Dielectric Constant of Barium Titanate Synthesized by Containerless Processing

2004 ◽  
Vol 848 ◽  
Author(s):  
Jianding Yu ◽  
Paul-François Paradis ◽  
Takehiko Ishikawa ◽  
Shinichi Yoda
Keyword(s):  
Dielectric Constant ◽  
Barium Titanate ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Undercooled Liquid ◽  
Electrostatic Levitation ◽  
Containerless Processing ◽  
Synthesis Technique ◽  
Loss Component

ABSTRACTContainerless processing is an attractive synthesis technique that permits deep undercooling and provides the possibility to solidify the undercooled liquid into a selected phase, and to synthesize materials with novel properties. Spheroidal BaTiO3 samples with a diameter of approximately 2mm were solidified by containerless processing, using an electrostatic levitation apparatus. Single crystal hexagonal BaTiO3 and polycrystalline perovskite BaTiO3 were successfully synthesized at different undercoolings levels. An oxygen-deficient single crystal of hexagonal BaTiO3 obtained with this method, exhibited a giant permittivity higher than 100000, with a loss component tanδ of about 0.1 at room temperature. The permittivity showed weak temperature dependence in the 70 K to 300 K range, and a dramatic drop by 2 orders of magnitude below 70 K. In comparison, the polycrystalline perovskite BaTiO3 showed a permittivity of 4000 at room temperature.

scholarly journals Температурная зависимость напряжения, вызванного спиновым током в гетероструктуре манганит/иридат

2021 ◽  
Vol 63 (9) ◽  
pp. 1321
Author(s):  
Т.А. Шайхулов ◽  
К.Л. Станкевич ◽  
К.И. Константинян ◽  
В.В. Демидов ◽  
Г.А. Овсянников
Keyword(s):  
Thin Film ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Hall Effect ◽  
Ferromagnetic Resonance ◽  
Room Temperature ◽  
Ferromagnetic Layer ◽  
Spin Current ◽  
Epitaxial Thin Film ◽  
Inverse Spin Hall Effect

The temperature dependence of the voltage induced by the spin current was studied in an epitaxial thin-film La0.7Sr0.3MnO3 / SrIrO3 heterostructure deposited on a single-crystal NdGaO3 substrate. The spin current was generated by microwave pumping under conditions of ferromagnetic resonance in the La0.7Sr0.3MnO3 ferromagnetic layer and was detected in the SrIrO3 layer due to inverse spin Hall effect. A significant increase of half-width of the spin current spectrum along with the rise of amplitude of the spin current upon cooling from room temperature (300 K) to 135 K were observed.

Crystal Distortions Associated with Magnetic Ordering in the Antiferromagnetic Compound VF2

1970 ◽  
Vol 14 ◽  
pp. 433-440
Author(s):  
W. S. McCain ◽  
D. L. Albright ◽  
W. O. J. Boo
Keyword(s):  
Single Crystal ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Magnetic Ordering ◽  
The Body ◽  
The Other ◽  
Magnetic Interactions ◽  
One Dimensional ◽  
Lattice Constants ◽  
Vanadium Ions

AbstractLattice constants were measured as a function of temperature by single crystal diffracrometry in the temperature range which includes the Néel temperature of VF2(TN= 7°K). The lattice constants of VF2(D4h14=P42m n m) were measured from room temperature down to 4.2°K. In this range rhe tetragonal c-axis contracts 0.58% from 3.2359 Å (RT) to 3.2170 Å (4.2°K). On the other hand, the a-axes show a net expansion of 0.18% from 4.8023 Å (RT) to 4.8110 Å at 4.2°K. The temperature dependence of the lattice constants can be correlated with anisotropy of exchange forces. Vanadium Ions occupy the center and corner positions of the unit cell. Strong magnetic interactions are directed parallel to the c-axis >001< with considerably weaker interactions parallel to the body diagonals >111< The relative strengths of the two exchange integrals are J >001< = 50 J >111<. As a consequence the magnetic ordering is one-dîmensional along the c-axis and the associated distortions arise from the strong magnetic interactions along this axis.

Temperature dependence of the AV3O7 (A = Ca, Sr) structure

2007 ◽  
Vol 63 (6) ◽  
pp. 836-842 ◽  
Author(s):  
Sebastian Prinz ◽  
Karine M. Sparta ◽  
Georg Roth
Keyword(s):  
Single Crystal ◽  
Temperature Dependence ◽  
Crystal Structures ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Groups ◽  
Temperature Ranges ◽  
First Time

The V4+ (spin ½) oxovanadates AV3O7 (A = Ca, Sr) were synthesized and studied by means of single-crystal X-ray diffraction. The room-temperature structures of both compounds are orthorhombic and their respective space groups are Pnma and Pmmn. The previously assumed structure of SrV3O7 has been revised and the temperature dependence of both crystal structures in the temperature ranges 297–100 K and 315–100 K, respectively, is discussed for the first time.

Transport Studies in Single-Crystal Films of Cosi2 and Nisi2

1983 ◽  
Vol 25 ◽  
Author(s):  
J. C. Hensel ◽  
R. T. Tung ◽  
J. M. Poate ◽  
F. C. Unterwald ◽  
D. C. Jacobson
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Transport Studies ◽  
Single Crystal Films ◽  
Crystal Films ◽  
The Difference ◽  
Temperature Resistivity

ABSTRACTTransport studies have been performed on thin films of CoSi 2 and NiSis2 in the temperature range 1 to 300 K. The conductivities are metallic with essentially the same temperature dependence; however, the residual resistivities are markedly different even though the two silicides are structurally similar (the room temperature resistivity of NiSi2 being at least twice that of CoSi2 of 15 μΩ cm). The difference is attributed to intrinsic defects in NiSi2. This defect has been simulated by ion bombardment of the film where it is also shown that Matthiesen's rule is obeyed over a remarkable range of bombardment doses.

Effect of MnO2 Impurity on the PZT-PMN System Ceramics for Piezoelectric Transformer

2008 ◽  
Vol 55-57 ◽  
pp. 189-192
Author(s):  
Y. Suwan ◽  
Anuson Niyompan ◽  
Rungnapa Tipakontitikul ◽  
Pitak Laoratanakul
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Phase Transformation ◽  
Physical Properties ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Piezoelectric Properties ◽  
Relative Dielectric Constant ◽  
Linear Shrinkage ◽  
Poling Process

The PZT-PMN ceramics system was derived from Pb(Zr0.5Ti0.5)O3 and Pb(Mg2/3Nb1/3)O3 based compositions those obtained via the columbite method. The effect of MnO2 addition on microstructure, physical properties and piezoelectric properties were investigated. In this study, the composition with PZT/PMN ratio of 1:1 was selected. To observe the effect of MnO2 adding, its concentration was varied in range 0-10 mol%. Green pellets were sintered at temperature 1250oC for 4 hours. For piezoelectric investigation, the ceramics pellets were subjected to a poling process. The XRD results show that there is no phase transformation observed for all sintered PZT-PMN samples with presence of MnO2. The SEM micrographs reveal that MnO2 can enhance sinterability as evidenced by lowering of porosity and increasing of grain size with increasing of MnO2 content. Increasing of linear shrinkage and apparent densities also confirmed such effect. Improvement of d33 from 28 to 114 pC/N could only found for MnO2 in range 0 to 4 mol%. For higher MnO2 content, there is only slightly increased. However, increasing of kp with increasing of MnO2 is clearly observed. While dielectric constant measured at room temperature and at frequency 1 kHz is higher for ceramics without MnO2 doping and it decreases with increasing MnO2 concentration. The temperature dependence of relative dielectric constant go to peak of value about 6000 at temperature around 180oC and shifting of these peaks with frequency can only be observed for samples with higher MnO2 content. This indicates a normal ferroelectric behavior for sample with lower MnO2 and there are converted to relaxor after MnO2 increased.

Dielectric Properties of Pulsed Excimer Laser Ablated BaBi2Nb2O9 Thin Films

2002 ◽  
Vol 748 ◽  
Author(s):  
Apurba Laha ◽  
S. B. Krupanidhi ◽  
S. Saha
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Dielectric Constant ◽  
Temperature Dependence ◽  
Loss Tangent ◽  
Dielectric Response ◽  
Room Temperature ◽  
Dielectric Constant And Loss ◽  
Wide Range ◽  
Room Temperature Dielectric Constant

ABSTRACTThe dielectric response of BaBi2Nb2O9 (BBN) thin films has been studied as a function of frequency over a wide range of temperatures. Both dielectric constant and loss tangent of BBN thin films showed a ‘power law’ dependence with frequency, which was analyzed using the Jonscher's universal dielectric response model. Theoretical fits were utilized to compare the experimental results and also to estimate the value of temperature dependence parameters such as n(T) and a(T) used in the Jonscher's model. The room temperature dielectric constant (ε') of the BBN thin films was 214 with a loss tangent (tanδ) of 0.04 at a frequency of 100 kHz. The films exhibited the second order dielectric phase transition from ferroelectric to paraelectric state at a temperature of 220 °C. The nature of phase transition was confirmed from the temperature dependence of dielectric constant and sponteneous polarization,respectively. The calculated Currie constant for BBN thin films was 4 × 105°C.

Pt–Cu2O–Cu double injection diodes

1977 ◽  
Vol 55 (7-8) ◽  
pp. 727-734
Author(s):  
K. T. Chee ◽  
F. L. Weichman
Keyword(s):  
Single Crystal ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Platinum Electrode ◽  
Negative Resistance ◽  
Air Pressure ◽  
Constant Voltage ◽  
Double Injection ◽  
High Injection ◽  
Field Dependent

We report here on recent measurements made on our Pt–Cu2O–Cu diodes, annealed at an air pressure of 1 to 2 Torr, which we interpret as due to double injection, i.e. injection of holes from the platinum electrode and injection of electrons from the copper–Cu2O junction into the single crystal Cu2O region. The measurements discussed here include the forward I–V characteristics at various temperatures, current vs. thickness relationship at constant voltage, the effect of photo-memory on the I–V characteristics, and the discovery of a negative resistance regime at below room temperature at sufficiently high injection levels. The analysis of the temperature dependence of the current in the ohmic and the [Formula: see text] regimes, together with the effect of photomemory on the I–V characteristics enable us to identify the [Formula: see text] regime as the Ashley–Milnes regime with field dependent mobility.

Crystallization of Spherical Single Crystal of Silicon from Undercooled Droplet under Containerless Processing

2005 ◽  
Vol 475-479 ◽  
pp. 2603-2606
Author(s):  
Zeng Yun Jian ◽  
Kazuhiko Kuribayashi ◽  
Wan Qi Jie
Keyword(s):  
Single Crystal ◽  
Thin Plate ◽  
High Speed ◽  
Growth Process ◽  
Present Model ◽  
High Speed Camera ◽  
Undercooled Liquid ◽  
Containerless Processing ◽  
Critical Undercooling

The images of the growing crystal in the growth process of the undercooled droplets of silicon were lively recorded by using a high-speed camera. The number of crystal that nucleated spontaneously from the undercooled liquid was found to decrease to 1 when the undercooling was higher than 5K. The morphology of the growing single crystal of silicon was a thin plate. A model for predicting the critical undercooling of growing single crystal of silicon from undercooled liquid has been developed. The theoretically predicted value of the undercooling from present model for silicon is in agreement with the experimentally measured result.

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