Effect of Different Catalysts and Growth Temperature on the Photoluminescence Properties of Zinc Silicate Nanostructures Grown via VLS Method

Herein, we explore the photoluminescence properties of zinc silicate (Zn2SiO4) nanostructures synthesized by vapor-liquid-solid (VLS) mode of growth using three different catalysts (Sn, Ag and Mn). Different catalysts significantly influence the growth rate which in turn has an impact on the structure and hence the photoluminescence of the prepared zinc silicate nanostructures. Zn2SiO4 has a wide bandgap of about 5.5 eV and in its pure form, it does not emit in visible region due to its inner shell electronic transitions between the 3d5 energy levels. However, the incorporation of different catalysts (Sn, Ag and Mn) at different growth temperatures into the Zn2SiO4 crystal growth kinetics provides wide visible spectral range of photoluminescence (PL) emissions. PL analysis shows broad multi-band spectrum in the visible region and distinct colours (red, yellow, green, blue, cyan and violet) are obtained depending on the crystalline structure of the prepared nanostructures. The allowed transitions due to the effect of different catalysts on zinc silicate lattice offer a huge cross-section of absorption that generates strong photoluminescence. The correlation between the structural and optical properties of the synthesized nanostructures is discussed in detail. The synthesized photoluminescent nanostructures have potential applications in solid-state lighting and display devices.

Comparing Zinc Oxide- and Zinc Silicate-Related Metal-Organic Networks via Connection-Based Zagreb Indices

Metal-organic networks (MONs) are among the unique complex and porous chemical compounds. So, these chemical compounds consist of metal ions (vertices) and organic ligands (edges between vertices). These networks represent large pore volume, extreme surface area, morphology, excellent chemical stability, highly porous and crystalline materials, and octahedral clusters. MONs are mostly used in assessment of chemicals, gas and energy storage devices, sensing, separation and purification of different gases, heterogeneous catalysis, environmental hazard, toxicology, adsorption analysis, biomedical applications, and biocompatibility. Recently, drug delivery, cancer imaging, and biosensing have been investigated by biomedical applications of zinc-related MONs. The versatile applications of these MONs make them helpful tools in many fields of science in recent decade. In this paper, we discuss the two different zinc oxide and zinc silicate related MONs according to the number of increasing layers of metal and organic ligands together. We also compute the connection-based Zagreb indices such as first Zagreb connection index (ZCI), second ZCI, modified first ZCI, modified second ZCI, modified third ZCI, and modified fourth ZCI. Moreover, a comparison is also included between the zinc-related MONs by using numerical values of connection-based Zagreb indices. Finally, we conclude that zinc silicate-related MON is better than zinc oxide-related MON for all values of n.

A novel approach to the preparation of manganese - doped zinc silicate luminescent material according to the precipitation method

The purpose of this work is to study the effect of some precipitation conditions on the luminescent properties of manganese-doped zinc silicate when synthesized in a new approach - impregnated precipitation method. The samples are characterized by thermal analysis, infrared IR, luminescent spectrum (PL), X-ray diffraction spectrum and scanning electron microscope (SEM). The results showed that manganese - doped zinc silicate luminescent material prepared by the impregnated precipitation method has higher luminescence than the traditional co-precipitation method. Samples with the highest luminescent properties were synthesized under the following conditions: concentration of Zn (CH3COO)2 is 1M, the precipitate aging time of 20 minutes, the washed filtered precipitate, impregnated with Mn2+ with a content of 1.5 % mol compared to the total metal, dried at 80 °C and then heat at 900 0C for 45 minutes. The obtained product is single-phase zinc silicate with composition of Zn1,97Mn0,03SiO4, rhombic structure with most particles varying in size of 0.3 - 0.5 µm, emitting green light with λmax = 525 nm when excited by UV rays with wavelength of 254 nm. Forming a single-phase Zn2SiO4 crystal at 900 0C for 45 minutes allowed to reduce the energy required for the sintering process compared with the solid - phase reaction method.