Luminescence properties of sodalite-type Zn₄B₆O₁₃:Mn²⁺

Chen, Cuili,Cai, Peiqing,Qin, Lin,Wang, Jing,Bi, Shala,Huang, Yanlin,Seo, Hyo Jin Elsevier 2018 Journal of luminescence Vol.199 No.-

<P><B>Abstract</B></P> <P>Luminescence properties of sodalite Zn<SUB>4</SUB>B<SUB>6</SUB>O<SUB>13</SUB>:Mn<SUP>2+</SUP> are investigated by optical and laser excitation spectroscopy in the temperature range 10 – 300 K. The samples of Zn<SUB>4</SUB>B<SUB>6</SUB>O<SUB>13</SUB>:Mn<SUP>2+</SUP> are prepared in the carbon reducing atmosphere. The green emission at 540 nm are observed in Zn<SUB>4</SUB>B<SUB>6</SUB>O<SUB>13</SUB>:Mn<SUP>2+</SUP> for various Mn<SUP>2+</SUP> concentration. Optimum Mn<SUP>2+</SUP> concentration and critical distances between Mn<SUP>2+</SUP> ions in Zn<SUB>4</SUB>B<SUB>6</SUB>O<SUB>13</SUB> are obtained by the luminescence intensity as functions of Mn<SUP>2+</SUP> concentration. The decays of Mn<SUP>2+</SUP> emission depend strongly on Mn<SUP>2+</SUP> concentration due to the energy transfer and energy diffusion in Zn<SUB>4</SUB>B<SUB>6</SUB>O<SUB>13</SUB>:Mn<SUP>2+</SUP>. The fine structures consisting of the intense zero phonon line (ZPL) and weak vibrational sidebands are observed at low temperature. The relevant mechanism of excitation bands, ZPL, vibrational sidebands and the bandwidth as functions of temperature are interpreted in detail by energy level diagram of the 3d<SUP>5</SUP> transition metal ions and configuration coordinated diagram. The high thermal stability of the Zn<SUB>4</SUB>B<SUB>6</SUB>O<SUB>13</SUB>:Mn<SUP>2+</SUP> phosphor are observed in the temperature range 10–300 K.</P>

Hydrothermal synthesis and upconversion luminescence of Y₂WO₆:Yb³⁺/Er³⁺ crystals

Chen, Cuili,Cai, Peiqing,Qin, Lin,Wang, Jing,Huang, Yanlin,Seo, Hyo Jin Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.747 No.-

<P><B>Abstract</B></P> <P>The Y<SUB>2</SUB>WO<SUB>6</SUB>:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> crystals were synthesized by the hydrothermal method. The needle-shaped morphology is controllably formed and a number of crystals aggregate as spheres by adding the surfactant of sodium dodecylbenzenesulfonate (SDBS) into the reaction system. The crystal structure, morphology and upconversion luminescence properties of the Y<SUB>2</SUB>WO<SUB>6</SUB>:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> crystals are conducted on the basis of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), FTIR and emission spectra. The different emission intensity ratio of the red and green bands is observed for the Y<SUB>2</SUB>WO<SUB>6</SUB>:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> precursors under different heat treatments. The different intensity ratio are illustrated according to the upconversion mechanism.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The needle-shaped Y<SUB>2</SUB>WO<SUB>6</SUB>:Yb<SUP>3+</SUP>/Er<SUP>3+</SUP> crystals were synthesized by the hydrothermal method. </LI> <LI> The morphology was controlled by surfactant SDBS and the relevant mechanism. </LI> <LI> The different emission intensity ratios of the red and green bands were observed due to heat treatments. </LI> <LI> The distinct luminescence performance was illustrated according to the upconversion mechanism. </LI> </UL> </P>

Preparation, characterization and luminescent properties of red-emitting phosphor: LiLa₂NbO₆ doped with Mn⁴⁺ ions

Qin, Lin,Bi, Shala,Cai, Peiqing,Chen, Cuili,Wang, Jing,Kim, Sun Il,Huang, Yanlin,Seo, Hyo Jin Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.755 No.-

<P><B>Abstract</B></P> <P>Series of Mn<SUP>4+</SUP>-activated LiLa<SUB>2</SUB>NbO<SUB>6</SUB> red emitting phosphors were prepared by the solid state method. The structural and luminescence properties are investigated on the basis of X-ray diffraction (XRD), emission and excitation spectra, and luminescence decay curves. The LiLa<SUB>2</SUB>NbO<SUB>6</SUB>:Mn<SUP>4+</SUP> phosphors can be efficiently excited by near-UV to blue light and exhibit bright red emission at around 712 nm, which can be assigned to the <SUP>2</SUP>E<SUB>g</SUB>→<SUP>4</SUP>A<SUB>2g</SUB> transition of the 3 d<SUP>3</SUP> electrons in [MnO<SUB>6</SUB>] octahedra. Temperature dependent emission spectra and decay curves from 10 to 480 K are analyzed to understand the luminescence mechanism of Mn<SUP>4+</SUP> in LiLa<SUB>2</SUB>NbO<SUB>6</SUB> lattice. Notably, such a novel red emitting phosphor shows special anti-thermal quenching behavior.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We provide a comprehensive study of the luminescence mechanism of the Mn<SUP>4+</SUP> ion. </LI> <LI> Sharp emission lines belong to vibrational modes are observed at low temperature. </LI> <LI> The LiLa<SUB>2</SUB>NbO<SUB>6</SUB>:Mn<SUP>4+</SUP> phosphor shows special anti-thermal stability at low temperature. </LI> </UL> </P>

Thermal Quenching and Luminescence Decay in Self-activated La2W3O12

Cheol Woo Park,Peiqing Cai,Cuili Chen,Qin Lin,Cheng Han,Jing Wang,Thi Hang Dang,Thi Quynh Vu,Sun Il Kim,Hyo-Jin Seo 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.3

Lanthanum tritungstates, La2W3O12, were prepared by using a conventional high-temperature solid-state reaction. The formation of a single-phase compound with the monoclinic structure of La2W3O12 was verified through X-ray diffraction (XRD) studies. The luminescence propeities of La2W3O12 were investigated by using optical and laser-excitation spectroscopy. The excitation and the emission spectra and the decay curves were measured in the temperature range 7 − 300 K. The charge-transfer transition of WO2− 4 was identified in the excitation and the emission spectra under excitation by ultraviolet radiation. A strong green luminescence was observed at 500 nm with a bandwidth of 4240 cm−1 at temperatures lower than 60 K; then the thermal quenching occurred with increasing temperature. The thermal quenching behaviors of the luminescence intensity and the decay time could be explanined by using a simple thermal quenching model.

Optical Thermometry Based on Vibration Sidebands in Y₂MgTiO₆:Mn⁴⁺ Double Perovskite

Cai, Peiqing,Qin, Lin,Chen, Cuili,Wang, Jing,Bi, Shala,Kim, Sun Il,Huang, Yanlin,Seo, Hyo Jin American Chemical Society 2018 Inorganic Chemistry Vol.57 No.6

<P>Mn<SUP>4+</SUP>-doped Y<SUB>2</SUB>MgTiO<SUB>6</SUB> phosphors are synthesized by the traditional solid-state method. Powder X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectrometer are employed to characterize the samples. The Mn<SUP>4+</SUP>-doped Y<SUB>2</SUB>MgTiO<SUB>6</SUB> phosphors show the far-red emission at ∼715 nm, which is assigned to the <SUP>2</SUP>E<SUB>g</SUB> → <SUP>4</SUP>A<SUB>2</SUB> spin-forbidden transition of Mn<SUP>4+</SUP>. The temperature-dependent luminescent dynamics of Mn<SUP>4+</SUP> is described by a complete model associated with electron-lattice interaction and spin-orbit coupling. The noncontact optical thermometry of Y<SUB>2</SUB>MgTiO<SUB>6</SUB>:Mn<SUP>4+</SUP> is discussed based on the fluorescence intensity ratio of thermally coupled anti-Stokes and Stokes sidebands of the efficient ∼715 nm far-red emission in the temperature range of 10-513 K. The maximum sensor sensitivity of Y<SUB>2</SUB>MgTiO<SUB>6</SUB>:Mn<SUP>4+</SUP> is determined to be as high as 0.001 42 K<SUP>-1</SUP> at 153 K, which demonstrates potential applications for the optical thermometry at low-temperature environments.</P><P>The vibration sidebands-based Mn<SUP>4+</SUP> doped Y<SUB>2</SUB>MgTiO<SUB>6</SUB> double perovskite was designed for ratiometric optical temperature sensing in the range from 10 to 513 K; the Mn<SUP>4+</SUP> ions can be located at the Ti<SUP>4+</SUP> sites and form MnO<SUB>6</SUB> octahedron with deep red emission under UV excitation. The highest relative temperature sensitivity was obtained as 0.001 42 K<SUP>−1</SUP> at 153 K.</P> [FIG OMISSION]</BR>

Energy Transfer and Luminescence Properties of Dy3+ Ions Doped in La2W3O12 Lattices

Cheol Woo Park,Peiqing Cai,Cuili Chen,Qin Lin,Cheng Han,Jing Wang,Thi Hang Dang,Thi Quynh Vu,Sun Il Kim,Hyo-Jin Seo 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.10

La2W3O12:Dy3+ phosphors were synthesized by using a high-temperature solid-state reaction. The Dy3+ concentration in the La2W3O12 lattice was varied from 0.01 to 100 %. The crystalline phases of the samples were confirmed by using an X-ray diffraction analyses. Emission and excitation spectra and decay curves of Dy3+ ions in the La2W3O12 lattices were measured at room temperature. The two charge-transfer (CT) bands that overlapped in the wavelength region 210 - 320 nm were identified as being due to the CT transitions of O2−-Dy3+ and WO2− 4 . The decay times of the 4F9/2 emission were shortened with increasing Dy3+ concentration, and the decay curves were slightly nonexponential even at low Dy3+ concentration. The decay curves were well fitted by the Inokuti- Harayama model based on the energy-transfer process between two Dy3+ ions at concentrations lower than 10 mol%. On the other hand, the energy diffusion among Dy3+ ions dominate the energy-transfer process at higher Dy3+ concentrations up to 100 mol%.

Luminescence, energy transfer and optical thermometry of a novel narrow red emitting phosphor: Cs₂WO₂F₄:Mn⁴⁺

Cai, Peiqing,Qin, Lin,Chen, Cuili,Wang, Jing,Seo, Hyo Jin The Royal Society of Chemistry 2017 Dalton Transactions Vol.46 No.41

<▼1><P>Novel thermometry based on two coupled vibrational sidebands of Mn<SUP>4+</SUP>.</P></▼1><▼2><P>A novel red emitting Cs2WO2F4:Mn<SUP>4+</SUP> phosphor was successfully synthesized by a two-step wet chemical method. The crystal structure, morphology, and elemental composition were confirmed by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The luminescence properties were investigated from emission, excitation and luminescence decay curves in the temperature region of 10–500 K. The application of non-contact optical thermometry of Cs2WO2F4:Mn<SUP>4+</SUP> based on the fluorescence intensity ratio (FIR) of the two coupled anti-Stokes and Stokes sidebands is discussed. The as-prepared Cs2WO2F4:Mn<SUP>4+</SUP> phosphor shows a bright narrow red emission at 632 nm under excitation by a blue lamp at 470 nm and it also presents a broad and yellow-white intrinsic tungstate emission (∼520 nm) under UV excitation. The mechanism of energy transfer from [WO2F4]<SUP>2−</SUP> (the sensitizer) to Mn<SUP>4+</SUP> (the activator) is discussed.</P></▼2>

Enhanced Visible Light-Driven Photocatalysis by Eu³⁺-Doping in BaNb₂V₂O₁₁ with Layered Mixed-Anion Structure

Qin, Lin,Cai, Peiqing,Chen, Cuili,Cheng, Han,Wang, Jing,Kim, Sun Il,Seo, Hyo Jin American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.24

<P>Europium- (Eu-) doped BaNb(2)V(2)O(11)powders with layered mixed -anion structure were prepared through the solid state method successfully. The obtained powders were characterized using X-ray powder diffraction (XRD), structural refinement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet visible (UV-vis) absorption spectra, and photoluminescence (PL) measurements. The experimental results demonstrate that BaNb2V2O11 powders could absorb the UV-vis light effectively with the band gap energy of 2.219 eV. The introduction of Eu5 in the host contributes to the decrease of the band gap energy (2.137 eV). Moreover, the photocatalytic activities of the obtained powders were evaluated through the photocatalytic degradation of the methylene blue (MB) solutions under visible light irradiation as a function of time. All the results indicate that the BaNb2V2O11 powders can be used as a potential visible -light -driven photo catalyst. Notably, due to the introduction of Eu3+, the photocatalytic degradation rate of MB solutions could be improved dramatically. The influence of the existence of Eu3+ on the photocatalytic properties is further discussed in detail based on the crystal structure characteristic.</P>

Charge transfer transition and energy transfer in Eu³⁺-doped Gd₁₀V₂O₂₀

Cheng, Han,Qin, Lin,Cai, Peiqing,Chen, Cuili,Wang, Jing,Il Kim, Sun,Huang, Yanlin,Seo, Hyo Jin Elsevier 2018 Journal of luminescence Vol.195 No.-

<P><B>Abstract</B></P> <P>Eu<SUP>3+</SUP>-doped Gd<SUB>10(1-<I>x</I>)</SUB>Eu<SUB>10<I>x</I> </SUB>V<SUB>2</SUB>O<SUB>20</SUB> (<I>x</I> = 0 – 1) phosphors were synthesized via the sol-gel process. The formation of a single phase compound was verified through the X-ray diffraction studies. Luminescence properties of Gd<SUB>10</SUB>V<SUB>2</SUB>O<SUB>20</SUB>:Eu<SUP>3+</SUP> are investigated by optical and laser excitation spectroscopy. The emission and excitation spectra, luminescence decays were measured in the temperature region 7–300K. The strong emission due to the vanadate group of Gd<SUB>10</SUB>V<SUB>2</SUB>O<SUB>20</SUB>:Eu<SUP>3+</SUP> is observed at low temperature. The charge transfer transition of Eu<SUP>3+</SUP> depends strongly on the Eu<SUP>3+</SUP>-concentration in Gd<SUB>10</SUB>V<SUB>2</SUB>O<SUB>20</SUB>:Eu<SUP>3+</SUP>. The emission intensity as a function of Eu<SUP>3+</SUP> concentration under excitation of charge transfer band is inconsistent with that of the 4<I>f</I> <SUP>7</SUP> states (the <SUP>5</SUP>L<SUB>6</SUB> state) of Eu<SUP>3+</SUP>. The energy transfer occurs between two Eu<SUP>3+</SUP> ions at low Eu<SUP>3+</SUP> concentration (< 10mol%), while energy diffusion dominates at high Eu<SUP>3+</SUP> concentration.</P>

Optical performance of the Ba₅Al₃F₁₉:Eu²⁺ blue phosphors with high thermal stability

Qin, Lin,Cai, Peiqing,Chen, Cuili,Wang, Jing,Kim, Sun Il,Huang, Yanlin,Seo, Hyo Jin Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.738 No.-

<P><B>Abstract</B></P> <P>Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB>:Eu<SUP>2+</SUP> blue-emitting phosphors were synthesized by the solid state reaction in a reductive atmosphere. The crystal structure of Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB>:Eu<SUP>2+</SUP> phosphors were characterized by using the X-ray powder diffraction (XRD) measurement. The luminescence properties are investigated systematically based on the crystal structure. Emission and excitation spectra of the Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB>:Eu<SUP>2+</SUP> phosphor along with the decay curves were characterized. Under the excitation of UV light, the phosphor exhibits a broad band emission around 410 nm ascribed to the allowed 4<I>f</I> <SUP>6</SUP>5<I>d</I>→4<I>f</I> <SUP>7</SUP>(<SUP>8</SUP>S<SUB>7/2</SUB>) transition, together with a sharp line at 360 nm corresponding to the forbidden 4<I>f</I> <SUP>7</SUP>(<SUP>6</SUP>P<SUB>7/2</SUB>)→4<I>f</I> <SUP>7</SUP>(<SUP>8</SUP>S<SUB>7/2</SUB>) transition of the Eu<SUP>2+</SUP> ions. The temperature dependent emission spectra and decay curves were measured to investigate the origins of the emission and the thermal stabilities of the as-prepared phosphors. The as-prepared Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB>:Eu<SUP>2+</SUP> phosphors display interesting and stable luminescence properties, which can act as promising blue-emitting phosphor candidates.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We developed Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB> fluoride by a simple solid state method. </LI> <LI> The phosphor exhibits a bright broad band emission. </LI> <LI> 4<I>f</I> <SUP>7</SUP>(<SUP>6</SUP>P<SUB>7/2</SUB>)→4<I>f</I> <SUP>7</SUP>(<SUP>8</SUP>S<SUB>7/2</SUB>) transition of the Eu<SUP>2+</SUP> ions can be observed in this system; </LI> <LI> The Ba<SUB>5</SUB>Al<SUB>3</SUB>F<SUB>19</SUB>:Eu<SUP>2+</SUP> phosphor shows excellent thermal stability at high temperature. </LI> </UL> </P>