Journal of Molecular and Engineering Materials

In the field of nanoscience, the ability to prepare high-quality nanocrystals is crucial for fundamental research and technology development. Herein, we review a general route for the colloidal preparation of monodisperse nanocrystals, which is divided into five different stages, namely (i) nucleation, (ii) growth, (iii) Ostwald ripening, (iv) surfactant capping and (v) precipitation. Each of the five stages is discussed in detail to provide a comprehensive understanding of the mechanism behind nanocrystal formation and the subsequent processing steps. We put emphasis on the classical theories and experimental techniques that are most frequently practiced. These are useful for the successful design and fabrication of nanocrystals with properties that are beneficial for use in a plethora of technological applications.

The ultrasonic properties like ultrasonic sound velocity in the hexagonal structured Cr₂Nb compound have been studied along unique axis at room temperature. The second- and third-order elastic constants (SOECs and TOECs) have been calculated for this compound using Lennard–Jones potential. The velocities V_L and V_S1 have minima and maxima respectively with 45° with unique axis of the crystal, while V_S2 increases with the angle from unique axis. Debye average sound velocities of Cr₂Nb have been found to be increasing with the angle and has maximum at 55° with unique axis at room temperature. Hence, when a sound wave travels at 55° with unique axis of this material, then the average sound velocity is found to be maximum. The inconsistent behavior of angle dependent velocities is associated to the action of SOECs. The ultrasonic properties are discussed in correlation with elastic, thermal and electrical properties. It has been found that the thermal conductivity is the main contributor to the behavior of ultrasonic attenuation and the cause of attenuation is phonon–phonon interaction. The mechanical properties of Cr₂Nb are better than other chromium-based alloys (Cr₂Ta, Cr₂Zr and Cr₂Hf) at room temperature, because it has high ultrasonic velocity and low ultrasonic attenuation.

Zinc tris-thiourea sulphate (ZTS) is a well known nonlinear optical (NLO) crystal widely used for various NLO applications. The NLO, physical and chemical properties can be modified by adding impurities and/or modifying crystal growth conditions. The impurities present in the growth solution and growth conditions can affect the crystal growth parameters at great extent. Thus, the study on the nature of intermolecular interaction with the dopant in the solution during crystal growth process becomes important. In the present investigation, the ultrasonic velocity was measured in the aqueous solutions of pure and cadmium sulphate mixed ZTS in the supersaturation state at 313.15 K. The thermodynamic parameters such as adiabatic compressibility, inter molecular free length, acoustic impedance and relative associations have been calculated from the ultrasonic data and densities of water and solutions at 313.15 K, and the nature of intermolecular interaction has been discussed. FT-IR spectra of all mixtures in the solid form at room temperature were recorded and the shifts in the absorption peaks corresponding to the functional groups of ZTS have been reported.

This work reports the effects of introducing diverse chemical functionalities onto the surface of polystyrene microcarrier beads on their ability to function as injectable cell carriers. Cellular adhesion and proliferation, as well as cellular outgrowths from microcarrier surfaces, using human umbilical vein endothelial cells (HUVECs), were examined in detail. It was observed that initial cell adhesion appeared to be most significantly decreased by hydrophobicity, whilst cell proliferation appeared to be improved in most chemical functional groups over unmodified polystyrene. Overall, our study highlights the importance of surface chemistry in directing the growth and function of human endothelial cells.

Modern technologies require materials with unusual combination of properties that cannot be met by conventional metal alloys, ceramic, etc. In our work, we prepared the samples of metal alloys such as Al356-TiB2. Processing of samples is done by artificial neural network (ANN) which is one of the promising fields of research in predicting experimental results. In our investigation we worked on grain size analysis, micro hardness, regression analysis, friction test, wear test and microstructure analysis of samples to describe the materials properties of Al356-TiB2.

Ba_0.5Sr_0.5Co_xFe_1-x-yNi_yO_3-δ (BSCFNi; x = 0.4, 0 ≤ y ≤ 0.25) were studied in relation to their potential use as intermediate temperature solid oxide fuel cell (IT-SOFC) cathode. An emphasis is made on the effect of Ni-doping on crystal structure, thermal expansion coefficient (TEC) and dc electrical conductivity. A cubic perovskite structure was observed in the X-ray diffraction (XRD) measurement. The TEC of BSCFNi obtained for 0 ≤ y ≤ 0.25, varies in the range of (12.38–18.81) × 10^-6 K^-1, measured in the temperature range of 30°C to 800°C. The electrical conductivity which is a major defect of Ba_0.5Sr_0.5Co_xFe_1-xO_3-δ (BSCF) was improved by Ni-doping. The compound with y = 0.20 and 0.25 demonstrated a conductivity of σ = 62.59 S-cm^-1 and 72.64 S-cm^-1 at 400°C and 77.01 S-cm^-1 and 89.68 S-cm^-1 at 500°C.

An organic nonlinear optical (NLO) crystal of Guanidinium carbonate (GUCT) was synthesized by the slow evaporation solution growth method using water as solvent. The GUCT crystalized in the tetragonal crystal system with non-centrosymmetric space group P4₃2₁2, which has been confirmed by single-crystal X-ray diffraction. The crystalline perfection of the grown crystals has been analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The UV-Vis-NIR spectrum studies have been carried out to identify the optical transmittance, lower cut off wavelength and optical band gap energy of GUCT crystal. The luminescence spectrum of crystal contains a green emission band with λ_max, 545 nm. From thermo-gravimetric analysis (TGA), the thermal stability of the grown crystal is found to be 117°C. The dielectric tensor components ε₁₁ and ε₂₂ of the grown crystal were evaluated as a function of frequency at 40°C. The mechanical strength and its parameters of the grown crystals have been determined by Vickers' microhardness test. The Kurtz-powder technique reveals that the second harmonic generation (SHG) efficiency of the grown crystal is 5.2 times greater than that of KDP.