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The vanadate-sillenite Bi 25 VO 40 nanoparticles were prepared through the facile Pechini method. The average size is about 70 nm. The sample was investigated by X-ray powder diffraction (XRD) and the structural refinement. The surface properties of the nanoparticles were investigated by the measurements such as the transmission electron microscopy (TEM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopic (XPS) and Brunauer–Emmett–Teller (BET) measurements. The nanoparticles have indirect allowed electronic transition and a narrow band gap of 2.31 eV. The photocatalysis was detected by the photodegradation of methylene blue (MB) solutions under the irradiation of visible-light. Hybridization of the 6s and 6p orbitals of Bi 3 + and the resulting lone electron pair yield interesting properties. The photocatalytic activity was discussed on the base of the structural characteristics such as the strong polarizing fields, rich oxygen ion vacancies, and high structure openness degree of the lattice. Bi 25 VO 40 nanoparticles could be potential in the application as a photocatalyst under visible light.

Eu 3+ -doped perovskite-related tungstate Ba 4 Na 2 W 2 O 11 was synthesized by high-temperature solid state reaction. The red-emitting phosphor was characterized by X-ray powder diffraction, structural refinement, and scanning electron microscope and photoluminescence excitation and emission measurements. The optimal doping concentration of Ba 4 Na 2 W 2 O 11 :Eu 3+ is about 7 mol%. This phosphor can be efficiently excited by near-ultraviolet and blue light to realize the stronger red luminescence than the Y 2 O 2 S:Eu 3+ phosphor. The phosphor presents the dominated 5 D 0 → 7 F 1 transition at a low doping level, and the 5 D 0 → 7 F 2 transition becomes the strongest one in the Eu 3+ -heavily doped samples. The doping induces the luminescence color changing from reddish-orange to pure red. The photoluminescence properties of the phosphor are discussed on the base of the crystal structure.

A new red-emitting phosphor of Eu 3+ -doped Na 3 La 8 V 3 O 21 was successfully synthesized by the high-temperature solid state reaction. The phase formation was confirmed by X-ray powder diffraction (XRD) analysis. The morphology of the phosphor was analyzed by scanning electron microscopy (SEM). The optimal doping concentration of Na 3 La 8 V 3 O 21 :Eu 3+ is about 20 mol%. The detailed luminescence properties, e.g., the excitation spectra, the luminescence spectra and quantum efficiency under the excitation of near-UV, and decay lifetimes were reported. The phosphors can be efficiently excited by near-ultraviolet light and exhibit a bright red luminescence around 618 nm ascribed to the forced electric dipole transition 5 D 0 → 7 F 2 of Eu 3+ ions. The thermal stabilities and the absolute luminescence quantum efficiency (QE) were reported. The phosphors of Eu 3+ -activated Na 3 La 8 V 3 O 21 have been discussed as a candidate for white solid state lighting indicating.

Aurivillius-type photocatalyst of Bi4V2O11 nanoparticles with an average particle size of 45 nm was prepared by the modified Pechini method. The sample was investigated by X-ray powder diffraction (XRD) and the structural refinement. The nanoparticles were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopic (XPS) and UV–vis absorption spectrum. Bi4V2O11 nanoparticles show an efficient absorption in the UV–vis light wavelength region with a narrowed band gap energy of 2.08 eV and an indirect allowed electronic transition. The photocatalytic activities of Bi4V2O11 nanoparticles were evaluated by photodegradation of methylene blue (MB) under visible-light irradiation in air atmosphere. These results indicate that Bi4V2O11 could be a potential photocatalyst driven by visible-light. Hybridization of the 6s and 6p orbitals of Bi3+ and the resulting lone electron pair yields interesting properties. The effective photocatalytic activity was discussed on the base of the crystal structure characteristic such as polar (VO3.5□0.5)2− anionic groups, Aurivillius-type (Bi2O2)2+ layers and long distance of the nearest V–V in the lattices, etc.

Nanosized particles of strontium bismuth vanadate SrBi3VO8 were prepared via the Pechini method on the base of citrate-complexation route. The samples were characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectra (EDX), X-ray photoelectron spectroscopic (XPS), and UV–vis absorption spectrum. This bismuth-containing vanadate presents an efficient absorption in the UV–visible light wavelength region with a narrow band-gap energy of 2.36 eV and an indirect allowed electronic transition. It is well-known that hybridization of the 6s and 6p orbitals of Bi3+ could result in lone electron pair and yield some very interesting properties. The photocatalytic activities of SrBi3VO8 nanoparticles were evaluated by the photodegradation of methylene blue (MB) under visible light irradiation in air atmosphere. These results indicate that SrBi3VO8 could be a potential photocatalyst driven by visible light. To understand the charge generation and separation process, the luminescence as well as the decay lifetimes was investigated in the same samples for photocatalysis.

Polycrystalline Cs5V3O10 micro-particles were synthesized by a solid-state reaction. The vanadate shows intrinsic self-activated luminescence of a single broad band with a peak at 520 nm, extending from about 400 nm to 720 nm. This asymmetric band is composed of two bands due to the electronic transitions from the 3T1 and 3T2 excited states to the 1A1 ground state in [VO4]3− centers. The same emission band was obtained for micro- and nanoparticles. It is suggested that the broadening of the emission band arises from single [VO4]3− molecules. The emission and decay curve profiles indicate that the emission is not due to different kinds of [VO4]3− centers but only one kind of [VO4]3− center. When the temperature is increased from 10 K to 450 K, the emission intensity increases below 150 K and decreases above 150 K, and an unusual blue shift is observed. The observed temperature dependence can be understood by the relaxation processes of the emitting 3T1 and 3T2 states including the thermal feeding by the lower-energy 3T1 state to the higher-energy 3T2 state.

A self-activated yellow-emitting phosphor of nano-sized Cs 5 V 3 O 10 was synthesized by the Pechini method. The crystal phase and structure were investigated by X-ray diffraction (XRD) and structural refinement. The nanoparticles were characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopic (XPS) measurements. Luminescence properties such as excitation and emission spectra as well as the absolute external quantum efficiency ( η ) are presented. Cs 5 V 3 O 10 is efficiently excited by UV light and X-ray and presents a bright yellow luminescence with the maximum η of 85.2%. It is suggested that Cs 5 V 3 O 10 is expected to be an efficient phosphor for lighting and display.

La(Ni0.75W0.25)O3 perovskite oxide was prepared via the sol–gel Pechini route. The pure crystalline phase was verified via X-ray diffraction measurements and Rietveld structure refinements. Some measurements were applied to characterize the surface of the nanoparticles such as transmission electron microscopy, scanning electron microscope, energy-dispersive X-ray spectroscopy, specific surface area, and X-ray photo-electron spectroscopy measurements. The optical measurement confirmed that this perovskite oxide can absorb the visible light presenting low band energy of 2.41 eV. The d–d allowed transitions in Ni2+-O octahedral have great contributions to the narrow band-gap. The Ni2+-containing perovskite was applied as a photocatalyst showing the desirable photodegradation ability for methylene blue solutions under the excitation of visible-light. The photocatalysis activities were discussed in the relationship with its special perovskite-type structure such as the NiO6 color centers and multivalent cation ions etc.

Ca2B2O5:RE (RE = Eu3+, Tb3+, Dy3+) nanofibers were synthesized by the hydrothermal reaction method. The structural refinement was conducted on the base of the X-ray powder diffraction (XRD) measurements. The surface properties of the Ca2B2O5:RE (RE = Eu3+, Tb3+, Dy3+) nanofibers were investigated by the measurements such as the scanning electron microscope (SEM), transmission electron microscope (TEM), and the energy dispersive spectrum (EDS). The nanofiber has a diameter of about 100 nm and a length of several micrometers. The luminescence properties such as photoluminescence excitation (PLE) and emission spectra (PL), decay lifetime, color coordinates, and the absolute internal quantum efficiency (QE) were reported. Ca2B2O5:Eu3+ nanofibers show the red luminescence with CIE coordinates of (x = 0.41, y = 0.51) and the luminescence lifetime of 0.63 ms. The luminescence of Ca2B2O5:Tb3+ nanofibers is green color (x = 0.29, y = 0.53) with the lifetime of 2.13 ms. However, Dy3+-doped Ca2B2O5 nanofibers present a single-phase white-color phosphor with the fluorescence decay of 3.05 ms. Upon near-UV excitation, the absolute quantum efficiency is measured to be 65, 35, and 37 % for Eu3+-, Tb3+-, Dy3+-doped Ca2B2O5 nanofibers, respectively. It is suggested that Ca2B2O5:RE (RE = Eu3+, Tb3+, Dy3+) nanofibers could be an efficient phosphor for lighting and display.

A visible-light-driven photocatalyst of Bi 7 VO 13 nanoparticles was prepared by the Pechini method. The nanoparticles were characterized with the measurements such as X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and UV–vis absorption spectrum. Bi 7 VO 13 presents the indirect allowed electronic transition with narrow band gap energy of 2.13 eV. The photocatalyst shows an excellent activity on the photo-degradation of methylene blue (MB) under visible-light irradiation. The photocatalysis was discussed on the base of the structure characteristics such as (Bi 2 O 2 ) 2+ layers connected by the isolated VO 4 groups and the good conductivity. This vanadate could be a potential photocatalyst.

A Ni2+-containing vanadate, K2Ni(VO3)4 was developed as a new visible-light-driven photocatalyst. The nanoparticles were prepared by the modified Pechini method. The sample was characterized by the measurements such as X-ray powder diffraction, scanning electron microscope, and UV–Vis absorption spectrum. The photocatalytic activity of K2Ni(VO3)4 nanoparticles was evaluated by the photodegradation of methylene blue under visible-light irradiation in air. K2Ni(VO3)4 shows a photocatalytic activity due to the efficient absorption in the UV–Visible-light wavelength region with a narrowed band-gap energy of 2.08 eV and an indirectly allowed electronic transition. These results indicate that this vanadate garnet could be a potential photocatalyst driven by visible light. The effective photocatalytic activity was discussed on the basis of the special structural characteristic such as heavily distorted NiO6, rich, activated optical centers with tunnel structure for high photocatalytic capacity, and discussed on the basis of the photoluminescence and the decay lifetime.

Bi8V2O17 (4Bi2O3·V2O5) nanoparticles with the uniform size of about 50 nm were fabricated through the Pechini method. The crystal structure was investigated by X-ray powder diffraction and the structural refinement. The surface of the as-synthesized samples was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy, and X-ray photoelectron spectroscopy. The optical properties, band structure, and the degradation mechanisms were discussed. The experimental results demonstrate that Bi8V2O17 nanoparticles have an efficient visible-light absorption with band-gap energy of 1.85 eV and a direct allowed electronic transition. The photocatalytic activity was evaluated by the photodegradation of the methylene blue (MB) under visible-light irradiation (λ > 420 nm) as a function of time. These results indicate that Bi8V2O17 could be a potential photocatalyst driven by visible light. The effective photocatalytic activity was discussed on the base of the crystal structure characteristic.

A novel calcium silicate borate Ca11Si4B2O22 ceramic was firstly prepared by the conventional solid-state reaction. In vitro hydroxyapatite mineralization was investigated by soaking the ceramics in simulated body fluid (SBF) solutions at body temperature (37 °C) for various time periods. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) measurements were applied to investigate the samples before and after the immersion of ceramics in SBF solution. The elemental compositions of a hydroxyapatite layer on the ceramics during the mineralization were confirmed by X-ray energy-dispersive spectra (EDS). Meanwhile, the bending strength and elastic modulus of Ca11Si4B2O22 ceramics were also measured, which indicate that the biomaterials based on Ca11Si4B2O22 ceramics possess bioactivity and might be a potential candidate as biomaterials for hard tissue repair. The bioactive mineralization ability was evaluated on the base of its crystal structural characteristics, i.e., silanol (Si-OH) and B-OH groups can be easily induced on the surface of Ca11Si4B2O22 ceramics soaked in SBF solutions.