A series of single-composition trichromatic white-emitting Sr_3.5Y_6.5O₂(PO₄)_1.5(SiO₄)_4.5 (SYPSO) : Ce³⁺, Tb³⁺, Mn²⁺ phosphors were investigated, and the crystal structures and luminescence properties, especially the energy transfer behavior, are discussed in detail. It was found that the SYPSO : Ce³⁺, Tb³⁺, Mn²⁺ phosphors can yield three major RGB emission bands in the visible spectral region: blue emission from the 5d–4f transitions of Ce³⁺, green emission from the ⁵D₄–⁷F_J (J = 3, 4, 5, 6) transitions of Tb³⁺ and red emission from the ⁴T₁(⁴G)–⁶A₁(⁶S) transition of Mn²⁺ ions. The energy transfer process between Ce³⁺ and Tb³⁺ and between Ce³⁺ and Mn²⁺ have both been demonstrated to be a resonant type via a dipole–dipole mechanism, and the energy transfer (ET) efficiency, as well as the critical distance, have also been estimated. Based on the energy transfer, the emission colors of the obtained phosphors can be tuned from blue to green/red, and eventually to white emission by controlling the doping content of the Tb³⁺/Mn²⁺ ions. A white light emitting-diodes (w-LEDs) lamp was finally fabricated using the present phosphor (with the composition of SYPSO : 0.05Ce³⁺, 0.25Tb³⁺, 0.25Mn²⁺), which exhibited a high color rendering index (R_a) of 89.95 at a correlated color temperature of 6189 K and CIE coordinates of (0.320, 0.318). These results suggested that the present phosphor is a potential single-component white-light phosphor for n-UV-pumped w-LED.

Methyl orange (MO) is a common anionic azo dye that is harmful to the environment and biology, so it must be treated innocuously before it can be discharged. Adsorption is an effective method to remove anionic dyes. Nanotube mineral is a natural one-dimensional adsorption material, and its unique morphology and structure endow it with good adsorption capacity. Although there are many related studies, there is a lack of in-depth discussions on the influence of nanotube’s composition and structure on the adsorption of dyes and other pollutants. In this paper, two kinds of natural one-dimensional silicate minerals [halloysite nanotubes (HNTs) and chrysotile nanotubes (ChNTs)] with similar morphology but slightly different compositions and crystal structures were used as adsorbents, and MO solution was used as simulate pollutants. It is the first time to discuss in depth the influence of the composition and structure of nanotube minerals on their charge properties and the adsorption performance of methyl orange dyes. It is found that HNTs and ChNTs have different adsorption capacity due to the difference of electronegativity between Al³⁺ and Mg²⁺ in the crystal, so they possess negative and positive charges respectively in near-neutral solution, which leads to the adsorption capacity of MO by ChNTs with positive charges which is greater than that of HNTs.

A novel single-phase white light emitting phosphor Ca₉La(PO₄)₅(SiO₄)F₂:Dy³⁺ was prepared through traditional high-temperature solid state technology.