Optical, piezoelectric and mechanical properties of xylenol orange doped ADP single crystals for NLO applications

Investigation on the growth aspects and properties of rubidium hydrogen succinate hydrate single crystal for NLO applications

A novel semiorganic nonlinear optical single crystal of rubidium hydrogen succinate hydrate (RbHSH) was grown at room temperature using the slow evaporation solution growth technique (SEST) with water as a solvent for nonlinear optical applications. The grown crystal is a triclinic system with a centrosymmetric space group of P1̄ and the compound is stabilized by intramolecular O-H-O and C-H-O bonding. FTIR spectral studies were used to determine the various functional groups present in the material. The optical transmission spectra of the grown crystal demonstrated that a transparency of 89%, with a low cut off wavelength of 240 nm and an energy band gap of 5.21 eV, which is beneficial to developing advanced photonic and optoelectronic devices in the solar blind UV area. The grown crystal is thermally stable upto 174 °C. The electrical properties of RbHSH crystal exhibit low dielectric loss and a low dielectric constant at high frequencies tends to have good optical characteristics. Mechanical analysis demonstrated that the grown crystal shows the normal indentation size effect (ISE) and falls into the hard material category with n = 1.4. Photoconductivity measurements revealed negative photoconductivity. Photoluminescence studies showed that RbHSH emits blue light with a wavelength of 484 nm. Hirshfeld surface analysis was used to analyze intermolecular interactions in the RbHSH crystal. The grown RbHSH crystal piezoelectric charge coefficient have been calculated (d33 = 13 pC N-1) and it is suitable for piezoelectric device applications. Under continuous-wave laser excitation, the third order nonlinear refractive index (n2), absorption coefficient (β), and susceptibility (χ(3)) of the RbHSH crystal were found to be 1.6639 × 10-12 (cm2 W-1), 1.1739 × 10-5 (cm W-1) and 4.86331 × 10-9 esu, respectively.

Prediction of the Effective Work Function of Aspirin and Paracetamol Crystals by Density Functional Theory-A First-Principles Study

Crystals of active pharmaceutical ingredients (API) are prone to triboelectric charging due to their dielectric nature. This characteristic, coupled with their typically low density and often large aspect ratio, poses significant challenges in the manufacturing process. The pharmaceutical industry frequently encounters issues during the secondary processing of APIs, such as particle adhesion to walls, clump formation, unreliable flow, and the need for careful handling to mitigate the risk of fire and explosions. These challenges are further intensified by the limited availability of powder quantities for testing, particularly in the early stages of drug development. Therefore, it is highly desirable to develop predictive tools that can assess the triboelectric propensity of APIs. In this study, Density Functional Theory calculations are employed to predict the effective work function of different facets of aspirin and paracetamol crystals, both in a vacuum and in the presence of water molecules on their surfaces. The calculations reveal significant variations in the work function across different facets and materials. Moreover, the adsorption of water molecules induces a shift in the work function. These findings underscore the considerable impact of distinct surface terminations and the presence of molecular water on the calculated effective work function of pharmaceuticals. Consequently, this approach offers a valuable predictive tool for determining the triboelectric propensity of APIs.

DFT study of superhalogen and superalkali doped graphitic carbon nitride and its non-linear optical properties

DFT calculations are carried out to investigate nonlinear optical (NLO) properties of superhalogen (BCl4) and superalkali (NLi4) doped graphitic carbon nitride (GCN). It is noted that the geometries of doped GCN are sufficiently stable. The energy gap for GCN is 3.89 and it reduces to 0.53 eV in our designed molecule G4. Change in the dipole and transition dipole moment is observed along with small transition energies which are responsible for higher hyperpolarizabilities. Doped GCN has larger first and second hyperpolarizabilities which are basic requirements for NLO response. The second hyperpolarizability of GCN enhances from 1.59 × 104 to 2.53 × 108 au when doping with BCl4 and NLi4. TD-DFT calculations show the absorption maxima of doped GCN range from 700 nm to 1350 nm. EDDM analysis provides information on electronic distribution from excited to ground state. All these consequences show doped GCN can be a promising NLO material.

Theoretical predication of the high hydrogen evolution catalytic activity for the cubic and tetragonal SnP systems

Both the cubic and tetragonal SnP systems, with a layered structure similar to phosphorene, can exhibit a considerably high HER catalytic activity over a wide range of hydrogen coverage.