Small Amount Of Mn Research Articles

Influence of Mn on the superconductivity of the TlBaCaCuO system

In order to study how Mn substitution changes the superconducting properties of the TlBaCaCuO compound, we have prepared samples with Mn in place of Cu, Tl and Ca respectively by solid-state reactions. We have examined their superconductive transitions by measurements of their resistive and magnetic behaviors, which show that Mn has a negative effect on the superconductivity. It has been found by energy dispersive spectrometry (EDS) and by secondary-ion mass spectrometry (SIMS) that even a relatively small amount of Mn can cause a significant loss of Cu and Tl in the Tl compound. X-ray diffraction and morphological analysis have shown that Mn can also bring in precipitated phases of BaCuO 2 and MnO 2.

Structural study of electrodeposited aluminum-manganese alloys

Aluminum-manganese alloys with compositions ranging between 0 and 27 wt pct Mn were electrodeposited at 150°C onto copper substrates from a chloroaluminate molten salt electrolyte with a controlled addition of MnCl2. The specimens were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and X-ray diffraction. The addition of small amounts of Mn results in the formation of a supersaturated fcc solid solution of Mn in Al. At the higher Mn content, an amorphous phase is established. The highly faceted crystalline surface of pure Al and Al−Mn solid solution becomes smooth and nearly specular when the amorphous phase is present. The amorphous phase appears in the form of rounded grains and has a lower limit of Mn concentration close to the Al6Mn composition. There is a concentration discontinuity between the above limit and the higher Mn concentration limit of the fcc phase (about 9 wt pct). Appearance of the amorphous phase in the alloy results in a decrease in the Mn concentration in solid solution to about 2 wt pct. Crystallization of the amorphous phase starts at the fcc-amorphous phase interface at 230°C. As a result of treatment at 230 °C to 340 °C, the amorphous phase completely transforms into Al6Mn, while the fcc phase is unaffected. Prior to crystallization, the amorphous phase shows a modification that could be interpreted as the formation of a fine-grained icosahedral phase. The formation and distribution of phases by electrodeposition and rapid solidification are discussed.

A study of the oxidation of selected metal silicides

I n situ ellipsometry was used to investigate the oxidation behavior of a group of silicides, CoSi2, CrSi2, Ir3Si5, Ru2Si3, and WSi2, on single-crystal silicon substrates. These observations were complemented by ex situ ellipsometric measurements on these silicides, as well as on Mn11Si19, MoSi2, NiSi, NiSi2, and ReSi2. Refractive index measurements necessary for the oxide thickness calculations were made using ellipsometry on the bare silicide surfaces. Three regimes of oxidation behavior were identified: one group of silicides oxidized much faster than Si itself, CoSi2, CrSi2, NiSi, and NiSi2; another group was intermediate in oxidation rate between the fast group and Si at low temperature, typically comprising the refractory silicides MoSi2 and WSi2; the third group oxidized at about the same rate as Si and included the semiconducting silicides Ir3Si5, ReSi2, and Ru2Si3. The oxidation of Mn11Si19 led to an oxide containing a small amount of Mn. The oxidation rates of the silicides scale with both the reported carrier concentrations and the measured absorption index. Thus, the electronic properties of the silicides are thought to be responsible for the oxidation behavior. Buffered HF etch rates of the oxides grown on silicides indicate that the oxides grown on the rapidly oxidizing silicides are less dense than the oxides on the intermediate and slowly oxidizing silicides.

The Effect of Manganese Ingestion, Phosphate Depletion, and Starvation on the Morphology of the Epiphyseal Growth Plate

Oral administration of manganese to young rats results in poorly mineralized primary spongiosa and an irregularly thickened growth plate with a histologic resemblance to that in vitamin D-deficiency rickets. In the present study, the rachitic lesions were characterized by stereologic methods at the light microscopic level. With increasing doses of Mn in the diet, the animals developed rachitic lesions of increasing severity, i.e., the total height of the growth plate and the relative volume of the hypertrophic zone increased. The experimental animals developed hypophosphatemia, which was dependent on the Mn dose. The observed serum concentrations of Mn and phosphorus are compatible with the idea that MnHPO4 is precipitated in the gut, leaving only small amounts of Mn and phosphate available for absorption. Furthermore, the severity of the rachitic lesions were inversely correlated to the concentration of phosphate in serum. The most important pathomechanism in Mn rickets is phosphate depletion, which per se causes similar rachitic changes, even though Mn also seems to have other effects. Starvation caused a decrease in the height of the growth plate and in the volume fraction of the hypertrophic zone, thus changes contrary to the rachitic lesions.

A neutron powder diffraction study of the crystal and magnetic structures of ilvaite from 305 K to 5 K ? a mixed valence iron silicate with an electronic transition

The crystal and magnetic structures of ilvaite Ca(Fe2+, Fe3+)Fe2+Si2O7O(OH) have been obtained by profile refinement of high resolution neutron powder data from a natural sample from Seriphos, Greece. Below about 400 K an electronic transition from an itinerant to an ordered state is expected, with the structure changing from orthorhombic to monoclinic. The structure remains monoclinic P2 1/a down to 5 K, with Fe2+ almost completely ordered on one of the A-sites and Fe3+ on the other: the ordering may increase with decreasing temperature. The B-site contains Fe2+ plus a small amount of Mn2+ impurity. There are two magnetic transitions, at 116 K and 40 K: at 80 K the Fe2+ and Fe3+ spins on the A-sites along one infinite c-axis chain are parallel, and antiparallel to those along the adjoined edge-sharing centrosymmetrically related chain. The spin vectors are all perpendicular to the plane of these chains, i.e. almost parallel to the crystallographic b-axis. At 5 K, this order is maintained, but the Fe2+ spins on the B-sites order antiferromagnetically as well, again almost along the b-axis. These results explain the earlier Mossbauer and magnetisation measurements.

Stress sensitivity in Ni-Mn, Ni-Mn-Co and Ni-Mn-Co-Cu ferrites

The magnetization of the nickel ferrites with small amount of Mn, Co and Cu ions, with general formula Ni 0.98− x− y Mn 0.02 Co x Cu y Fe 2O 4, where x = 0 to 0.027 and y = 0 or 0.15, is decreased by tension, and these ferrites contract when magnetized. Stress sensitivity coefficient d = (∂B/∂ T) H = (∂S/∂H) T = (∂1/1 ∂H) T , which characterizes these properties, was determined for these ferrites. The greatest stress sensitivity ( d=-6nW/N) was observed for ferrites with the smallest magnetocrystalline anistropy, containing maximum of cobalt ( x=0.027) ions.

都市ごみを原料とするメタン発酵残留物中の重金属の形態

Chemical forms of such heavy metals as Pb, Cr, Mn, and Zn in the sludge from methane fermentation of municipal solid waste were analyzed, by the sequential extraction technique developed by Stover et al. Most(amount) of Cr6+ is unextracted and one third of Pb in the sludge remains unextracted in this method. A half amount of Pb and Zn seem to be bound to organics and the rest is distributed in the form of carbonate and sulfide. A small amount of Mn is present in adsorbates and ion-exchangeable form. The rest of the Mn is equally distributed among a form bound to organics, carbonate, and sulfide.

Syntheses and superstructures of (Cd,M)5(PO4)3OH(M=Mn,Fe,Co,Ni,Cu,Hg)

Divalent ions of the first series transition elements and Hg were introduced into a cadmium hydroxyapatite Cd5(PO4)3OH by replacing a part of Cd2+, and the effects on the crystal growths and the structural changes were studied. Cd2+ can be exchanged with Mn2+ up to about 30 mol %, with Ni2+ or Hg2+ up to about 10 mol %, and with a little amount of Fe2+ or Cu2+. It was found that Cd5(PO4)3OH forms a superstructure when it contains a small amount of Mn2+, Fe2+, Co2+, Ni2+, Cu2+ or Hg2+ ion. Infrared spectra of Cd5(PO4)3OH containing these ions show some new bands in addition to those of Cd5(PO4)3OH. The average structures of the crystals containing a small amount of Hg2+ and Ni2+, and the superstructure of the crystal containing Mn2+ were refined with the full-matrix least-squares method, although the amounts and sites of the substituting ions could not be determined except for the crystals containing Hg2+. The superstructure belongs to P63 (a=16.1990(3), c=6.6485(1)A and Z=6) and has more distorted PO4 tetrahedra than the structure of pure Cd5(PO4)3OH.

Effects of fume particles from stainless steel welding on sister chromatid exchanges and chromosome aberrations in cultured chinese hamster cells.

The frequencies of sister chromatid exchanges (SCE) and chromosome aberra-tions were examined in cultured Chinese hamster cells (Don) exposed to two sorts of fume particles collected from different procedures of stainless steel welding.It was confirmed that the frequencies of SCE and chromosome aberrations in the cells treated with these fume particles increased with increasing fume doses within the range of the fume concentration tested. The fume partticles collected from manual metal arc (MMA) welding were more powerful than those from metal inert gas (MIG) welding. In order to cause the same increase in SCE frequency the fume particles from MIG welding needed to be about 100 times as much as those from MMA welding. The fume particles from MMA welding showed a higher so-lubility of Cr than those from MIG welding. The amount of dissolved Cr from the former was about 60 times as much as that from the latter when culture medium was used as a solvent. Small amounts of Mn, Ni, Fe and Mg were also detected in the supernatants of both fume suspensions. There were no significant differences in the amounts of these metals as was found with Cr when comparing MMA weld-ing with MIG welding. The frequencies of SCE and chromosome aberrations were also increased by the addition of the supernatants of these suspensions.From these results, it was assumed that dissolved hexavalent Cr may be involved in the cytogenetic effect of the fume particles from stainless steel welding.

Ａｌ‐Ｚｎ‐Ｍｇ系合金溶接熱影響部の時効挙動に及ぼす合金組成の影響

Aging behaviors of the heat-affected zones in Al-24.5%Zn-1.24%Mg alloys welds were examined by means of hardness measurements and X-ray small angle scattering methods. The heat-affected zones in all the Al-Zn-Mg alloys welds are regions in the alloys which have been heated at 100°C or above by weld thermal cycles, where dissolution, reversion or partial reversion occurs. A re-solution treated or reverted area in the heat-affected zone is extended in the alloys containing more of Zn. Recovery rate of hardness in the heat-affected zone also increases with increase in Zn content except for the alloys containing small amounts of Mn, Cr, Zr, Cu and Fe. Softened areas are formed in the heat-affected zones of all the Al-Zn-Mg alloys welds during post-weld aging at room temperature. It is wider and remains longer in the Al-Zn-Mg alloys containing more of Mg.

Superconducting properties of layered transition metal NbSe2 doped with Mn

We have measured the critical temperature of NbSe2 doped with Mn by d.c. resistivity measurements and by microwave absorption of 2.4 GHz. The concentration of the Mn intercalated inside the crystals was determined by atomic absorption.To was found to be a monotonic decreasing function of the analysed concentration with a critical concentration of 0.7 mol %. We report also on measurements of critical fieldsHc2 parallel and perpendicular to the layers. The anisotropy is found to initially increase with a small amount of Mn before decreasing. Possible explanations for this physical result will be discussed.

FIXATION OF MANGANESE BY CLAY MINERALS

ABSTRACT Samples of bentonite, illite, and kaolinite clays were studied for their Mn fixation properties under various pH levels, alternate wetting and drying conditions, and incubation at moisture saturation. Bentonite and illite fixed significant quantities of Mn under wetting and drying. Fixation was directly related to pH and the amount of Mn added. Incubation of treated samples at moisture saturation resulted in considerably less than half the amount of Mn fixed as when subjected to repeated wetting and drying. Kaolinite fixed relatively small amounts of Mn as compared to bentonite and illite regardless of treatment. Since x-ray did not reveal a mineralogical change, it was concluded that Mn was fixed as a result of precipitation, physical entrapment in clay lattice wedge zones, or because it was oxidized to higher valence oxides and/or strongly adsorbed at the exchange sites. Cation exchange capacity (CEC) values were inversely related to Mn fixation.

Al-Mg合金板の深絞り性におよぼす第3元素添加の影響

This report dealt with the additional effect of third element on deep drawing properties and ear after drawing of Al-Mg system alloy sheets.The X-ray texture, “n” value and “r” value of tarnary alloy sheets to which very small amounts of Mn, Cr, Zr and Ti were added were measured.The results obtained were as follows:(1) Very small additions of Mn, Cr, Zr and Ti as third elements promoted refinement of the grain, and increased the values of tensile strength and 0.2% proof stress. Especially, the addition of Mn and Cr was effective for grain refinement.(2) Very small additions of Cr, Zr and Ti as third elements tended to reduce deep drawing properties with an increase in alloying addition. However, Al-5.85%Mg-0.14%Mn alloy sheets did not reduce the deep drawing properties but increase the strength.(3) The ear emergent direction and earing ratio were fairly compatible with the “r” value, and with an increase in the addition of the third element, the earing ratio appeared to be reduced.(4) As to recrystallization texture, (310)[\bar132] and (001)[310] appeared strongly and all ears emerged in a 45° direction.

Ordering of V 2+ , Mn 2+ , and Fe 3+ Ions in Zoisite, Ca 2 Al 3 Si 3 O 12 (OH)

The presence of very small amounts of Mn(2+), V(2+), and Fe(3+) ions in zoisite can be easily detected by the electron paramagnetic resonance technique at room temperature. The Mn(2+) and Fe(3+) ions are completely ordered and are probably located in the Ca(1)- and Al(II)-sites, respectively, whereas the V(2+) ions probably occupy both Ca(1)- and Ca(2)-sites, with a preference for the Ca(1)-site.

Abnormal grain growth in Al-Mg (68%) alloys containing under 0.4% of Mn and Cr

Al-Mg(68%) alloy ingots containing small amounts of Mn and/or Cr were prepared in a melting-casting apparatus protected by argon atmosphere.Macrostructure, grain size, hardness and density of dispersed fine particles were examined on the plate specimens of the ingot.X-ray pole figure was also examined on the sheets containing 5%Mg and small amounts of Mn and Cr.The results obtained were as follows:(1) There were upper and lower limits of Mg content in abnormal grain growth of Al-Mg alloys.(2) The limits were explained from the relation between the initial grain growth and the density of dispersed fine particles, according to M. Hillbert's Theory on abnormal grain growth.(3) The aggregate structure of secondary recrystallization of 5056 alloy sheets were found to be composed of (110) [111], (001) [110], (113) [110] and (hkl) [110] planes.

Abnormal grain growth in 5056 alloy plates

Abnormal grain growth was observed in 5056 alloy.Metallographic examinations were made for the following two series of alloys.Series A: Al-Mg binary system, hot and cold rolled.Series B: Al-5%Mg alloys containing small amounts of Mn and/or Cr, hot and cold rolled.The results obtained were as follows.(1) The abnormal grain growth in 5056 alloy was closely related with Cr and/or Mn contents. The phenomenon took place at under 0.3%Cr contents and/or 0.4% of Mn contents.(2) The secondary recrystallization temperature was higher and the ultimate maximum grain size was smaller with the increase in Mn and/or Cr contents.(3) The abnormal coarse grains in the outer layer of the plate were discoidal; while, the grains in the middle layer remained fine.

The paramagnetism of small amounts of Mn dissolved in Cu-Al and Cu-Ge alloys

Previous measurements of the valency of Mn in Cu-- Zn alloys were confirmed by measurements with the isoelectronic Cu-Al and Cu-Ge alloys as matrices for Mn. The valency, having the value 1 in pure copper, decreased slightly with increasing electron to atom ratio attaining the values 0.9 and 0.8 at the limiting composition in the Al and Ge alloys respectively. The apparent size of Mn in these alloys is discussed. (auth)