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Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles
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Na(2/7)Gd(4/7)MoO4: a modulated scheelite-type structure and conductivity properties.
V Morozov1, A Arakcheeva, B Redkin
1Chemistry Department, Moscow State University, 119991 Moscow, Russia. morozov@tech.chem.msu.ru
Inorganic Chemistry
|April 21, 2012
Summary
This study reveals the complex (3+2)D incommensurately modulated structure of cation-deficient sodium gadolinium molybdate, uncovering cation and vacancy ordering. These findings offer new insights into controlling properties of defect scheelite-type materials.
Area of Science:
- Solid-state chemistry
- Crystallography
- Materials science
Background:
- Scheelite-type compounds are of interest due to their stability, ease of synthesis, and optical properties.
- Cation vacancies and ordering in scheelite structures offer a route to tune material properties.
- Defect scheelite compounds like Nd(3+):M(2/7)Gd(4/7)□(1/7)MoO(4) have been explored for diode-pumped lasers.
Purpose of the Study:
- To grow a single crystal of Na(2/7)Gd(4/7)MoO(4) with a scheelite-type structure.
- To elucidate the complex crystal structure of this cation-deficient compound.
- To investigate the high-temperature electrical conductivity of Na(2/7)Gd(4/7)MoO(4).
Main Methods:
- Single crystal growth using the Czochralski method.
- Transmission electron microscopy (TEM) for structural analysis.
- Single-crystal diffraction data analysis to solve the modulated structure.
- High-temperature conductivity measurements along crystallographic axes.
Main Results:
- A single crystal of Na(2/7)Gd(4/7)MoO(4) was successfully grown.
- TEM revealed a (3+2)D incommensurately modulated structure, not a random distribution.
- The crystal structure was solved in superspace group I4 (α-β0,βα0)00, showing partial disorder of cations and vacancies.
- Electrical conductivity at 973 K was measured as σ = 1.13 × 10(-5) Ω(-1) cm(-1) along specific orientations.
Conclusions:
- Na(2/7)Gd(4/7)MoO(4) exhibits a complex (3+2)D incommensurately modulated structure.
- The structure reveals a partially disordered distribution of Na, Gd, and vacancies.
- The study provides fundamental insights into the structure-property relationships of cation-deficient scheelites.
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