Decrease Of Critical Temperature Research Articles

Conductivity of the one-dimensional holographic p -wave superconductors in the presence of nonlinear electrodynamics

We investigate analytically as well as numerically effects of nonlinear Born-Infeld (BI) electrodynamics on the properties of (1+1)-dimensional holographic $p$-wave superconductor in the context of gauge/gravity duality. We consider the case in which the gauge and vector fields backreact on the background geometry. We apply the Sturm-Liouville eigenvalue problem for the analytical approach as well as the shooting method for the numerical calculations. In both methods, we find out the relation between critical temperature $T_{c}$ and chemical potential $\mu$ and show that both approaches are in good agreement with each other. We find that if one strengthen the effect of backreaction as well as nonlinearity, the critical temperature decreases which means that the condensation is harder to form. We also explore the conductivity of the one-dimensional holographic $p$-wave superconductor for different values of b and $T/T_{c}$. We find out that the real and imaginary parts of the conductivity have different behaviors in higher dimensions. The effects of different values of temperature is more apparent for larger values of nonlinearity parameter. In addition, for the fixed value of $T/T_{c}$ by increasing the effect of nonlinearity we observe larger values for Drude-like peak in real part of conductivity and deeper minimum for imaginary part.

Single-phase indium-doped cupric oxide films prepared through DC reactive magnetron sputtering: Influence of substrate temperature on microstructure, optical and electrical behavior

Cupric oxide (CuO) films with high electrical conductivity are crucial to their potential application in heterojunction solar cells. However, intrinsic CuO films usually have low electrical conductivity. The doping of proper ions into CuO is effective for the improved electrical conductivity. Herein, a series of monoclinic, indium-doped cupric oxide (CuO:In) films was prepared at different substrate temperature (Tsub) values via low-cost DC reactive magnetron sputtering. The influence of Tsub was intensively studied on the film’s microstructure, optical and electrical behaviors. A conducting transition from p type to n type occurs at 400 °C Tsub for CuO:In films rather than 500 °C Tsub for intrinsic CuO films. The decrease in critical transition temperature is mainly caused by the substitution of copper by indium. With increase of Tsub, the film crystallization is enhanced and the point defect content is reduced in the films, thereby increasing the film’s mobility and free carrier concentration. Increased Tsub helps the effective substitution of copper by indium and thus forms the n-type conduction. Compared with undoped CuO film, the CuO:In films have quite low mobility, improved electrical conductivity and large optical absorption edge. This finding indicates that CuO:In films can be used as absorption layer material in heterojunction solar cells rather than as hole-transporting layer material in perovskite solar cells.

Conductivity Fluctuation and Some Parameters of High temperature Superconductor Polycrystalline Y1Ba2Cu3O7−δ doped with Silver Nanoparticles

In this study, we report the effect of Ag nanoparticles doping on the dimensional fluctuations of superconducting order parameters, crystal structure, and some parameters of Y1Ba2Cu3O7−δ + × Ag (x = 0.0, 0.06, 0.1, 0.3, and 0.6 wt%) polycrystalline ceramics. By increasing the content of Ag in YBCO matrix, X-ray diffraction (XRD) with the Rietveld refinement technique revealed that the crystal lattice parameters changed and the orthorhombicity decreased slightly. Also, the increase of Ag wt% caused a decrease of superconducting transition temperatures (Tc) which are determined from the standard four-probe method and dropped abruptly. Aslamazov–Larkin (AL) model was used to analyze excess conductivity fluctuation. Lawerence–Doniach (LD) temperature named TLD which is responsible for the dimensional nature of fluctuation inside the grains is influenced by nano-silver combination in the compound. Crossover temperature from 2D to 3D (TLD) decreased in the mean-field region as a resultant dominance of 3D region by increasing of Ag in YBCO matrix. The decrease in zero-resistance critical temperature (Tc zero), zero-temperature coherence length along the c-axis ξc(0), and super layer length d values implies the degradation of inter-grain weak links, more disorder state of samples and unsettling of the mean free path for the charge carriers respectively with addition of silver nanoparticles. The calculations based on AL and LD model showed the highest anisotropy (γ = 1.34681) for the x = 0.6 sample. The size of the Ag ions, being larger compared to Cu ions, and the number of substitution sites affects the coupling between the CuO2 planes and that results in higher anisotropy. Critical magnetic fields Bc1(0), Bc2(0), and critical current density Jc(0) were indirectly calculated from the Ginzburg–Landau (GL) number and GL equations. By increasing the doping level of silver nanoparticle, these parameters were found to be higher in Ag-added YBCO samples compared to the pure Y123, meaning better intrinsic flux pinning properties of doped Y123. The silver nanoparticle inclusion reduces the grain size and increases the strength and hardness of the parent compound.

Conductivity of the holographic p-wave superconductors with higher order corrections

We investigate the holographic p-wave superconductors in the presence of the higher order corrections on the gravity as well as on the gauge field side. On the gravity side, we add the Gauss–Bonnet curvature correction terms, while on the gauge field side we take the nonlinear Lagrangian in the form {mathcal {F}}+b {mathcal {F}}^{2}, where {mathcal {F}} is the Maxwell Lagrangian and b indicates the strength of the nonlinearity. We employ the shooting method for the numerical calculations in order to obtain the ratio of the critical temperature T_{c} over rho ^{1/(d-2)}. We observe that by increasing the values of the mass and the nonlinear parameters the critical temperature decreases and thus the condensation becomes harder to form. In addition, the stronger Gauss–Bonnet parameter alpha hinders the superconducting phase in Gauss–Bonnet gravity. Furthermore, we calculate the electrical conductivity based on the holographic setup. The real and imaginary parts are related by the Kramers–Kronig relation, which indicates a delta function and a pole in low frequency regime, respectively. However, at enough large frequencies the trend of the real part can be interpreted by Re[sigma ]=omega ^{(d-4)}. Moreover, in holographic model the ratio omega _{g}/T_{c} is always much larger than the BCS value 3.5 due to the strong coupling of holographic superconductors. In both kinds of gravity, decreasing the temperature or increasing the effect of nonlinearity shifts the gap frequency toward larger values. Besides, the gap frequency occurred at larger values by enlarging the Gauss–Bonnet parameter. In general, the behavior of the conductivity depends on the choice of the mass, the nonlinear and the Gauss–Bonnet parameters.

Gauss–Bonnet holographic superconductors in exponential nonlinear electrodynamics

The low-energy limits of the string theory lead to the higher-order curvature corrections for Einstein gravity. Also, they give the higher-order derivative corrections for the Maxwell or linear electrodynamics, which suggests the nonlinear electrodynamics. Inspired by this, in this paper we investigate $d$-dimensional holographic superconductors in the probe limit in the framework of Einstein-Gauss-Bonnet gravity and exponential nonlinear electrodynamics. Based on the Sturm-Liouville eigenvalue method, we compute the critical temperature, the condensation value, and the critical exponent. It is observed that the critical temperature decreases when the Gauss-Bonnet (GB) parameter or the nonlinear parameter increases, but it increases with the higher dimension of the spacetime at the efficiently low charge density. In addition, we found that the condensation value becomes larger as increasing the GB parameter, the nonlinear parameter as well as the spacetime dimension. Finally, we calculate the optical conductivity and study the effects of the GB term and exponential nonlinear electrodynamics on superconducting energy gap.

Superconductivity at 250 K in lanthanum hydride under high pressures.

With the discovery1 of superconductivity at 203 kelvin in H3S, attention returned to conventional superconductors with properties that can be described by the Bardeen-Cooper-Schrieffer and the Migdal-Eliashberg theories. Although these theories predict the possibility of room-temperature superconductivity in metals that have certain favourable properties-such as lattice vibrations at high frequencies-they are not sufficient to guide the design or predict the properties of new superconducting materials. First-principles calculations based on density functional theory have enabled such predictions, and have suggested a new family of superconducting hydrides that possess a clathrate-like structure in which the host atom (calcium, yttrium, lanthanum) is at the centre of a cage formed by hydrogen atoms2-4. For LaH10 and YH10, the onset of superconductivity is predicted to occur at critical temperatures between 240 and 320 kelvin at megabar pressures3-6. Here we report superconductivity with a critical temperature of around 250 kelvin within the [Formula: see text] structure of LaH10 at a pressure of about 170 gigapascals. This is, to our knowledge, the highest critical temperature that has been confirmed so far in a superconducting material. Superconductivity was evidenced by the observation of zero resistance, an isotope effect, and a decrease in critical temperature under an external magnetic field, which suggested an upper critical magnetic field of about 136 tesla at zero temperature. The increase of around 50 kelvin compared with the previous highest critical temperature1 is an encouraging step towards the goal of achieving room-temperature superconductivity in the near future.

The change in the phase diagram of a simple substance at decreasing of the nano-system size

On the basis of proposed earlier the three-phase model of simple matter and the RP(vac)-model of a nanocrystal, the equation for the free Helmholtz energy of a nanocrystal, in which take into account both lattice vacancies and delocalized (diffusing) atoms was obtained. A model of the Gibbs surface is proposed, on which a part of the cells is vacant, and some of the atoms are in a delocalized state. It is taken into account that some of the delocalized atoms are delocalized according to the “bulk” manner and some by the “surface” way. The state equation was calculated for argon, the atoms of which interacted by the Mie-Lennard-Jones pairwise potential. Calculations for the macro-system showed that at middle temperatures the state equation has two S-loops on isotherms that correspond to phase transitions (PT) crystal-liquid (C-L) and liquid-gas (L-G). At high temperatures, the S-loop for PT L-G decreases to a critical point. At low temperatures, two S-loops of the PT C-L and L-G merge into one large S-loop corresponding to the PT crystal-gas. When the number of atoms (N) in nano-system decreases the S-loops for PT C-L and L-G on the isotherm decreases, and for a certain value of the number of atoms (N0), the S-loop for PT C-L disappears. It is shown that the value of N0 increases both with increasing temperature on the isotherm and when the shape of the nano-system deviates from the most energetically optimal shape (for a RP(vac)-model, this is a cube). In a cluster of N < N0 atoms, the PT C-L are no longer present. Such a cluster at an isothermal increase in the specific volume smoothly passes into the liquid phase. At a decrease in the number of atoms, the S-loop for the PT of L-G also decreases. The parameters of the critical point for the L-G phase transition at a decrease in the number of atoms also change: the critical temperature and pressure decrease, and the critical specific volume increases.

Fabrication and optimization of Bi-2212 high temperature superconductors with K and Ag co-incorporation

Polycrystalline bulks Bi2.1Sr1.96CaKxCu2.0O8+δ + yAg (Bi-2212) with different K incorporation content of x = 0, 0.02, 0.05 and 0.10 and addition of Ag nanoparticles with weight ratio of y = 0.10 wt% were fabricated by a hot-pressing (HP) process. The influences of K+ ions and Ag nanoparticles on the lattice parameters, phase composition, microstructures and related superconducting properties were systematically investigated. The introductions of K+ and Ag both obviously affected the thermodynamic parameters of Bi-2212 system. Accordingly the sintering temperature during HP process changed dramatically. After the HP process, increases of average grain size were obtained with Ag incorporation, based on both XRD and SEM analysis, which implied the formation of better texture alignment structure. Slight decrease of critical temperature was observed corresponding to the changing valence of Cu2+ ions on superconducting layer. Increase of superconducting phase volume was achieved on the K and Ag co-incorporated bulk. And the enhancement of current capacity was also achieved on the very same sample, under the magnetic field higher than 1 T. The different flux pinning mechanism between K and K/Ag incorporated sample from point pinning to surface pinning could be related to the microstructure change, which can be recognized as a solid evidence for the different effects of K and Ag.

Magnetization and ac susceptibility study of the cubic chiral magnet Mn1−xFexSi

We present a comprehensive and systematic magnetization and ac susceptibility study of Mn$_{1-x}$Fe$_{x}$Si over an extensive range of ten Fe concentrations between $x$ = 0 - 0.32. With increasing Fe substitution, the critical temperature decreases but the magnetic phase diagrams remain qualitatively unaltered for $x$ $\leq$ $x^*$ $\approx$ 0.11 with clear boundaries between the helical, conical, and skyrmion lattice phase as well as an enhanced precursor phase. A notably different behavior sets in for $x$ $=$ 0.11, 0.13 and 0.14, where certain characteristics of helimagnetic correlations persist, but without clear phase boundaries. Although a qualitative change already sets in at $x^*$, the transition temperature and spontaneous magnetization vanish only at $x_C$ = 0.17 where also the average magnetic interactions change sign. Although the Curie-Weiss temperature reaches -12~K for $x$ = 0.32, no signature of long-range magnetic order is found down to the lowest temperature, indicating a possible significant role for quantum fluctuations in these systems.

Study on the Effect of 1-Butanol Soluble Lignin on Temperature-Sensitive Gel.

A protocol for the fractionation of lignin with 1-butanol as solvent has been proposed in order to improve the utilization of industry alkali lignin. 1-butanol soluble lignin (BSL) was used as a building block for temperature-sensitive hydrogel with N-isopropylacrylamide (NIPAAm) through graft polymerization. The result shows that 1-butanol fractionation is an effective method to improve the molecular weight homogeneity of lignin (PDI, 2.5 to 1.83) and increase the hydroxyl group content (0.585–1.793 mmol/g). The incorporation of BSL into the temperature-sensitive hydrogel can enhance the thermal stability and increase the hydrophobicity of the gel, which leads to a decrease in lower critical solution temperature (LCST). In addition, the compression strength, swelling ratio, and pore size of the gel can be adjusted by the dosage of lignin. This stimuli-responsive gel, with an LCST around 32 °C, is expected to be applied in the agricultural field as a pesticide carrier by stimulating release and absorption properties based on the change in natural environmental temperature.

Monte Carlo simulation of equilibrium and dynamic phase transition properties of an Ising bilayer

Magnetic properties of an Ising bilayer system defined on a honeycomb lattice with non-magnetic interlayers which interact via an indirect exchange coupling have been investigated by Monte Carlo simulation technique. Equilibrium properties of the system exhibit ferrimagnetism with $P$-, $N$- and $Q$- type behaviors. Compensation phenomenon suddenly disappears with decreasing strength of indirect ferrimagnetic interlayer exchange coupling. Qualitative properties are in a good agreement with those obtained by effective field theory. In order to investigate the stochastic dynamics of kinetic Ising bilayer, we have introduced two different types of dynamic magnetic fields, namely a square wave, and a sinusoidally oscillating magnetic field form. For both field types, compensation point and critical temperature decrease with increasing amplitude and field period. Dynamic ferromagnetic region in the presence of square wave magnetic field is narrower than that obtained for sinusoidally oscillating magnetic field when the amplitude and the field period are the same for each type of dynamic magnetic fields.

Optical properties of Born–Infeld-dilaton-Lifshitz holographic superconductors

In this letter, we first study the Lifshitz-dilaton holographic superconductors with nonlinear Born–Infeld (BI) gauge field and obtain the critical temperature of the system for different values of Lifshitz dynamical exponent, z, and nonlinear parameter b. We find that for fixed value of b, the critical temperature decreases with increasing z. This indicates that the increase of anisotropy between space and time (encoded in Lifshitz exponent z) prevents the phase transition. Also, for fixed value of z, the critical temperature decrease with increasing b. Then, we investigate the optical properties of (2+1) and (3+1)-dimensional BI-Lifshitz holographic superconductors in the presence of dilaton field. We explore the refractive index of the system. This is an important study, since it discloses the effects of anisotropy between space and time as well as nonlinearity of electrodynamics model and dimension on strange metamaterial behavior of the holographic superconductor. For z=1 and (2+1)-dimensional holographic superconductor, we observe negative real part for permittivity Re[ϵ] as frequency ω decreases. Thus, in low frequency region our superconductor exhibit metamaterial property. This behavior is independent of the nonlinear parameter and can be seen for either linear (b=0) and nonlinear (b≠0) electrodynamics. Interestingly, for (3+1)-dimensional Lifshitz-dilaton holographic superconductors, we observe metamaterial behavior neither in the presence of linear nor nonlinear electrodynamics.

Influence of coronene addition on some superconducting properties of bulk MgB2

This study reports the effect of coronene (C24H12) addition on some superconducting properties such as critical temperature (Tc), critical current density (Jc), flux pinning force density (Fp), irreversibility field (Hirr), upper critical magnetic field (Hc2), and activation energy (U0), of bulk MgB2 superconductor by means of magnetisation and magnetoresistivity measurements. Disk-shaped polycrystalline MgB2 samples with varying C24H12 contents of 0, 2, 4, 6, 8, 10 wt%, were produced at 850 °C in Ar atmosphere. The obtained results show an increase in field-Jc values at 10 and 20 K resulting from the strengthened flux pinning, and a decrease in critical temperature (Tc) because of C substitution into MgB2 lattice, with increasing amount of C24H12 powder. The Hc2(0) and Hirr(0) values are respectively found as 144, 181, 172 kOe, and 128, 161, 145 kOe for pure, 4 wt% and 10 wt% C24H12 added samples. The U0 depending on the magnetic field curves were plotted using thermally activated flux flow model. The maximum U0 values are respectively obtained as 0.20, 0.23 and 0.12 eV at 30 kOe for pure, 4 wt% and 10 wt% C24H12 added samples. As a result, the superconducting properties of bulk MgB2 at high fields was improved using C24H12, active carbon source addition, because of the presence of uniformly dispersed C particles with nanometer order of magnitude, and acting as effective pinning centres in MgB2 structure.

AC Susceptibility of BaZrO3 Nanoparticles Added YBa2Cu3O7−δ Superconductor Prepared via Coprecipitation Method

In this work, magnetic properties of polycrystalline samples YBa2Cu3O7−δ added with x mol.% of BaZrO3 (BZO) nanoparticles (x = 0.0, 1.0, 2.0, 3.0, 5.0, and 7.0) were studied by AC susceptibility (ACS) measurement. The samples were prepared using coprecipitation (COP) method. X-ray diffraction (XRD) results showed that all the samples were composed of Y-123 as the major phase and Y-211 as the secondary phase. XRD peak of BZO was also observed in the samples added with BZO nanoparticles. The intensity of the peak became higher with increasing amount of BZO addition indicating the presence of increased amount of the unreacted nanoparticles in the samples. The refined lattice parameters indicated that all the samples have an orthorhombic crystal structure without the occurrence of orthorhombic-tetragonal phase transformation. Scanning electron microscopy (SEM) images showed that the samples have randomly distributed grains with irregular shape. The average grain size increased from 0.30 μ m for the pure sample to 0.50 μ m for the BZO addition of 7.0 mol.%. ACS measurement showed a slight decrease of onset critical temperature, Tc−onset (< 1 K) with BZO addition. Both phase lock-in temperature, Tcj, and coupling peak temperature, Tp, remained relatively unchanged for BZO addition up to 3.0 mol.%. Based on the Bean critical state model, the calculated intergranular critical current density, Jcm, for the pure sample is 1.88 A/cm2 at Tp = 84.8 K. For the sample added with 7.0 mol.% of BZO, Jcm at Tp = 83.6 K is 1.95 A/cm2.

Finite size effects in strongly interacting matter at zero chemical potential from Polyakov loop Nambu-Jona-Lasinio model in the light of lattice data

We study finite volume effects within the Polyakov loop Nambu-Jona-Lasinio model for two light and one heavy quarks at vanishing baryon chemical potential and finite temperatures. We include three different Polyakov loop potentials and ensure that the predictions of our effective model in bulk are compatible with lattice QCD results. Finite size effects are taken into account by means of the Multiple Reflection Expansion formalism. We analyze several thermodynamic quantities including the interaction measure, the speed of sound, the surface tension, and the curvature energy and find that they are sensitive to finite volume effects, specially for systems with radii below sim 10hbox { fm} and temperatures around the crossover one. For all sizes, the system undergoes a smooth crossover. The chiral critical temperature decreases by around 5 % and the deconfinement temperature by less than a 2% when the radius goes from infinity to 3 fm. Thus, as the drop’s size decreases, both temperatures become closer. The surface tension is dominated by the contribution of strange quarks and the curvature energy by u and d quarks. At large temperatures both quantities grow proportionally to T^{3/2} but saturate to a constant value at low T.

Holographic p-wave superconductor with high-order derivative correction

In the probe limit, we numerically study the holographic p-wave superconductor phase transition in the high-order derivative theory. Concretely, we study the influences of the high-order derivative correction term αRF2 on the Maxwell complex vector model (MCV) in the five-dimensional AdS black hole and soliton backgrounds, respectively. In the black hole background, the improving correction parameter α increases the critical temperature and thus enhances the conductor/superconductor phase transition. Meanwhile, as the RF2 correction becomes stronger, the ratio of the energy gap to the critical temperature decreases from 9.858 to 5.995, which obviously deviates from the universal value. In the soliton background, we find that the correction does not affect the critical chemical potential. However, as the correction parameter α increases, the vector condensate grows faster, which might suggest that the improving α enhances the insulator/superconductor in some sense. The location of the second pole of imaginary part of conductivity increases with α, which implies that the energy of the quasiparticle excitation increases with the improving correction. In addition, the effects of α on the superfluid density agree with the one on the critical value as well as the condensate in both models. Furthermore, the critical exponent of condensate and superfluid density near the critical point is always 1/2 and 1, respectively.

Tunable critical temperature and magnetocaloric effect in ternary Prussian blue analogue

A comprehensive study of structural, magnetic and magnetocaloric properties in the ternary Prussian blue analogue (PBA) Ni1.5[Fe(CN)6]x[Cr(CN)6]1-x·nH2O (x = 0, 0.25, 0.5, 0.75 and 1) is presented. For all compounds the second-order magnetic phase transition from high temperature paramagnetic to the low temperature ferromagnetic state at the Curie temperature (Tc) is observed. We show the possibility of tuning the magnetic and magneto-caloric properties of PBA materials by changing the compositional factor of the metal centres involved in the cyano-bridging. An increase in Fe content leads to increase in the coercive field, whereas the critical temperature decreases from 60 to 22 K. The magnetic entropy change ΔS, as well as the related Relative Cooling Power (RCP), vary with x parameter in the regular way. The highest value of ΔS was observed for sample with x = 1 and was equal to 3.49 J mol−1K−1 under a magnetic field of 50 kOe, whereas the RCP varied from 62 J mol−1 (145.35 J kg−1) to 118 J mol−1 (273.33 J kg−1), when x decreased from 1 to 0.

Size Effect in the Phase Separation of Cr–W Solid Solutions

Size effects in phase transformations of nanoscale systems show up as significant changes in their phase diagram. Here, using a thermodynamic approach we demonstrate how the immiscibility region of Cr–W solid solutions is influenced by their particle size. For 40- and 70-nm-diameter particles, we consider two thermodynamically stable states with a core–shell configuration, differing in the composition of the core phase. It is shown that, in the nanometer range, one of these states becomes metastable and that the phase diagrams of the stable and metastable states differ significantly. Reducing the particle size leads to a decrease in the upper critical dissolution temperature (UCDP) by 300–400 K and marked changes in the mutual solubility of the components at temperatures comparable to the UCDP.

Holes doping effect on the phase transition of VO2 film via surface adsorption of F4TCNQ molecules

The holes doping effect on the metal–insulator transition (MIT) behavior of VO2 film is investigated via the tetrafluorotetracyanoquinodimethane (F4TCNQ) molecules adsorption induced surface charge transfer. Comparing with the MIT process of pristine VO2 film, a critical temperature decrease of about 4 °C for the F4TCNQ covered VO2 sample is observed. The MIT depression mechanism is deeply investigated based on detailed experiments including synchrotron radiation photon electronic spectroscopy (SRPES), X-ray absorption near-edge structure (XANES) spectroscopy and variable temperature Raman spectroscopy. Results indicate that the electronic structures of F4TCNQ covered VO2 sample are changed clearly due to the effective holes doping. In addition, the doped holes also change the V 3d orbital occupancy and weaken the electron–electron correlation as well, lowering the crystalline stability energy. Both of the above effects are in favor of triggering the earlier occurrence of MIT, resulting in the decrease of critical temperature.

Thermal Decomposition Kinetics of Nitroguanidine Propellant under Different Pressures

AbstractThermal decomposition of a nitroguanidine‐based propellant at different pressures was investigated under non‐isothermal conditions by high‐pressure differential scanning calorimetry (PDSC). It was found that only one visible exothermic peak appeared in DSC curves at the pressure. With the increase of the environment pressure, the peak temperature decreased, and the decomposition heat increased. Application of elevated pressures changed the mechanism of thermal decomposition of the nitroguanidine propellant as compared with that at 0.1 MPa. The reaction followed the sigmoidal model, where n=0.97 (0.1 MPa), or n=0.96 (high pressures). The mechanism of the process at 0.1 MPa can be classified as chemical reaction, and the kinetic equation can be ; whereas at high pressures, it shifts to nucleation and growth, with at 2 MPa and at 4 MPa. Pressure increase lowered the decrease in critical temperature, and lowered entropy of activation (ΔS≠), enthalpy of activation (ΔH≠), free energy of activation (ΔG≠), as well as the thermal safety of the nitroguanidine propellant.