New strontium borate halides: Sr[sub 5](BO[sub 3])[sub 3]X (X = F, Br)

Journal Article · Wed Jan 06 04:00:00 EST 1993 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00053a017· OSTI ID:6769845

Alekel, T III; Keszler, D A ^[1]

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1. Oregon State Univ., Corvallis (United States)

For many years haloapatites [(Ca,Sr)[sub 5](PO[sub 4])[sub 3](Cl,F)] have been employed as host materials in commercial phosphors for fluorescent lighting. Their robust physical properties coupled with high quantum efficiencies have made them standard phosphor hosts for optically active dopants such as Sb[sup 3+], Mn[sup 2+], and Eu[sup 2+]. Borates also intrinsically possess characteristics that are advantageous for optical materials, which include high photon flux damage thresholds and wide optical transparency windows. Two new strontium borate halides, Sr[sub 5](BO[sub 3])[sub 3]F and Sr[sub 5](BO[sub 3])[sub 3]Br, have been synthesized and structurally characterized by single-crystal X-ray diffraction techniques. The two compounds are structurally similar, 3-dimensional frameworks of interconnecting Sr polyhedra and orthoborate groups but do not crystallize with the same symmetry. The fluoride forms in the centrosymmetric orthorhombic space group, Pnma, with cell parameters a = 7.220 (2) [Angstrom], b = 14.092 (2) [Angstrom], c = 9.810 (1) [Angstrom], and Z = 4. Three distinct Sr-centered O environments exist in this structure: distorted SrO[sub 7]F undecahedra, irregular SrO[sub 6]F coordination sites, and distorted SrO[sub 8] square antiprisms, monocapped by a very weak Sr-O interaction of 3.04 [Angstrom]. A trio of Sr atoms caps each F atom to form a shallow pyramid. Sr[sub 5](BO[sub 3])[sub 3]Br crystals are also orthorhombic in the noncentrosymmetric space group C222[sub 1] with a = 10.002 (2) [Angstrom], b = 14.197 (1) [Angstrom], c = 7.458 (2) [Angstrom], and Z = 4. Four Sr-centered polyhedra join to each other: distorted SrO[sub 7]Br[sub 2] tricapped trigonal prisms, irregular octacoordinate SrO[sub 6]Br[sub 2] undecahedra, and two dissimilar SrO[sub 8] distorted square antiprisms. Six Sr nearest neighbors bond to each Br atom and define Sr octahedra that share triangular faces along the c direction to form zigzag chains. 18 refs., 4 figs., 4 tabs.

• OSTI ID: 6769845
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 32:1; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360600 -- Other Materials
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKALINE EARTH METAL COMPOUNDS
BORATES
BORON COMPOUNDS
BROMIDES
BROMINE COMPOUNDS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DATA
DIFFRACTION
EXPERIMENTAL DATA
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
INFORMATION
LATTICE PARAMETERS
NUMERICAL DATA
OXYGEN COMPOUNDS
SCATTERING
STRONTIUM BROMIDES
STRONTIUM COMPOUNDS
STRONTIUM FLUORIDES
X-RAY DIFFRACTION