Abstract
Some physical properties of hexahalometallate K
2
XBr
6
(X = Se, Pt) were computed in the zinc blend structure using GGA-PBESOL. The cell constant of K
2
SeBr
6
and K
2
PtBr
6
is consistent ...to the experiment value quoted in the literature, where the error is 0.95% and 1%. K
2
SeBr
6
and K
2
PtBr
6
present covalent bonding, high anisotropy and are ductile. The elastic constants of K
2
SeBr
6
and K
2
PtBr
6
are significantly smaller due to their larger reticular distances, lower Coulomb forces and then they are soft and damage tolerant. The interatomic separation is greater in K
2
SeBr
6
than in K
2
PtBr
6
, hence the Coulomb interaction in K
2
PtBr
6
is greater than that of K
2
SeBr
6
. The internal coordinate of Br atom in K
2
PtBr
6
is lower than that of the same atom in K
2
SeBr
6
, and this can be explained by the fact that it is inversely proportional to the atom radius of Se and Pt. There are two major plasmonic processes, with intensities 3.7 and 1.35 located around 53.5 nm and 72.8 nm for K
2
SeBr
6
and K
2
PtBr
6
.
In this work, the optical and mechanical properties of Fe
2
O
3
nanoparticles (NPs)/chitosan nanocomposite films have been investigated. Nanocomposite films of different weight ratios of Fe
2
O
3
...NPs/chitosan (0, 1, 5, 10, 20 and 30 wt%) were fabricated using casting technique. The optical properties of colloidal Fe
2
O
3
NPs and Fe
2
O
3
NPs/chitosan nanocomposite films were recorded using UV–visible spectrophotometer. As the ratio of Fe
2
O
3
NPs to chitosan increases from 0 to 30%, the energy band gap of Fe
2
O
3
NPs/chitosan films decreases from 3.16 to 2.11 eV. This decrease is due to quantum confinement effect. The mechanical properties of the nanocomposite films as a function of sweeping temperature were measured using a dynamic mechanical analyzer. An enhancement in storage modulus, stiffness and glass transition temperature (T
g
) has been observed as the ratio of Fe
2
O
3
NPs/chitosan increases. T
g
of Fe
2
O
3
NPs/chitosan nanocomposite film shifts towards higher temperature side with respect to pure chitosan film from 152.1 to 166.3 °C as the ratio of Fe
2
O
3
NPs/chitosan increases from 0 to 30 wt%. The increase in T
g
is mainly attributed to the decrease in free volumes and vacancies in the nanocomposite films as the weight ratio of Fe
2
O
3
NPs/chitosan increases.
The symmetric and anti-symmetric form factors of the parents binary compounds were calculated in order to predict the electronic band structures of ternary alloys studied. The convergence of binary ...compounds is obtained for Ecut = 20 Hartree and 20 k-points. Elastic constants of ternary alloys studied for some values of phosphorus content are reported for the first time. AlPxAs1-x shows an indirect band gap (Г-X), while GaPxAs1-x and InPxAs1-x have a direct band gap (Г- Г). The band gap of AlPxAs1-x and GaPxAs1-x in the range 1.42 eV–3.54 eV makes these materials useable as semiconductors lasers operating in the ultraviolet spectral region. The lattice constant and band gap show a great parallelism with the available experimental values.
•The structural, elastic, electronic and lattice dynamic properties of AlPxAs1-x, GaPxAs1-x and InPxAs1-x alloys are studied and considered to be helpeful for the fabrication of optoelectronic devices.•The elastic constants and their related elastic moduli are done and their variation with P content x has been examined.•The longitudinal and transversal phonon frequencies have been studied at various phosphorus content.•The calculated quantities in this work may be of great interest for the possibility of developing new electronic devices.
The effects of AgO addition on the mechanical, optical, and radiation attenuation parameters of 46V
2
O
5
–46P
2
O
5
–xB
2
O
3
–yAgO glass system, namely VP-BxAy: (x,y) = (8,0), (6,2), (4,4), (2,6), ...and (0,8) mol%, was examined. Values of molar polarizability (α
m
, 19.397 × 10
–24
to 18.820 × 10
–24
cm
3
) were in direct relation with the molar refractivity (R
m
, 48.882—47.427 cm
3
/mol
)
, while the optical transmission (T) parameter showed an inverse relation with reflection loss (R
L
) as a function of AgO concentrations. Both static (ε
static
) and optical (ε
optical
) dielectric factors showed a direct relation with each other and an opposite trend with the other factors. The values of the bulk modulus (K
B-C
) were increased from 59.99 to 64.67 GPa. The shear modulus (G
B-C
) was increased from 32.91 to 36.37 GPa, longitudinal modulus (L
B-C
) was increased from 103.77 to 103.05 GPa, and Young’s modulus (E
B-C
) was increased from 83.48 to 91.89 GPa, respectively. The results of Poisson’s ratio (σ
C-B
) have a decreasing trend from 0.268 to 0.263. Moreover, the radiation attenuation properties of VP-BxAy glasses for photons, neutrons (fast and thermal), and charged particles (electron, proton, and alpha) are investigated. The Monte Carlo method was employed via FLUKA code to investigate photons attenuation properties of the examined glasses. The simulation implementation was experimentally and theoretically confirmed. Linear attenuation coefficients (LAC) of VP-BxAy glasses followed the trend: (LAC)
VP-B0A8
> (LAC)
VP-B2A6
> (LAC)
VP-B4A4
(LAC)
VP-B6A2
> (LAC)
VP-B8A0
. Therefore, AgO addition played an improvement role in the photon attenuation processes. The VP-BxAy glasses showed superior attenuation properties for photons beam compared with different photon attenuators. This indicates that the VP-BxAy glasses have superior features to use as promising shields for various applications against photons beam (X or gamma radiation).
In this work, tailoring the energy band gap (E
g
) of ternary alloyed Pb
1−x
Zn
x
S quantum dots (QDs) for photovoltaic applications has been investigated. Different zinc molar ratios (x: 0, 0.1, ...0.2, 0.3 and 0.4) in Pb
1−x
Zn
x
S QDs were adsorbed onto TiO
2
(titania) nanoporous films using sub-sequential chemical deposition technique. The morphology of the prepared QDs is studied using a scanning and transmission electron microscope. The structural properties were measured using an X-ray diffractometer and an energy dispersive X-ray technique. The optical properties were recorded using a UV–visible spectrophotometer. The optical bowing constant (b) of alloyed Pb
1−x
Zn
x
S has been deduced and equals 1.49 eV. To the best of our knowledge, this is the first time that the bowing constant of alloyed Pb
1−x
Zn
x
S is determined. The photovoltaic characteristics (short circuit current density J
sc
, open circuit voltage V
oc
, fill factor FF and energy conversion efficiency η) of the assembled alloyed Pb
1−x
Zn
x
S QDs sensitized solar cells (QDSSCs) are measured under AM1.5 conditions. The optimal photovoltaic parameters of the alloyed Pb
1−x
Zn
x
S QDSSCs were found at x = 0.2. The open circuit voltage decay of the assembled QDSSCs is measured. This novel result is attributed to suppressing of the electron–hole pairs recombination processes.
The discovery of highly active and cost-effective materials capable of catalyzing the oxygen evolution reaction (OER) is essential for water splitting. In the present study, we developed a new method ...for producing the structural components of advanced non-precious metal electrocatalysts NiS/CeS nanocomposite supported on stainless steel strip (SSS) represented as NiS/CeS/SSS that are both innovative and practical. To accomplish a current density of 10 mA cm
−2
, the NiS/CeS/SSS requires OER overpotential of 289 mV, which is smaller than the pure NiS/SSS (319 mV) and CeS/SSS (309 mV), and with enhanced stability of 40 h tested in 1.0 M KOH electrolyte. The higher efficiency of OER is due to the strong electrical contacts between NiS/SSS and CeS/SSS, the availability of active centers, and also the lower charge transfer resistance.
This study aims to investigate the utility of using 15PbF2–(60x)TeO2–25WO3–xNd2O3 (0.1≥x≥1.5) glasses in the nuclear shielding applications for mixed radiation fields at energies ranging from 15keV ...to 15MeV. The effect of Nd3+ ions on gamma attenuation properties of the present glass system was discussed in detail. The radiation attenuation features were investigated for the present glass system by using Monte Carlo radiation transport simulation via Geant4 toolkit. The simulation results were theoretically approved by using Phy-X approach over the entire considered energy range. The obtained results indicate that the values of Zeff and Neff were both highest in the in the τ/ρ dominated energies due to the atomic number dependence of the cross sections of the τ/ρ absorption processes. Moreover, FNRCS values were 0.1152, 0.1152, 0.1153, and 0.1153cm−1 for PWTN1, PWTN2, PWTN3, and PWTN4 respectively. Finally, an extensive comparative study is also presented between the studied glass system and standard traditional shielding materials. The study suggests PWTN4 is the best photon shield amongst the studied PWTN-glasses.
Este estudio tiene como objetivo investigar la utilidad del uso de vidrios 15PbF2–(60x)TeO2–25WO3–xNd2O3 (0,1≥x≥1,5) en las aplicaciones de blindaje nuclear para campos de radiación mixtos a energías que van desde 15keV hasta 15MeV. Se discute en detalle el efecto de los iones Nd3+ sobre las propiedades de atenuación gamma de este sistema de vidrio. Se investigan las características de atenuación de radiación para este sistema de vidrio utilizando la simulación de transporte de radiación de Monte Carlo con el conjunto de herramientas Geant4. Los resultados de la simulación se han corroborado teóricamente utilizando la aproximación Phy-X en todo el rango de energías considerado. Los resultados obtenidos indican que los valores de Zeff y Neff fueron los más altos en las energías dominantes en τ/ρ debido a la dependencia con el número atómico de las secciones transversales de los procesos de absorción τ/ρ. Además, los valores de FNRCS fueron 0,1152; 0,1152; 0,1153 y 0,1153cm−1 para PWTN1, PWTN2, PWTN3 y PWTN4, respectivamente. Por último, también se presenta un extenso estudio comparativo entre el sistema de vidrio analizado y los materiales de blindaje estándar y tradicionales. El estudio muestra que PWTN4 es el mejor escudo de fotones de entre los vidrios PWTN estudiados.
This work presents a detailed study on the effects of reducing PbO content on the elastic and radiation shielding properties of germanate glasses described by the chemical formula 50GeO
2
...-(50-x)PbO-xZnO, where x between 0 and 50 mol % with step of 10. A theoretical analysis based on Makishima-Mackenzie’s theory (MM-theory) was employed to obtain the elastic moduli of the studied glass specimens. Moreover, the Monte Carlo simulations were applied via Geant4 platform to assess the radiation shielding ability of the GeO
2
-PbO-ZnO glass system by evaluating several fundamental properties such as gamma and neutron transmission factors, total cross sections, effective atomic numbers, 1/e penetration depths, and exposure buildup factors. We found that the bulk elastic modulus increased from 50.751 GPa to 85.389 GPa as the PbO content decreased from 50 mol% to 0. The results of the linear attenuation coefficient show that the cross sections of
σ
PE
,
σ
CS
, and
σ
PP
dominates the photon attenuation at 0.15 ≤ E
≤
0.08; 0.8 < E < 8, and 8 < E < 15 MeV, respectively. Moreover, the present glasses have superior photon absorbing capacity compared to ordinary and barite concrete; RS-253-G18 and RS-360 commercial glass shields. This suggests that the GeO2-PbO-ZnO glass system can be used as a non-toxic shielding material in the nuclear facilities.
Structural, electronic, elastic and magnetic properties of Ln
3
QIn (Ln = Ce, Pr and Nd; Q = C and N) anti-perovskites were studied using density functional theory. The measured structural parameters ...were much reliable with experiments and decreased with the contraction of atomic radii of R and Q atoms. Electronic properties show that the overlapping of Ln-f states around the Fermi level is responsible for the metallic property of these compounds. The electrical resistivity of these compounds shows that the compounds under study show good conductivity at 25°C. Elastic properties of these compounds show that they are mechanically stable with an anisotropic and ductile nature. Magnetic susceptibility and magnetic ordering show that all the compounds are
A
-type antiferromagnetic, having Neel temperatures of 9 K to 12 K, respectively. Due to the antiferromagnetic nature of these compounds, magnetic probes are unable to read the data stored in the antiferromagnetic moments, and data remains unaffected through disturbing magnetic fields.
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