実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report
2017/5/29

課題番号 Project No.

装置責任者 Name of responsible person

2016B0005

Takashi Kamiyama

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Magnetic structure of 12L-perovskites Ba4LnMn3O12SuperHRPD (BL-08)

実験責任者名 Name of principal investigator

実施日 Date of Experiment

Yoshihiro Doi

3/20-3/26

所属 Affiliation
Hokkaido University
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
12L-perovskites Ba4LnMn3O12 (four powdered samples with Ln = Ce, Pr, Tb, and Ho)
B-site-defect 12L-perovskite Ba2La2ZnW2O12 (powdered sample)
Layered oxides BaSrFe4Ox (two powdered samples with different chemical treatments)
Layered oxides BaCaFe4Ox (two powdered samples with different chemical treatments)
Melilite-related oxides Sr 2MnGe2O7 (powdered sample)
Complex oxides with a low-dimensional structure BaCa2Mn6Sb3O18 (powdered sample)

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

(1) 12L-perovskite Ba4CeMn3O12
In order to determine the crystal structure and magnetic structure of 12L-perovskite Ba4CeMn3O12, threemeasurements were carried out at 5 K, 20 K, and room temperature by using the cryostat (5K refrigerator). Fig. 1
shows the neutron diffraction profile at room temperature. From this data, it is found that Ba4CeMn3O12 has theCe and Mn occupy different octahedral sites (CeO6 octahedronand Mn3O12 trimer) with no structural disordering and oxygen
defect. At 8.2 K this compound shows an antiferromagnetictransition due to the long-range magnetic ordering of Mn3O12trimer having an S = 3/2 spin at low temperatures. However,Intensity /arb. unit

12L-perovskite structure (Fig. 2) in which the B site cations
Ba4CeMn3O12 RT

0.5

1.0

1.5

2.0

2.53.03.5

the profiles collected at 5 and 20 K are almost the same, andd /Å

any magnetic Bragg peaks were not detected in the 5 K data

Fig. 1 Neutron diffraction profile of12L-perovskite Ba4CeMn3O12.

below TN. This discrepancy may be due to that the ordered12. 実験方法及び結果（つづき） Experimental method and results (continued)
magnetic moment of Mn4+ ion is too small. Among three Mn ions in Mn3O12
RO6

trimer, there exists a strong antiferromagnetic interaction between adjacent

BaMn ion, and this cluster behaves as a magnetic cluster with ground state ofup-down-up spin state (a net spin is S = 3/2 per cluster). The result of neutron
diffraction may indicate that the Mn ions lost its localized spin at low

Mn3O12trimer

temperatures. In addition, it is considered that the magnetic frustration due tothe triangular arrangement of clusters also reduces the ordered moments.
(2) 12L-perovskite Ba4TbMn3O12c

We have measured the neutron diffraction profiles for the new compound
aa12L-perovskite Ba4TbMn3O12 at 5, 20, and 50 K. Form the data at 50 K, it isclarified that this compounds adopts the same 12L-perovskite structure. TheBa4TbMn3O12 shows a ferrimagnetic transition at 40 K arising from theFig. 2
Crystal structure of
12L-perovskite
Ba4LnMn3O12(Ln = Ce, Pr, Tb, and Ho).

magnetic interaction between Tb4+ ion and Mn3O12 cluster. From the data atlower temperatures, we found the magnetic reflections with k = (0, 0, 0) and analyzed the magnetic structure.
The ordered magnetic moments of Tb4+ ions are parallel to c-axis with a ferromagnetic arrangement (5.5 B perTb at 5 K). On the other hand, the magnetic moments of Mn4+ ions are not detected in these data, which may bederived from the same reason as Ba4CeMn3O12.
(3) 12L-perovskites Ba4PrMn3O12 and Ba4HoMn3O12
In view of the difficulty in the detection of Mn magnetic reflection in this series of compounds and the low
TN of these two compounds, we have carried out the measurements only at room temperature. From thesemeasurements, we have determined their crystal structures in detail. The Pr compound adopts the same structure
as Ce and Tb analogues; however, it is found that the Ho compound has a significant oxygen defect, i.e., theexact chemical formula is Ba4HoMn3O12–. In this 12L-perovskite structure, there are two crystallographic sites
for oxygen ions (O1: edge oxygen in the Mn3O12 trimer; O2: inner oxygen in the trimer). From the Rietveld
analysis, it is determined that this defect is equally observed in both sites and total amount  is ~0.4. This fact
may mean that the oxidation state of Mn ions is tetravalent despite the difference in the oxidation state of Lnions.
(4) B-site-defect 12L-perovskite Ba2La2ZnW2O12
In order to determine the detailed crystal structure, we have performed the measurements for seven samples
at room temperature. As one of them, we show the result of Ba2La2ZnW2O12. This compound also has a
12L-perovskite-related structure and the B-site defect with an ordered arrangement among the vacancy, Zn, andW ions. From the Rietveld analysis of the data, we found new information about this type of compounds: thecorrect structural model (R–3) against the established model (R–3m) for a long time (1960s ~) and the layered
ordering of A site cations (Ba and La). This series of compounds Ba2La2MW2O12 (M = transition metals) is
attracting attention as new candidates of two-dimensional triangular magnets; thus, we obtained important results
to understand their physical properties.

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