Crystal structure of the mixed Mn4+/Mn5+ 2H-perovskite-type Ba4Mn2NaO9 oxide

Microwave synthesis, structure, and magnetic properties of quasi-one-dimensional complex oxide Sr4LiMn2O9

“…The average Mn-O distance in the first chain (1.94Å) is within the typical values for Mn 4+ cations in octahedral oxide positions [5,14,21]. The presence of Li + cations in the octahedral positions of the second chain results in a decrease Table 2 Interatomic distances d (Å) for Sr4LiMn2O9.…”

“…1 and 2 display experimental, theoretical, and difference X-ray and neutron powder diffraction patterns for a sample of Sr 4 LiMn 2 O 9 , respectively. The results of crystal structure refinement listed in Table 1 confirm that the complex oxide Sr 4 LiMn 2 O 9 is isostructural with Sr 4 AMn 2 O 9 (A = Cu [13,14], Co [15], Zn, Mg [14,16]) and Ba 4 NaMn 2 O 9 [5] and belongs to the family of 2H-hexagonal perovskites A 3n+3m A n Mn 3m+n O 9m+6n at m = 1 and n = 3. The trigonal cell parameters in the space group P321 (No.…”

“…Synthesis of Ba 4 NaMn 2 O 9 , which has a quasi-1D structure with parameters a = 10.006(2)Å, c = 8.210(3)Å (space group P321) and belongs to the A 3n+3m A n B 3m+n O 9m+6n (n = 3, m = 1) family, was reported in [5,6]. This compound was synthesized electrochemically as single crystals in NaOH melt.…”

“…Attempts to synthesize this compound from BaCO 3 /Ba(OH) 2 ·3H 2 O, MnO 2 /Mn 2 O 3 , and Na 2 CO 3 using the solid-state reaction in different experiment conditions (during heating in air, in nitrogen or NaOH flux flow) failed. The authors [5] believe that Ba 4 NaMn 2 O 9 is the first compound containing manganese in the form of cations with the average oxidation state +4.5. The structural studies showed that trigonal-prismatic positions in Ba 4 NaMn 2 O 9 are occupied by Na + cations, whereas manganese is in octahedral positions.…”

Complex rare-earth-substituted lead titanate piezoceramics: II

“…Compounds with at least two oxidation states are known for almost all these metals. Using Mösbauer measurements and reflection spectra, it has been found that in perovskite compounds, ions of the same element co-exit in two oxidation states [8][9][10] : Ti +4 / Ti +3 , Eu 3+ / Eu +2 , Mn +4 / Mn +5 . Some of the properties of the material are affected by the dopants, their concentration and oxidation state 11 , and it is a practice to introduce a specific dopant or substituent to obtain materials with desired properties 12 .…”