Sm Samples Research Articles

Crystal Structures and Thermoelectric Properties of Sm-Filled Skutterudite Compounds Sm y Fe x Co 4 - x Sb 12

Polycrystalline samples of Sm partially filled skutterudites Sm y Fe x Co 4 - x Sb 12 were prepared by melting and Spark Plasma Sintering technique. The results of Rietveld refinement showed that the obtained Sm y Fe x Co 4 - x Sb 12 samples possessed filled skutterudite structures. The thermal parameter ( B) of Sm is larger than that of Sb, Fe, and Co, indicating that Sm “rattled” in Sb-icosahedron voids. The effects of filling atom Sm on thermoelectric properties of these compounds were investigated. With the increase of Sm filling fraction ( y), electrical conductivity decreased, Seebeck coefficient increased and had a maximum value when y was 0.38; thermal conductivity reduced and had a minimum value when y was 0. 32. At 750 K, the highest figure of merit of 0.68 was obtained for Sm 0.32Fe 1.47Co 2.53Sb 12.

돈육 뒷다리 부위의 발골시간이 프레스햄의 품질 특성에 미치는 영향

ABSTRACT To investigate the effects of deboning time and muscle type of ham on quality characteristics of cooked press ham, a total of twelve pigs (barrow, 100 ± 5kg) were slaughtered and split in half. The left side ham of carcasses was deboned immediately after slaughter whereas the right side ham was deboned after chilling for 24 hours at 4. Each of two muscles (SM ; Semimembranosus, BF; Biceps femoris) was used to make a press ham. The pH of hot-boning muscles was significantly (p0.05) higher than that of cold- boning muscles, and the pH of SM samples was significantly (p 0.05) higher than BF samples. Hot-boning muscles showed significantly (p<0.05) longer sarcomere length compared with cold-boning muscles. There was no significant difference in myoglobin (Mb) percentage between SM and BF muscles, but SM samples of hot-boning showed significantly (p<0.05) lower L* value compared to hot-boning BF samples. The lightness (L*) of hot-boning muscles was significantly (p<0.05) lower than that of cold-boning muscles. These results suggested that the dark color of hot-boning samples might be due to not only the high muscle pH but also the long sarcomere length without difference in Mb percentage. Hardness and gumminess of hot-boning press ham were significantly (p<0.05) lower than those of cold-boning samples. These results implied that color and pH of press ham did not affected by deboning time or muscle type of ham. However data suggested that texture and panel test of press ham might be improved by using hot-boned muscle due to long sarcomere length of raw meat. (

Catalytic Performance of Sulfated Silica MCM-41 for the Cyclization of Pseudoionone to Ionones

Abstract A series of sulfated silica MCM-41 samples denoted as SM and ASM were prepared by calcination at different temperatures using H2SO4 and (NH4)2SO4 solution as the promoter, respectively. The mesostructure, sulfation process, and surface acidity of the two samples were investigated by N2 adsorption-desorption, temperature-programmed desorption of adsorbed NH3 (NH3-TPD), thermogravimetric analysis (TG-DTG), elemental analysis, and Fourier transform infrared (FT-IR) spectroscopy. The activity of the samples for the traditional liquid acid-catalyzed cyclization reaction of pseudoionone to ionones was investigated. For the SM and ASM samples calcined at 450°C (denoted as SM-450 and ASM-450, respectively), SO42- was successfully chelated onto the silica surface in bidentate complex forms, and no free H2SO4 molecules existed as the original promoter or intermediate of thermal decomposition inside the mesopores. The in situ pyridine adsorption FT-IR and NH3-TPD measurements revealed that ASM-450 contained both Bronsted and Lewis acid sites of weak strength. The catalytic performance of SM-450 and ASM-450 was comparable with that of the commercial acid resin Amberlyst-15, and the chelating structure of SO42-/SiO2, which was generally considered to be inactive, was responsible for the high activity. ASM-450 showed better catalytic performance compared with Amberlyst-15 at relatively low temperature, and it could be reused 5 times with good activity.

Siderophile-element anomalies in CK carbonaceous chondrites: Implications for parent-body aqueous alteration and terrestrial weathering of sulfides

CK chondrites constitute the most oxidized anhydrous carbonaceous chondrite group; most of the Fe occurs in magnetite and in FeO-rich mafic silicates. The two observed CK falls (Karoonda and Kobe), along with thirteen relatively unweathered CK finds, have unfractionated siderophile-element abundance patterns. In contrast, a sizable fraction of CK finds (9 of 24 investigated) shows fractionated siderophile abundance patterns including low abundances of Ni, Co, Se and Au; the most extreme depletions are in Ni (0.24 of normal CK) and Au (0.14 of normal CK). This depletion pattern has not been found in other chondrite groups. Out of the 74 CK chondrites listed in the Meteoritical Bulletin Database (2006; excluded considerably paired specimens; see http://tin.er.usgs.gov/meteor/metbull.php) we analyzed 24 and subclassified the CK chondrites in terms of their chemical composition and sulfide mineralogy: sL (siderophiles low; six samples) for large depletions in Ni, Co, Se and Au (>50% of sulfides lost); sM (siderophiles medium; two CKs) for moderately low Ni and Co abundances (sulfides are highly altered or partly lost); sH (siderophiles high; one specimen) for enrichments in Ni, Co, Se and Au; ‘normal’ for unfractionated samples (13 samples). The sole sH sample may have obtained additional sulfide from impact redistribution in the parent asteroid. We infer that these elements became incorporated into sulfides after asteroidal aqueous processes oxidized nebular metal; thermal metamorphism probably also played a role in their mineral siting. The siderophile losses in the sL and sM samples are mainly the result of oxidation of pentlandite, pyrite and violarite by terrestrial alteration followed by leaching of the resulting phases. Some Antarctic CK chondrites have lost most of their sulfides but retained Ni, Co, Se and Au, presumably as insoluble weathering products.

Structure and electrochemical properties of Sm 0.5Sr 0.5Co 1 − xFe xO 3 − δ cathodes for solid oxide fuel cells

Crystal structure, thermal expansion coefficient, electrical conductivity and cathodic polarization of compositions in the system Sm 0.5Sr 0.5Co 1 − x Fe x O 3 − δ with 0 ≤ x ≤ 0.9 were studied as function of Co / Fe ratio and temperature, in air. Two phases, including an Orthorhombic symmetry for 0 ≤ x ≤ 0.4 and a cubic symmetry for 0.5 ≤ x ≤ 0.9, were observed in samples of Sm 0.5Sr 0.5Co 1 − x Fe x O 3 − δ at room temperature. The adjustment of thermal expansion coefficient (TEC) to electrolyte, which is one of the main problems of SSC, could be achieved to lower TEC values with more Fe substitution. High electrical conductivity above 100 S/cm at 800 °C was obtained for all specimens, so they could be good conductors as cathodes of IT-SOFC. The polarization behavior of SSCF as a function of Fe content was evaluated by means of AC impedance using LSGM electrolyte. It was discovered that the Area Specific Resistance (ASR) of SSCF increased as the amount of substitution of Fe for Co increased. When the amount of Fe reached to 0.4, the highest ASR was obtained and then the resistance started decreasing above that. The electrode with a composition of Sm 0.5Sr 0.5Co 0.2Fe 0.8O 3 − δ showed high catalytic activity for oxygen reduction operating at temperature ranging from 700 to 800 °C.

Round robin tests on large grain melt processed Sm–Ba–Cu–O bulk superconductors

On-going, round robin tests of the trapped field at the top and bottom surfaces of twocarbon fibre reinforced polymer (CFRP)-clad, epoxy resin-reinforced large grain samples ofSm–Ba–Cu–O fabricated at ISTEC, Japan, by top-seeded melt growth (TSMG) havebeen performed by four European laboratories over a period of 16 months. Fluxprofiles were measured by scanning Hall probe by the participating groups andwere found to agree to within approximately 7% over the measurement periodwhen the effects of incomplete flux penetration in some of the tests were takeninto account. Overall the measurements suggest that the trapped flux profile ismost sensitive to changes in magnetizing field, experimental geometry and thesample–Hall probe separation. As a result, variations in these parameters shouldbe minimized during flux mapping. In general a magnetizing field of times the maximum trapped field for field cooled (FC) samples is required to ensurecomplete magnetization of a homogeneous cylindrical sample with an aspect ratio of, corresponding to the geometry of the samples measured here. Finally, 20 min relaxationtime following magnetization was observed to be sufficient to yield consistent measurementof the peak trapped field within the error of the measurement, which was typically lessthan 4%. Other than the recommended magnetizing field of 3 T, which should bedetermined by aspect ratio, temperature and maximum trapped field rather than bepredefined, the experimental conditions were confirmed by this interim report generallyto lie within the guidelines described in a draft International ElectrotechnicalCommission (IEC) Technical Committee 90 (TC90) standardization document on fluxmapping. On the basis of the present preliminary results the proposed 5% spreadin measured trapped field and a 20 min relaxation period do not appear to beunreasonable criteria for trapped field measurements performed at different laboratories.

Round robin measurements of the flux trapping properties of melt processed Sm–Ba–Cu–O bulk superconductors

Scanning Hall probe round robin measurements of the trapped field of two CFRF-clad, epoxy resin-reinforced large grain samples of Sm–Ba–Cu–O fabricated at ISTEC-SRL by top seeded melt growth (TSMG) have been performed by five European laboratories over a two year period under the auspice of the Versailles Project on Advanced Materials and Standards (VAMAS) and Technical Committee 90 (TC90) of the International Electrotechnical Commission (IEC). This study completes the interim report of the round robin tests presented at the fourth PASREG Workshop, Jena, July 2003. The peak fields derived from flux profiles measured by the different groups are found to correlate to within 6% over the measurement period. The flux trapping ability of the samples, measured by the peak field in the upper surface, deteriorated over the period of measurement by around 2% and 1%, respectively. Overall the measurements suggest that the trapped flux profile is most sensitive to changes in magnetizing field, experimental geometry and the sample–Hall probe separation. As a result, variations in these parameters should be minimized during flux mapping. In general a magnetizing field of 1.75 times the maximum trapped field for field cooled (FC) samples is required to ensure complete magnetization of a homogeneous cylindrical sample with an aspect ratio of ≈2.5, corresponding to the geometry of the samples measured here. Finally, 20 min relaxation time following magnetization was observed to be sufficient to yield consistent measurement of the peak trapped field within the error of the measurement, which was typically less than 4%. Other than the recommended magnetizing field of 3 T, which should be determined by aspect ratio, temperature and maximum trapped field rather than pre-defined, the experimental conditions were confirmed to lie within the guidelines described in a draft International Electrotechnical Commission (IEC) Technical Committee 90 (TC90) standardization document on flux mapping. On the basis of the present results the proposed 5% spread in measured trapped field and a 20 min relaxation period appear to be reasonable criteria for trapped field measurements performed at different laboratories.

Magnetic and structural properties of Sm 1.5 Gd 0.5 Fe 17−x Co x N y with 0 ≤ x ≤ 3 and y ≈ 3

The effect of nitrogen insertion on the structural and magnetic properties of (Sm 1 . 5 Gd 0 . 5 )Fe 1 7 - x Co x compounds has been investigated. X-ray powder diffraction analysis shows that all the nitrides are single phase and crystallize in the Th 2 Zn 1 7 -type structure. The lattice parameters of the (Sm/Gd) 2 Fe 1 7 - x Co x N y compounds increase with increasing x. Magnetization studies indicate that all the samples are ferromagnetic at room temperature. Nitrogen insertion leads to an increase in the Curie temperature T c from 520 K for Sm 1 . 5 Gd 0 . 5 Fe 1 6 Co to 880 K for Sm 1 . 5 Gd 0 . 5 Fe 1 6 CoN 2 . 9 . Moreover, the nitrogen insertion increases the saturated magnetization M s . M s increases from 107.67 emu/g for x = 0 to 149.92 emu/g for y = 3. X-ray diffraction measurements on magnetically aligned powder samples of Sm 1 . 5 Gd 0 . 5 Fe 1 7 - x Co x N y reveal a change in the easy magnetization direction from planar to conical after nitrogen insertion.

Synthesis and structure refinements for (Ti,Cu)Sr 2(RE 0.8Ce 0.2) 2Cu 2O 10− δ

We have synthesized (Ti,Cu)Sr 2(RE 0.8Ce 0.2) 2Cu 2O 10− δ (RE=Sm, Eu, and Gd). Powder X-ray diffraction indicated that the average crystal structure of these samples has a body-centered tetragonal 1222 structure with space group I4/mmm, and these samples contained SrTiO 3 and CeO 2 impurities. The lattice parameters of (Ti,Cu)Sr 2(RE 0.8Ce 0.2) 2Cu 2O 10− δ are a=0.38516(5) nm and c=2.8314(4) nm for RE=Sm, a=0.38536(2) nm and c=2.8389(2) nm for RE=Eu, and a=0.38456(3) nm and c=2.83566(5) nm for RE=Gd. The superconducting transitions were observed for RE=Eu ( T c=20 K) and Sm ( T c=25 K) samples in the electrical resistivity and magnetic susceptibility measurements.

Measurement of Neutron Total Cross Section of Ag and Sm at Pohang Neutron Facility

The neutron total cross section of natural Ag and Sm has been measured in the energy region from 0.1 eV to 100 eV by the neutron time-of-flight method at Pohang Neutron Facility, which consists of an electron linear accelerator, a water-cooled Ta target with a water moderator, and an 11 m long time-of-flight path. A 6Li-ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.6 cm has been used as a neutron detector and metallic plates of Ag and Sm samples have been used for the neutron transmission measurement. The background level has been deterrnined by using notch-filters of Co, In, and Cd sheets. In order to reduce the gamma rays from Bremsstrahlung and that from neutron capture, we have employed a neutron-gamma separation system based on their different pulse shapes. The present measurements are in general agreement with the previous ones and the evaluated data in ENDF/B-VI. The resonance parameters of Ag isotopes (107Ag and 109Ag) have been extracted from the transmission data by using the SAMMY code.

Effect of Partial Substitutions of Rare-earth Metals for Na-site on the Thermoelectric Properties of Na&lt;SUB&gt;&lt;i&gt;x&lt;/i&gt;&lt;/SUB&gt;Co&lt;SUB&gt;2&lt;/SUB&gt;O&lt;SUB&gt;4&lt;/SUB&gt; Prepared by the Polymerized Complex Method

Polycrystalline (Na 1 - y M y ) x Co 2 O 4 (M=Nd, Sm, Dy and Yb; y = 0.01 ∼ 0.05) samples were synthesized by a polymerized complex method. The effects of partial substitution of rare-earth metals for a Na-site on the thermoelectric properties of Na x Co 2 O 4 were investigated, and their differences with the sample prepared by a conventional solid-state reaction (SSR) method were evaluated. In case of the Nd, Sm and Dy-substituted samples, each rare-earth metal content in the matrix phase was slightly higher than that of the sample prepared by the SSR method, resulting in the slight increase in the thermoelectric power. Dy-substituted samples with y = 0.03 and 0.05 showed the decrease in the electrical resistivity compared to the non-substituted sample because of the enhanced c-axis orientation. The power factors of the Dy-substituted samples were higher than that of the non-substituted sample over the entire temperature range, and the sample with y = 0.05 showed the maximum power factor value of 1.5 x 10 - 3 Wm - 1 K - 2 at 1073 K. On the other hand, Yb-substituted samples with y ≤ 0.03 were almost single Na x Co 2 O 4 phase. The maximum Yb content in the matrix phase corresponded to y . = . 0.03 from the EDX analysis. The value was remarkably higher than that of the sample prepared by the SSR method. For the Yb-substituted samples with y < 0.03, the c-axis orientation was enhanced with increasing the nominal Yb composition in conjunction with the rise in the lattice parameter, c. The Yb substitution caused the increase in the electrical resistivity and thermoelectric power compared to the non-substituted sample over the entire temperature range, which is considered to be due to the reduction in the carrier density resulted from the Yb substitution for Na-site. The power factor of the sample with y = 0.03 was enhanced over the entire temperature range, and the maximum power factor, 1.5 × 10 - 3 Wm - 1 K - 2 was obtained at 1073 K.

Specific heat at high temperature and magnetic measurements in Nd 0.5Sr 0.5MnO 3 and R 0.5Ca 0.5MnO 3 (R = Nd, Sm, Dy and Ho) samples

We have made a magnetic and specific heat characterization of five manganese samples. Ferromagnetic, antiferromagnetic and charge ordering transitions in our samples agree with previous reports. Each specific heat curve was successfully fitted at high temperatures by an Einstein model with three optical phonon modes. Close to the charge ordering and ferromagnetic transition temperatures the specific heat curves showed peaks superposed to the characteristic response of the lattice oscillations.

Nanostructured melt-spun Sm(Co,Fe,Zr,B)/sub 7_5/ alloys for high-temperature magnets

High coercivity, the highest for Cu-free 2 : 17 Sm-Co ribbons, has been obtained in as-spun (= 211 kOe) and short time annealed (= 232 kOe) samples of Sm(CobalFe Zr B)7 5 alloys, with varying B, Zr, and Fe content (= 0-0 06, = 0-0 16, = 0 08-0 3) and wheel speed. In as-spun samples, the TbCu7 type structure and in annealed samples the Th2Zn17 and CaCu5 type structures is observed, plus fcc Co as minority phase is observed. Reduced remanence () is higher than 0.7. High-temperature magnetic measurements show very good stability above 300 C with coercive field as high as 5.2 kOe at 330 C. For annealed Sm(CobalFe0 3Zr0 02B0 04)7 5, very good loop squareness and high maximum energy product of 10.7 MGOe have been obtained. Increasing Zr content results in less uniform microstructure of annealed ribbons.

The preparation, microstructures and magnetostrictive properties of Samfenol-D

A high-pressure arc furnace has been used to prepare button- and rod-shaped samples of Sm 0.86Dy 0.14Fe y alloys. Sm losses as a result of volatilisation during melting were found to be lower than those encountered when using conventional arc melting techniques, while higher arc currents could be employed leading to more effective melting. The effects of annealing on the microstructures and the magnetomechanical coupling factor, k 33, have also been investigated. X-Ray diffraction and scanning electron microscopy analysis indicated that annealing samples at 850 °C under vacuum for periods up to 10 h gives a pseudo-single phase microstructure. A double partial zoning technique, followed by annealing, was devised to prepare rod samples with high magnetomechanical coupling factors.

Structural, dielectric and electrical properties of Sm xBi 1− xFeO 3 ceramics

Polycrystalline samples of Sm x Bi 1− x FeO 3 were prepared by standard solid state reaction technique with x=1, 0.8, 0.6, 0.4 and 0.2. The single-phase formation of the compounds was confirmed by X-ray diffraction (XRD) technique. The XRD patterns were examined for the confirmation of the crystal structure and for the calculation of the lattice parameters. The crystal structure of the sample with x=1, 0.8, 0.6, and 0.4 is orthorhombic and triclinic for x=0.2. Further these samples were characterized by IR technique to understand the aspect of bonding in Sm x Bi 1− x FeO 3. The dielectric constant ( ε′) and dissipation factor (tan δ) were measured as a function of frequency in the range 100 Hz–1 M Hz at room temperature. Also the variations of ε′ and tan δ with temperature were studied at certain fixed frequencies namely 1, 10, 100 kHz and 1 MHz. A peak in tan δ measurement observed for the sample x=0.4 as a function of frequency at room temperature reflects the occurrence of the relaxation process. The anomalous behavior in case of x=1 (i.e. SmFeO 3) has been observed as a function of temperature near 700 K, which is associated with antiferromagnetic transition. The DC and AC resistivity measurements were carried out using two probe methods and the results have been discussed.

Specific heat at low temperatures and magnetic measurements inNd0.5Sr0.5MnO3andR0.5Ca0.5MnO3(R=Nd,Sm, Dy, and Ho) samples

We studied the magnetization as a function of temperature and magnetic field in the compounds Nd0.5Sr0.5MnO3, Nd0.5Ca0.5MnO3, Sm0.5Ca0.5MnO3, Dy0.5Ca0.5MnO3 and Ho0.5Ca0.5MnO3. Ferromagnetic, antiferromagnetic and charge ordering transition in our samples agreed with previous reports. The intrinsic magnetic moments of Nd3+, Sm3+, Dy3+ and Ho3+ ions experienced a short range order at low temperatures. We also did specific heat measurements with applied magnetic fields between 0 and 9 T and temperatures between 2 and 30 K in all five samples. Below 10 K the specific heat measurements evidenced a Schottky-like anomaly for all samples. However, we could not successfully fit the curves to either a two level nor a distribution of two-level Schottky anomaly.

Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium

The purpose of the present work is to measure the neutron cross sections of samarium accurately. The most significant isotope is 149Sm, which has a large neutron absorption cross section at thermal energies and is a 235U fission product with a 1% yield. Its cross sections are thus of concern to reactor neutronics.Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Institute (RPI) LINAC facility using metallic and liquid Sm samples. The capture measurements were made at the 25-m flight station with a multiplicity-type capture detector, and the transmission total cross-section measurements were performed at 15- and 25-m flight stations with 6Li glass scintillation detectors. Resonance parameters were determined by a combined analysis of six experiments (three capture and three transmission) using the multilevel R-matrix Bayesian code SAMMY version M2.The significant features of this work are as follows. Dilute samples of samarium nitrate in deuterated water (D2O) were prepared to measure the strong resonances at 0.1 and 8 eV without saturation. Disk-shaped spectroscopic quartz cells were obtained with parallel inner surfaces to provide a uniform thickness of solution. The diluent feature of the SAMMY program was used to analyze these data. The SAMMY program also includes multiple-scattering corrections to capture yield data and resolution functions specific to the RPI facility.Resonance parameters for all stable isotopes of samarium were deduced for all resonances up to 30 eV. Thermal capture cross-section and capture resonance integral (RI) calculations were made using the resultant resonance parameters and were compared to results obtained using resonance parameters from ENDF/B-VI updated through release 3. Extending the definition of the capture RI to include the strong 0.1-eV resonance in 149Sm, present measurements agree within estimated uncertainties with ENDF/B-VI release 3. The thermal capture cross section was calculated from the present measurements of the resonance parameters and also agrees with ENDF within estimated uncertainties. The present measurements reduce the statistical uncertainties in resonance parameters compared to prior measurements.

Magnetic monitoring of the hydrogenation–decomposition–desorption–recombination process in SmFe-based alloys

A clear understanding of the reactions and phase changes that occur during the processing of a material is vital if we want to be able to achieve the best properties. In this series of experiments, we have used a vibrating-sample magnetometer (VSM) to monitor the magnetic state of compacted powder samples of Sm 13.7Fe 86.3 and Sm 13.8Fe 82.2Ta 4.0 during a standard hydrogenation–disproportionation–desorption–recombination (HDDR) cycle. The samples were mounted in the VSM and heated at 4°C/min in 1 bar of flowing hydrogen to 750°C, they were then held for 60 min under hydrogen and approximately 120 min under vacuum before being cooled to room temperature under vacuum at 4°C/min. The results show that the initial absorption of hydrogen by the Sm 2Fe 17-type phase results in an increase in magnetization as well as T C. At higher temperatures, the disproportionation reactions of the Sm 13.7Fe 86.3 and Sm 13.8Fe 82.2Ta 4.0 materials were observed to proceed at a faster rate for the second and third cycles of the HDDR procedure than for the first. The results are in agreement with our previous transmission electron microscopy studies, which showed that much of the Ta that was initially dissolved in the Sm 2Fe 17-type phase of the cast Sm 13.8Fe 82.2Ta 4.0 material was reformed as Ta-based precipitates after a single HDDR cycle leaving the Sm 2Fe 17-type phase with much less dissolved Ta.

Enhancement of low-field magnetoresistance in Ce doped manganite Sm 0.55Sr 0.45MnO 3

We report on the magnetization, resistivity and magnetoresistance measurements on polycrystalline samples of Sm 0.55Sr 0.45− x Ce x MnO 3 ( x=0 and 0.05). Substitution of Ce( x=0.05) reduced the para–ferromagnetic transition from ∼140 K ( x=0) to ∼90 K. For x=0, the colossal magnetoresistance (CMR) (−100( ρ B − ρ 0)/ ρ 0) effect of 55% (143 K) was observed in a field of 0.6 Oe. On the other hand, for the x=0.05 sample, at 93 K, the CMR effect which was 32% in the field of 65 Oe increased to 87% in the field of 0.6 T. Our data rule out grain boundary effects as the principal cause but point out the applicability of the phase separation model.

Hydrodesulfurization of thiophene over synthetic cobalt-containing smectite-like mesoporous materials

Mesoporous smectite-like materials containing cobalt, SM(Co), were synthesized by a hydrothermal method under different conditions. The materials were used as catalysts for hydrodesulfurization (HDS) of thiophene. The SM(Co) sample is a new type of active HDS catalyst. The activity depends on the synthetic conditions used, but the product distribution does not change so much, giving trans-2-butene, cis-2-butene, and 1-butene with a minor product of n-butane. The high HDS activity of SM(Co) samples may be explained by higher degrees of cobalt dispersion due to the method of preparation used. In addition, the treatment of SM(Co) samples with ammonia solution is effective in enhancing their HDS activities, in particular for originally less active ones. The treatment removes Na + species involved and this may suppress structural changes of SM(Co) samples by HDS reactions. The ammonia-treated samples maintain high surface area and include much lower concentrations of Na + species, which would have a negative effect on the activity, and so they indicate enhanced HDS activity.