Double core-shell fluorescent materials and preparation methods thereof

A preparation method of a double core-shell fluorescent material, comprising the following steps:

• obtaining a metal particle sol;
• dissolving the metal particle sol into an alcohol solvent and weak alkaline solution, adding tetraethyl orthosilicate to react and preparing a suspension in which silicon dioxide coats a metal particle as an inner shell;
• preparing a mixture solution containing at least one of yttrium nitrate and gadolinium nitrate with europium nitrate, adding a precipitant or gel, dissolving each nitrate salt and the precipitant or gel utilizing solvent, and adding the suspension in which silicon dioxide coats a metal particle as a inner shell to obtain a precursor of the double core-shell fluorescent material;
• and
• calcining the precursor of the double core-shell fluorescent material to form a phosphor outer shell coating the silicon dioxide inner shell and represented by the following chemical formula:
• (R1-x, Eux)2O3, wherein R is Y, Gd or a combination thereof, 0.02≦x≦0.1, and obtaining the double core-shell fluorescent material.