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Tytuł:
A comparative study on the performance of radiation detectors from the HgI2 crystals grown by different techniques
Autorzy:
Martins, J. F. T.
Costa, F. E.
dos Santos, R. A.
de Mesquita, C. H.
Hamada, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/146916.pdf
Data publikacji:
2012
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
crystal growth
iodide mercury crystal
physical vapor transport (PVT)
radiation detector
semiconductor crystal
Opis:
In this work, the establishment of a technology for HgI2 purification and crystal growth is described, aiming at a future application of this crystal as a room temperature radiation semiconductor detector. Two methods of crystal growth were studied in the development of this work: (1) physical vapor transport (PVT) and (2) saturated solution from dimethylsulphoxide (DMSO) complexes. In order to evaluate the crystals obtained using each of these methods, systematic measurements were carried out for determining the stoichiometry, structure, orientation, surface morphology and impurity of the crystal. The influence of these physicochemical properties of the crystals developed was evaluated in terms of their performance as a radiation detector. The best response to radiation was found for the crystals grown by the PVT technique. Significant improvement in the performance of HgI2 radiation detector was found, purifying the crystal by means of two successive growths by the PVT technique.
Źródło:
Nukleonika; 2012, 57, 4; 555-562
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Second phase morphology in the Zn-Ti0.1-Cu0.1 single crystals obtained at different growth rates
Morfologia drugiej fazy w monokryształach Zn-Ti0.1-Cu0.1 otrzymywanych przy różnych szybkościach wzrostu
Autorzy:
Boczkal, G.
Powiązania:
https://bibliotekanauki.pl/articles/355011.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
monokryształy
cynk
faza międzymetaliczna
crystal structure
crystal morphology
single crystal growth
zinc compounds
Opis:
The influence of growth rate on a morphology, distribution and crystallographic relationship of the intermetallic phase Zn16Ti in Zn-Ti0.1-Cu0.1 single crystals were investigated. The crystals obtained at rates in range of from 1.8mm/h to 16mm/h were tested. In all cases a strong elongation of the Zn16Ti particles along the [11-20] direction is observed. Moreover, it is found that a lamellar phase existing in the crystals develop in range of the growth rate from 6 to 10 mm/h and grows in the f10-11gplanes. In the case of the growth rate of 16mm/h oval-shaped areas of α phase (solid solution of zinc and 0.1wt.% of copper with trace content of titanium) elongated along [10-10] direction and surrounded by needle shaped precipitations are formed in the structure.
W pracy badano wpływ szybkości wzrostu monokryształów Zn-Ti0.1-Cu0.1 na morfologię, rozkład i zależności krystalograficzne fazy międzymetalicznej Zn16Ti. Do testów użyto kryształów wyhodowanych z prędkościami z zakresu od 1.8mm/h do 16mm/h. We wszystkich przypadkach zaobserwowano istnienie cząstek tylko jednej fazy Zn,sub>16Ti, wydłużonych na kierunku [11-20]. Ponadto stwierdzono, że przy szybkości wzrostu z zakresu 6 do 10mm/h, obserwowana faza międzymetaliczna ma postać płytkowa, preferująca płaszczyzny wzrostu f10-11g. W przypadku szybkości wzrostu 16mm/h zaobserwowano tworzenie się fazy iglastej, która otacza obszary czystej osnowy (roztwór stały cynku z dodatkiem 0.1% miedzi oraz niewielką zawartością tytanu) tworzące owale wydłużone na kierunku [10-10].
Źródło:
Archives of Metallurgy and Materials; 2012, 57, 2; 479-484
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystal-to-crystal investigations of highly thermally stable three-dimensional coordination polymer based on sodium(I) ions and 4,4’-stilbenedicarboxylic acid
Autorzy:
Groszek, Marcin
Łyszczek, Renata
Ostasz, Agnieszka
Vlasyuk, Dmytro
Powiązania:
https://bibliotekanauki.pl/articles/24085725.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
coordination polymer
4,4’stilbenedicarboxylic acid
crystal structure
thermal analysis
crystal-to-crystal transformation
Opis:
The new three-dimensional coordination polymer termed {[Na2SDC(H2O)]} n (SDC2-= C16H10O42-) has been synthesized using workstation Easymax 102 while controlling the conditions and monitoring in-situ reagents. The metal complex was obtained in the reaction of sodium hydroxide with a suspension of 4,4’-stilbenedicarboxylic acid in aqueous medium. The compound was characterized by elemental analysis, single crystal, and powder X-ray diffraction methods, ATR-FTIR spectroscopy, SEM and optical microscopy, TG-DSC and TG-FTIR thermal analysis in air and nitrogen atmosphere. In the crystal structure of {[Na2SDC(H2O)]} n appears penta- and hexacoordinated sodium atoms joined by octa- and decadentate SDC2- linkers. Aqua ligand acts as bridge between Na1 and Na2 atoms. The as-synthesized sodium complex is thermally stable up to 86°C whereas its dehydrated form has extreme stability up to 491°C. Removal of water molecule leads to the crystal-to-crystal transformation yielded changes in coordination modes of COO groups. Reversibility of the hydration process in the studied complex was also examined.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 4; art. no. 172683
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three Insensitive Energetic Co-crystals of 1-Nitronaphthalene, with 2,4,6-Trinitrotoluene (TNT), 2,4,6-Trinitrophenol (Picric Acid) and D-Mannitol Hexanitrate (MHN)
Autorzy:
Hong, D.
Li, Y.
Zhu, S.
Zhang, L.
Pang, C.
Powiązania:
https://bibliotekanauki.pl/articles/1063066.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
co-crystal
insensitive energetic material
crystal structure
explosive properties
Opis:
Co-crystallization is proposed as an effective method to alter the physicochemical properties of energetic materials, e.g. density, sensitivity and solubility. As reported in this paper, it was found that 1-nitronaphthalene could form cocrystals with TNT, picric acid and MHN in a 1:1 molecular ratio. The sensitivity and thermal stability of the 1-nitronaphthalene co-crystals was greatly improved compared with that of pure TNT, picric acid and MHN. In addition, the melting points of TNT, picric acid and MHN were lowered through co-crystallization with 1-nitronaphthalene. The electrostatic potential surface of 1-nitronaphthalene, calculated by the DFT method, showed that the electron-rich 1-nitronaphthalene has a tendency to be a proton donor and to co-crystallize with other energetic materials. The structures of the co-crystals of 1-nitronaphthalene with TNT and picric acid were characterized by single crystal X-ray diffraction (SXRD). The 1-nitronaphthalene/MHN co-crystal was studied by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and FTIR.
Źródło:
Central European Journal of Energetic Materials; 2015, 12, 1; 47-62
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Predicted Crystal Structures, Analysis, Impact Sensitivities and Morphology of Solid High-Energy Complexes: Alkaline-Earth Carbohydrazide Perchlorates
Autorzy:
Liu, Y.
Zhang, R.
Feng, C.-G.
Yang, L.
Zhang, T.-L.
Powiązania:
https://bibliotekanauki.pl/articles/358890.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
crystal structure
density of state
thermodynamic property
impact sensitivity
crystal morphology
Opis:
The crystal structures, density of states, energy gap, thermodynamic properties, impact sensitivities and morphology of beryllium carbohydrazide perchlorate ([Be(CHZ)3](ClO4)2), magnesium carbohydrazide perchlorate ([Mg(CHZ)3](ClO4)2), calcium carbohydrazide perchlorate ([Ca(CHZ)3] (ClO4)2), strontium carbohydrazide perchlorate ([Sr(CHZ)3](ClO4)2) and barium carbohydrazide perchlorate ([Ba(CHZ)3](ClO4)2) were investigated using the density functional theory (DFT) and crystal morphology theory. The results show that all of the complexes have six-coordinated distorted octahedra, which is different from previous works. This was rationalised by consideration of the intermolecular interactions in the crystal structures. Hence the crystal structure is now more reliable. The chemical reactions of the whole molecule may be triggered by an electron transition of CHZ or ClO4 −. Furthermore the energy gaps were observed, and the values of the impact sensitivities were inferred to have the following sequence: [Be(CHZ)3](ClO4)2 > [Mg(CHZ)3](ClO4)2 > [Sr(CHZ)3](ClO4)2 > [Ca(CHZ)3](ClO4)2 > [Ba(CHZ)3](ClO4)2. In addition, the thermodynamic equations at 25-1000 K were obtained. The positive values of the standard molar free enthalpies shows that carbohydrazide perchlorates are stable at 298.15 K. The (1 0 -1) and (0 0 2) faces are the most important growth directions of the crystal morphologies, and have the minimum growth rates. From the cleaved main growth faces, it can be deduced that surface active agents with active hydrogen atoms in the functional groups could be used as crystal-control reagents to control the crystal morphology for alkaline-earth carbohydrazide perchlorates.
Źródło:
Central European Journal of Energetic Materials; 2015, 12, 2; 229-248
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Processing Conditions on Crystal Structure of Bi6Fe2Ti3O18 Ceramics
Autorzy:
Lisińska-Czekaj, A.
Lubina, M.
Czekaj, D.
Rerak, M.
Garbarz-Glos, B.
Bąk, W.
Powiązania:
https://bibliotekanauki.pl/articles/353909.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
influence
condition
crystal structure
Opis:
Aim of the present research was to apply a solid state reaction route to fabricate Aurivillius-type ceramics described with the formula Bi6Fe2Ti3O18 (BFTO) and reveal the influence of processing conditions on its crystal structure. Pressureless sintering in ambient air was employed and the sintering temperatures were 850 and 1080 °C. It was found that the fabricated BFTO ceramics were multiphase ones. They consisted of two Bim+1Fem-3Ti3O3m+3 phases, namely the phase with m=5 (i.e. the stoichiometric phase) and m=4 (i.e. the phase with a reduced number of layers in the slab). Detailed X-ray diffraction patterns analysis showed that both phases adopted the same orthorhombic structure described with Fmm2 (42) space group. The ratio of weight fractions of the constituent phases (m=5): (m=4) was ~30:70.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 2A; 881-886
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth and study of nonlinear optical crystals at the Hungarian Academy of Sciences
Autorzy:
Földvári, I.
Polgár, K.
Péter, A.
Beregi, E.
Szaller, Z.
Powiązania:
https://bibliotekanauki.pl/articles/308743.pdf
Data publikacji:
2000
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
crystal growth
nonlinear optical materials
Opis:
The former Research Laboratory for Crystal Physics continues the growth and defect structure investigation of nonlinear optical single crystals in a new organization, as a part of the Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences. The aim of the activity is to prepare specific crystals for basic and applied research as well as for applications. We improve the quality or modify the properties of well known nonlinear oxide and borate crystals and develop new materials. The principle nonlinear optical crystals in our profile are the followings: Paratellurite (TeO2), congruent, Mg-doped and stoichiometric lithium niobate (LiNbO3), a variety of sillenite structured crystals (Bi12MeO20, Me=Si, Ge, Ti, etc.), bismuth tellurite (Bi2TeO5) and nonlinear borates (BBO-beta-BaB2O4, LBO-LiB3O5, LTB-Li2B4O7, CLBO-CsLiB6O10 and YAB-YAI3(BO3)4). Details of the crystal preparation and the major achievements are discussed in the paper.
Źródło:
Journal of Telecommunications and Information Technology; 2000, 1-2; 37-41
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prognosis of energetic compounds stability in solid phase
Autorzy:
Manelis, G. B.
Nazin, G. M.
Prokudin, V. G.
Powiązania:
https://bibliotekanauki.pl/articles/358925.pdf
Data publikacji:
2009
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
monomolecular reactions
crystal state
retarding
Opis:
Results of the analysis and specification of phenomenological models of the monomolecular reactions running homogeneously in volume of undisturbed crystal lattice or localized on its defects are presented. It is shown, that within the limits of these models it is possible to calculate with satisfactory accuracy the ratio of rate constants in liquid and solid phases KT = kliq/ksol, and thus on known kliq to predict ksol, describing stability of substance.
Źródło:
Central European Journal of Energetic Materials; 2009, 6, 1; 31-44
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of binding interactions of dibromoflavonoids with transthyretin.
Autorzy:
Muzioł, Tadeusz
Cody, Vivian
Wojtczak, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/1044031.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
dibromoflavone complex
crystal structure
transthyretin
Opis:
The crystal structure of rat transthyretin (rTTR) complex with the dibromoflavone EMD21388 was determined to 2.3 Å resolution and refined to R = 0.203 and Rfree = 0.288. Two different orientations of EMD21388, which differ in the channel penetration by 1.6 Å, were found in the A/C binding site of rTTR. The single ligand position observed in the B/D site is intermediate between the two positions found in the A/C site. The position of the dibromoflavone in the B/D site is similar to that reported for dibromoaurone in human TTR. The bromine atoms of EMD21388 form strong interactions in the P3 and P3' pockets of rTTR. Due to the different molecular architectures of both ligands, dibromoflavone forms only one interaction with Lys-15 near the channel entrance, while direct interactions with the pair of Lys-15 were reported for dibromoaurone. The C3* methyl group of EMD21388 mediates the bridging interactions between two TTR subunits in the P2 pockets. The interactions of the O2* hydroxyl group of dibromoaurone with the Thr-119 side chain in the P3 pockets are not matched by similar interactions in EMD21388. Both these alternative interactions can explain the competitive binding of 3',5'-dibromoflavonoids to transthyretin.
Źródło:
Acta Biochimica Polonica; 2001, 48, 4; 885-892
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Clinopyroxene from an alkali pyroxenite xenolith, Louená-Oberwiesenthal Volcanic Centre, Bohemian Massif: crystal chemistry and structure
Autorzy:
Ulrych, D.
Niznansky, D.
Pertlik, F.
Giester, G.
Ertl, A.
Brandstätter, F.
Powiązania:
https://bibliotekanauki.pl/articles/2058921.pdf
Data publikacji:
2006
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Krušné hory/Erzgebirge Mts.
lower crust origin
alkali pyroxenite xenoliths
crystal chemistry
crystal structure
clinopyroxene
Opis:
Alkali pyroxenite (and ijolite) xenoliths occur in the Tertiary Loučná-Oberwiesenthal Volcanic Centre associated with the Ohře/Eger Rift. The alkali pyroxenite xenoliths represent fragments of an intracrustal complex with Sr-Nd isotope ratios consistent with mantle sources of HIMU-affinity. The crystal structure of diopside from an alkali pyroxenite xenolith with the formula (...) and the lattice parameters a = 9.773(2), b = 8.886(2), c = 5.308(1) [] and = 105.89(3) [°] was refined to an R-value of 0.025 for 1174 reflections. The mean interatomic distances are: within theMe1-O6 octahedron <2.067> , within theMe2-O8 polyhedron <2.498> . The last value reflects the occupation of this atomic position by significant amounts of Fe2+ and Ti4+. The enlargement determined for the bond length to 1.657 is in accordance with the site population for this position: (Si1.69Al0.31). The molar ratio Fe2+/Fe3+ determined by Mössbauer spectroscopy is equal to 0.786. The AlIV deficiency in T-sites of clinopyroxene of rims is negligible (up to 0.019 a.p.f.u.) restricted to sporadic local electronmicroprobe analyses. The presence of Fe3+ in the T-position of Si- and Al-poor clinopyroxenes was not confirmed by X-ray structural analyses because of its low quantity. Nevertheless, the Mössbauer spectroscopy measurements (isomer shift of 0.36 mm/s) imply that Fe3+ is present only in the Me1-O6 positions.
Źródło:
Geological Quarterly; 2006, 50, 2; 257-264
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Crystal w Londynie – nowy wyznacznik w kreowaniu miast typu smart city?
The Crystal in London – a new determinant in creating smart cities?
Autorzy:
Gorgol, N. K.
Powiązania:
https://bibliotekanauki.pl/articles/345580.pdf
Data publikacji:
2017
Wydawca:
Politechnika Krakowska im. Tadeusza Kościuszki. Wydział Architektury. Katedra Kształtowania Środowiska Mieszkaniowego
Tematy:
współczesne miasto
smart city
smart building
rozwój zrównoważony
The Crystal
contemporary city
sustainable development
Crystal
Opis:
Artykuł podejmuje temat idei smart city oraz sposobu jej wdrożenia na przykładzie obiektu firmy Siemens – The Crystal w Londynie. Budynek ten jest jednocześnie obiektem typu smart building, jak i przestrzenią wystawienniczą prezentująca smart city w trzech, powiązanych ze sobą, skalach: mega, makro i mikro. Pierwsza z nich odnosi się do globalnych uwarunkowań kształtujących współczesne miasta, takich jak: coraz szybsza urbanizacja wraz z rosnącym znaczeniem miast, zmiany klimatu oraz zmiany demograficzne. Skala makro odnosi się do współczesnych miast: ich formy urbanistycznej, czy użytych instrumentów planistycznych. Skala mikro akcentuje perspektywę mieszkańca danego miasta oraz postrzeganie przez niego przestrzeni miejskiej. Autor stawia pytanie, czy zastosowana systematyka i zaprezentowane kierunki wdrażania idei smart city opartej na modelu przedstawionym w pawilonie wystawowym firmy Siemens mogą stanowić wyznacznik przy transformacji danego ośrodka.
The article tackles a problem of the smart city idea and how it has been implemented on the example of the Siemens’ building- The Crystal in London. The building is simultaneously a smart building, as well as an exhibition space presenting the smart city idea in three interconnected scales: mega, macro and micro. The mega area looks at the global megatrends which shape contemporary cities, such as: rapid urbanization with the growing importance of cities; climate change and demographic change. The macro scale refers to contemporary cities: their urban form and planning methods. The micro scale emphasizes the perspective of a inhabitant of a given city and their perception of urban space. The author poses a question whether the applied systematics and the smart city methods presented in the Siemens’ building may be a determinant in cities’ transformation.
Źródło:
Środowisko Mieszkaniowe; 2017, 19; 21-27
1731-2442
2543-8700
Pojawia się w:
Środowisko Mieszkaniowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stabilization Studies of Crystal Structure of Optimally Th-Doped Lead Zirconate Perovskite
Autorzy:
Elsabawy, Khaled M.
El-Hawary, Waheed F.
Powiązania:
https://bibliotekanauki.pl/articles/1191373.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Crystal Structure
Doping
Perovskite
Visualization
XRD
Opis:
The optimally thorium-doped Pb0.9Th0.1ZrO3 was selected for studying thorium doping effect on the structural parameters of lead zirconate crystal. The investigations were made on the low concentrations range of thorium doping 0.0 ≤ x ≤ 0.25 mole. The present investigations are concerned by confirming that thorium dopings play an important role as stabilizing agent inside internal structure of crystal lattice of Pb1-xThxZrO3 where x = 0.1 mole. XRD-measurements indicated that Thorium dopant substitutes successfully on the A-sites of lead zirconate without damaging the main crystal structure at x = 0.1 mole. Visualization and theoretical investigations were concerned by matching and comparison of bond distances ,torsions on angles of investigated compound to clarify success of thorium doping on the perovskite structure.
Źródło:
World Scientific News; 2016, 33; 56-66
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison study of crystal and electronic structures for chalcopyrite $(CuFeS_2)$ and pyrite $(FeS_2)$
Autorzy:
Li, Yuqiong
Liu, Yingchao
Chen, Jianhua
Zhao, Cuihua
Cui, Weiyong
Powiązania:
https://bibliotekanauki.pl/articles/1448811.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chalcopyrite
pyrite
crystal structures
electronic structures
Opis:
Chalcopyrite $(CuFeS_2)$ and pyrite $(FeS_2)$ are commonly associated with each other, and they both belong to semiconductor minerals. The difference in crystal and electronic structures is an important factor for their flotation separation. Using the density functional method (DFT) combined with Hubbard U correction, their crystal and electronic properties are comparatively studied. The calculated results suggest that the use of antiferromagnetic calculations and Hubbard U correction are very important to the accuracy of the chalcopyrite results. Antiferromagnetic calculations combined with a U value of 2.0 eV on chalcopyrite show a band gap of 0.53 eV, which is very consistent with the experimental results of ~0.5 eV. The density of states (DOS) and Mulliken bond population results indicate that stronger hybridization between Fe 3d and S 3p states in chalcopyrite than in pyrite leads to a stronger covalency of Fe-S bonds in chalcopyrite, causing a reduction in the spin magnetic moment (3.5 μB) from the ideal value. In addition, the greater covalency of bonds in chalcopyrite results in greater hydrophobicity of chalcopyrite than pyrite. The DOS results suggest that S has similar electronic properties in pyrite and chalcopyrite. The oxidation states of Fe and Cu ions in chalcopyrite are discussed based on the coordination field theory according to the calculation results, which confirms an oxidation state of $Fe^{3+}Cu^{1+}S_2$.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 1; 100-111
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetoresistance effect in layered cobaltite Sr0.9Y0.1CoO2.63
Autorzy:
Bushinsky, M.
Tereshko, N.
Mantytskaya, O.
Fedotova, V.
Lanovsky, R.
Powiązania:
https://bibliotekanauki.pl/articles/118492.pdf
Data publikacji:
2018
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
crystal structure
magnetic structure
magnetization
magnetoresistance
Opis:
The structure and the magnetic and magnetotransport properties of the perovskite sample Sr0.9Y0.1CoO2.63 have been studied using different diffraction methods and magnetization and conductivity measurements. Synchrotron X-ray diffraction shows that the sample is structurally two-phase. The majority phase has a tetragonally distorted unit cell and is described by the space group I4/mmm. A very strongly broadened superstructure peak observed at small angles in X-ray diffraction patterns at temperatures below 400 K are explained by the existence of a monoclinic phase with large unit cell whose phase fraction is much smaller than that of the tetragonal phase, but which is dominant in the sample Sr0.8Y0.2CoO2.65. The spontaneous magnetization strongly increases with increasing the Y content up to 20% due to formation of the monoclinic phase. The magnetic structure is predominantly antiferromagnetic G-type with magnetic moments 1.5 μB in the layers of CoO6 octahedra and 2 μB in the anion-deficient CoO4+γ layers. The electrical conductivity of the sample Sr0.9Y0.1CoO2.63 has semiconducting character. The magnetoresistance reaches 58% for the field B = 14 T at 5 K and decreases strongly with the increasing temperature and Y content.
Struktura i właściwości magnetyczne i magnetotransportowe perowskitu Sr0.9Y0.1CoO2.63 zostały zbadane przy użyciu różnych metod dyfrakcyjnych oraz pomiarów namagnesowania i przewodnictwa. Dyfrakcja rentgenowska mierzona na synchrotronie pokazuje, że próbka ma strukturę dwufazową. Główna faza ma tetragonalnie zniekształconą komórkę elementarną i jest opisana przez grupę przestrzenną I4 /mmm. Pik o bardzo mocno poszerzonej superstrukturze obserwowano pod niewielkimi kątami w dyfraktogramach rentgenowskich w temperaturach poniżej 400 K i jest związany z istnieniem fazy monoklinowej o dużej komórce elementarnej, której frakcja fazowa jest znacznie mniejsza niż faza tetragonalna, ale która jest dominujący w próbce Sr0.8Y0.2CoO2.65. Spontaniczne namagnesowanie silnie wzrasta wraz ze wzrostem zawartości Y do 20% z powodu tworzenia się fazy monoklinowej.
Źródło:
Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej; 2018, 13; 105-114
1897-7421
Pojawia się w:
Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 297

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