Wyniki wyszukiwania - BazTech

1

Crystal-to-crystal investigations of highly thermally stable three-dimensional coordination polymer based on sodium(I) ions and 4,4’-stilbenedicarboxylic acid

Groszek Marcin, Łyszczek Renata, Ostasz Agnieszka, Vlasyuk Dmytro

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 4

art. no. 172683

EN

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.

2

Metal Pillared Bentonite Synthesis and Its Characteristics Using X-Ray Diffraction

Sisnayati, Said Muhammad, Aprianti Nabila, Komala Ria, Dwipayana Hendra, Faizal Muhammad

Journal of Ecological Engineering

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2022

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Vol. 23, nr 12

68--74

EN

Modification of bentonite by the Al/Fe metal oxide pillarization process was carried out with metal oxides. The bentonite pillars were successfully characterized using an X-Ray Diffraction (XRD) spectrophotometer. The results of XRD characterization showed the peak diffraction angle (2θ) in metal-pillared bentonite was 26.84° at 698.98 cps. Meanwhile, in thermally and chemically activated bentonite, the peak angles were marked at 20.64° and 26.7°. There is a shift in the peak angle after activation and pillarization. XRD patterns showed dioctahedral smectite and quartz accessory minerals.

3

Rietveld crystal structure refinement of the natural rhombohedral grossular-andradite garnet from Serbia

Tančić Pavle, Kremenović Aleksandar

Geological Quarterly

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2022

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Vol. 66, No. 1

art. no. 7

EN

Four macroscopically visible B–E (rim) zones of the natural grossular-andradite garnet with Grs58-64subAdr36-42>Sps2composition were crystallographically studied. The applied procedure includes the Rietveld refinements of the crystal structures in a series of six space groups, which were followed by the comparative analysis of the R-values, site occupancy factors, and the bond lengths and angles. It was established that it crystallized in the rhombohedral R-3c space group. Various polyhedral distortions and structural order-disorder variations between the studied zones were also observed, determined and discussed. Therefore, rhombohedral symmetry of the studied grandite could be treated as primary and residual strain as the second cause for its slight optical anisotropy.

4

Kwas hypodifosforowy i jego sole nieorganiczne

Kinzhybalo Vasyl, Otręba Marta, Ślepokura Katarzyna, Lis Tadeusz

Wiadomości Chemiczne

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2021

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[Z] 75, 3-4

423--466

EN

Hypodiphosphoric acid is the lower oxoacid of phosphorus of H4P2O6 composition. It contains the direct P—P bond, in contrast to its closest analog - pyrophosphoric acid, H4P2O7. In comparison to other phosphates the knowledge on hypodiphosphoric acid and its inorganic salts is quite limited. Since its discovery almost 150 years ago, establishment of the proper molecular and structural formula of the acid has initiated intensive research and dispute in the literature, which was decisively ended in 1964, when the first complete X-ray crystal structure determination of diammonium hypodiphosphate was reported. Since then structural studies have led to the discovery of ferroelectric properties in the above-mentioned diammonium salt and dehydration-induced staggerer-eclipsed transformation of hypodiphosphate in tetrabutylammonium salt, experimental electron density distribution determination in cubic tetralithium hexahydrate and last but not least crystal structure elucidation of hypodiphosphate analogs of adenosine diphosphate. In this mini-review the information on synthesis techniques, chemical and physical properties, applications of hypodiphosphates along with crystallochemical description of reported up-to-date crystal structures are presented.

5

Application of mixed collectors on quartz-feldspar by fluorine-free flotation separation and their interaction mechanism : a review

Li Peiyue, Ren Zijie, Xie Enjun, Duan Shutong, Gao Huimin, Wu Jianxin, He Yuhao

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 4

139--156

EN

Quartz and feldspar are usually exist in symbiosis in nature, and they are difficult to be separated effectively by conventional physical methods owing to their similarities in crystal structures and surface characteristics. Flotation is the most resultful method, and especially, flotation with hydrofluoric acid (HF) is the most efficient way. Because HF may cause serious environmental and health problems, the effective and environmentally friendly separation of quartz and feldspar remains a formidable challenge. The crystal structure, surface broken bonds, surface energy, and solid–liquid interface properties of quartz and feldspar are investigated in this paper. In particular, some types of mixed cationic/anion collectors and their interaction mechanism on the quartz and feldspar surfaces with acidic, alkaline, and neutral media in the absence of fluorine are discussed, and the grade and scheme of quartz and feldspar for the practical application are illustrated. This review proposes concrete research approaches and provides perspectives for the advanced processing of quartz and feldspar in an environmentally friendly and economical way.

6

Dopant ions size impact on structural properties of ordered poly(3,4-ethylenedioxythiophene) systems

Śniechowski Maciej, Kozik Tomasz A., Łużny Wojciech

Polimery

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2020

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T. 65, nr 9

639--643

EN

The purpose of this work was to determine whether the structures of ordered part of novel poly(3,4-ethylenedioxythiophene) PEDOT : OTf (doped with trifluoromethanesulfonate anions) and PEDOT : HSulf (doped with hydrogensulfate anions) systems could really be simply the layered structure of PEDOT : Tos (doped with tosylate anions) with the counter ion changed to the appropriate one. Insight into this problem could be provided by molecular dynamics simulations but also by swarm intelligence optimization, developed earlier for the purpose of investigating the other structures.

PL

Zbadano zdolność struktury uporządkowanej części nowych układów domieszkowanych poli(3,4-etylenodioksytiofenu) (PEDOT) [PEDOT : OTf (domieszkowane anionami trifluorometanosulfonianowymi) i PEDOT : HSulf (domieszkowane anionami wodorosiarczanowymi)] do powielania znanej z literatury warstwowej struktury PEDOT : Tos (domieszkowane anionami tosylanowymi) z jonem domieszki zmienionym na odpowiedni. Poszukiwania nowych struktur wspomagano symulacjami dynamiki molekularnej, a także z zastosowaniem optymalizacji opartej na algorytmach inteligencji stadnej.

7

Synthesis, growth and studies of pristine and nickel doped L-valinium picrate crystals for organic light emitting diodes applications

Ragunathan A. S., Selvapandiyan M.

Materials Science Poland

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2020

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Vol. 38, No. 2

374--380

EN

Single crystals of L-Valinium Picrate (LVP), 0.1 mol% Ni2+ doped L-Valinium Picrate, and 0.2 mol% Ni 2+ doped L-Valinium Picrate were grown by low temperature solution growth method, especially by solvent evaporation technique at ambient temperature. Function groups and modes of vibration were identified by FT-IR studies. The grown crystals belong to monoclinic system which has been revealed by powder XRD. The estimated band gaps were found to be 3.86 eV for LVP, 3.72 eV for 0.1 mol% Ni2+ doped LVP, and 3.70 eV for 0.2 mol% Ni2+ doped LVP crystals, respectively. The PL excitation wavelength of the grown materials is 370 nm. All the elements (C, N, O, Ni, and Cl) as per molecular formula were present in the EDAX spectrum of the grown materials. The 0.2 mol% Ni2+ ion doped LVP materials had higher thermal stability (208 °C) than LVP and 0.1 mol% Ni2+ doped LVP.

8

X-Ray Diffraction Study of Bismuth Layer-Structured Multiferroic Ceramics

Lisińska-Czekaj A., Czekaj D., Garbarz-Glos B., Bąk W., Kuźniarska-Biernacka I.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 2

811--815

EN

Goal of the present research was to apply a solid state reaction route to fabricate bismuth layer-structured multiferroic ceramics described with the formula Bi5FeTi3O15 and reveal the influence of processing conditions on its crystal structure and phase composition. Simple oxide powders Bi2O3, TiO2 and Fe2O3 were used to fabricate Aurivillius-type bismuth layer-structured ferroelectrics. Pressureless sintering in ambient air was employed and the sintering temperature was TS = 900°C, TS = 1000°C and TS = 1040°C. The phase composition as well as crystal structure of ceramics sintered at various processing conditions was examined with powder X-ray diffraction method at room temperature. The Rietveld refinement method was applied for analysis of X-ray diffraction data. It was found that ceramics adopted orthorhombic structure Cmc21. The unit cell parameters of bismuth layer-structured multiferroic ceramics increased slightly with an increase in sintering temperature.

9

Structural and thermal properties of Zn-containing magnesium aluminate spinels obtained by wet chemical method

Kaygili Omer, Bulut Niyazi, Ates Tankut, Ercan Ismail, Koytepe Suleyman, Seckin Turgay, Tatar Cengiz, Gunduz Bayram, Kebiroglu Hanifi

Materials Science Poland

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2019

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Vol. 37, No. 2

238--243

EN

In the present study, the dopant effect of Zn on the crystal structure, thermal properties and morphology of magnesium aluminate (MgAl₂O₄) spinel (MAS) structure was investigated. A pure and two Zn-containing MASs (e.g. MgAl_1.93Zn_0.07O and MgAl_1.86Zn_0.14O) were synthesized for this purpose via a wet chemical method, and the as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy techniques. It was found that the crystal structure, thermal properties and morphology of the MAS system change with the increase in the amount of Zn. MgO phase formation was observed. The values of the lattice parameter, unit cell volume and crystallite size increased, and the crystallinity percentage decreased. The morphology was also affected by adding of Zn.

10

Enhancement of yttrium ion on the properties of L-histidine nitrate single crystal for frequency conversion applications

Sathiyanathan S., Selvapandiyan M.

Materials Science Poland

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2019

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Vol. 37, No. 4

615--621

EN

Nonlinear optical single crystals of L-histidine nitrate (LHN) as well as 0.05 mol % Y2+ doped LHN and 0.10 mol % Y2+ doped LHN were successfully grown by slow evaporation technique at room temperature. The lower cutoff wavelength and transmittance were 339 nm, 343 nm, 347 nm and 84 %, 86 % and 87 % for LHN, 0.05 mol % and 0.10 mol % yttrium doped LHN, respectively. Powder XRD studies revealed that the grown materials belong to an orthorhombic system with the space group P212121. FT-IR peak at 534 cm−1 due to yttrium coordinated with oxygen was observed. The EDAX analysis confirmed the presence of such elements as C, N, O and Y in the grown materials. High intensity PL emission peak was obtained at 420 nm.

11

Aging effect of the precursor solution on the structural, morphological and opto-electrical properties of spray deposited CdO thin films

Raja N., Nagarethinam V. S., Balu A. R.

Materials Science Poland

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2019

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Vol. 37, No. 1

1--7

EN

Nanostructured CdO thin films have been prepared on glass substrates by spray pyrolysis technique using perfume atomizer from fresh and aged (1, 2, 3 and 4 days) precursor solutions. XRD studies confirm that all the films exhibit cubic crystal structure with a (1 1 1) preferential orientation. The preferential orientation factor f(1 1 1) increases with an increase in aging the period of precursor solution. The 2θ value of the (1 1 1) plane shifts towards lower Bragg angles with aging inferring an expansion in the lattice volume of the aged films. Increased crystallite size is observed for the 3-days aged film for which minimum strain and dislocation density values are obtained. Optical transparency increases with an increase in aging period of the precursor solution and the optical band gap exhibits a red shift from 2.48 eV to 2.32 eV. Minimum resistivity of 0.78 × 10−2 Ω·cm is observed for the CdO film prepared from 3-days aged solution. The obtained results infer that the CdO film prepared from 3-days aged solution exhibits better physical properties than the others.

12

Stabilization of the cubic γ-U structure in U-T alloys (T = Mo, Pt, Nb, Ru, Ti)

Sowa Sylwia, Kim-Ngan Nhu-Tarnawska Hoa, Krupska-Klimczak Magdalena, Buturlim Volodymyr, Drozdenko Daria, Minarik Peter, Havela Ladislav

Journal of Machine Construction and Maintenance - Problemy Eksploatacji

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2019

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no. 1

39--46

EN

We present the results of the stabilization of the γ-U phase with a cubic structure in U-T alloys by means of combined ultrafast cooling (with a cooling rate 106 K/s) and doping with alloying elements in the VI and VIII group (T = Mo, Pt, Nb, Ru, Ti). The X-ray diffraction data have confirmed the cubic structure presented in all U-T alloys with the alloying element content T≥15 at.% (atomic percentage concentration). Some results of the microstructure analysis, phase distribution and orientation of selected samples by using electron backscatter diffraction are also shown.

PL

Zaprezentowaliśmy wyniki stabilizacji fazy γ-U ze strukturą kubiczną w związkach U-T za pomocą techniki ultraszybkiego chłodzenia (z szybkością chłodzenia 106 K/s) oraz domieszkowania pierwiastkami z grup VI i VIII (T= Mo, Pt, Nb, Ru, Ti). Dane dyfrakcji rentgenowskiej potwierdziły obecność kubicznej struktury we wszystkich związkach U-T posiadających zwartość pierwiastków domieszkujących T≥15 at.% (procent atomowy). Wyniki analizy mikrostruktury, rozkładu fazowego i orientacji wybranych próbek zostały również pokazane, używając dyfrakcji wstecznego rozpraszania elektronów.

13

Crystal Structure and Thermal Behaviour of Imidazolium 2,4,5-Trinitroimidazolate

Jian Chen, Pengbao Lian, Lizhen Chen, Jianlong Wang, Jun Chen

Central European Journal of Energetic Materials

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2019

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Vol. 16, no. 4

547--563

EN

In this work, imidazolium 2,4,5-trinitroimidazolate was obtained from 2,4,5-tri-iodoimidazole in a yield of 48%. Single-crystal X-ray diffraction analysis showed that this compound belongs to the triclinic crystal system with space group P-1. Thermogravimetric-differential scanning calorimetry (TG-DSC) was performed under a nitrogen atmosphere at heating rates of 5, 10, 15 and 20 °C·min−1. Compound 3 clearly exhibits an exothermic decomposition. The activation energy (E) and pre-exponential factor (lnA) calculated by the Kissinger method were 113.67 kJ·mol−1 and 25.30 s−1, respectively. The E values obtained by the FWO and KAS methods changed slightly from 103.33 to 113.69 kJ·mol−1 and from 101.52 to 111.97 kJ·mol−1, respectively, which makes us believe that its thermal decomposition can be described using only one reaction model. The Šatava-Šesták method and the compensation effect were used to study the thermal decomposition mechanism of imidazolium 2,4,5-trinitroimidazolate. [Formula] is regarded as the most appropriate thermal decomposition kinetic equation. The impact sensitivity, friction sensitivity, detonation velocity and explosion pressure of imidazolium 2,4,5-trinitroimidazolate were 43 cm, 46%, 7056.9 m·s−1 and 1.9703 · 1010 Pa (ρ = 1.538 g·cm−3), respectively. Imidazolium 2,4,5-trinitroimidazolate is incompatible with RDX, HMX, TKX-50 and CL-20.

14

Magnetoresistance effect in layered cobaltite Sr0.9Y0.1CoO2.63

Bushinsky M., Tereshko N., Mantytskaya O., Fedotova V., Lanovsky R.

Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej

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2018

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Nr 13

105--114

EN

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.

PL

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.

15

Molekularne materiały magnetyczne

Löffler M., Gałkowska A., Korabik M., Utko J., Lis T.

Wiadomości Chemiczne

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2018

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[Z] 72, 7-8

523--541

EN

The „molecular” term appears more and more often in the materials chemistry. The Nobel Prize in 2016 was awarded to Jean-Pierre Sauvage, Sir J. Fraser Stoddart and Bernard R. Feringa „for the design and synthesis of molecular machines”. Magnetism in molecular scale, also known as molecular nanomagnetism, has been developing intensively since the second half of the last century. This branch of science involves the magnetic properties of coordination compounds of d- and f-electron metals. The paper presents results of the magnetic studies of molecular magnets of copper(II) and dysprosium(III), which have been pursuing in two doctoral thesis. The compounds form trinuclear and triangular molecules. The spin frustration phenomenon observed in the triangular relationship of copper(II) has been described. Since dysprosium(III) ion is characterized by a large magnetic anisotropy, the triangular, trinuclear coordination compound of dysprosium(III) of the formula [Dy3L5HLCl4]∙HL (where HL = 2-methoxyethanol) presents the characteristic properties of molecular magnets (SMMs) behavior. Two values of the energy barier were determined as Ueff/kB = 84,6 K and 31,2 K with the corresponding relaxation times τ0 = 1,82·10-6 s and 5,19·10-5 s. The data are probably attributed to different geometry of the coupled dysprosium ions.

16

Kompozytowe elektrody dla ogniw SPCFC

Skubida W., Cichy K., Świerczek K.

Materiały Ceramiczne

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2018

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T. 70, nr 2

138--151

PL

Celem niniejszej pracy było opracowanie kompozytowych elektrod dla ogniw SPCFC (ang. symmetrical proton ceramc fuel cell). W pracy zaprezentowano wyniki badań strukturalnych dwóch związków zsyntezowanych metodą wysokotemperaturowej reakcji w fazie stałej: materiału elektrolitowego Ba0,9La0,1Zr0,25Sn0,25In0,5O3−δ oraz elektrodowego SrFe0,75Mo0,25O3-δ. Niezależnie od warunków syntezy, oba tlenki przyjęły strukturę krystaliczną perowskitu prostego (grupa przestrzenna Pm-3m). Na drodze wysokotemperaturowych pomiarów dyfrakcyjnych wykazano również, że symetria Pm-3m dla obu związków utrzymuje się w całym analizowanym zakresie temperatur, tj. od 25 °C do 900 °C. Wartości współczynników rozszerzalności termicznej wyniosły dla elektrolitu i elektrody odpowiednio 12,4(2)∙10-6 K-1 i 18,5(4)∙10-6 K-1. Przedstawione zostały również wyniki elektrochemicznych pomiarów przewodnictwa gęstego spieku materiału elektrolitowego (ponad 95% gęstości teoretycznej) oraz ogniwa z kompozytowymi elektrodami w układzie symetrycznym, skonstruowanego w oparciu o badane materiały ceramiczne. Badania przeprowadzono w atmosferach nawilżonego powietrza syntetycznego i mieszaniny

EN

The main aim of this work was to develop composite electrodes for SPCFC (Symmetrical Proton Ceramic Fuel Cell). The paper presents the results of structural studies of two compounds synthesized by the solid state high-temperature reaction: electrolyte Ba0.9La0.1Zr0.25Sn0.25In0.5O3-δ and electrode SrFe0.75Mo0.25O3-δ. Regardless of the synthesis conditions, both oxides adopted the cubic perovskite crystalline structure (space group Pm-3m). By means of high-temperature diffraction measurements, it was also shown that Pm-3m symmetry for both compounds is maintained throughout the analyzed temperature range, i.e. from 25 °C to 900 °C. The values of coefficients of thermal expansion were calculated to be 12.4(2)∙10-6 K-1 and 18.5(4)∙10-6 K-1 for the electrolyte and the electrode, respectively. The results of electrochemical measurements of conductivity of dense electrolyte material sinter (above 95% of theoretical density) and a cell with composite electrodes in a symmetrical system constructed on the basis of studied ceramics are also presented. The tests were carried out in atmospheres of humidified synthetic air and Ar/H2 mixture. The total cell conductivity was 3.80•10-4 S•cm-1 at 500 °C.

17

Synthesis, growth, structural, thermal and third order nonlinear optical properties of novel organic single crystal: 4-methylpyridinium 3-nitrophthalate

Reena Devi S., Suresh S., Kalaiyarasi S., NizamMohideen M., Mohan Kumar R.

Materials Science Poland

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2018

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Vol. 36, No. 4

597--608

EN

A novel 4-methylpyridinium 3-nitrophthalate (4MP3NP) was synthesized and the crystals were grown by using slow evaporation method. The structural data of the grown crystal was collected by single crystal X-ray diffraction. It revealed that the 4MP3NP crystal belongs to triclinic crystal system with a space group P1. Structure of the synthesized compound was established using SHELXL 97 program package. The crystalline nature and composition of the grown crystal was established using high resolution X-ray diffraction and FT-IR analyses. UV-Vis transmittance and photoluminescence studies revealed the optical transmission window and electronic transition mechanism of ions, respectively. The laser damage threshold of the grown crystal was estimated by Nd:YAG laser and these results were mutually related to specific heat capacity of the grown crystal. The third-order nonlinear optical susceptibility of the grown crystal was studied by Z-scan technique.

18

Substitutional effect of copper on the cation distribution in cobalt chromium ferrites and their structural and magnetic properties

Zeeshan T., Anjum S., Iqbal H., Zia R.

Materials Science Poland

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2018

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Vol. 36, No. 2

255-263

EN

A series of copper substituted cobalt chromium ferrites, CuxCo1 - xCr0.5Fe1.5O4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) has been synthesized, by employing powder metallurgy method. Calcination of the samples has been carried out for 24 hours at 1100 °C. The resultant materials have been investigated by using a variety of techniques, including X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM)), scanning electron microscopy (SEM), and ultraviolet visible spectroscopy (UV-Vis). The XRD patterns confirmed that all compositions had a cubic spinel structure with a single phase and the lattice parameter was found to increase with increasing copper concentration. FT-IR spectroscopy has been used for studying the chemical bonds in the spinel ferrite. Shifting of the bands ν1 and ν2 has been observed. It has been revealed from VSM analysis that saturation magnetization and coercivity decrease with rising the Cu+2 doping. Magnetic properties have been explained on the basis of cation distribution. Scanning electron microscopy (SEM) has been used to study the surface morphology of prepared samples. UV-Vis analysis revealed the optical absorption of the samples. An increase in band gaps has been observed with increasing copper concentration in the sample.

19

Influence of dopants on structure of polycrystalline bismuth niobate

Czekaj D., Lisińska-Czekaj A.

Advances in Materials Science

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2018

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Vol. 18, nr 4(58)

35--41

EN

Bismuth niobate (BiNbO4) has attracted attention as a low-fired ceramics with promising microwave application potential. BiNbO4 ceramics was fabricated by mixed oxide method and sintered at temperature T<1000°C. As the sintering aids a small amount of CuO oxide was used. The crystalline structure of the ceramic samples was examined by X-ray diffraction method at room temperature. The Rietveld refinement method was used for analysis of diffraction data. As a result an influence of dopants on crystal structure of bismuth niobate (BiNbO4) ceramics was revealed. It was found that fabricated BiNbO4 ceramics adopted the orthorhombic symmetry (α-BiNbO4 phase, Pnna (52) space group). Small differences in elementary cell parameters were found.

20

Struktura a nieelastyczne rozpraszanie neutronów przez kryształy molekularne z wiązaniami wodorowymi

Rok M., Bator G., Sobczyk L.

Wiadomości Chemiczne

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2017

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[Z] 71, 7-8

533--557

EN

The molecular crystals, which are built of organic or organic-inorganic molecules, are characterized by the weak intermolecular interactions. From the viewpoint of the potential applications in electronics or optoelectronics the electric properties of the crystals are essential. In turn these properties are related to their crystal structure as well as the dynamics of the molecules in the solid state. The existence of the hydrogen bonds in the crystal structures, conventional and unconventional, is crucial from the viewpoint of the electric properties of the crystals. The dynamics of methyl groups present in the structure can be a measure of the molecular interactions in the crystals. In this work the dynamical properties, first of all taking into account the research results concerning the neutron scattering, will be discussed. The neutron technique is very effective as regards the methyl group dynamics investigations. The relationship between a formation of the conventional and unconventional hydrogen bonds and a tunneling of the methyl groups at low temperature will be discussed. The method of the interpretation of the INS spectra will be described taking into account the theoretical model, the parameters of which are fitted to the experimental data. The examples will regard the following molecular crystals: p-N,N’-1,10-tetraacethyldiaminodurene (TADD) (Figs. 2 and 4), 2,3,5,6-tetramethylpyrazine with chloranilic acid (TMP·CLA) (Figs. 5, 6 and 7), 2,3,5,6- tetramethylpyrazine with bromanilic acid (TMP·BRA) (Figs. 5 and 6) and the crystal of 3,4,7,8-tetramethylphenantroline (Me4phen) and its complex with picric acid (Me4phen·PIC) (Figs. 8 and 9). In this paper we have shown that the surrounding of the methyl group and its interactions with the adjacent molecules has a stronger effect than the changes in the electronic charge density in the molecule.