Takanori Mori

Crystal structure of DyMnO3

Abstract A single crystal of DyMnO3 was grown by floating zone method and the crystal structure was determined by single crystal X-ray diffractometry. The structure of DyMnO3 belongs to the orthorhombic system (space group is Pnma, No. 62) with the lattice parameters a=5.842(2), b=7.378(2), c=5.280(2) A and Z=4.

Crystal growth and crystal structures of the LnMnO3 perovskites: Ln=Nd, Sm, Eu and Gd

Abstract Single crystal of LnMnO3 (Ln=Nd, Sm, Eu and Gd) was grown by floating zone method, and the crystal structure was determined by single crystal X-ray diffractometry. The structure of LnMnO3 belongs to the orthorhombic system (space group is Pnma, No. 62) with the lattice parameters a≈ 2 ap, b≈2ap, c≈ 2 ap and Z=4, where ap is ideal cubic perovskite cell parameter.

Neutron diffraction study of Sr2Mn2O5

Abstract The crystal and magnetic structure of SrMnO 2.5 has been investigated by neutron power diffraction from 20 to 425 K. The compound has orthorhombic crystal structure with the unit cell dimensions a =0.55307(4), b =1.07829(8), c =0.38145(3) nm at 425 K, where space group is Pbam and Z =4. Below T N =375 K, an antiferromagnetic order occurs and the magnetic unit cell is orthorhombic with the dimensions a m = a c , b m = b c , c m =2 c c , where a c , b c and c c are the parameters of the crystallographic unit cell. The ferromagnetic and antiferromagnetic coupling coexist in the c-plane according to the difference of Mn–O–Mn angle and the coupling between adjacent planes is antiferromagnetic. The direction of the magnetic moments is along the crystallographic b-axis. The magnitude of magnetic moment at 20 K is 3.44 μ B /Mn.

Phase behavior in the system LaxSr1−xMnO(5+x)/2 (x=0.8–1.0) with trivalent state of manganese ion

Abstract The oxygen defect perovskite La x Sr 1− x MnO (5+ x )/2 phases ( x =0.8–1.0) with valence state adjusted to trivalent manganese ion have been prepared by reducing oxygen content from the series of La x Sr 1− x MnO 3 solid solutions. These phases have been characterized by powder X-ray diffractometry and magnetization measurement. The crystal systems of La x Sr 1− x MnO (5+ x )/2 are orthorhombic ( x =1.0–0.9) and rhombohedral ( x =0.8). The phase of La x Sr 1− x MnO 3+ δ for x =0.9 shows structural change from rhombohedral to orthorhombic symmetry by degree of oxygen nonstoichiometry, while the compounds for x =1.0 and 0.8 do not show structural change by oxygen nonstoichiometry. The random distribution of the oxygen vacancies are assumed in each structure. For x =0.8, the behavior of the temperature dependence of gram magnetization is quite different for finite-field cooling and for zero-field cooling, whereas the magnetic transition temperature exists at around 138 K for both cases. It seems that the magnetic ordered state of this sample is weak ferromagnetic.

Growth and structure analysis of single crystal of tetragonal BaGd2Mn2O7 with a superlattice structure

Abstract Single crystal of BaGd 2 Mn 2 O 7 was grown by the floating zone method, and its crystal structure was determined using single crystal X-ray method. This compound has the ordered structure of tilting oxygen octahedron surrounding a central manganese ion (space group P4 2 /mnm). The lattice constants are a =0.55374(8), c =2.0618(1) nm and Z =4. The oxygen octahedron surrounding a central manganese ion is slightly distorted and mutually tilts between the neighboring oxygen octahedrons with an angle of several degrees. These single crystal data confirmed our previous results from the Rietveld analysis of powder X-ray diffraction patterns [J. Alloys Compd. 311 (2000) 69].

Crystal structure and magnetic property of La2MnRuO6 phase

Abstract A perovskite compound La 2 MnRuO 6 was synthesized and the detailed crystal structure has been determined by Rietveld analysis of powder X-ray diffraction data. The nonstoichiometric range of La 2 MnRuO 6+ x phase was determined from x =−0.015 to +0.152. The lattice constants with the orthorhombic space group Pnma (No 62) decrease with increase of oxygen nonstoichiometry from a =0.56921(8), b =0.78354(3) and c =0.55513(7) nm near stoichiometric composition to a =0.55594(2), b =0.78309(3) and c =0.55484(2) nm for hyperstoichiometric composition. The oxygen octahedron is almost regular and tilts each other in zigzag way by several degrees. The magnetic measurements of this phase showed a spin glass like behavior with a characteristic peak phenomenon below 100 K in the susceptibility–temperature curve ( χ – T ) at low temperature.

The layered structure of La substituted SrMnO3

Abstract The La-substituted manganites (La x Sr 1− x MnO 3 ) in La poor side were studied by means of X-ray diffraction. The La-poor side for La x Sr 1− x MnO 3 (0≤ x ≤0.1) transformed at high temperature. La x Sr 1− x MnO 3 have cubic perovskite structure, but at high temperature, each perovskite structure transformed into layer structure. La 0.025 Sr 0.975 MnO 3 , La 0.05 Sr 0.95 MnO 3 and La 0.1 Sr 0.9 MnO 3 transformed to 4-layer structure, 15-layer structure and 6-layer structure, respectively.

Synthesis and high temperature X-ray diffraction studies on the perovskite SrLaMnRuO6

Abstract The compound SrLaMnRuO 6 has been prepared and the crystallographic phase transition from orthorhombic phase with the space group Pnma (GdFeO 3 -type) to rhombohedral phase with R 3 c was found near 500 K by high temperature X-ray diffractometry and thermal analysis. The crystal structure of SrLaMnRuO 6 has been refined by the Rietveld method with X-ray powder diffraction data between room temperature and 773 K.

Crystal growth and structural analysis of PrMnO3 and TbMnO3

Single crystals of PrMnO3 and TbMnO3 were grown by floating zone method and the crystal structure was determined by single crystal X-ray diffractometry. The structure of these compounds belongs to the orthorhombic system (space group is Pnma, No. 62) with the lattice parameters alpha approximate to root (.) - a(p), b approximate to 2 (.) a(p) , c approximate to root 2.a(p) and Z = 4, where a(p) is ideal cubic perovskite cell parameter.