Study of Electrical Conductivity in WO3-doped Nonstoichiometric LiTaO3

2012 ◽  
Vol 57 (8) ◽  
pp. 834
Author(s):  
M. Tahiri ◽  
N. Masaif ◽  
A. Jennane ◽  
E.M. Lotfi
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Ternary System ◽  
Curie Temperature ◽  
Solid Solutions ◽  
Theoretical Approach ◽  
Defect Structure ◽  
Experimental Conductivity ◽  
Theoretical Results ◽  
Good Agreement

The results of experimental and analytical studies of the electrical conductivity for different solid solutions synthesized in a vicinity of LiTaO3 in the ternary system Li2O–Ta2O5–(WO3)2 are presented. It is shown that the electrical conductivity increases linearly with the Curie temperature. The experimental conductivity between 200 and 700 ºC was measured using an LCR bridge HP4192A on ceramics sintered at 1250 ºC. Within the theoretical approach to the defect structure analysis combined with our proposed vacancy models, the theoretical results are in a good agreement with the experimental data.

scholarly journals Analysis of Correlation between Density Variations and Defect Structure of W6+ : LiTaO3

2018 ◽  
Vol 63 (4) ◽  
pp. 347 ◽  
Author(s):  
M. Tahiri ◽  
A. Jennane ◽  
N. Masaif ◽  
E. M. Lemdek ◽  
E. M. Lotfi
Keyword(s):  
Ternary System ◽  
Solid Solutions ◽  
Theoretical Approach ◽  
Defect Structure ◽  
Dopant Concentration ◽  
Lithium Tantalate ◽  
Experimental Results ◽  
Substitution Mechanism

We investigate the defect structure of non-stoichiometric solid solutions of WO3-doped LiTaO3 in correlation with the evolution of the density within our theoretical approach. The dopant concentration and the mechanism of substitution, which depends of the ionic rays of different cations that exit into the network, have an effect on crystalline parameters and, consequently, on the density. In order to explain the defect structure of solid solutions synthesized in the ternary system Li2O–Ta2O5–(WO3)2 in a vicinity of LiTaO3,, we have shown a convergence between theoretical and experimental results by the application of our theoretical approach combined with the new proposed vacancy models. We conclude that the new vacancy models are able to describe the defect structure and the substitution mechanism in each solid solutions of WO3-doped lithium tantalate.

Explanation of the Influence of Inflow Air Content on the Lift of Cavitating Hydrofoils

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Lift Coefficient ◽  
Cavity Surface ◽  
Air Bubbles ◽  
Incoming Flow ◽  
Fluid Density ◽  
Air Content ◽  
Theoretical Results ◽  
Good Agreement

According to several known experiments, an increase of the incoming flow air content can increase the hydrofoil lift coefficient. The presented theoretical study shows that such increase is associated with the decrease of the fluid density at the cavity surface. This decrease is caused by entrainment of air bubbles to the cavity from the surrounding flow. The theoretical results based on such explanation are in a good agreement with the earlier published experimental data for NACA0015.

Thermodynamic Modeling of the Mg-Ni-La-Cu System

2011 ◽  
Vol 314-316 ◽  
pp. 1262-1267 ◽  
Author(s):  
Xue Hui An ◽  
Qian Li ◽  
Jie Yu Zhang
Keyword(s):  
Experimental Data ◽  
Isothermal Section ◽  
Ternary System ◽  
Hydrogen Storage ◽  
Vertical Section ◽  
Solidification Path ◽  
Hydrogen Storage Alloys ◽  
Equilibrium Solidification ◽  
Good Agreement ◽  
Phase Relationships

The isothermal section at 573 K of the Ni-Cu-La system was experimentally validated as well as the Mg-La-Cu system was thermodynamically evaluated. Four sample alloys in the Ni-Cu-La system were prepared and analyzed by ICP, XRD and BSE/EDS. All the experimental results were compared favorably with the calculated phase relationships. For the Mg-La-Cu ternary system, the isothermal section at 673 K was assessed on the basis of the available results in literatures, which showed a good agreement with the experimental data. Based on the thermodynamic models and parameters of the six binaries and four ternaries, the Mg-Ni-La-Cu system was finally modeled. The non-equilibrium solidification path La0.7Mg0.3Ni2.8-xCux (x=0-0.4) and the vertical section of LaNi5-Mg2Cu were calculated and analyzed from the viewpoint of hydrogen storage alloys design.

Tsallis-Statistical Approach to the Specific Heat of LIQUID 4HE: Comparison with Other Results

1997 ◽  
Vol 11 (19) ◽  
pp. 2303-2310 ◽  
Author(s):  
Sergio Curilef ◽  
Andrés R. R. Papa
Keyword(s):  
Experimental Data ◽  
Comparative Analysis ◽  
Quantum Group ◽  
Specific Heat ◽  
High Precision ◽  
Theoretical Approach ◽  
Statistical Approach ◽  
Precision Measurements ◽  
Best Fitting ◽  
Theoretical Results

A theoretical approach within a quantum-group formalism has recently been proposed and successfully compared to Greywall's high precision measurements of the liquid 4 He specific heat. We calculate here the specific heat for 4 He using Tsallis' non-extensive thermostatistics. A comparative analysis reveals that there is a temperature range where our theoretical results yield the best fitting to experimental data.

Stability of Unsymmetrical Rigid Rotor Supported by Self-Acting Gas-Lubricated Journal Bearings

1983 ◽  
Vol 105 (4) ◽  
pp. 656-661 ◽  
Author(s):  
S. Yoshimoto ◽  
Y. Nakano
Keyword(s):  
Theoretical Approach ◽  
Journal Bearings ◽  
Center Of Gravity ◽  
Rigid Rotor ◽  
Load Bearing ◽  
Bearing Clearance ◽  
Axial Deviation ◽  
Bearing Load ◽  
Theoretical Results ◽  
Good Agreement

In order to determine the threshold of instability for an unsymmetrical rigid rotor supported by two identical self-acting, plain-cylindrical gas journal bearings, a theoretical approach is made by the use of the quasi-static nonliner PH method. Influence of various parameters affecting the threshold of instability of the unsymmetrical rotor is experimentally shown and compared with the theoretical results. The experimental variables considered in this paper include bearing load, bearing length, bearing clearance, the axial deviation of the center of gravity from the center of the rotor span. Good agreement was obtained between the experimental and theoretical results.

In-Plane Vibrations of Thick Circular Rings With T or I Cross Sections

1979 ◽  
Vol 46 (2) ◽  
pp. 470-472
Author(s):  
H. Lecoanet ◽  
J. Piranda
Keyword(s):  
Experimental Data ◽  
Eigenvalue Problem ◽  
Cross Section ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Circular Rings ◽  
Theoretical Results ◽  
Good Agreement

This paper deals with the problem of eigenfrequencies and eigenvectors for rings whose cross section may be decomposed in basic rectangular cross sections. The solution is derived from a solution of the in-plane eigenvalue problem for rectangular cross-section thick rings. A good agreement between theoretical results and experimental data is obtained.

Analysis of Thermal Effects in Hydrodynamic Bearings

1986 ◽  
Vol 108 (2) ◽  
pp. 219-224 ◽  
Author(s):  
R. Boncompain ◽  
M. Fillon ◽  
J. Frene
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Effects ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Heat Transfer Equation ◽  
Reversed Flow ◽  
Theoretical Results ◽  
Generalized Reynolds Equation ◽  
Good Agreement

A general THD theory and a comparison between theoretical and experimental results are presented. The generalized Reynolds equation, the energy equation in the film, and the heat transfer equation in the bush and the shaft are solved simultaneously. The cavitation in the film, the lubricant recirculation, and the reversed flow at the inlet are taken into account. In addition, the thermoelastic deformations are also calculated in order to define the film thickness. Good agreement is found between experimental data and theoretical results which include thermoelastic displacements of both the shaft and the bush.

Thermal Behavior and Friction in Journal Bearings

1970 ◽  
Vol 92 (3) ◽  
pp. 373-380 ◽  
Author(s):  
Al. Nica
Keyword(s):  
Experimental Data ◽  
Thermal Behavior ◽  
Heat Dissipation ◽  
Journal Bearings ◽  
Friction Torque ◽  
Operating Characteristics ◽  
Lubricant Flow ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Good Agreement

This paper deals with friction and the field of temperature in the lubricant film of journal bearings. Theoretical results regarding the thermal behavior are checked with experimental data and good agreement is found. Emphasis is put on the variation of temperature and lubricant flow with the operating characteristics of the bearing and it is seen that theoretical predictions for minima of friction torque are backed by temperature measurements. Further on, the friction torque and the mechanism of heat dissipation in bearings are dealt with, in order to verify the assumptions used in the calculation schemes. The means of efficiently cooling the bearing are also discussed, as well as the part played by the divergent zone in this process.

scholarly journals Added Mass and Damping of a Vibrating Rod in Confined Viscous Fluids

1976 ◽  
Vol 43 (2) ◽  
pp. 325-329 ◽  
Author(s):  
S. S. Chen ◽  
M. W. Wambsganss ◽  
J. A. Jendrzejczyk
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Cylindrical Shell ◽  
Closed Form Solution ◽  
Added Mass ◽  
Form Solution ◽  
Viscous Fluids ◽  
Series Of Experiments ◽  
Theoretical Results ◽  
Good Agreement

This paper presents an analytical and experimental study of a cylindrical rod vibrating in a viscous fluid enclosed by a rigid, concentric cylindrical shell. A closed-form solution for the added mass and damping coefficient is obtained and a series of experiments with cantilevered rods vibrating in various viscous fluids is performed. Experimental data and theoretical results are in good agreement.

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