Effect of Co Doping on the Structure and Magnetic Properties of TmMn1-xCoxO3

We report the structure and magnetic properties of Co-doped TmMnO3 polycrystals for Co doping levels of 0 ≤ x ≤ 0.9. TmMnO3 (x = 0) prepared at ambient pressure was hexagonal. Hexagonal and orthorhombic phases coexisted in TmMn1−xCoxO3 for 0 ≤ x < 0.5. We obtained almost single-phase orthorhombic samples with 0.5 ≤ x ≤ 0.9 using complex polymerization. Ferromagnetic orthorhombic TmMn1−xCoxO3 formed upon Co doping. The ionic states of Tm, Mn, and Co were determined through magnetization measurements. The rapid decrease in magnetization for 0.5 ≤ x ≤ 0.7 below about 25 K was explained using a model consisting of a combination of ferromagnetic Mn–Co and paramagnetic Tm sublattices

Structures and Magnetic Properties of Tm1-yYyMn1-xCoxO3

The structure and magnetic properties of Tm1−y Y y Mn1−x Co x O3 with 0 ≦ x ≦ 0.5 and 0 ≦ y ≦ 0.3 were investigated by X-ray diffraction, specific heat and magnetization measurements. Thulium manganite TmMnO3 prepared by solid-state synthesis at ambient pressure is hexagonal and antiferromagnetic with a Nèel temperature T N of 86 K. The substitution of Y for Tm in TmMnO3 does not greatly affect the fundamental hexagonal structure. The magnetization and specific heat measurement results for Tm1−y Y y MnO3 can be qualitatively explained in terms of the dilution effect of Tm by Y. On the other hand, the structure of TmMn1−x Co x O3 changes gradually from hexagonal to orthorhombic with the substitution of Co for Mn; hexagonal and orthorhombic phases coexist in samples for x ≦ 0.3 whereas TmMn0.6Co0.4O3 is almost a single orthorhombic phase. The magnetization of TmMn0.6Co0.4O3 in a field of 250 Oe increases rapidly at about 60K with decreasing temperature. The difference between zero-field-cooled (ZFC) and field-cooled (FC) magnetizations increases remarkably at about 60 K. Moreover, the temperature dependences of the ZFC and the FC magnetizations exhibit peaks at about 40 and 30K, respectively. Thus, TmMn1−x Co x O3 exhibits complex magnetic properties

Local density of states and superconducting gap in the iron chalcogenide superconductor Fe1+δ_{1+\delta}Se1−x_{1-x}Tex_{x} observed by scanning tunneling spectroscopy

We report on the first investigation of the quasiparticle local density of states and superconducting gap in the iron chalcogenide superconductor Fe$_{1+\delta}$Se$_{1-x}$Te$_{x}$ ($T_{\mathrm{c}} \sim 14$ K). The surface of a cleaved crystal revealed an atomic square lattice, superimposed on the inhomogeneous background, with a lattice constant of $\sim 3.8$ \AA without any reconstruction. Tunneling spectra measured at 4.2 K exhibit the superconducting gap, which completely disappears at 18 K, with a magnitude of $\sim 2.3$ meV, corresponding to $2\Delta / k_{\mathrm{B}}T_{\mathrm{c}}=3.8$.In stark contrast to the cuprate superconductors, the value of the observed superconducting gap is relatively homogeneous, following a sharp distribution with a small standard deviation of 0.23 meV. Conversely, the normal-state local density of states observed above $T_{\mathrm{c}}$ shows spatial variation over a wide energy range of more than 1 eV, probably due to the excess iron present in the crystal.Comment: 4 pages, 5 figure

新規多環式炭化水素の合成を指向した遷移金属触媒によるビフェニレンの触媒的炭素-炭素結合開裂

早大学位記番号:新8389早稲田大

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Kodak社製のUltraspeed歯科用X線フィルム2種類とEktaspeed歯科用X線フィルム2種類について,それぞれの特性曲線をtime scaling法により描いた。結果としては,Ektaspeedグループの特性曲線は,各測定管電圧においてほぼ同一の曲線を示したが,Ultraspeedグループの特性曲線は異っていた。この違いの原因は,各フィルムのフィルムベースもしくは乳剤,あるいはその両方の違いにあることが想像された。The characteristic curves obtained from two types of the Kodak Ultraspeed dental X-ray films and two types of the Kodak Ektaspeed dental X-ray films were drawn by means of time scaling method. The Ektaspeed group showed almost the same curves at each observed tube voltage, but those of the Ultraspeed group were different from one another. It was expected that the origin of this difference might be caused by the differences of the film base and/or emulsion of each film

Effects of Chemical Pressure on Rare-Earth Oxide GdNIn0.7Co0.3O3 with Nonmagnetic Element Substitution

We studied the effects of chemical pressure on Gd1-yRyMn0.7Co0.3O3 (R = nonmagnetic rare-earth element) with y = 0.1, 0.3, and 0.5. The substitution of Gd with La, Y, or Lu in orthorhombic Gd1-yRyMn1-xCoxO3 induced a systematic change in the unit-cell volume. Our results reveal that increasing or decreasing the average ionic radius of the rare-earth element in the compound affects the magnetic ordering temperature T-C. The reduction in the proportion of Gd owing to substitution by nonmagnetic elements weakens the spin reversal effect

Amorphization Effect for Kondo Semiconductor CeRu₂Al₁₀

We measured the magnetic susceptibility , electrical resistivity , and specific heat of a sputtered amorphous (a-)CeRu2Al10 alloy. value for a-CeRu2Al10 alloy follows a Curie-Weiss paramagnetic behavior in the high-temperature region, and magnetic transition was not observed down to 2 K. The effective paramagnetic moment is 1.19 /Ce-atom. The resistivity shows a typical disordered alloy behavior, that is, small temperature dependence for the whole temperature range. We observed an enhancement of and in the low-temperature region of  K. The enhancement in is suppressed by applying a magnetic field. It is suggested that this behavior is caused by the Kondo effect

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口腔領域の悪性血管内皮腫は,ほとんどの場合,X線検査のみによって,診断や術後観察が行われてきたといえる。われわれは,本腫瘍の術後観察を,RIアンギオグラフィーと骨シンチグラフィーで行い,X線所見と比較検討した。得られたRIアンギオグラムは,下顎骨正中部における血流量の減少を示し,骨シンチグラムは同部の骨欠損像を示した。これらの所見から,本腫瘍の診断や術後観察に,RIアンギオグラフィーや骨シンチグラフィーは,極めて有用であろうと考えられた。A case of malignant hemangioendothelioma is presented in which the postoperative observation was carried out by means of radionuclide angiography and bone scintigraphy with 99m-Tc labeled methylene diphosphonate. In addition, these two modalities were compared with conventional dental radiography. The angiographic images obtained as a serial scintigrams from the first pass revealed an extremely decreased bone blood flow in the incisor region of the mandible, in which the radiographic images could not be contrasted without contrast media. The static scan bone images showed a well defined bone defect corresponding to the angiographic images and radiographic images. All findings obtained using these modalities showed that radionuclide angiography and bone scintigraphy were useful in following up the postoperative progress of malignant hemangioendothelioma

<CLINICAL REPORT>Computed Tomography and Ultrasound Study in Craniofacial Fibrous Dysplasia

24歳の女性に認められたcraniofacial fibrous dysplasiaの検索に際して,病変の範囲を確認する目的で,CT検査と超音波検査を行った。また,病変が単骨peであるか多骨性であるかを鑑別するために^TC標識methylene diphosphonateによる骨シンチグラフィーを実施した.CT検査により,右側下顎骨に存在する嚢胞様病変と右側上顎骨に存在する骨性病変が明かにされた。また,骨性病変の著しい増大による右側上顎洞と右側篩骨洞の縮小も明らかとなった。超音波検査では,病変の細部にわたる観察は不可能であったが,右側上顎骨における骨性病変の存在と,右側下顎骨の著しい膨隆を確認することが可能であった。骨シンテグラフィーでは,顎顔面領域に強い陽性像を認めるものの,その他の骨格系には何らの異常も認められなかった。従って,本症例は,polyostotic fibrous dysplasiaの1型であるcraniofacial fibrous dysplasiaであるとの鑑別が可能であった。In diagnosing craniofacial fibrous dysplasia observed in a 24-year-old woman, computed tomography and ultrasound study were used to define the extent of the bony lesions. Bone scintigraphy with ^Tc labeled methylene diphosphonate was also carried out to differentiate the disease to be monostotic or polyostotic. The sagittal and coronal scan CT images showed a monocystic bony lesion with a mottled appearance in the right mandible, which was growing toward the ramus. The axial scan CT images demonstrated a thickened ramus in the right mandible, an expansible bony lesion in the right maxilla, an increased osseous mass occupying the almost half of the right maxillary sinus, and the almost entirely closed right ethmoidal sinus. Expansible diploe in the right side of the patient\u27s skull was also observed. The ultrasound images with axial scans revealed an expansible lesion in the right mandible and an osseous mass in the right maxilla. The bone scan images showed no abnormalities in the whole body skeleton except for the remarkable uptakes in the craniofacial regions