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Abstract: Eu3+-doped Ca2SnO4 (solid solutions of Ca2− x Eu2 x Sn1− x O4, 0⩽x⩽0.3) and Eu3+ and Y3+-codoped Ca2SnO4 (Ca1.8Y0.2Eu0.2Sn0.8O4) were prepared by solid-state reaction at 1400°C in air. Rietveld analysis of the X-ray powder diffraction patterns revealed that Eu3+ replaced Ca2+ and Sn4+ in Eu3+-doped Ca2SnO4, and that Eu3+ replaced Ca2+ and Y3+ replaced Sn4+ in Ca1.8Y0.2Eu0.2Sn0.8O4. Red luminescence at 616nm due to the electric dipole transition 5 D o→7 F 2 was observed in the photoluminescence (PL) spectra of Ca2− x Eu2 x Sn1− x O4 and Ca1.8Y0.2Eu0.2Sn0.8O4 at room temperature. The maximum PL intensity in the solid solutions of Ca2− x Eu2 x Sn1− x O4 was obtained for x=0.1. The PL intensity of Ca1.8Y0.2Eu0.2Sn0.8O4 was 1.26 times greater than that of Ca2− x Eu2 x Sn1− x O4 with x=0.1. [Copyright &y& Elsevier]

Compounds in a CaO–Y2O3–SnO2 system were prepared by a solid-state reaction at 1673 K. The phase relation in this system was investigated by powder X-ray diffraction. Besides the previously reported ternary compounds, CaSnO3, Ca2SnO4, Y2Sn2O7, and a quaternary compound Ca0.4Y1.2Sn0.4O3, solid-solution series of Ca2− xY2 xSn1− xO4 with 0≤ x≤0.5, and Ca1− yY2 ySn1− yO3 with 0≤ y≤0.2 and 0.95≤ y≤1.0 were found. The cell parameters of these solid-solution series were refined. The changes of rhombohedral cell parameters in the samples prepared in the range 0.565< y<0.714 of Ca1− y Y2 ySn1− yO3 suggested the existence of solid solutions of Ca0.4Y1.2Sn0.4O3, although their single phases could not be prepared, except at y=0.6. [ABSTRACT FROM AUTHOR]

A new quaternary oxide, calcium yttrium stannate, Ca0.8Y2.4Sn0.8O6, is isostructural with Mg3TeO6 (trigonal, R ). The empirical formula can be expressed as (Ca0.2667Y0.7333)6(Y0.4Sn0.6)SnO12. The Ca/Y site has a distorted coordination octa­hedron of O atoms, with Ca/Y—O distances ranging from 2.227 (3) to 2.350 (3) Å, while the octa­hedra of O atoms that coordinate to the Sn and Y/Sn sites are nearly regular, with an Sn—O distance of 2.066 (2) Å and a Y/Sn—O distance of 2.147 (3) Å. [ABSTRACT FROM AUTHOR]

A new quaternary compound in the Ca-Eu-Sn-O system, namely calcium europium tin heptaoxide, Ca1.5 Eu3Sn0.5 O7, was prepared by solid-state reaction at 2073 K. All atoms in the structure are on 4i special positions (on mirrors) in space group C2/m. Ca/Eu sites are situated within two O octahedra and within two sevenfold coordination sites surrounded by O-capped trigonal prisms. A Ca/Eu/Sn site is coordinated by five O atoms. The structural formula can be represented as (Ca0.28 Eu0.72)(Ca0.16 Eu0.84)(Ca0.46 Eu0.54)(Ca0.28 Eu0.72)(Ca0.32 Eu0.18 Sn0.50)O7. The crystal structure is a new type and is related to the structure of B-form Eu2O3.