Vibrational, mechanical and thermodynamical properties of RE2Ti2O7 (RE = Sm, Gd, Dy, Ho, Er and Yb) pyrochlores

2017 ◽  
Vol 31 (21) ◽  
pp. 1750145
Author(s):  
A. K. Kushwaha
Keyword(s):  
Bond Strength ◽  
Bulk Modulus ◽  
Force Constant ◽  
Present Calculation ◽  
Neighbor Interaction ◽  
Thermodynamical Properties ◽  
Bending Force ◽  
Young’S Moduli ◽  
Bond Bending ◽  
The One

Vibrational, mechanical, thermodynamical properties and thermal conductivities of RE2Ti2O7 (RE = Sm, Gd, Dy, Ho, Er and Yb) pyrochlores have been calculated using a proposed eight-parameter bond-bending force constant model. The main outcome of present calculation is that the first neighbor interaction (Ti–O) is stronger than the second neighbor interactions (RE–O). This means that the bonding between Ti and O is more ionic than the one between RE and O. It is also found that the bond strength of RE–O and the bulk modulus decrease in the sequence Sm [Formula: see text] Gd [Formula: see text] Dy [Formula: see text] Ho [Formula: see text] Er [Formula: see text] Yb. The bulk moduli and Young’s moduli of RE2Ti2O7 also decrease when RE changes from Sm to Yb.

Ab Initio Investigation of Structural and Electronic Properties of ErPb3 in AB3 Structure

2016 ◽  
Vol 28 ◽  
pp. 39-42 ◽  
Author(s):  
Shubha Dubey ◽  
Gitanjali Pagare ◽  
Ekta Jain ◽  
Sankar P. Sanyal
Keyword(s):  
Bulk Modulus ◽  
Total Energy ◽  
Electronic Properties ◽  
Density Of States ◽  
Experimental Results ◽  
Energy Calculation ◽  
Present Calculation ◽  
Full Potential ◽  
Local Spin Density Approximation ◽  
Calculated Density

The structural properties and electronic properties of the intermetallic compound ErPb3 which crystallize in AuCu3 type structure (AB3) are studied by means of first principles total energy calculation using full potential linearized plane wave method (FP-LAPW) within the generalized gradient approximation of Perdew, Burke and Ernzrhof (PBE) and local spin density approximation (LSDA) for the exchange correlation functional and including spin magnetic calculation. The total energy is computed as a function of volume and fitted to the Birch-Murnaghan equation of state. The ground state properties of this compound such as equilibrium lattice parameter (a0), bulk modulus (B), and its pressure derivative (B’) are calculated and compared with the available experimental results. We find good agreement with the other theoretical and experimental results. For the compounds, the values of lattice constants obtained by PBE-GGA overestimates and by LSDA underestimates the available experimental values for the same, which verifies the reliability of the present calculation. The value obtained for the bulk modulus is 50.63 GPa. The analysis of electronic properties is achieved by the calculation of the band structures and the density of states in both the spin up and spin down modes, which show a metallic character of ErPB3 due to zero band gap. The values of calculated density of states are found to be 0.36 eV/states and 11.46 eV/states in spin-up and spin-down mode respectively. The calculated magnetic moment (μm) of ErPb3 is 2.06.

Temperature Dependences of the Elastic Constants of Precipitation-Hardened Aluminum Alloys 2014 and 2219

1977 ◽  
Vol 99 (2) ◽  
pp. 181-184 ◽  
Author(s):  
D. T. Read ◽  
H. M. Ledbetter
Keyword(s):  
Aluminum Alloys ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Temperature Dependence ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Ultrasonic Pulse ◽  
Young’S Moduli ◽  
Temperature Dependences ◽  
Sound Velocities

Elastic properties of precipitation-hardened aluminum alloys 2014 and 2219 were studied between 4 and 300 K using ultrasonic pulse techniques. Both the longitudinal and transverse sound velocities were measured. Also reported are the Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio. For both alloys, the Young’s moduli are about ten percent higher than for unalloyed aluminum, and they increase about ten percent on cooling from 300 to 4 K. All the elastic constants show normal temperature dependence.

scholarly journals Effect of Immediate Dentin Sealing and Surface Conditioning on the Microtensile Bond Strength of Resin-based Composite to Dentin

2019 ◽  
Vol 44 (6) ◽  
pp. E289-E298 ◽  
Author(s):  
CRG van den Breemer ◽  
M Özcan ◽  
MS Cune ◽  
AP Almeida Ayres ◽  
B Van Meerbeek ◽  
...  
Keyword(s):  
Bond Strength ◽  
Analysis Of Variance ◽  
Water Storage ◽  
Silica Coating ◽  
Microtensile Bond Strength ◽  
Surface Conditioning ◽  
Clinical Procedures ◽  
Significant Difference ◽  
The One ◽  
Storage Times

SUMMARY This study evaluated the microtensile bond strength (μTBS) of resin-based composite (RBC) to dentin after different immediate dentin sealing (IDS) strategies and surface-conditioning (SC) methods and on two water storage times. Human molars (n=48) were randomly divided into eight experimental groups involving four different IDS strategies—IDS-1L with one layer of adhesive, IDS-2L with two layers of adhesive, IDS-F with one layer of adhesive and one layer of flowable RBC, and DDS (delayed dentin sealing) with no layer of adhesive (control)—and two different SC methods—SC-P with pumice rubbing and SC-PC with pumice rubbing followed by tribochemical silica coating. The μTBS test was performed after one week and after six months of water storage, being recorded as the “immediate” and “aged” μTBS, respectively. Composite-adhesive-dentin microspecimens (0.9×0.9×8–9 mm) were stressed in tension until failure to determine the μTBS. Failure mode and location of failure were categorized. Two-way analysis of variance was applied to analyze the data for statistically significant differences between the experimental groups (p<0.05). Two-way analysis of variance revealed no significant differences between the one-week μTBS specimens for IDS strategy (p=0.087) and SC methods (p=0.806). However, the interaction of IDS strategy and SC methods appeared statistically significant (p=0.016). The six-month specimen evaluation showed no significant difference in μTBS for SC (p=0.297) and SC/IDS interaction (p=0.055), but the μTBS of the IDS strategies differed significantly among them (p=0.003). For tribochemical silica-coated IDS, no significant effect of aging on μTBS was recorded (p=0.465), but there was a highly significant difference in μTBS depending on the IDS strategy (p<0.001). In addition, the interaction of IDS and aging was borderline statistically significant (p=0.045). The specimens failed mainly at the adhesive-dentin interface for all experimental groups. Dentin exposure during clinical procedures for indirect restorations benefits from the application of IDS, which was shown to result in higher bond strength. No significant differences were found between cleaning with solely pumice or pumice followed by tribochemical silica coating.

Vibrational, mechanical and thermodynamical properties of indium thiospinelsMIn2S4(M= Cd, Zn and Mg)

2016 ◽  
Vol 30 (06) ◽  
pp. 1650018 ◽  
Author(s):  
A. K. Kushwaha ◽  
R. Khenata ◽  
S. Bin Omran
Keyword(s):  
Mechanical Properties ◽  
Debye Temperature ◽  
Theoretical Data ◽  
Experimental Results ◽  
Neighbor Interaction ◽  
Thermodynamical Properties ◽  
Good Agreement ◽  
Rigid Ion Model ◽  
Sound Velocities

In this paper, interatomic interactions, zone-center phonon frequencies, mechanical properties, sound velocities and Debye temperature of indium thiospinels MIn2S4(M = Cd, Zn and Mg) have been calculated using rigid-ion model. We found that the first neighbor interaction is stronger than the second neighbor interaction. We have compared our calculated results with the available experimental and theoretical data and find good agreement with the experimental results.

scholarly journals In vitro analysis of shear bond strength and adhesive remnant index of different metal brackets

2016 ◽  
Vol 21 (6) ◽  
pp. 67-73 ◽  
Author(s):  
Fernanda de Souza Henkin ◽  
Érika de Oliveira Dias de Macêdo ◽  
Karoline da Silva Santos ◽  
Marília Schwarzbach ◽  
Susana Maria Werner Samuel ◽  
...  
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Fold Increase ◽  
Optical Microscope ◽  
General Evaluation ◽  
Adhesive Remnant Index ◽  
The One ◽  
Vitro Analysis ◽  
In Vitro Analysis

ABSTRACT Introduction: There is a great variety of orthodontic brackets in the Brazilian market, and constantly evaluating them is critical for professionals to know their properties, so as to be able to choose which product best suits their clinical practice. Objectives: To evaluate the bond strength and the adhesive remnant index (ARI) of different brands of metal brackets. Material and Methods: A total of 105 bovine incisors were used, and brackets of different brands were bonded to teeth. Seven different bracket brands were tested (MorelliTM, American OrthodonticsTM, TP OrthodonticsTM, Abzil-3MTM, OrthometricTM, TecnidentTM and UNIDENTM). Twenty-four hours after bonding, shear bond strength test was performed; and after debonding, the ARI was determined by using an optical microscope at a 10-fold increase. Results: Mean shear bond strength values ranged from 3.845 ± 3.997 (MorelliTM) to 9.871 ± 5.106 MPa (TecnidentTM). The majority of the ARI index scores was 0 and 1. Conclusion: Among the evaluated brackets, the one with the lowest mean shear bond strength values was MorelliTM. General evaluation of groups indicated that a greater number of bond failure occurred at the enamel/adhesive interface.

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