Zinc blende versus wurtzite ZnS nanoparticles: control of the phase and optical properties by tetrabutylammonium hydroxide

Abstract

We demonstrated phase control, mediated by the presence of tetrabutylammonium hydroxide, in the growth of ZnS crystals by using a cost effective MAS method; a very moderate temperature (140 °C) and a very fast reaction time are sufficient to produce nanostructures with a good degree of crystallinity.

Correlation between structural and electronic order–disorder effects and optical properties in ZnO nanocrystals

“…The presence of OH À ions plays a key role in the growth mechanism of ZnO nanoowers and their degree of crystallinity, since these ions act in the process of formation of the [Zn(OH) 4 ] 2À complex in aqueous solution, and which can be considered the basic units for the growth of ZnO nanostructures. 40,[42][43][44][45] Our results suggest that the self-assembly process is responsible for producing ower-like ZnO microcrystals from the aggregation of structures formed by several ZnO nanorods hierarchically ordered. Basically, the aggregation of ZnO nanorods occurs at the edge of the top face and the crystal growth process involves several stages during processing in MAH.…”

Novel Gd(OH)3, GdOOH and Gd2O3 Nanorods: Microwave-Assisted Hydrothermal Synthesis and Optical Properties

“…In this study, the most important difference between the crystalline phases is the coordination of the gadolinium ions in the ideal crystal structure. The hexagonal Gd(OH) 3 structure has a ninecoordination complex with [Gd(OH) 9 ] clusters, the monoclinic GdOOH structure has a seven-coordination complex with [GdO(OH) 7 ] clusters, and the cubic Gd 2 O 3 structure has a six-coordination complex with [GdO 6 ] clusters. It is well known that lanthanide ions have a wide variety of coordination environments, and in general tend to form complex clusters with high coordination numbers, nine-coordination being particularly important in the structure of f-block elements 22 .…”

“…Indeed, it is well known that the crystal structure depends on the experimental conditions such as heat treatment, which may cause changes to its electronic structure, and thus, has an important role in the PL profile 9 . We can observe that the Gd(OH) 3 compound presents the most intense PL emission (Fig 4b).…”

“…The PL emission can be a probe for the structural evaluation of materials 9,36,38 . Therefore, direct observation of oxygen vacancies is difficult, but spectroscopic studies can provide indirect evidences in support of them.…”

“…This method provides a simple and fast approach for the large-scale production of new emergent complex functional materials. In addition, it also enables the shape-controlled synthesis of micro-and/or nanomaterials at a lower cost, for their industrial exploitation with unprecedented capabilities in the new technologies [9][10][11][12][13][14] .…”