Nonlinear physical properties of some nonconventional semiconducting Bi–Pb–Ba–O glasses

1998 ◽  
Vol 13 (8) ◽  
pp. 2328-2333
Author(s):  
D. K. Modak ◽  
G. Banerjee ◽  
M. Karar ◽  
M. Sadhukhan ◽  
A. K. Bera ◽  
...  
Keyword(s):  
Glass Matrix ◽  
Glass Network ◽  
Nonlinear Behavior ◽  
Local Instability ◽  
Temperature Dependent ◽  
Structural Units ◽  
Local Ordering ◽  
Fast Quenching ◽  
Heat Capacity Anomaly ◽  
Glass Compositions

Semiconducting Bi1−xPbxBaO3−δ (or BPB) glasses with x = 0 to 0.8 have been prepared by fast quenching from the melt. Interesting anomalies in the temperature-dependent polaronic conductivity and dielectric constant have been observed in all these glass compositions at temperatures, Tp, varying from 310 to 330 K (depending on Pb concentration). This nonlinear behavior is considered to be associated with the local ordering or the displacements of the BiO3 type pyramidal structural units present in the glass matrix (observed from the infrared spectra of these glasses). This type of ordering/displacement gives rise to a local instability in the glass network structure which is also supported by the observed heat capacity anomaly around the same temperatures Tp.

Study of Structure and Li+ Ions Dynamics in Presence of Fe2O3 in Bi2O3∙B2O3 Glasses

2010 ◽  
Vol 161 ◽  
pp. 51-61 ◽  
Author(s):  
S. Rani ◽  
S. Sanghi ◽  
A. Agarwal ◽  
N. Kishore
Keyword(s):  
Glass Matrix ◽  
Structural Modification ◽  
Iron Concentration ◽  
Glass Network ◽  
Transition Metal Ions ◽  
Electronic Conduction ◽  
Frequency Range ◽  
Modulus Formalism ◽  
Structural Units ◽  
Dielectric Parameters

Glasses having composition xLi2O∙(30-x)Fe2O3∙20Bi2O3∙50B2O3 (0 ≤ x ≤ 30, in mol%) have been prepared using normal melt-quench technique. The variation in density and molar volume with composition has been investigated in terms of the structural modification that takes place in the glass matrix on decreasing Fe2O3. Infrared spectra of these glasses were recorded over continuous spectral range (400-4000 cm-1) in an attempt to study their structure systematically. IR spectra show that with increase in Li2O/Fe2O3 ratio there is formation of more structural units (e.g. [FeO4/2]-Li+) in the glass network. Bi3+ cations are present as [BiO6] octahedral units and acts as modifier in this glass system. Further, the effect of transition metal ions (iron) on the dynamics of lithium bismuth borate glasses has been studied in the frequency range of 20 Hz - 1 MHz and in the temperature range 240 – 350 °C using impedance spectroscopy. Possible conduction mechanisms are discussed. Various AC and DC electrical and dielectric parameters have been calculated and analyzed. The results show that the contribution of electronic conduction towards conductivity decreases with decreasing iron concentration, which is understood to be due to hopping of electrons from Fe2+→Fe3+. The frequency dependent conductivity has been studied using both conductivity and modulus formalism. The absence of maximum observed in dielectric permittivity in the temperature and frequency range studied, indicate the non-ferroelectric behavior of the glasses.

IR AND RAMAN SPECTROSCOPIC INVESTIGATIONS OF Cr2O3-TeO2-B2O3-SrO GLASSES

2004 ◽  
Vol 18 (09) ◽  
pp. 367-373 ◽  
Author(s):  
I. ARDELEAN ◽  
N. MUREŞAN ◽  
P. PĂŞCUŢĂ
Keyword(s):  
Raman Spectra ◽  
Glass Network ◽  
Ir And Raman Spectra ◽  
Structural Units ◽  
Raman Spectroscopic ◽  
Chromium Ions ◽  
Spectroscopic Investigations ◽  
Ir And Raman

The Cr 2 O 3 content influence on the structure of 70 TeO 2·25 B 2 O 3·5 SrO glasses, was investigated by infrared and Raman spectroscopies. The results show that BO 3 and BO 4 are among the main structural units in the investigated glasses, together with TeO 3 and TeO 4 units. The presence of chromium ions located in the glass network is well evidenced in the IR and Raman spectra.

ISUM: Its Birth, Growth and Future

2016 ◽  
Author(s):  
Sherif Rashed
Keyword(s):  
Nonlinear Behavior ◽  
Impact Loads ◽  
Coarse Mesh ◽  
Structural Units ◽  
Large Size ◽  
Linear Behavior ◽  
Large Ship ◽  
Non Linear ◽  
Recent Developments ◽  
Future Potential

ISUM (The Idealized Structural Unit Method) was born in 1972 to efficiently and accurately analyze the behavior of large size structures up to and beyond their ultimate strength. In this method a structure is divided into large elements, basically its structural units (members). Geometric and material non-linear behavior inside the element is formulated and expressed at a limited number of nodal points at the element boundaries. In this way a large structure can be modeled using a coarse mesh while still being able to consider the nonlinear behavior until the collapse of the structure. Several ISUM elements have been formulated and used to analyze the non-linear behavior of large ship structures. In further developments, more elements with more accurate formulations have been developed and more types of structures have been analyzed using this method. The same ISUM concept has been applied to the analysis of welding deformation of large welded structures and to failure analysis of structural and mechanical components subjected to impact loads. In this paper, the basic ISUM concept is outlined, and several elements are presented. Examples of applications to ships and marine structures are presented demonstrating the effectiveness of the method. Recent developments are also reviewed and future potential is explored.

scholarly journals Design and Analysis of a 1D Actively Stabilized System with Viscoelastic Damping Support

Actuators ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 33
Author(s):  
Josef Passenbrunner ◽  
Gerald Jungmayr ◽  
Wolfgang Amrhein
Keyword(s):  
Degrees Of Freedom ◽  
Nonlinear Behavior ◽  
Axial Rotation ◽  
Test System ◽  
Axial Position ◽  
Viscoelastic Damping ◽  
Temperature Dependent ◽  
Temperature Dependent Properties ◽  
Rotor Dynamic ◽  
Damping Capability

Passively magnetically stabilized degrees of freedom yield the benefit of reduced complexity and therefore costs. However, the application of passive magnetic bearings (PMBs) also features some drawbacks. The poor damping capability leads to exaggerated deflection amplitudes when passing the resonance speeds of the applied system. This results in the necessity of external damping. Complying with the goal of costs and complexity, viscoelastic materials offer a suitable solution. However, these materials show high frequency and temperature dependent properties which induce the necessity of a proper model. Thus, the design of systems, as presented in this paper, requires accurate modeling of the dynamic behavior including the nonlinear characteristic of damping elements to predict the system displacements. In the investigated setup only two degrees of freedom remain to be controlled actively. These are the axial rotation and the axial position of the rotor which are controlled by the motor and an active magnetic axial bearing (AMB). This article focuses on the rotor dynamic modeling of a radial passively magnetically stabilized system especially considering the nonlinear behavior of viscoelastic damping elements. Finally, the results from the analytic model are verified by measurements on a manufactures test system.

Structural Studies of Lead Sodium Borate Glasses

2010 ◽  
Vol 93-94 ◽  
pp. 439-442
Author(s):  
Pruittipol Limkitjaroenporn ◽  
Jakrapong Kaewkhao ◽  
Suparat Tuscharoen ◽  
Pichet Limsuwan ◽  
Weerapong Chewpraditkul
Keyword(s):  
Molar Volume ◽  
Glass Network ◽  
Sodium Borate ◽  
Borate Glasses ◽  
Structural Studies ◽  
Melt Quenching ◽  
Network Modifier ◽  
Ir Analysis ◽  
Quenching Method ◽  
Glass Compositions

Glass compositions xPbO : 20Na2O : (80-x)B2O3 (x = 5,10,15,20,25,30,35,40,45,50 and 55 %mol) have been prepared using melt-quenching method. The density and molar volume of these glass samples have been found to be compositional dependent. The results indicate that PbO acts on the glass structures were different between the range 0≤ x ≤ 20 %mol and beyond x = 20 %mol (with inflection at x = 20 %mol). These due to the PbO can enter the glass network both as a network modifier and also as a network former. This role depends on the type of bond between lead and oxide. These results are interpreted in term of IR analysis.

Investigation on Glasses in Strontium Zinc Borosilicate System as Sealants for Solid Oxide Fuel Cell

2012 ◽  
Vol 585 ◽  
pp. 195-199 ◽  
Author(s):  
Babita Tiwari ◽  
S.C. Gadkari ◽  
G.P. Kothiyal
Keyword(s):  
Heat Treatment ◽  
Glass Ceramics ◽  
Glass Network ◽  
Solid Solution Phase ◽  
Structural Units ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Zinc Borosilicate ◽  
B2o3 Glass ◽  
Quench Method

Glasses in the SrO-ZnO-B2O3-SiO2 (SZBS) system with different additives like V2O5, Cr2O3, TiO2, and Al2O3 have been prepared by melt-quench method. Glasses were subjected to controlled heat treatment for conversion into glass-ceramics. Investigated glasses and glass-ceramics have thermal expansion coefficients (TEC) in the range of 95-120 x 10-7/oC (30-600 oC) which closely match with TEC of other SOFC components. XRD indicates the crystallization of Sr2ZnSi2O7 solid-solution phase in glasses upon heat treatment. Structural studies revealed that mainly Q1 and Q2 silicate structural units are present in the glass network and B2O3 enters in the network as triangular borate (BO3) structural units. Only small fraction of B2O3 enters as tetragonal borate (BO4) structural units at higher concentration of B2O3. Glass network depolymerizes with the addition of additives and concentration of Q1 units increases at the expense of Q2 units. Small addition of V2O5 in SZBS glass is beneficial for increasing TEC and achieving better flowability at lower sealing temperature. Studied SZBS glasses also show good bonding with Crofer-22-APU. Elemental line scans indicate that interdiffusion of Fe, Cr, Sr and Si across interface is responsible for good bonding with Crofer-22-APU. To show suitability of material for high temperature sealing, seals have been prepared and tested for vacuum integrity at 850oC for 500h.

On the analysis and prediction of elastic properties in alkali Na2O–B2O3–V2O5 glasses under the substitution of V2O5 by Na2O

2019 ◽  
Vol 60 (6) ◽  
pp. 213-221
Author(s):  
Amin Abd El-Moneim ◽  
Hassan Y. Alfifi
Keyword(s):  
Elastic Properties ◽  
Dissociation Energy ◽  
Packing Density ◽  
Poisson’S Ratio ◽  
Elastic Moduli ◽  
Unit Volume ◽  
Dominant Role ◽  
Glass Network ◽  
Poisson's Ratio ◽  
Structural Units

In this article, we have continued our recent work(30,42) on the prediction of elastic properties in alkali borovanadate glasses. Changes in the elastic moduli and Poisson’s ratio due to the substitution of V2O5 by Na2O in the ternary alkali Na2O–B2O3–V2O5 glasses have been analysed and predicted on the basis of the theories and approaches that existing in the field. Both the packing density and dissociation energy per unit volume of the glass were evaluated in terms of the basic structural units that constitute the glass network. In addition to this, the theoretical values of elastic moduli and Poisson’s ratio were calculated from the Makishima–Mackenzie’s model and compared with the corresponding experimental values. The results revealed that the concentrations of the basic structural units BO3, BO4, VO5 and VO4 play a dominant role in correcting the anomalous behaviour between experimental elastic moduli and calculated dissociation energy per unit volume. An excellent agreement between the theoretical and experimental elastic moduli was achieved for majority of the samples. The correlation between bulk modulus and the ratio between packing density and mean atomic volume has also been achieved on the basis of Abd El-Moneim and Alfifi’s approaches.

Temperature dependent blue second harmonic generation in Ba5Li2Ti2Nb8O30 microcrystals embedded in TeO2 glass–matrix

2009 ◽  
Vol 355 (28-30) ◽  
pp. 1517-1520 ◽  
Author(s):  
M. Niyaz Ahamad ◽  
A. Vasudevarao ◽  
Venkatraman Gopalan ◽  
Himanshu Jain ◽  
K.B.R. Varma
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Glass Matrix ◽  
Second Harmonic ◽  
Temperature Dependent

Raman spectra of quasi-binary glasses As2S3−GeS2 doped with Er

2013 ◽  
Vol 37 (1) ◽  
pp. 33-38
Author(s):  
V. B. Petrović ◽  
I. O. Gúth ◽  
S. R. Lukić-Petrović
Keyword(s):  
Raman Spectroscopy ◽  
Rare Earth ◽  
Raman Spectra ◽  
Chalcogenide Glasses ◽  
Glass Matrix ◽  
Earth Element ◽  
Structural Units ◽  
Low Intensity ◽  
Quasibinary System ◽  
Different Origin

Abstract This work is concerned with a study of chalcogenide glasses doped with the rare-earth element erbium. The study was carried out on samples of the quasibinary system As2S3−GeS2 doped with erbium at the concentrations of 0, 0.01, 0.1, 0.5 and 1 at %. Raman spectroscopy was used to identify the presence of particular structural units in the glass matrix. The spectra of all the samples are characterized by an intense peak appearing as a consequence of the stretching of the As-S and Ge-S bonds. Further, several low-intensity peaks of different origin were also registered. These peaks arise due to the stretching of the bonds in the ring S8 and the bonds resulting from the existence of the ethane-type molecules (GeSn) in some of the samples. The peaks in the spectrum of the sample with the highest erbium content are characterized by the peaks that can be attributed to the stretching of the bond Er-S.

STRUCTURAL INVESTIGATIONS OF MnO-Bi2O3 AND MnO-Bi2O3-As2O3 GLASS SYSTEMS BY IR SPECTROSCOPY

2003 ◽  
Vol 17 (09) ◽  
pp. 355-359 ◽  
Author(s):  
I. ARDELEAN ◽  
IOANA TODOR ◽  
P. PĂŞCUŢĂ ◽  
V. IONCU
Keyword(s):  
Ir Spectroscopy ◽  
Glass Matrix ◽  
Gradual Increase ◽  
Glass Structure ◽  
Structural Units ◽  
Structural Investigations

Glasses from x MnO · (100-x) Bi2O3 and x MnO · (100-x)[ Bi2O3 · As2O3 ] systems, with 0≤ x≤ 50 mol% were obtained in the same conditions and characterized by IR spectroscopy. The influence of a gradual increase of MnO content on the glass structure and the effect of changing the glass matrix compositions, were projected. The presence and the dependence of the bismuthate structural units BiO3 and BiO6 on the MnO content was analyzed.

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