Values Of Bulk Modulus Research Articles

Structural stability and anomalous compressibility of isoelectronic compounds- URh3 and UIr3

The compound was synthesized using arc-melting technique and high-pressure X-ray diffraction studies were carried out up to 25 GPa. It is found to remain in its parent AuCu3 type structure up to the highest pressure studied. Birch-Murnaghan equation of state fit of pressure-volume data gives the bulk modulus to be 262 GPa while the bulk modulus of the similar isoelectronic compound – URh3 is 133 GPa. Rh and Ir being isoelectronic transition metals, their compounds with uranium metal show a dramatic change in the compressibility of the material. First principle computations indicate a significantly large contribution of 5-f electrons of uranium in UIr3. A strong f-d hybridization in UIr3, as compared to URh3, results in high bulk modulus values of UIr3. The high structural stability of UIr3 is also predicted from the density of state plots as compared to URh3. Computed elastic constants of UIr3 indicate the mechanical stability of the lattice.

Structural, thermo-elastic, electro-magnetic and thermoelectric attributes of quaternary CoNbMnX (X = Al, Si) Heusler alloys

This investigation consists of performing the structural, thermodynamic, electronic, magnetic and thermoelectric characteristics of the quaternary Heusler CoNbMnX (X = Al, Si) alloys using DFT within Wien2k code. Our calculations show that the atomic arrangement of the two alloys CoNbMnAl and CoNbMnSi is Type-I. From the elastic constant and the formation energy values, these compounds are predicted to be mechanically and thermodynamically stable, thus can be formed experimentally. The calculated values of their bulk modulus and cohesive energy values show that CoNbMnSi is more rigid than CoNbMnAl. From the analysis of the electronic properties, CoNbMnAl is identified to be paramagnetic and semiconductor alloy with 0.15 eV narrow indirect (Γ-X) band gap. Whereas, CoNbMnSi is characterized as a ferromagnetic alloy with half-metallicity character having a total magnetic moment of 1μB. The charge density contours and Fermi surface, predict a combined covalent and ionic bond between the atoms of CoNbMnX alloys. The calculated thermoelectric parameters assume that these alloys tend to behave as p-type with the same thermoelectric efficiency for either charge carriers; hole or electron. Depending on the high Seebeck coefficient value and ZT = 1 of the present alloys, potential applications are predicted, such as spin injection materials and spintronic applications.

Mechanical behavior of high entropy carbide (HfTaZrTi)C and (HfTaZrNb)C under high pressure: Ab initio study

AbstractThe evolution of structural, elastic, and electronic properties of high entropy carbide (HfTaZrTi)C and (HfTaZrNb)C under high pressure have been studied within the framework of density functional theory (DFT) in conjunction with special quasirandom structures. With increasing pressure, lattice constants of high entropy carbides (HfTaZrTi)C and (HfTaZrNb)C gradually decrease, so volumes shrink, and densities gradually increase. Under high pressure up to 200 GPa, elastic stiffness coefficients for both carbides are almost linearly hardened and meet the elastic stability criteria. With increasing pressure, elastic moduli and Debye temperature of both high entropy carbides (HfTaZrTi)C and (HfTaZrNb)C increase, while theoretical Vickers hardness decreases, although Vickers hardness of (HfTaZrNb)C is always higher than (HfTaZrTi)C in the whole pressure. The ductility of (HfTaZrTi)C and (HfTaZrNb)C is improved under pressure, and brittle‐ductile transition occurs at about 50 and 60 GPa, respectively. The electronic structure demonstrates that, with increasing pressure, covalent bonds between transition metal atoms and carbon atoms are strengthened, accompanying delocalization. This effect is responsible for high values of bulk modulus and shear modulus under pressure and enhanced ductility. The ionic bonds of both high entropy carbides weaken with increasing pressure, and (HfTaZrTi)C is affected more strongly by the pressure.

Pressure-induced structural transition and metallization in MnSe2

The high-pressure behavior of manganese diselenide MnSe2 was investigated by synchrotron angle-dispersive X-ray diffraction (ADXRD) and infrared reflection spectroscopy equipped with a diamond-anvil cell. It was found that MnSe2 with a pyrite-type structure undergoes a transformation into a disordered intermediate phase at ~ 12.5 GPa, with a ground state composed of an arsenopyrite-type structure, as confirmed by laser-heating treatment. The pyrite to arsenopyrite phase transition was found to be coupled to a large collapse in the unit-cell volume (∆V ~ 19%) and an electronic transition from a high-spin to low-spin state for manganese cations (Mn2+). With a fixed value for the pressure derivation of the bulk modulus K' = 4, fitting of the pressure–volume data to a second-order Birch–Murnaghan equation of state yielded isothermal bulk modulus values of K0 = 56.1(9) GPa and K0 = 93.1(4) GPa for the pyrite-type and arsenopyrite-type phases, respectively. The measured infrared reflectivity (Rsd) for MnSe2 showed a drastic increase at pressures between 13 and 20 GPa, but became insensitive to pressure under further compression, implying a pressure-induced transition from an insulator to metallic state.

Novel III-V Nitride Polymorphs in the P42/mnm and Pbca Phases.

In this work, the elastic anisotropy, mechanical stability, and electronic properties for P42/mnm XN (XN = BN, AlN, GaN, and InN) and Pbca XN are researched based on density functional theory. Here, the XN in the P42/mnm and Pbca phases have a mechanic stability and dynamic stability. Compared with the Pnma phase and Pm-3n phase, the P42/mnm and Pbca phases have greater values of bulk modulus and shear modulus. The ratio of the bulk modulus (B), shear modulus (G), and Poisson’s ratio (v) of XN in the P42/mnm and Pbca phases are smaller than those for Pnma XN and Pm-3n XN, and larger than those for c-XN, indicating that Pnma XN and Pm-3n XN are more ductile than P42/mnm XN and Pbca XN, and that c-XN is more brittle than P42/mnm XN and Pbca XN. In addition, in the Pbca phases, XN can be considered a semiconductor material, while in the P42/mnm phase, GaN and InN have direct band-gap, and BN and AlN are indirect wide band gap materials. The novel III-V nitride polymorphs in the P42/mnm and Pbca phases may have great potential for application in visible light detectors, ultraviolet detectors, infrared detectors, and light-emitting diodes.

First Principles Study on the Structural, Elastic, Electronic and Optical Properties of Cubic ‘Half-Heusler’ Alloy RuVAs Under Pressure

The pressure effect (0 to 40 GPa) on the structural, elastic, electronic, and optical properties of half-metallic compound RuVAs has been investigated employing the DFT based on the first-principles method. The CASTEP computer code is used for this investigation. The calculated lattice parameter show slide deviation from the synthesized and other theoretical data. The normalized lattice parameter and volume are decreased with increasing pressure. The zero pressure elastic constants and also the pressure-dependent elastic constants are positive up to 40 GPa and satisfy the Born stability condition which ensured that the compound RuVAs is stable in nature. At zero pressure, the electronic band gap of 0.159 eV is observed from the band structure calculations which ensured the semimetallic nature of RuVAs. No band gap is observed in the electronic band structure at 40 GPa which indicates the occurrence of phase transition of compound RuVAs at this pressure. We have calculated the value of bulk modulus B, shear modulus G, Young’s modulus E, Pugh ratio B/G, Poisson’s ratio ν and anisotropy factor A of this compound by using the Voigt-Reuss-Hill (VRH) averaging scheme under pressure. The bulk modulus shows a linear response to pressure so that the hardness of this material is increased with increasing pressure. Furthermore, the optical properties such as reflectivity, absorptivity, conductivity, dielectric constant, refractive index, and loss function of RuVAs were evaluated and discussed under pressure up to 40 GPa.

Using Adaptive Neuro Fuzzy Inference System to Predict Rate of Penetration from Dynamic Elastic Properties

Rate of penetration plays a vital role in field development process because the drilling operation is expensive and include the cost of equipment and materials used during the penetration of rock and efforts of the crew in order to complete the well without major problems. It’s important to finish the well as soon as possible to reduce the expenditures. So, knowing the rate of penetration in the area that is going to be drilled will help in speculation of the cost and that will lead to optimize drilling outgoings. In this research, an intelligent model was built using artificial intelligence to achieve this goal. The model was built using adaptive neuro fuzzy inference system to predict the rate of penetration in Mishrif formation in Nasiriya oil field for the selected wells. The mean square error for the results obtained from the ANFIS model was 0.015. The model was trained and simulated using MATLAB and Simulink platform. Laboratory measurements were conducted on core samples selected from two wells. Ultrasonic device was used to measure the transit time of compressional and shear waves and to compare these results with log records. Ten wells in Nasiriya oil field had been selected based on the availability of the data. Dynamic elastic properties of Mishrif formation in the selected wells were determined by using Interactive Petrophysics (IP V3.5) software and based on the las files and log records provided. The average rate of penetration of the studied wells was determined and listed against depth with the average dynamic elastic properties and fed into the fuzzy system. The average values of bulk modulus for the ten wells ranged between (20.57) and (27.57) . For shear modulus, the range was from (8.63) to (12.95) GPa. Also, the Poisson’s ratio values varied from (0.297) to (0.307). For the first group of wells (NS-1, NS-3, NS-4, NS-5, and NS-18), the ROP values were taken from the drilling reports and the lowest ROP was at the bottom of the formation with a value of (3.965) m/hrs while the highest ROP at the top of the formation with a value (4.073) m/hrs. The ROP values predicted by the ANFIS for this group were (3.181) m/hrs and (4.865) m/hrs for the lowest and highest values respectively. For the second group of wells (NS-9, NS-15, NS-16, NS-19, and NS-21), the highest ROP obtained from drilling reports was (4.032) m/hrs while the lowest value was (3.96) m/hrs. For the predicted values by ANFIS model were (2.35) m/hrs and (4.3) m/hrs for the lowest and highest ROP values respectively.

Mechanical properties of YBCO superconductor under high-pressure

Background/Objectives: The crystal structure of YBCO Superconductor has fascinated the material science research group. The calculation of mechanical properties of YBCO Superconductor under pressure is the main focus in this research work. Methods/Statistical analysis: Density Functional Theory calculations using Quantum ESPRESSO under high pressure increasing systematically have been calculated and performed for YBa2Cu3o7 Superconductor. The only input required is the lattice parameters at corresponding pressure of materials which are predicted using first principle computational methods at desired high-pressure state. Findings: The lattice constants, variations, volume, density, Bulk modulus (B), Young modulus (E), Shear modulus (S) and Poisson ratio (n)values are calculated under pressure up to 30 GPa for YBCO Superconductor. Voigt-Reuss-Hill Approximations, Debye Sound velocities(ϑD), Debye temperature(θD) and Pugh\'s ratio(B/G) values have been calculated under pressure for YBCO Superconductor in this research work. Novelty/Applications: A larger poisson\'s ratio value indicates ductile behavior and another criterion often used to differentiate between ductile and brittle behavior is the Poisson\'s ratio. Poisson\'s ratio greater than 0.26 implies the ductile behavior. With the application of elastic constants, we have obtained the Debye temperature and other physical quantities of YBa2Cu3o7 under pressure. Keywords: YBCO superconductor; density functional theory (DFT); lattice constants; pressure; quantum ESPRESSO

Comparative investigation on the thermostability, sensitivity, and mechanical performance of RDX/HMX energetic cocrystal and its mixture.

Molecular mechanics (MM) and molecular dynamics (MD) simulation method were applied to explore the impact of temperature (220-380K) on the thermostability, sensitivity, and mechanical performance of RDX (1,3,5-trinitro-1,3,5-triazacyco-hexane)/HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) energetic cocrystal and mixture models. The mechanical property, the maximum trigger bond length ([Formula: see text]), binding energy, and cohesive energy density (CED) of the pure RDX, β-HMX crystal, the cocrystal, and mixture models were acquired and compared. The results manifest that temperature has an important impact on the binding capacity between the components of the cocrystal and mixture. The binding energies decrease as the temperature rises, and the cocrystal has larger values than those of mixture. For all the models, the [Formula: see text] increases and the CEDs decrease with the rising temperature, implying that the sensitivity of the explosives increases, while the [Formula: see text] values of the cocrystal are smaller than those of HMX and the CED values are between those of RDX and β-HMX, indicating that the sensitivity has been enhanced through co-crystallization. As the temperature increases, the shear modulus (G), bulk modulus (K), and tensile modulus (E) values of all models have an evident downtrend. Simultaneously, G, K, and E values of the cocrystal model are less than those of RDX and β-HMX, while the K/G ratio and Cauchy pressure (C12-C44) are larger, signifying that co-crystallization can weaken the brittleness and enhance the ductility of the pure crystals. Compared with the mixture, the cocrystal has better ductility and stability.

Compressibility and thermoelasticity of CrN

ABSTRACT We report experimental determination of compressibility and thermoelasticity for CrN based on in situ high pressure/high temperature synchrotron x-ray diffraction measurements. The pressure-induced cubic-to-orthorhombic phase transition is observed at ∼ 5 GPa in high-quality CrN samples synthesized using a high pressure reaction route. Equation of state, bulk modulus and axial compressibility of this material are obtained by analysis of high pressure x-ray diffraction data collected at room temperature. Both cubic and orthorhombic phases have a similar bulk modulus value of 257 (5) and 262 (6) GPa, respectively. For orthorhombic CrN, the b-axis has the most axial incompressibility, which should be associated with magnetic properties. In addition, the isothermal equation of states is also determined at different temperatures of 300, 400, 600, 800, 1000, and 1200 K, respectively. Some of the important thermoelastic properties of cubic CrN are thus derived, including temperature derivative of bulk modulus and volumetric thermal expansivity where a 0 = 1.95 (16) × 10−5 K−1 and a 1 = 4.39 (3) × 10−9 K−1.

A comparative theoretical investigation of optoelectronic and mechanical properties of KYS2 and KLaS2

The ternary sulfides KYS2 and KLaS2 are two promising candidates for numerous applications, as much as white LED, X-ray phosphor and transparent conductor materials. However, theoretical studies on these materials are lacking, and many of their physical properties are still unknown. The aim of this work is to investigate the physical properties of the ternary sulfides KYS2 and KLaS2 namely, structural, elastic, optoelectronic, thermodynamic analysis, and set the substitution effect of Y and La elements in the two compounds. The fundamental properties calculations are based on ab-initio pseudopotential framework, with both local density approximation (LDA) and generalized gradient approximations (GGA) along with an expanded set of plane waves. The Becke, 3-parameter, Lee–Yang–Parr (B3LYP) hybrid functional is also employed to describe the electronic structures and optical properties. The optimized crystal parameters are correlated very well with the existing experimental data. The predicted values of the elastic constants demonstrate that the two compounds are mechanically stable and can be classified as brittle materials. The band structure analysis reveals that both KYS2 and KLaS2 have indirect band gap. The optical properties, like the refractive index, extinction, absorption and reflectivity coefficients, are determined for various polarizations of incident light, while both compounds present optical anisotropy. The obtained optical properties indicate the high transparency of KYS2 and KLaS2 in the infrared and visible regions, which makes them promising candidates for many of transparent applications. The thermodynamic properties are investigated with the help of quasiharmonic Debye model approximation. KYS2 has a larger bulk modulus value, which make it more beneficial in engineering applications. Calculations of thermodynamical properties indicate that KYS2 compound has better thermal conductivity, stronger chemical bonds and bigger hardness.

Determination of dynamic elastic properties of dry, wet and partially CO2 saturated coals from laboratory scale ultrasonic response

We present the longitudinal (VP) and shear (VS) wave velocities and their anisotropy of coal-samples under dry, water, and partially CO2 saturated conditions. The elastic-constants have also been subsequently computed and presented. The results show that the VS generally increases when the pores are filled with a less compressible fluid which effectively raises the bulk modulus. VP depends on the combination of both bulk and shear modulus; it is highest for partially CO2 saturated samples when the combined values of bulk and shear moduli are highest. Velocity anisotropy of VS is of comparable order for dry and partially CO2 saturated samples (13.42 % and 15.08 %, respectively), while wet samples show the lowest VS anisotropy (5.44 %). For VP, the wet samples exhibit 2.75 % lower anisotropy than dry samples; while partially CO2 saturated samples have the highest VP anisotropy (15.62%). The relationships between VS and VP, Young’s Modulus (E) and VP under different fluid saturation in pores are quantified and presented using a linear regression method. Correlation between the ratio of the square of VP and VS and Poisson’s ratio was performed by polynomial fitting. Hypothesis testing (T-test) has been conducted on regression relationships using T statistics. We show that the regression relationships among all elastic parameters and ultrasonic wave velocities are not occurring by chance; rather true relationships prevail between the parameters under consideration. We finally conclude that under atmospheric or low confinements, the elastic properties of coal reservoirs are hardly affected by the type of pore fluids present in the reservoir.

High pressure X-ray diffraction study of sodium oxide (Na2O): Observations of amorphization and equation of state measurements to 15.9 GPa

We have investigated the high-pressure behavior of sodium oxide (Na2O) up to 30 GPa by synchrotron angle-dispersive powder X-ray diffraction in a diamond anvil cell at room temperature. Between 15.9 and 17.3 GPa crystalline Na2O transforms to an amorphous state, and on decompression the amorphous structure recrystallizes back between 4.9 and 10.3 GPa. The zero-pressure bulk modulus of Na2O is obtained in experimental observations for the first time. The pressure-volume data is fitted according to the third-order Birch-Murnaghan equation of state and yields four bulk modulus values by setting the V0 or B0’ either as a constant or variable. The bulk modulus values of Na2O are smaller than α-Li2O, which is in good agreement with the previous calculation results.

Anomalous lattice compression in the hexagonal La2O3– A high pressure X-ray diffraction, Raman spectroscopy and first principle study

High pressure behavior of hexagonal rare earth sesquioxide La2O3 have been investigated using X-ray diffraction, Raman spectroscopy and first principle calculations. Though the hexagonal structure is stable up to 26.5 GPa, incompressibility along the a axis is visible above 9.7 GPa. Rietveld structure refinements in conjunction with the Stephans anisotropic strain broadening model revealed the onset of an atypical bond compression and modification in the relative intensities of the diffraction peaks at ∼5.6 GPa. A significant increase in the intensity of 100 reflection and a clear reduction in the intensity of 103 reflection above 5.6 GPa suggests that pressure induces sliding of the adjacent La–O layers in opposite directions rather than compressing along the a axis. Further, a negative correlation of in-plane strain with pressure above 5.6 GPa indicate the layer sliding is accompanied by a reduction of in-plane strain in the hexagonal structure. Raman studies show the lifting of the degeneracy of the two stretching modes, in-plane Eg and out of plane A1g, and the change of slope of ω vs. P curve for the two in-plane Eg modes at 3.6 GPa. First principle density functional theory calculation substantiates our experimental observations that the pressure induced anisotropic strain distribution is driving the system into low energy configurations. The Birch –Murnaghan equation of state fit to the experimental pressure-volume data yielded a bulk modulus value of B0 = 102(5) GPa with B′0 = 9.8(1.0) for P ≤ 9.7 GPa, in good agreement with the 114 GPa of density functional theory calculations.

A comparative simulation: Difference between chemical grafting and physical doping of cellulose by using polysilsesquioxane

In order to study the effect of different modification methods on polysilsesquioxane (POSS) modified cellulose, a molecular dynamics method was used to establish a pure cellulose model and a series of modified models modified by polysilsesquioxane in different ways. And their thermodynamic properties were calculated. The results showed that the performance of cellulose models was better than that of unmodified model, and the modified effect was the best when two cellulose chains were grafted onto polysilsesquioxane by chemical bond (M2 model). Compared with pure cellulose model, the cohesive energy density and solubility parameters of M2 model are increased by 9%, and the values of tensile modulus, bulk modulus, shear modulus and Cauchy pressure increased by 38.6%, 29.5%, 41.1% and 29.5%, respectively. In addition, the free volume fraction and mean square displacement of each model were calculated and analyzed in this work. Compared with the pure cellulose model, the molecular chain entanglement of cellulose was increased due to the existence of the chemical bonds in the M2 model, which made the cellulose molecular chains occupy more free volume, so that the system had a smaller free volume fraction, inhibited the chain movement of cellulose chains, and thus improved the thermal stability of cellulose.

Theoretical calculation into the structures, stability, sensitivity, and mechanical properties of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12 hexaazai-sowurtzitane (CL-20)/1-amino-3-methyl-1,2,3-triazoliumnitrate (1-AMTN) cocrystal and its mixture

Molecular dynamics (MD) simulation was conducted to research the effect of temperature (200–350 K) on the thermal stability, sensitivity, and mechanical properties of 1-AMTN (1-amino-3-methyl-1,2,3-triazoliumnitrate), CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazai-sowurtzitane), cocrystal, and composite explosive. The binding energy, the maximum trigger bond length ($$ {L}_{N-{NO}_2} $$), and cohesive energy density (CED), as well mechanical properties of the pure CL-20, 1-AMTN, cocrystal, and composite, were got and contrasted. The results demonstrate that temperature has a great influence on the binding capacity between CL-20 and 1-AMTN molecules in the cocrystal. The binding energies decrease with the rising temperature and the cocrystal has larger values than those of mixture. The $$ {L}_{N-{NO}_2} $$of all models increases and the CEDs decrease with the rising temperature, demonstrating that their sensitivities increase. While the $$ {L}_{N-{NO}_2} $$ values of cocrystals are all smaller than those of CL-20 and the CED values are all between those of CL-20 and 1-AMTN, indicating that the sensitivity has been reduced through co-crystallization. The mechanical properties of all models have an evident downtrend. Simultaneously, the tensile modulus (E), bulk modulus (K), and shear modulus (G) values of the cocrystal model are between those of CL-20 and 1-AMTN at the same temperature, thus co-crystallization can weaken the brittleness and enhance the ductility of CL-20. Compared with the mixture, the cocrystal has better ductility and stability.

The equation of state of TaC0.99 by X-ray diffraction in radial scattering geometry to 32 GPa and 1073 K

We have performed in situ synchrotron X-ray diffraction experiments on TaC0.99 compressed in a diamond anvil cell along 3 isothermal paths to maximum pressure (P)-temperature (T) conditions of 38.8 GPa at 1073 K. By combining measurements performed in axial diffraction geometry at 296 K and in radial geometry at 673 K and 1073 K, we place constraints on the pressure-volume-temperature (P-V-T) equation of state of TaC in a wide range of conditions. A fit of the Birch-Murnaghan equation to the measurements performed in axial geometry at ambient temperature yields a value of the isothermal bulk modulus at ambient conditions KT0=305±5(1σ)GPa and its pressure derivative (∂KT/∂P)T0=6.1±0.5. The fit of the Birch-Murnaghan-Debye model to our complete P-V-T dataset allows us to constrain the Grüneisen parameter at ambient pressure γ0=V(∂P/∂E)V0 to the value of 1.2 ± 0.1.

Relationship between ethane and ethylene diffusion inside ZIF-11 crystals confined in polymers to form mixed-matrix membranes

Self-diffusivities of ethane were measured by multinuclear pulsed field gradient (PFG) NMR inside zeolitic imidazolate framework-11 (ZIF-11) crystals dispersed in several selected polymers to form mixed-matrix membranes (MMMs). These diffusivities were compared with the corresponding intracrystalline self-diffusivities in ZIF-11 crystal beds. It was observed that the confinement of ZIF-11 crystals in ZIF-11/Torlon MMM can lead to a decrease in the ethane intracrystalline self-diffusivity. Such diffusivity decrease was observed at different temperatures used in this work. PFG NMR measurements of the temperature dependence of the intracrystalline self-diffusivity of ethylene in the same ZIF-11/Torlon MMM revealed similar diffusivity decrease as well as an increase in the diffusion activation energy in comparison to those in unconfined ZIF-11 crystals in a crystal bed. These observations for ethane and ethylene were attributed to the reduction of the flexibility of the ZIF-11 framework due to the confinement in Torlon leading to a smaller effective aperture size of ZIF-11 crystals. Surprisingly, the intra-ZIF diffusion selectivity for ethane and ethylene was not changed appreciably by the confinement of ZIF-11 crystals in Torlon in comparison to the selectivity in a bed of ZIF-11 crystals. No ZIF-11 confinement effects leading to a reduction in the intracrystalline self-diffusivity of ethane and ethylene were observed for the other two studied MMM systems: ZIF-11/Matrimid and ZIF-11/6FDA-DAM. The absence of the confinement effect in the latter MMMs can be related to the lower values of the polymer bulk modulus in these MMMs in comparison to that in ZIF-11/Torlon MMM. In addition, there may be a contribution from possible differences in the ZIF-11/polymer adhesion in different MMM types.

Effect of granular particles on the properties of the fouling release coatings based on polydimethylsiloxane with the incorporation of phenylmethylsilicone oil, especially for the leaching behavior of phenylmethylsilicone oil

For polydimethylsiloxane (PDMS)-phenylmethylsilicone oil (PSO) blend coatings, the leaching of PSO could improve the antifouling performance of the blend coatings. In this study, granular particles reinforced PDMS-PSO blend coatings were investigated, including the surface properties, the mechanical properties, especially the leaching behavior of PSO and the antifouling performance. The results showed that increasing surface roughness of the blend coatings increased the water contact angle of the blend coatings. Yet for fumed silica and nano-silica reinforced blend coaiting, the hydroxyl groups from particles decreased the water contact angle of the blend coatings. The enhancement of the mechanical properties increased the difficulty of leaching PSO, which caused the decrease of biofilm detachment performance. Further, with the increase of the pigment volume concentration (PVC) value, the bulk modulus of the reinforced coating increased which increased the difficulty of leaching PSO in the interior of the reinforced coating by the form of oil storage sac. Under the same content of PSO, the bulk modulus value of the reinforced coatings with different granular particles was the same, when the PVC value was up to PVCM, which was defined as the minimum PVC value without leaching PSO. It also indicated that the effect of granular particles on the leaching behavior of PSO depended mainly on the change in the bulk modulus of the reinforced coatings.

Comments on the paper entitled “Pressure variation of melting temperatures of alkali halides”

The expressions for the pressure dependences of bulk modulus and the Grüneisen parameter used by Arafin and Singh [Int. J. Mod. Phys. B 30, 1750031 (2016)] in the Lindemann law for determining melting curves of 14 alkali halides have been found to yield no results which are consistent with the recent studies on equations of state. It is demonstrated here that Arafin–Singh’s expressions are physically not acceptable as they are shown here to give unrealistic values of bulk modulus and Grüneisen parameter for the materials at high pressures.