•The upconversion luminescence of Eu3+ ion in calcium aluminoborate glass was demonstrated.•β-NaYF4 crystal was melted into aluminoborate matrix to form a homogeneous vitreous material.•The existences of β-NaYF4 and Bi3+ ion can enhance the upconversion luminescence of Eu3+.•The UC emission of Eu3+ in glass matrix can be induced by two-photon simultaneous absorption.The upconversion luminescence (UCL) of Eu3+ ion in calcium aluminoborate glass matrix with the composition of CaO–Al2O3–B2O3 (CaAlB) under 800 nm laser excitation has been demonstrated and the structural, thermal and optical properties of Eu3+-doped glasses were investigated by X-ray diffractometry (XRD), Fourier transform infrared (FT-IR), thermogravimetry-differential scanning calorimetry (TG-DSC) and photoluminescence (PL) analyses. The results revealed that these glasses possess good thermal, chemical and mechanical stabilities. For improving the UCL of Eu3+, β-NaYF4 crystal was successfully melted into CaAlB matrix to form a homogeneous vitreous material (CaAlB/NaYF4). The result indicated that the UC emission of Eu3+ in CaAlB/NaYF4 composite matrix observably increases due to reduced phonon energy of CaAlB matrix and high UC quantum efficiency of NaYF4 matrix. Similarly, additive Bi3+ ion can improve the UC emission of Eu3+ ion via reducing the phonon energy of the host. The UC emission of Eu3+ in CaAlB/NaYF4 composite matrix can be induced by two-photon simultaneous absorption. The results imply that these investigated glasses may be potential candidates for UCL and fiber materials.

The tin dioxide (SnO2) nanocrystals were synthesized by direct precipitation method and a series of SnO2 samples were obtained via calcining SnO2 at different temperatures. The characteristics of SnO2 samples were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), Brunauer Emmett Teller (BET), photoluminescence spectroscopy (PL), and UV–vis diffuse reflectance spectroscopy (DRS). The effects of calcination temperatures and additives on the photodegradation of methylene blue (MB) on SnO2 samples under UV-light irradiation have been researched. The results showed that the SnO2 sample with low temperature-treated (T≤200 °C) exhibits the highest degradation efficiency, while with increasing temperature-treated (from 400 °C to 1000 °C) SnO2 samples show decreasing degradation activities. The additives, such as methanol, sodium fluoride, Fe(III), Ag+, and terephthalic acid showed different influences on MB degradation in UV/SnO2 systems. It has been demonstrated that in SnO2-MB systems both hydroxy radicals (OH) generated on the surface of SnO2 and photogenerated holes (h+vb) in the valence band (VB) of SnO2 jointly control the photo-oxidation process of MB. In SnO2 system with increasing temperature-treated (T≥400 °C) the contribution of OH to MB degradation gradually decreased due to the diminution of surface-bonding hydroxyl groups (–OH) and chemisorbed water (H2O) molecules on the surface of SnO2, by comparison, the contribution of h+vb increased. The effects of Ag+ and Fe(III) species on MB degradation and the formation of OH were investigated in detail and the mechanisms have been discussed. The presence of Ag+ ion at low concentration promotes the degradation of MB by capturing the photogenerated electrons (ecb−) on the surface of SnO2 catalyst, suppressing the recombination of photogenerated electrons and holes. The presence of Ag+ ion at high concentration observably reduces the degradation in catalyst system which the photodegradation process is controlled by OH, conversely, it intensively promotes the degradation in which the photodegradation process is controlled by h+vb. The effects of Fe(III) species on the degradation are similar to those of Ag+ ions.

The Dy3+ single doped calcium aluminoborate glass (CaO–Al2O3–B2O3–Dy2O3) was synthesized by melt quenching method and the photoluminescence properties of Dy3+ were studied. Under UV-light excitation the CaO–Al2O3–B2O3–Dy2O3 glass shows a yellowish white light emission and the optimum content of Dy3+ in glass is found at 0.022 mol. For getting pure white light emission, the Dy3+/Eu3+ co-doped glasses with the compositions of Ca0.978−yAlB:Dy3+0.022, Euy3+ (y = 0–0.0938 mol) have been synthesized and the chromatic coordinates were calculated from their emission spectra. The results showed that the white light has been achieved by exciting Dy3+/Eu3+ co-doped glass with ultraviolet or blue light. The energy transfer phenomenon between Dy3+ and Eu3+ ions was validated in Dy3+/Eu3+ co-doped glasses and the decay rates for 4F9/2 level of Dy3+ ions have been measured. The energy transfer probabilities (Pda) are linear with acceptor (Eu3+) contents in the range of 0–0.0563 mol, confirming the fact that the dipole–dipole interaction is responsible for the energy transfer (ET) process of Dy3+ → Eu3+.Highlights► A new Dy3+/Eu3+ co-doped calcium aluminoborate glass was synthesized. ► The luminescences and chromatic coordinates of glasses were investigated. ► White light emission is achieved by excited Dy3+/Eu3+ co-doped glass with UV light. ► The energy transfer between Dy3+ and Eu3+ was validated. ► The electric dipole–dipole interaction is responsible for the ET process of Dy3+ → Eu3+.

The Eu3 +/Tb3 +/Tm3 + triply-doped glasses with the composition of CaO―Al2O3―B2O3―RE2O3 (RE = Eu,Tb,Tm) have been synthesized by melt quenching method. The photoluminescence of these Eu3 +/Tb3 +/Tm3 + triply-doped glasses (CaAlB:RE3 +) were studied and the emission spectra combining with blue, green and reddish orange bands were observed. Under 360 nm wavelength excitation the white light emission is achieved when the concentration (x) of Tm3 + in Ca0.931 −xAlB:Eu3 +0.038,Tb3 +0.031,Tm3 +x glass is in the range of 0.0013-0.011 per mol matrix. In addition, the energy transfer (ET) between Tb3 + and Eu3 + ions in Eu3 +/Tb3 +/Tm3 + triply-doped glasses was validated and the electric dipole–dipole interaction is responsible for the ET process of Tb3 + → Eu3 + at low concentrations. Hence, the Eu3 +/Tb3 +/Tm3 + triply-doped aluminoborate glass could be a potential candidate for white LEDs.Highlights► A new Eu3 +/Tb3 +/Tm3 + triply-doped calcium aluminoborate glass was fabricated. ► The luminescences of the series of full-color emitting glasses were investigated. ► The white light emission is achieved in Eu3 +/Tb3 +/Tm3 + triply-doped glass. ► The energy transfer process of Tb3 + → Eu3 + was confirmed. ► The electric dipole–dipole interaction is responsible for the ET process.