Formation of Hollow Gallium Nitride Spheres via Silica Sphere Templates

Abstract

We report the formation of hollow GaN spheres using silica sphere templates. First, silica spheres with an average diameter of ∼130 nm were synthesized. A mixture of GaCl 3 , silica spheres, water, and urea in 2-propanol was prepared and heated to 100°C for 24 h to generate silica spheres with γ-Ga 2 O 3 nanoparticle shells. Decomposition of urea and its reaction with water slowly increased the solution pH to ∼8; this controlled reaction is the key to forming uniform γ-Ga 2 O 3 shells with a thickness of about 13 nm. The amounts of urea and water have been varied to find the optimal conditions for the preparation of the oxide shells. Transfer of the colloidal particle solution to silicon substrates and ammonolysis at 850°C for 6 h produced the SiO 2 -GaN core-shell nanostructures. Immersion of the silicon substrates in an HF solution removed the silica cores, and hollow GaN spheres with a shell thickness of around 8 nm were formed. The morphologies and crystal structures of the oxide and nitride shells have been carefully examined. The GaN shell materials show an absorption band at 350-360 nm and a broad defect-related emission band centered at around 570 nm.

Controlled synthesis and catalytic properties of mesoporous nickel–silica core–shell microspheres with tunable chamber structures

“…Various methods have been developed for preparing silicate materials with hollow structure. The common route for preparing hollow microspheres is to coat nanocrystals on the surfaces of templates followed by removing the templates through etching or calcinations [13][14][15]. For example, nickelsilica and copper-silicate composite hollow microspheres have been synthesized through such method [5,15].…”

Bifunctional AlN:Tb semiconductor with luminescence and photocatalytic properties

“…This is probably due to crystal defects from the aggregations composed of small AlN particles. 20 As studied previously, 5,21 vacancies and certain oxygen-related impurities were common defects in AlN nanostructures. However, a value of 3.9 eV for AlN:0.5%Tb is obtained.…”

Preparation of Inorganic Hollow Spheres Based on Different Methods

“…For instance, These reports involve removing the core by calcinations 21,32 or dissolution into solvents. 31,33 Recently, wu et al reported a facile approach to prepare monodisperse hollow silica or titania spheres via a one-step process. [34][35][36] In that method, aqueous ammoniacal alcohol was used as the catalyst and medium.…”