Annealing-Induced Structural Behavior of Mn Dopant Ions in Calcium Orthovanadate Ca3(VO4)2 Single Crystals

Galina M Kuz'micheva; Liudmila I Ivleva; Irina A Kaurova; Evgeny V Khramov; Vladimir A Lazarenko; Victor B Rybakov; Yuri A Fionov; Alexander V Fionov

doi:10.1021/acs.inorgchem.2c00503

Annealing-Induced Structural Behavior of Mn Dopant Ions in Calcium Orthovanadate Ca₃(VO₄)₂ Single Crystals

Inorg Chem. 2022 May 9;61(18):7060-7068. doi: 10.1021/acs.inorgchem.2c00503. Epub 2022 Apr 26.

Authors

Galina M Kuz'micheva¹, Liudmila I Ivleva², Irina A Kaurova¹, Evgeny V Khramov³, Vladimir A Lazarenko³, Victor B Rybakov⁴, Yuri A Fionov⁵, Alexander V Fionov⁴

Affiliations

¹ MIREA - Russian Technological University, 78 Vernadskogo pr., Moscow 119454, Russia.
² Prokhorov General Physics Institute, Russian Academy of Sciences, 38 Vavilova str., Moscow 119991, Russia.
³ National Research Center ≪Kurchatov Institute≫, 1 Akademika Kurchatova pl., Moscow 123182, Russia.
⁴ Chemistry Department, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow 119991, Russia.
⁵ Peoples' Friendship University of Russia, 6 Mikluho-Maklaya str., Moscow 117198, Russia.

PMID: 35471861
DOI: 10.1021/acs.inorgchem.2c00503

Abstract

The crystal and local structures of Czochralski-grown calcium orthovanadate (Ca₃(VO₄)₂) single crystals doped with over-stoichiometric 0.05 wt % Mn₂O₃ (CVO:0.05Mn) and annealed under different conditions are studied by single-crystal conventional and synchrotron X-ray diffraction, X-ray absorption spectroscopy, and electron paramagnetic resonance for the first time. Bottom (annealing in air) and top (annealing in air and in vacuum) parts of the CVO:0.05Mn crystal differ in the manganese content (higher in the bottom part), formal charge (Mn⁴⁺ and Mn^(3+δ)+, respectively), and color (orange bottom part; light orange and yellow top parts annealed in air and vacuum, respectively). Manganese ions are located in one (Ca3, distorted two-capped trigonal prism) of five crystallographic Ca sites and have octahedral coordination, which is consistent with crystal-chemical properties of transition-metal ions. The presence of vacancies in one of three V sites is revealed. Formal charge 5+ for vanadium ions is confirmed by X-ray photoelectron spectroscopy. Different colors of CVO:Mn crystals and different formal charges of manganese are explained depending on the growth and post-growth treatment conditions.