Alkaline Earth Metal Zirconate Perovskites MZrO₃ (M=Ba²⁺, Sr²⁺, Ca²⁺) Derived from Molecular Precursors and Doped with Eu³⁺ Ions

Abstract

The effect of alkaline earth metal alkoxides on the protonation of zirconocene dichloride was investigated. This approach enabled the design of compounds with preset molecular structures for generating high-purity binary metal oxide perovskites MZrO3 (M=Ba(2+), Sr(2+), Ca(2+)). Single-source molecular precursors [Ba4 Zr2 (μ6 -O)(μ3 ,η(2)-OR)8 (OR)2(η(2) -HOR)2 (HOR)2 Cl4], [Sr4 Zr2 (μ6 -O)(μ3 ,η(2)-OR)8 (OR)2 (HOR)4 Cl4], [Ca4 Zr2 (μ6-O)(μ3 ,η(2)-OR)8 (OR)2 Cl4], and [Ca6 Zr2 (μ2 ,η(2)-OR)12 (μ-Cl)2 (η(2) -HOR)4 Cl6 ]⋅8 CH2 Cl2 were prepared via elimination of the cyclopentadienyl ring from Cp2 ZrCl2 as CpH in the presence of M(OR)2 and alcohol ROH (ROH=CH3OCH2 CH2OH) as a source of protons. The resulting complexes were characterized by elemental analysis, IR and NMR spectroscopy, and single-crystal X-ray diffraction. The compounds were then thermally decomposed to MCl2 /MZrO3 mixtures. Leaching of MCl2 from the raw powder with deionized water produced highly pure perovskite-like oxide particles of 40-80 nm in size. Luminescence studies on Eu(3+)-doped MZrO3 revealed that the perovskites are attractive host lattices for potential applications in display technology.

The use of mixed-metal single source precursors for the synthesis of complex metal oxides

“…It is generally considered that excluding halide ligands from precursors is advantageous for the formation of clean oxide materials, although several examples have now shown that post-calcination washing steps can remove any halide contaminants (which are often highly soluble) from the desired oxide phase. 12,26,83,89,91,92 Whilst it is difficult to straightforwardly collect the multitude of different SSPs into set categories, in the following sections we have attempted to group the literature examples into five major groupings of molecular SSPs, plus a group of extended framework precursors and a final section upon statistically mixed mixed-metal species.…”

Local Structure and Spectroscopic Properties of Eu3+-Doped BaZrO3

“…Apart from this, in the range of 350–550 nm, feeble excitation peaks are observed that are ascribed to the f–f transitions of Eu 3+ . This implies that a high quantum efficiency of PL excitation originates from the trap level …”

“…Because the MD transition is stronger, it is confirmed that Eu 3+ ions must occupy the inversion symmetry site in the BaZrO 3 matrix. Because of the difference in the ionic sizes of Ba 2+ (135 Å), Zr 4+ (72 Å), and Eu 3+ (95 Å), it could be considered that Eu 3+ ions must occupy centrosymmetric Zr 4+ sites in the BaZrO 3 lattice. , The emission spectrum of Eu 3+ -doped samples shows some weak peak above 700 nm due to the f–f transition of the Eu 3+ ion.…”

“…Cavalcante et al reported UV-excited blue and green emissions from an undoped BaZrO 3 phosphor powder. , Nishi et al and Ma et al successfully developed a titanium- and magnesium-doped BaZrO 3 phosphor using a solid-state reaction for long-lasting emission and photocatalytic applications. , The luminescence properties of RE (Yb 3+ , Er 3+ , Tm 3+ , Sm 3+ , and Tb 3+ )-doped BaZrO 3 phosphors have been investigated for various optical applications. − Limited work has been performed on the UV-excited luminescence properties of Eu 3+ -doped BaZrO 3 for LED applications. Drag-Jarzabek et al studied Eu 3+ -doped BaZrO 3 for display applications . Additionally, the luminescence properties of Eu 3+ -doped BaZrO 3 have been investigated for LED applications. ,− However, the details of the ET mechanism and spectroscopic properties with density functional theory (DFT) were not widely explored.…”

Influence of Metal Fragment Mobility and Solution Dynamics on Cationic Rearrangements in Multimetallic Alkoxide Frameworks

“…[1][2][3][4][5][6][7][8][9] The preorganized metal À oxygen (alkoxy) bonds and the intrinsic reactivity against nucleophilic attack as well as the thermally labile nature of the organic periphery makes metal alkoxides ([M(OR) x ], [MM'(OR) x + y ]) as preferred starting materials for sol À gel and chemical vapor deposition processes. [2,[10][11][12][13][14][15][16] Metal-organic compounds in general enable low temperature processing of nanostructured oxides and their solid-solutions or composites that are challenging to obtain by traditional solid-state reactions.…”