Synthesis of the uniform hollow spherical Sr2SiO4:Eu2+ phosphors via an h-BN protective method

• A facile method to synthesized high stable hollow spherical Sr2SiO4:Eu2+ green phosphor.
• The Sr2SiO4:Eu2+ green phosphor shows strong emission intensity under UV and blue light excitation.
• The h-BN protective film plays important roles in the formation of the spherical hollow structure of the phosphors.
• This spherical phosphor could be used in white LED and other display techniques.

The uniform hollow spherical Sr2SiO4:Eu2+ green emitting phosphors have been successfully synthesized using hollow silica spheres as templates by an h-BN protective method. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results directly confirmed the existence of the hollow spherical structure with a narrow size distribution and a shell thickness of 15–25 nm. The h-BN protective film, observed by high resolution TEM, plays an important role in the formation of the hollow spherical morphology and the improvement of photoluminescence properties. Comparing with the Sr2SiO4:Eu2+ micron-phosphor prepared by the traditional solid state reaction method, the hollow spherical phosphor with nano-sized grains exhibits stronger green emission under ultraviolet–blue light excitation. This could be attributed to the elimination of surface defects by the h-BN coating. This research gives an economic and convenient way to synthesize uniform spherical phosphors with high quantum efficiency.