Papers by Keyword: Mn²⁺

Abstract: Flame atomic absorption spectrometry (FAAS) can determinate the contention of Zn²⁺ in water samples rapidly. Choosing 2 - (5 - bromo-2-pyridylazo) -5 - diethylaminophenol (5-Br-PADAP) as a precipitating agent, Mn^{2 +} as the carrier ion to separate and enrich Zn²⁺ in water samples. And studies show that the selected system is affected by acidity, the amount of precipitant concentration, carrier usage and aging time factors. The detection limit is 0.117μg/L.Keywords 5-Br-PADAP、Mn²⁺、FAAS、Separation and enrichment、Zn²⁺

Abstract: The sunlight-excited red long afterglow phosphor ZnGa₂O₄:Cr³⁺ was prepared by the high-temperature solid state reaction. The emission lines around 690nm all originated from ²E→⁴A₂ of Cr³⁺ ions. The long-lasting phosphorescence (LLP) spectra indicated optimal long-lasting luminescence could obtain from ultraviolet (UV) light excitation. The thermoluminescence (TL) curve implied different depth of trap was caused by the dopant ions. The initial persistent luminescence was caused by the recombination between the captured electrons and Cr³⁺ ions, and this recombination process was accomplished through the conduction band. The linear dependence of the long afterglow intensity versus time in the decay curve maybe implied a new recombination mechanism.

Abstract: Ba_0.55Sr_0.4Ca_0.05TiO₃-MgO (BSCTM) with Mn²⁺ additive composite ceramics were prepared by the conventional solid state method with BaCO₃, SrCO₃, CaCO₃, MgO and MnCO₃ as raw materials and B₂O₃ and Li₂CO₃ as sintering agent. The influence of the MnCO₃ additive on the sinterability and dielectric properties of BSCTM composite ceramics are investigated. The morphologies were analysized by scanning electron microscopy (SEM). The dielectric constant and dielectric loss of ceramics were measured by LCR meter at 1 kHz and 1 MHz. The temperature dependences of dielectric constant were measured by high-low temperature incubator tank and LCR meter at 1 MHz and a temperature range from-55 to 125 °C. The dielectric tunabilities were tested by C-T-V converter and LCR meter at 1 MHz and room temperature (25 °C). SEM results showed that BSCTM ceramics became more compact with the increase of Mn²⁺ content, because Mn²⁺ helped to form more oxygen vacancies for accelerating densification process. The addition of Mn²⁺ largely reduced the dielectric loss while had little effect on dielectric constant. The dielectric constant and dielectric loss of 0.5mol% Mn²⁺ doped BSCTM ceramics were 222 and 0.001, respectively. The dielectric tunability increased at first and then decreased with the increase of Mn²⁺ content. The tunability of 0.5mol% Mn²⁺ doped BSCTM ceramics were 4.04% under a DC electric field of 8.2 kV/cm.

Abstract: High temperature solid state reaction has been used to prepare Zn₃(PO₄)₂: Mn²⁺. XRD analysis shows that different phases have been generated with different Mn²⁺ doping concentration at the same sintering temperature. Low Mn²⁺ doping concentration is conducive to form α phase, while γ is in favor of high Mn²⁺ doping concentration. In α phase, the emission spectrum of Mn²⁺ is a wide emission band peaking at 542 nm, green fluorescence. In γ phase, the emission spectrum of Mn²⁺ is a wide emission band peaking at 608 nm, red fluorescence. In the both phases, green and red afterglows have been observed. The red afterglow in γ phase has stronger initial brightness and longer afterglow decay time than the green afterglow in α phase, the reason of which lies in the larger trap concentration in γ phase.

Abstract: A new deep red-emitting Mn2+-activated SrLaGa3S6O phosphor was first prepared by a solid-state reaction method. Their luminescence properties were investigated by photoluminescence excitation and emission spectra. The emission spectrum shows a broad band with an emission maximum at 668 nm under the host excitation of 340 nm. The full width at half maximum (FWHM) of the emission peak is about 83 nm. The CIE chromaticity coordinates (x = 0.673 and y = 0.312) shows that the phosphor emission is in the deep red region and were very near to the NTSC standard values for red. Since the excitation band of the phosphor lies in the near UV excitable region, giving a deep red emission, it can be used for applications in near UV phosphor converted white LED lighting and display devices.

Abstract: Aluminium and hafnium oxide films doped with CeCl₃/TbCl₃/MnCl₂ were deposited at 300 °C by ultrasonic spray pyrolysis. The films analysed by X-Ray diffraction exhibit a very broad band typical of amorphous materials. Non-radiative energy transfer from Ce³⁺ to Tb³⁺ and Mn²⁺ is observed upon UV excitation at 280 nm (peak emission wavelength of AlGaN-based LEDs). Such energy transfer gives place to a simultaneous emission of the donor and acceptor ions in the blue, green, yellow and red regions, resulting in cold white light emission, with chromaticity coordinates and colour temperatures: (0.30,0.32) and 7300 K (AOCTM film), and (0.32,0.37) and 6400 K (HOCTM film). Thus, this type of thin films might contribute to the development of efficient AlGaN-based LEDs pumped phosphors for cold white light generation.

Abstract: In this letter, γ-Zn₃(PO₄)₂: Mn²⁺ phosphors have only one emission band centered at 620 nm while two emission bands are observed in γ-Zn₃(PO₄)₂: Mn²⁺, Ga³⁺, which are respectively centered at 507 nm and 620 nm. The spectral overlap between the green emission band and the excitation band monitored at 620 nm, which supports the occurrence of the energy transfer from Mn²⁺ (CN=4) to Mn²⁺ (CN=6), has been studied. The influence of Ga3+ ions on luminescence and long lasting phosphorescence properties of Mn²⁺ in phosphor γ-Zn₃(PO₄)₂: Mn²⁺, Ga³⁺ are also investigated. It is found that the green/red phosphorescence performance of Mn²⁺ ion such as brightness and duration is largely improved when Ga³⁺ ion is co-doped into the matrix in which Mn²⁺ ion acts as luminescent center and Ga³⁺ ion plays an important role of electron trap.

Abstract: By experiments, separate and purify efficient sulfate—reducing bacteria (SRB), which is identified as Desulfobacter. With its treatment of acid mine drainage(AMD) containing Fe²⁺ and Mn²⁺, obtain the optimum conditions that pH=6,temperature=37,vibrating intensity=100r/min, COD/SO₄^2- =2.Under this condition ,the removal rate of SO₄^2-、Fe²⁺ and Mn²⁺ is 88.16%、99.37% and 59.18% respectively with the initial concentration 1411mg/L for SO₄^2-,257mg/L for Fe²⁺ and 325mg/L for Mn²⁺.This puts a theoretical foundation for the further study.

Abstract: In this paper, Ba₃MgSi₂O₈: Eu²⁺, Mn²⁺ phosphor was synthesized by the sol-gel method and high temperature solid-state reaction method. The structure and emission spectrum excited by near violet light were investigated. we studied the process of phase change in roasting and determined the approximate crystallization temperature of Ba₃MgSi₂O₈: Eu²⁺, Mn²⁺ phosphors. Our results demonstrate that 514 nm emission bands were from Eu²⁺ ions replacing of the sites of Ba²⁺ in Ba₂SiO₄. 440 nm emission bands originated from Eu2+ ions substituting the sites of Ba²⁺ in Ba₃MgSi₂O₈, corresponded to 4f⁶5d¹→4f⁷ transition of Eu2+ ions. 615 nm emission bands ascribed to Mn2+ ions taking place of the sites of Mg²⁺ ions, corresponded to 4T→6A red launch of Mn²⁺ ions.

Abstract: A new afterglow green phosphor of Zn₂SiO₄: Mn²⁺, Zr⁴⁺ was prepared by high temperature solid-state method. Effects of various preparation techniques on the crystal characteristics, luminescent properties and afterglow performance have been investigated systematically. The phosphor powders were further investigated by photoluminescence excitation and emission spectra (PL) and brightness meter. The results showed that the PL of Zn₂SiO₄: Mn²⁺, Zr⁴⁺ was observed in the green region due to transitions from the ⁴T_1g(G) to the ⁵A_1g(S) configuration of the Mn²⁺ ions. This phosphor showed obvious long-lasting phosphorescence that could be clearly seen with naked eyes in a dark room for more than 2h after the irradiation source has been removed. The possible mechanism of this phosphor was also investigated based on the TL measurements.