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Neodymium-doped rare-earth oxycarbonates, Ln2O2CO3: x mol% Nd3+ (Ln = La, Gd, and Y, 0 ≤ x ≤ 5), were synthesized by a simple flux method using a 0.476Li2CO3–0.270Na2CO3–0.254K2CO3 eutectic mixture. The suitability of these oxycarbonates as stable, nontoxic bioimaging phosphors that exhibit near-infrared (NIR) emission under NIR excitation was investigated. Gd2O2CO3: x mol% Nd3+ and Y2O2CO3: x mol% Nd3+ were obtained in single-phase form with a hexagonal type-II structure. The particle sizes of the Gd2O2CO3: x mol% Nd3+ and Y2O2CO3: x mol% Nd3+ were on a submicron scale suitable for bioimaging, but that of La2O2CO3: x mol% Nd3+ was outside the suitable range for bioimaging. Gd2O2CO3: x mol% Nd3+ and Y2O2CO3: x mol% Nd3+ showed characteristic emissions corresponding to the f–f transitions of Nd3+. The strongest emission peak was observed at around 1064 nm under excitation at 823 nm in the samples containing 2 mol% of Nd3+. The emission intensity of Gd2O2CO3: 2 mol% Nd3+ was 1.25 times higher than that of Y2O2CO3: 2 mol% Nd3+. The emission intensity of both phosphors was also significantly higher than that of the indocyanine green in practical use as a bio-imaging reagent. [ABSTRACT FROM AUTHOR]

C-type cubic Y 2 O 3 –Pr 6 O 11 –Eu 2 O 3 solid solutions were synthesized by a co-precipitation method and their catalytic activities for direct NO decomposition were investigated. Among the catalysts synthesized, the (Y 0.78 Pr 0.15 Eu 0.07 ) 2 O 3± δ catalyst exhibited high NO decomposition activity; NO conversion to N 2 was as high as 84% at 900 °C in the absence of O 2 (NO/He atmosphere). This catalyst also sustained a high level of NO conversion even in the presence of O 2 or CO 2 , compared with those of the conventional perovskite-type catalyst for direct NO decomposition. [ABSTRACT FROM AUTHOR]

Novel green pigments based on (R 1- x R' x ) 2 Cu 2 O 5 (R = Y 3+ , R’ = Sc 3+ , Gd 3+ , Tm 3+ , Yb 3+ , and Lu 3+ ) solid solutions were synthesized and the dopant concentration was optimized. Among the samples, it was found that Su 2 Cu 2 O 5 based samples showed brilliant green hue. In response to the results, Sc 2 (Cu 1− x Zn x ) 2 O 5 (0 ≤ x ≤ 0.1) pigments were further synthesized and their color properties were characterized in an attempt to find a new environmentally friendly pigment that has more sufficient green chromaticity. Among the samples, the most vivid green hue was obtained for Sc 2 (Cu 0.92 Zn 0.08 ) 2 O 5 with a greenness value (− a *) of 41.2 in the CIE L * a * b * system, which was significantly larger than those of commercially available Cr 2 O 3 (− a * = 18.2), CoO∙ZnO (− a * = 25.3), and Co 2 TiO 4 (− a * = 35.2) pigments. Scandium, cupper, and zinc in Sc 2 (Cu 0.92 Zn 0.08 ) 2 O 5 are nontoxic elements; therefore, the pigment should be an effective alternative to the conventional toxic green pigments. [ABSTRACT FROM AUTHOR]

Abstract: A new synthesis route to easily obtain the II-type lanthanum oxycarbonate in a single phase has been developed by using a simple flux method, and photoluminescence properties of Eu3+- or Tb3+-doped La2O2CO3 were characterized. These new phosphors, the II-type La2O2CO3:Eu3+ and La2O2CO3:Tb3+, were synthesized by the calcination with a flux in a flow of 10%CO2–90%N2 gas, where lithium carbonate or a 0.476Li2CO3–0.270Na2CO3–0.254K2CO3 eutectic mixture was employed as the flux. The higher emission intensity was observed by employing the Li2CO3–Na2CO3–K2CO3 eutectic system, which has a considerably lower melting point (663K) than that of Li2CO3 (999K). The red and green emission intensities became maximum at the composition of La2O2CO3:6at.%Eu3+ and La2O2CO3:17at.%Tb3+, and the relative emission intensities compared with the commercial Y2O3:Eu3+ and LaPO4:Ce3+,Tb3+ phosphors were 22.5 and 60.0%, respectively. [Copyright &y& Elsevier]

Abstract: Cubic lanthanum oxide was prepared by the oxidation of lanthanum iodide at 700°C in air atmosphere. The oxide was characterized by X-ray fluorescence analysis, X-ray diffraction, and Fourier-transformed infrared spectroscopy. The cubic La2O3 is most likely a single lanthanum oxide phase containing periodate hydrate and hydroxycarbonate species. The cubic lanthanum oxide is found to be chemically stable even if they are dispersed in water because of the presence of hydroxycarbonate and periodate hydrate species which inhibit the bulk hydroxylation. [Copyright &y& Elsevier]

Abstract: New red emitting phosphors, hexagonal type-II La2O2CO3:Eu3+, Gd2O2CO3:Eu3+, and Y2O2CO3:Eu3+, were synthesized by the simple flux method using the 0.476Li2CO3–0.270Na2CO3–0.254K2CO3 eutectic mixture, and their photoluminescent properties were characterized. The red emission was observed in each sample and their particle sizes were in a submicron scale. The excitation wavelength of their charge transfer bands depended on the difference of the electronegativities of rare earth elements constituting the host lattices. In these phosphors, the highest emission was obtained at the composition of R2O2CO3:7at.%Eu3+ (R=La, Gd, and Y), and the relative emission intensities compared with that of the commercial Y2O3:Eu3+ phosphor were 23, 27, and 22% for La, Gd, and Y, respectively. [Copyright &y& Elsevier]

Abstract: New green emitting phosphors, hexagonal II-type Gd2O2CO3:Tb3+ and Y2O2CO3:Tb3+, were synthesized by the simple flux method and their luminescence properties were compared with that of II-La2O2CO3:Tb3+. Bright green emission was observed in each sample and their particle sizes were in submicron scale. The excitation spectrum consisted of a broad band and some sharp peaks, which were corresponding to the 4f–5d transition of Tb3+ and 4f–4f transition of Gd3+ and Tb3+, respectively. The excitation wavelength of the 4f–5d bands depends on the distance between Tb3+ and O2−, which affects the crystal field effect on the 5d levels of Tb3+. Among lanthanum, gadolinium, and yttrium oxycarbonates, Gd2O2CO3 is the most suitable host to obtain high emission intensity and the maximum intensity was obtained at the composition of Gd2O2CO3:17at.% Tb3+, where it was 101% of that of a commercial LaPO4:Ce3+,Tb3+ phosphor. [Copyright &y& Elsevier]