ELASTIC BEHAVIOR OF SOME SUBSTITUTED Sr–Zn W-TYPE HEXAGONAL FERRITES

1999 ◽  
Vol 13 (27) ◽  
pp. 991-998 ◽  
Author(s):  
Y. PURUSHOTHAM ◽  
P. VENUGOPAL REDDY
Keyword(s):  
Linear Relationship ◽  
Room Temperature ◽  
Elastic Moduli ◽  
Dopant Concentration ◽  
Elastic Behavior ◽  
Hexagonal Ferrites ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Pulse Transmission ◽  
Transmission Technique

In the present work, we investigate the elastic behavior of monovalent and divalent doped Sr–Zn W-type hexagonal ferrites at room temperature by measuring their longitudinal and shear wave velocities using a pulse transmission technique. The values of Young (E) and rigidity (G) moduli have been corrected to the theoretical density. The zero porosity values of both the elastic moduli are found to increase with increasing dopant concentration. Further, a linear relationship between the Debye temperature and the average sound velocity has also been observed and the behavior is explained qualitatively.

ELASTIC BEHAVIOR OF Pr SUBSTITUTED Y-123 SUPERCONDUCTING MATERIALS

2006 ◽  
Vol 20 (14) ◽  
pp. 843-847 ◽  
Author(s):  
B. N. DOLE ◽  
Y. PURUSHOTHAM ◽  
P. VENUGOPAL REDDY ◽  
S. S. SHAH
Keyword(s):  
High Temperature ◽  
Linear Relationship ◽  
Sound Velocity ◽  
Room Temperature ◽  
Elastic Moduli ◽  
High Temperature Superconductors ◽  
Elastic Behavior ◽  
Wave Velocities ◽  
Pulse Transmission ◽  
Transmission Technique

The longitudinal (Vl) and shear (Vs) wave velocities of Praseodymium substituted YB 2 Cu 3 O 7-δ high temperature superconductors were determined at room temperature by the pulse transmission technique. The values of Young's (E), rigidity (n) and bulk (k) moduli have been corrected to zero porosity. The zero porous corrected values of the elastic moduli are found to increase with increasing Praseodymium concentration. A linear relationship between the Debye temperature (θD) and average sound velocity (Vm) has also been observed and the behavior is explained qualitatively.

ELASTIC BEHAVIOR OF GERMANIUM-SUBSTITUTED LITHIUM FERRITES

1995 ◽  
Vol 09 (01) ◽  
pp. 39-44 ◽  
Author(s):  
Y. PURUSHOTHAM ◽  
P. VENUGOPAL REDDY ◽  
PRAN KISHAN ◽  
NITENDAR KUMAR
Keyword(s):  
Room Temperature ◽  
Elastic Moduli ◽  
Elastic Behavior ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Pulse Transmission ◽  
Power Equation ◽  
Lithium Ferrites ◽  
Transmission Technique ◽  
Germanium Concentration

The longitudinal and shear wave velocities of germanium-substituted lithium ferrites were determined at room temperature by the pulse transmission technique. Young's (E) and rigidity (n) moduli have been corrected to theoretical density by a power equation. The zero porous corrected values of both the elastic moduli (Young's and rigidity) are found to increase with increasing germanium concentration. A linear relationship between the Debye temperature and the average sound velocity has also been observed.

EFFECT OF Nb2O5 ON THE ELASTIC BEHAVIOR OF PZT FERROELECTRIC MATERIALS

2002 ◽  
Vol 16 (03) ◽  
pp. 79-85
Author(s):  
Y. PURUSHOTHAM ◽  
O. P. THAKUR ◽  
CHANDRA PRAKASH ◽  
P. VENUGOPAL REDDY
Keyword(s):  
Elastic Moduli ◽  
Solid State Reaction Method ◽  
Ferroelectric Materials ◽  
Ferroelectric Ceramics ◽  
Elastic Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Pulse Transmission

A series of ferroelectric ceramics with the compositional formula PbZr0.52Ti0.48O3 + x wt% of Nb2O5 were prepared by the solid state reaction method. Samples were characterized by studying their X-ray diffraction and dielectric measurements. The longitudinal and shear wave velocities and corresponding elastic moduli were determined at room temperature by using the pulse transmission technique. The values of Young's modulus (E), and the rigidity (n) and bulk (k) moduli were corrected to theoretical density and were found to increase with increasing dopant concentration. The variation of elastic moduli and other elastic parameters such as Debye temperature (θ D ) with composition are explained qualitatively.

Electrical and Elastic Behavior of In and Al Substituted Mg-Mn Ferrites

1998 ◽  
Vol 12 (22) ◽  
pp. 2247-2262 ◽  
Author(s):  
Y. Purushotham ◽  
Mahavir Singh ◽  
S. P. Sud ◽  
P. Venugopal Reddy
Keyword(s):  
Electrical Conductivity ◽  
Room Temperature ◽  
Elastic Moduli ◽  
Ultrasonic Pulse ◽  
Elastic Behavior ◽  
Pulse Transmission ◽  
Transmission Technique ◽  
Ultrasonic Pulse Transmission ◽  
Curie Temperatures ◽  
Suitable Explanation

Thermopower and electrical conductivity studies of polycrytslline In 3+ and Al 3+ substituted Mg-Mn ferrites having different compositions were undertaken in the temperature range 300–700 K, using differential and two-probe methods respectively. It has been observed that all the ferrites are found to exhibit clear and well-defined transtions near their respective Curie temperatures in both Seebeck coefficient and electrical conductivity versus temperature behavior. The elastic behavior of these ferrites has also been studied as a function of composition at room temperature using ultrasonic pulse transmission technique and it has been found that the elastic moduli decrease continuously with increasing Indium concentration and increase with increasing Aluminium dopants. Suitable explanation for the observed phenomena are given.

ULTRASONIC ANOMALIES IN Y–Ba–Cu–O HIGH-Tc SUPERCONDUCTING MATERIALS

1993 ◽  
Vol 07 (22) ◽  
pp. 1457-1465 ◽  
Author(s):  
P. VENUGOPAL REDDY ◽  
R. RAVINDER REDDY ◽  
K. BHUPAL REDDY ◽  
V. N. MULAY
Keyword(s):  
Shear Wave ◽  
Longitudinal Velocity ◽  
Sol Gel ◽  
Superconducting Materials ◽  
High Tc ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Pulse Transmission ◽  
Transmission Technique ◽  
Observed Behaviour

The longitudinal and shear wave velocities of Y–1–2–3 superconducting materials prepared by the sol–gel method have been measured by the pulse transmission technique over a temperature range of 80–300 K. The longitudinal velocity of both the samples, in general, is found to vary in an anomalous way. The observed behaviour has been explained qualitatively on the basis of a model.

ELASTIC BEHAVIOR OF Y-1-2-3/SILVER COMPOSITES

1995 ◽  
Vol 09 (08) ◽  
pp. 469-483 ◽  
Author(s):  
S. SHEKHAR ◽  
R. RAVINDER REDDY ◽  
P. VENUGOPAL REDDY ◽  
V. N. MULAY
Keyword(s):  
Dopant Concentration ◽  
Sol Gel ◽  
Elastic Behavior ◽  
Superconducting Transition ◽  
Pulse Transmission ◽  
Transmission Technique ◽  
Rigidity Modulus ◽  
Silver Composites ◽  
Binding Forces ◽  
Porosity Measurements

A series of Y-1-2-3/Ag high T c superconducting composites have been prepared using the sol–gel method by sintering at three different sintering temperatures, viz. 910°C, 945°C, and 975°C. After the usual characterization by XRD, electrical resistance, bulk density, and porosity measurements, the longitudinal (V1) and shear wave (V s ) velocities were measured by the pulse transmission technique. Using the experimental data, several elasticity parameters such as Young's modulus (E), rigidity modulus (G), etc. were evaluated. The variation of elastic constants with dopant concentration has been explained in terms of the binding forces between various atoms of the superconductor. A linear relationship between the superconducting transition temperature (T c ) and the Debye temperature (θ D ) has also been obtained.

FLUID SATURATION EFFECTS ON DYNAMIC ELASTIC PROPERTIES OF SEDIMENTARY ROCKS

Geophysics ◽  
1976 ◽  
Vol 41 (5) ◽  
pp. 895-921 ◽  
Author(s):  
A. R. Gregory
Keyword(s):  
Shear Wave ◽  
Elastic Moduli ◽  
Sedimentary Rocks ◽  
Compressional Wave ◽  
Reflection Coefficients ◽  
High Porosity ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Fluid Saturation ◽  
Saturation Effects

The influence of saturation by water, oil, gas, and mixtures of these fluids on the densities, velocities, reflection coefficients, and elastic moduli of consolidated sedimentary rocks was determined in the laboratory by ultrasonic wave propagation methods. Twenty rock samples varying in age from Pliocene to early Devonian and in porosity from 4 to 41 percent were tested under uniform pressures equivalent to subsurface depths of 0 to 18,690 ft. Fluid saturation effects on compressional‐wave velocity are much larger in low‐porosity than in high‐porosity rocks; this correlation is strengthened by elevated pressures but is absent at atmospheric pressure. At a frequency of 1 MHz, the shear‐wave velocities do not always decrease when liquid pore saturants are added to rocks as theorized by Biot; agreement with theory is dependent upon pressure, porosity, fluid‐mineral chemical interactions, and the presence of microcracks in the cementing material. Experimental results support the belief that lower compressional‐wave velocities and higher reflection coefficients are obtained in sedimentary rocks that contain gas. Replacing pore liquids with gas markedly reduces the elastic moduli of rocks, and the effect is enhanced by decreasing pressure. As a rule, the moduli decrease as the porosity increases; Poisson’s ratio is an exception to the rule. Liquid and gas saturation in consolidated rocks can also be distinguished by the ratio of compressional and shear wave velocities [Formula: see text]. The potential diagnostic value of elastic moduli in seismic exploration may stimulate interest in the use of shear‐wave reflection methods in the field.

LOW TEMPERATURE ELASTIC BEHAVIOR OF POTASSIUM-DOPED Bi-2212 SINGLE PHASE HIGH Tc SUPERCONDUCTORS

1994 ◽  
Vol 08 (18) ◽  
pp. 1097-1106 ◽  
Author(s):  
B. GOPALA KRISHNA ◽  
R. RAVINDER REDDY ◽  
P. VENUGOPAL REDDY ◽  
S. V. SURYANARAYANA
Keyword(s):  
Single Phase ◽  
Longitudinal Velocity ◽  
Solid State Reaction Method ◽  
Elastic Behavior ◽  
Velocity Measurements ◽  
High Tc Superconductors ◽  
Qualitative Explanation ◽  
High Tc ◽  
Pulse Transmission ◽  
Transmission Technique

A single phase Bi-2212 and two potassium-doped Bi-2212 samples have been prepared by the solid state reaction method. After the usual characterisation, the ultrasonic longitudinal velocity measurements of all the samples over a temperature range of 80–300 K were undertaken by the pulse transmission technique. The longitudinal velocity of the undoped sample is found to vary in an anomalous way followed by a maximum at 140 K. On the other hand, in the case of the two K-doped ones, the velocity is found to vary with temperature in a normal way up to 120 K followed by a maximum at 105 and 100 K respectively. A qualitative explanation for the observed behavior in all the three cases is given.

Estimation of Dry-Rock Elastic Moduli Based on the Simulation of Mud-Filtrate Invasion Effects on Borehole Acoustic Logs

2009 ◽  
Vol 12 (06) ◽  
pp. 898-911 ◽  
Author(s):  
Tobiloluwa B. Odumosu ◽  
Carlos Torres-Verdín ◽  
Jesús M. Salazar ◽  
Jun Ma ◽  
Benjamin Voss ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Shear Wave ◽  
Elastic Properties ◽  
Elastic Moduli ◽  
Compressional Wave ◽  
Shear Rigidity ◽  
Spatial Distributions ◽  
Wave Velocities ◽  
Shear Wave Velocities ◽  
Mud Filtrate

Summary Reliable estimates of dry-rock elastic properties are critical to the accurate interpretation of the seismic response of hydrocarbon reservoirs. We describe a new method for estimating elastic moduli of rocks in-situ based on the simulation of mud-filtrate invasion effects on resistivity and acoustic logs. Simulations of mud-filtrate invasion account for the dynamic process of fluid displacement and mixing between mud-filtrate and hydrocarbons. The calculated spatial distributions of electrical resistivity are matched against resistivity logs by adjusting the underlying petrophysical properties. We then perform Biot-Gassmann fluid substitution on the 2D spatial distributions of fluid saturation with initial estimates of dry-bulk (kdry) modulus and shear rigidity (µdry) and a constraint of Poisson's ratio (?d) typical of the formation. This process generates 2D spatial distributions of compressional and shear-wave velocities and density. Subsequently, sonic waveforms are simulated to calculate shear-wave slowness. Initial estimates of the dry-bulk modulus are progressively adjusted using a modified Gregory-Pickett (1963) solution of Biot's (1956) equation to estimate a shear rigidity that converges to the well-log value of shear-wave slowness. The constraint on dynamic Poisson's ratio is then removed and a refined estimate of the dry-bulk modulus is obtained by both simulating the acoustic log (monopole) and matching the log-derived compressional-wave slowness. This technique leads to reliable estimates of dry-bulk moduli and shear rigidity that compare well to laboratory core measurements. Resulting dry-rock elastic properties can be used to calculate seismic compressional-wave and shear-wave velocities devoid of mud-filtrate invasion effects for further seismic-driven reservoir-characterization studies.

Elastic Properties of Vanadium Doped Silica-Borotellurite Glasses

2020 ◽  
Vol 307 ◽  
pp. 321-326
Author(s):  
Nurhayati Mohd Nor ◽  
Halimah Mohamed Kamari ◽  
Amirah Abdul Latif ◽  
Nurisya Mohd Shah
Keyword(s):  
Elastic Properties ◽  
Room Temperature ◽  
Elastic Moduli ◽  
Molar Fraction ◽  
Glass Network ◽  
Ultrasonic Pulse ◽  
Ultrasonic Velocities ◽  
Wave Velocities ◽  
Network Glass ◽  
Pulse Echo

Silica borotellurite glasses doped with different molar fraction of V2O5 have been prepared by melt quenching technique. The elastic properties of {[(TeO2)0.7 (B2O3)0.3]0.8(SiO2)0.2}(1-x)(V2O5)x glasses are investigated using ultrasonic pulse echo measurements and their elastic properties have been characterized at room temperature. The density of the glasses was measured by Archimedes method using distilled water as buoyant liquid. The ultrasonic wave velocities (longitudinal, vl and shear, vS) were recorded at 5 MHz. Elastic moduli, Poisson’s ratio (σ) and microhardness (H) were then calculated to obtain quantitative analysis regarding the structure of these glasses. The results obtained showed that the doping of V2O5 with silica borotellurite enhances the strengthening of glass network. Glass with 0.03 molar fraction of V205 shows low ultrasonic velocities and low elastic moduli. The variation of elastic properties is related to the change of structure in the vanadium doped silica-borotellurite glass system.

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