3/SrTiO3, while the polarization and tetragonality are reduced with respect to those of bulk tetragonal PbTiO3 in superlattices PbTiO3/SrTiO3. 相似文献