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A new efficient blue phosphor, Eu2+ activated SrZnP2O7, has been synthesized at 1000 °C under reduced atmosphere and the crystal structure and photoluminescence properties have been investigated. The crystal structure of SrZnP2O7 was obtained via Rietveld refinement of powder X-ray diffraction (XRD) pattern. It was found that SrZnP2O7 crystallizes in space group of P21/n (no. 14), Z=4, and the unit cell dimensions are: a=5.30906(2) A, b=8.21392(3) A, c=12.73595(5) A, β=90.1573(3)°, and V=555.390(3) A3. Under ultraviolet excitation (200–400 nm), efficient Eu2+ emission peaked at 420 nm was observed, of which the luminescent efficiency at the optimal concentration of Eu2+ (4 mol%) was estimated to be 96% as that of BaMgAl10O17:Eu2+. Hence, the SrZnP2O7:Eu2+ exhibit great potential as a phosphor in different applications, such as ultraviolet light emitting diode and photo-therapy lamps.

Three rare earth borosilicate oxyapatites, RE {sub 5}Si{sub 2}BO{sub 13} (RE=La, Gd, Y), were synthesized via wet chemical method, of which RE {sub 5}Si{sub 2}BO{sub 13} (RE=Gd, Y) were first reported in this work. In the three oxyapatites, [BO{sub 4}] and [SiO{sub 4}] share the [TO{sub 4}] tetrahedral oxyanion site, and RE {sup 3+} ions occupy all metal sites. The differential scanning calorimetry-thermo gravimetry measurements and high temperature powder X-ray diffraction pattern revealed a vitrification process within 300-1200 deg. C, which was due to the glass-forming nature of borosilicates. From the VUV excitation spectra of Eu{sup 3+} and Tb{sup 3+} in RE {sub 5}Si{sub 2}BO{sub 13}, the optical band gaps were found to be 6.31, 6.54 and 6.72 eV for RE {sub 5}Si{sub 2}BO{sub 13} (RE=La, Gd, Y), respectively. The emission and excitation bands of Eu{sup 3+} and Tb{sup 3+} are discussed relating with their coordination environments. Among the three hosts, Y{sub 5}Si{sub 2}BO{sub 13} would be the best for Eu{sup 3+} and Tb{sup 3+}-doped phosphors. - Graphical abstract: The perspective view of RE {sub 5}Si{sub 2}BO{sub 13} (RE=La, Gd, Y) oxyapatite along [001] direction. All non-tetrahedral metal sites are occupied by RE {sup 3+}, and the tetrahedral sites bymore » SiO{sub 4} and BO{sub 4} groups. Y{sub 5}Si{sub 2}BO{sub 13} is a good host for both Eu{sup 3+} and Tb{sup 3+} activated phosphors.« less

Two new anhydrous sodium borophosphates with one-dimensional structure, Na3B6PO13 (1) and Na3BP2O8 (2), were synthesized by low-temperature molten salts techniques using boric acid and sodium dihydrogen phosphate as flux, respectively. The crystal structures were solved by means of single-crystal X-ray diffraction (1, orthorhombic, Pnma (no. 62), a = 9.3727 ( 4 ) A , b = 16.2307 ( 7 ) A , c = 6.7232 ( 3 ) A , Z = 4 ; 2 , monoclinic, C2/c (no. 15), a = 12.567 ( 4 ) A , b = 10.290 ( 3 ) A , c = 10.210 ( 3 ) A , β = 92.492 ( 5 ) ° , Z = 8 ). Compound 1 is characterized by an infinite chain of ∞ 1 { [ B 6 PO 13 ] } 3 - containing eight-membered rings in which all vertexes of borate groups contribute to interconnection. Compound 2 reveals an infinite straight chain ∞ 1 { [ BP 2 O 8 ] } 3 - built of vertex-sharing four-membered rings, and chains in neighboring layers arranged along different orientations. The relations between structures and the synthetic conditions with only traced water are discussed.

Two new lanthanum phosphite hydrates, La2(H2O)(HPO3)3 (1) and La2(H2O)2(HPO3)3 (2), were synthesized by a hydrothermal method. Their crystal structures were determined by X-ray single-crystal method (1, monoclinic, C 2 / c (No. 15); a = 20.820 ( 5 ) A , b = 6.717 ( 2 ) A , c = 14.123 ( 3 ) A , β = 101.261 ( 3 ) ° , V = 1937.0 ( 8 ) A 3 ; Z = 8 ; 2, triclinic, P-1 (No. 2); a = 8.168 ( 3 ) A , b = 8.439 ( 2 ) A , c = 9.337 ( 3 ) A , α = 115.641 ( 3 ) ° , β = 98.655 ( 3 ) ° , γ = 105.124 ( 3 ) ° , V = 533.87 ( 1 ) A 3 , Z = 2 ). Both crystal structures present three-dimensional open-framework structures containing channels, and 1 adopts intersecting type. In the two structures, the face-sharing dimers of LaOn ( n = 8 , 9 ) were observed. Other characterizations by IR and TG–DSC were also described. Furthermore, both the compounds doped with Ce+3 showed intensive broad emission band around 340 nm under UV excitation.