Host-sensitized phosphorescence of Mn4+, Eu3+, and Yb3+ in MgAl2Si2O8

Mn4+ doped and Eu3+, Yb3+ co-doped MgAl2 Si2O8-based phosphors were prepared by conventional solid state reaction at 1,300 C. They were characterized by thermogravimetry, differential thermal analysis, X-ray powder diffraction, photoluminescence, and scanning electron microscopy. The luminescence mechanism of the phosphors, which showed broad red emission bands in the range of 600–715 nm and had a different maximum intensity when activated by UV illumination, was discussed. Such a red emission can be attributed to the intrinsic 2E + 4A2 transitions of Mn4+

Oxide ionic conductivity properties of binary δ-(Bi2O3)1 - x (Yb2O3) x system

In this study, after doping ytterbium oxide (Yb2O3) to a-bismuth trioxide (a-Bi2O3) in the range of 9% n 20% in a series of different mole ratios, heat treatment was performed by applying a cascade temperature rise in the range of 700–790 C for 48 hours and new phases were obtained in the (Bi2O3)1 x(Yb2O3)x system. After 24 hours of heat treatment at 700 C and 750 C and 48 hours of heat treatment at 790 C, mixtures containing 9–20 mol% Yb2O3 formed a face-centered cubic phase. With the help of X-ray diffraction (XRD), the crystal systems and lattice parameters of the solid solutions were obtained and their characterization was carried out. The surfaces of the solid solutions were detected by a scanning electron microscope (SEM). Thermal measurements were made by using a simultaneous DTA/TGA (differential thermal analysis/thermogravimetric analysis) system. The total conductivity (sT) in the d-Bi2O3 doped with Yb2O3 system was measured using the four-probe DC method

Sythesis and investigation photoluminescence properties of La1.90Eu0.10Ru2O7 system

A2B2O7 tipindeki La1.90Eu0.10Ru2O7 sistemi yüksek sıcaklık katı hal yöntemlerinden seramik metot ile sentezlendi. Malzemenin sentez sıcaklığının belirlenmesi ve termal davranışlarının incelenmesi amacıyla termogravimetridiferansiyel termal analiz (TG/DTA) sistemi kullanıldı ve belirlenen sıcaklıklarda kül/tüp fırınında reaksiyon gerçekleştirildi. Malzemenin kristal yapısı x-ışınları toz kırınım difraktometresiyle (XRD) kontrol edildi, yüzey morfolojisi ve elementel analizi taramalı elektron mikroskop (SEM) ile yapıldı. Fotoluminesans özelliklerolan ışıma ve uyarma dalga boyu ile ışıma süresi fotoluminesans spektrofotometre (PL) ile belirlendi.A2B2O7 type La1.90Eu0.10Ru2O7 system was synthesized via ceramic method which is one of the high temperature solid-state reaction methods. To determine the materials sintering temperatures and investigate thermal properties, thermogravimetric and differential thermal analysis (TG/DTA) system were used and the reaction was done in furnace/tube furnace. The crystal structure of material was checked by x-rays powder diffractometer (XRD) and the surface morphology and elemental analysis were carried out with a scanningelectron microscope (SEM). Photoluminescence properties, the decay time, excitation and emission wavelengths were defined with photoluminescence spectrophotometer (PL)

Synthesis, characterization, photoluminescence and piezoelectric study of dy(1.98)Yb(0.02)Ti(2)O(7)and Lu1.98Er0.02Ti2O7

WOS:000549799500001Dy(1.98)Yb(0.02)Ti(2)O(7)and Lu(1.98)Er(0.02)Ti(2)O(7)with the cubic pyrochlore structure were prepared at 1050 degrees C and 1400 degrees C using solid state reaction method. The crystal structure and unit cell parameters of powder samples were determined by X-ray diffraction method (XRD). Using TG/DTA thermal analysis, we determined the thermal behaviours of starting materials and Curie temperature of fine samples. Dy(1.98)Yb(0.02)Ti(2)O(7)and Lu(1.98)Er(0.02)Ti(2)O(7)have high Curie temperature at 770 degrees C and 765 degrees C, respectively. To determine morphological structure, elemental composition, photoluminescence properties, dielectric constant, loss tangent, and piezoelectric charge constant of Dy(1.98)Yb(0.02)Ti(2)O(7)and Lu1.98Er0.02Ti2O7, scanning electron microscope (SEM), photoluminescence spectrophotometer (PL), LCR-meter and d(33-)meter were used. The results show that Dy(1.98)Yb(0.02)Ti(2)O(7)and Lu(1.98)Er(0.02)Ti(2)O(7)are multifunctional materials which show both photoluminescence properties and piezoelectric properties.The authors would like to thank to TUBITAK (The Scientific and Technological Research Council of Turkey) for the support to the project numbered 114Z438

Photoluminescence properties of Eu3+-activated silicate phosphors

WOS:000406089800010The silicate-type and Eu3+-activated Sr3SiO5 and Mg3SiO5 were prepared through the high temperature solid state reaction method under an open atmosphere. DTA/TG analysis was conducted to obtain information about the thermal behaviors of the mixed reactants. Using the DTA/TG results, the sintering process was achieved and the phase properties were characterized by X-ray diffraction (XRD). The effects of the same activator (Eu3+) and co-dopant (Dy3+) on the photoluminescence (PL) properties of the host lattices were investigated by using a photoluminescence spectrometer.Karamanoglu Mehmetbey University's, Scientific Research Projects Commission (BAP), Republic of Turkey [06-YL-14]The authors would like thank to Karamanoglu Mehmetbey University's, Scientific Research Projects Commission (BAP), 06-YL-14 project number in the, Republic of Turkey for their financial support

Investigations of M3Al8O15:Eu3+,Dy3+ (M = Ba, Ca, Mg) phosphors

WOS:000381049100026In this work, aluminate type phosphorescence materials were synthesized via the solid state reaction method and the photoluminescence (PL) properties, including excitation and emission bands, were investigated considering the effect of trace amounts of activator (Eu3+) and co-activator (Dy3+). The estimated thermal behavior of the samples at certain temperatures (> 1000 degrees C) during heat treatment was characterized by differential thermal analysis (DTA) and thermogravimetry (TG). The possible phase formation was characterized by X-ray diffraction (XRD). The morphological characterization of the samples was performed by scanning electron microscopy (SEM). The PL analysis of three samples showed maximum emission bands at around 610 nm, and additionally near 589 nm, 648 nm and 695 nm. The bands were attributed to typical transitions of the Eu3+ ions.Karamanoglu Mehmetbey University's Scientific Research Projects Commission (BAP), Republic of Turkey [05-YL-12]The author would like to thank to the Karamanoglu Mehmetbey University's Scientific Research Projects Commission (BAP), under the Project Number 05-YL-12, Republic of Turkey, for its financial support

Eu3+- and Ho3+-doped Ba3Al2O6- and MgAl2O4-type phosphors and their photoluminescent properties

WOS:000425965400022The aluminate hosts were basically activated with the Eu3+- and Ho3+-ions which were prepared by solid-state reaction in this study. The DTA/TG results were used as a reference for the heat treatments of the samples. The Ba3Al2O6:Eu3+, Ho3+ phosphor was well indexed to the expected phase, and MgAl2O4:Eu3+, Ho3+ could not be indexed as single phase by powder X-ray diffraction analysis to the any major phase in spite of repeated and increased heat treatments for this system. Thus, MgAl2O4 and MgO impurities were obtained. Noteworthy photoluminescent results were obtained since the transitions of Eu3+-ions occurred for both of the samples.Karamanoglu Mehmetbey University's Scientific Research Projects Commission (BAP) in the Republic of Turkey [17-M-14]The authors kindly thank Karamanoglu Mehmetbey University's Scientific Research Projects Commission (BAP, project number: 17-M-14), in the Republic of Turkey for its financial support

The investigation of the photoluminescent and piezoelectric effect of Eu3+ Check doped Y2Ti2O7 and Sm2Ti2O7 host crystals

WOS:000503099500094Y1.98Eu0.02Ti2O7 and Sm1.98Eu0.02Ti2O7 with a cubic pyrochlore-type structure were synthesized from stoichiometric mixtures of the constituent oxides using a solid solution reaction method at 1400 degrees C in an open atmosphere. Their crystal structures and lattice constants were determined by X-ray powder diffractometry. To determine the thermal behaviour of the mixtures of the starting materials, differential thermal analysis (DTA) and thermogravimetric (TG) analysis were used. The surface morphology and EDX analysis of the samples were investigated using a scanning electron microscope (SEM). The photoluminescence properties were measured and the red emission was observed from Y1.98Eu0.02Ti2O7 and Sm1.98Eu0.02Ti2O7 phosphors. Both materials show the typical emission bands of Eu 3- ions. The emission spectra of the Y1.98Eu0.02Ti2O7 and Sm1.98Eu0.02Ti2O7 phosphors consist of several intense peaks in the red spectral range, which correspond to the characteristic transitions of Eu3+ from D-5(0) to F-7(J) (J = 2, 3, 4). When Eu3+ ions are doped to Sm2Ti2O7 host crystal, the life time prolongs 800 times compared with Y2Ti2O7 host crystal and the luminescent intensity was remarkably improved by the incorporation of Eu3+ and Y2Ti2O7 host microcrystal. Also, the dielectric constant, loss tangent, piezoelectric charge constant and Curie temperature were investigated by LCR-meter, d(33)-m and TG/DTA, respectively. Y1.98Eu0.02Ti2O7 has the bigger piezoelectric charge constant and Sm1.98Eu0.02Ti2O7 (1561 degrees C) has a higher Curie temperature than Y1.98Eu0.02Ti2O7 (1449 degrees C)

The effect of Eu3+-doping on the photoluminescent properties of REInO3 (RE = Er, Sm) type phosphors

WOS:000600971900002The Eu3+ activated REInO3 (RE = rare-earth) hosts were composed by the solid state reaction (or ceramic) method. The stoichiometrically calculated phosphor batches were examined by Differantial Thermal Analysis (DTA) and Thermogravimetry (TG) to acquire their thermal behaviors between 50 degrees C - 1300 degrees C. The heat treatments were quite long process and needed high temperatures which were at 1000 degrees C for 10 h and 1500 degrees C for 12 h. The phase formation of samples were determined by powder X-ray diffraction (XRD) analysis, thus both of samples had similar patterns with single phases in hexagonal type structure. The phosphors particle morphologies and size distributions were analyzed and measured by scanning electron microscopy (SEM). The size distributions includes shredded and dispersed particles with an average diameter between 0.3 mu m and 4.2 mu m which were directly calculated by the SEM images. The photoluminescence (PL) analysis covering the excitation and emission spectra as well as decay curves (lifetimes) of phosphors were discussed in terms of Eu3+-rare-earth ion doping for both of REInO3 (RE = Er, Sm) type hosts.The authors would like to thank Karamanoglu Mehmetbey University, Scientific Research Projects Commission (BAP, project number: 19-M-18), Republic of Turkey for financial support. The authors are grateful to Prof. Dr. Adil Denizli from Hacettepe University, Department of Chemistry and Biochromatography and Biodiagnostics Research Group for their kind help