scholarly journals Суперсверхтонкая структура спектров ЭПР примесных ионов Nd-=SUP=-3+-=/SUP=- во флюорите CaF-=SUB=-2-=/SUB=-

2018 ◽  
Vol 60 (5) ◽  
pp. 910
Author(s):  
Л.К. Аминов ◽  
М.Р. Гафуров ◽  
И.Н. Куркин ◽  
Б.З. Малкин ◽  
А.А. Родионов
Keyword(s):  
Single Crystal ◽  
Microwave Power ◽  
Small Addition ◽  
Epr Spectrum ◽  
Superhyperfine Structure ◽  
Superhyperfine Interaction ◽  
Fluorine Ions ◽  
First Time

AbstractEPR spectra of a CaF_2 single crystal that was grown from melt containing a small addition of NdF_3 were studied. Signals corresponding to tetragonal centers of Nd^3+ ions and cubic centers of Er3+ and Yb3+ ions were found. Superhyperfine structure (SHFS) in the spectra of the Nd^3+ ions was observed for the first time in this crystal; parameters of the superhyperfine interaction of the Nd^3+ ions with the nearest nine fluorine ions were determined. The dependence of the resolution of the Nd^3+ EPR spectrum SHFS on the incident microwave power at the temperature of T ≈ 6 K was studied. Obtained results are discussed and compared with the literature data.

Influence of Metal Substitution on the Pressure-Induced Phase Change in Flexible Zeolitic Imidazolate Frameworks

2018 ◽  
Author(s):  
C. Michael McGuirk ◽  
Tomče Runčevski ◽  
Julia Oktawiec ◽  
Ari Turkiewicz ◽  
mercedes K. taylor ◽  
...  
Keyword(s):  
Phase Change ◽  
Single Crystal ◽  
Gas Adsorption ◽  
High Capacity ◽  
Phase Changes ◽  
Zeolitic Imidazolate Frameworks ◽  
Metal Substitution ◽  
Heat Management ◽  
Metal Organic ◽  
First Time

<p>Metal–organic frameworks that display step-shaped adsorption profiles arising from discrete pressure-induced phase changes are promising materials for applications in both high-capacity gas storage and energy-efficient gas separations. The thorough investigation of such materials through chemical diversification, gas adsorption measurements, and <i>in situ </i>structural characterization is therefore crucial for broadening their utility. We examine a series of isoreticular, flexible zeolitic imidazolate frameworks (ZIFs) of the type M(bim)<sub>2</sub> (SOD; M = Zn<sup> </sup>(ZIF-7), Co (ZIF-9), Cd (CdIF-13); bim<sup>–</sup> = benzimidazolate), and elucidate the effects of metal substitution on the pressure-responsive phase changes and the resulting CO<sub>2</sub> and CH<sub>4</sub> step positions, pre-step uptakes, and step capacities. Using ZIF-7 as a benchmark, we reexamine the poorly understood structural transition responsible for its adsorption steps and, through high-pressure adsorption measurements, verify that it displays a step in its CH<sub>4 </sub>adsorption isotherms. The ZIF-9 material is shown to undergo an analogous phase change, yielding adsorption steps for CO<sub>2</sub> and CH<sub>4</sub> with similar profiles and capacities to ZIF-7, but with shifted threshold pressures. Further, the Cd<sup>2+</sup> analogue CdIF-13 is reported here for the first time, and shown to display adsorption behavior distinct from both ZIF-7 and ZIF-9, with negligible pre-step adsorption, a ~50% increase in CO<sub>2</sub> and CH<sub>4</sub> capacity, and dramatically higher threshold adsorption pressures. Remarkably, a single-crystal-to-single-crystal phase change to a pore-gated phase is also achieved with CdIF-13, providing insight into the phase change that yields step-shaped adsorption in these flexible ZIFs. Finally, we show that the endothermic phase change of these frameworks provides intrinsic heat management during gas adsorption. </p>

Influence of alloying systems on the properties of single crystal nickel-based superalloys

2021 ◽  
Vol 112 (10) ◽  
pp. 794-799
Author(s):  
Alexander Glotka ◽  
Vadim Ol’shanetskii
Keyword(s):  
Single Crystal ◽  
Regression Models ◽  
Strength Properties ◽  
Term Limits ◽  
Alloying Elements ◽  
Structure Stability ◽  
Plastic Properties ◽  
Crystal Lattices ◽  
Predictive Regression ◽  
First Time

Abstract The purpose of the investigation was to obtain the predictive regression models that help correct the calculation of the mechanical properties of single crystal nickel-based superalloys without conducting prior experiments. The paper considers the influence of alloying elements on their tendency to form phases in foundry nickel-based superalloys. Using the elements influence on the phase formation, the coefficient Kc’ of the ratio of alloying elements for this class of alloys was set for the first time. We have revealed the short correlation of the ratio Kc’ with the dimensional misfit of γ and γ’ crystal lattices. Also, a high probability to predict the misfit for multicomponent nickel systems is shown, which significantly affected the strength properties. The regression models of correlation dependencies on the dimensional γ/γ’- misfit were offered to predict the short-term and long-term limits of the strength of alloys. We determined the operating temperature at which the misfit value should decrease to zero. The structure stability should increase because of the structural stresses minimizing. This has a positive effect on strength and plastic properties.

The effect of device geometry and crystal orientation on the stress-dependent offset voltage of 3C–SiC(100) four terminal devices

2015 ◽  
Vol 3 (34) ◽  
pp. 8804-8809 ◽  
Author(s):  
Afzaal Qamar ◽  
Hoang-Phuong Phan ◽  
Jisheng Han ◽  
Philip Tanner ◽  
Toan Dinh ◽  
...  
Keyword(s):  
Single Crystal ◽  
Crystal Orientation ◽  
Offset Voltage ◽  
Device Geometry ◽  
Stress Dependent ◽  
P Type ◽  
The Impact ◽  
First Time

This communication reports for the first time, the impact of device geometry on the stress-dependent offset voltage of single crystal p-type 3C–SiC four terminal devices.

scholarly journals Eightfold Electrophilic Methylation of Octacyanotungstate [W(CN)8]4−/3−: Preparation of Homoleptic, Eight-coordinate Methylisocyanide Complexes [W(CNMe)8]4+/5+

2021 ◽  
Author(s):  
Malte Sellin ◽  
Susanne Margot Rupf ◽  
Ulrich Abram ◽  
Moritz Malischewski
Keyword(s):  
Sulfur Dioxide ◽  
Single Crystal ◽  
Epr Spectroscopy ◽  
X Ray Diffraction ◽  
Liquid Sulfur ◽  
Methyl Fluoride ◽  
X Ray ◽  
First Time ◽  
Ir And Raman ◽  
Methyl Triflate

Homoleptic eight-fold coordinated methylisocyanide complexes of W(IV) and W(V) have been prepared for the first time. The reaction of [NBu4]4[W(CN)8] with methyl triflate MeOTf gives [W(CNMe)8][OTf]4. The even stronger methylating mixture of methyl fluoride MeF and arsenic pentafluoride AsF5 in liquid sulfur dioxide SO2 is able to fully alkylate both [NBu4]4[W(CN)8] and [NBu4]3[W(CN)8]. The paramagnetic octakis(methylisocyanide)- tungsten(V) [W(CNMe)8][AsF6]5 is thermally highly unstable above −30 °C. All compounds have been characterized via single-crystal X-ray diffraction, IR and Raman, as well as NMR or EPR spectroscopy<br>

scholarly journals Heat capacity of lithium tungstate single crystal by DSC calorimetry data in the temperature range of 319-997 K

2021 ◽  
Vol 2057 (1) ◽  
pp. 012048
Author(s):  
N I Matskevich ◽  
V N Shlegel ◽  
A A Chernov ◽  
D A Samoshkin ◽  
S V Stankus ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Phase Transitions ◽  
Single Crystal ◽  
Weight Control ◽  
Czochralski Technique ◽  
Temperature Range ◽  
First Time ◽  
Lithium Tungstate ◽  
Dsc Calorimetry ◽  
Calorimetry Data

Abstract The heat capacity of lithium tungstate single crystal (Li2WO4) was measured for the first time in the temperature range of 319-997 K. The experiments were carried out by DSC calorimetry. The Li2WO4 single crystal was first grown by low-temperature-gradient Czochralski technique with weight control. The temperature dependence of Li2WO4 heat capacity in the temperature range 319-997 K was monotonic. According to results of our studies, there were no phase transitions in Li2WO4 in the investigated temperature range.

The EPR spectrum of Os(CO)5+ trapped in a single crystal of Cr(CO)6∗

1982 ◽  
Vol 49 (2) ◽  
pp. 225-232
Author(s):  
T Lionel ◽  
J.R Morton ◽  
K.F Preston
Keyword(s):  
Single Crystal ◽  
Epr Spectrum

scholarly journals Two Dibenzoquinones from the Fungus Acremonium cavaraeanum

2017 ◽  
Vol 12 (11) ◽  
pp. 1934578X1701201
Author(s):  
Qiao Xu ◽  
Miao-Miao Zhang ◽  
Shu-Zhen Yana ◽  
Lu-Fen Cao ◽  
Qiang Lia ◽  
...  
Keyword(s):  
Single Crystal ◽  
2D Nmr ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Time

Two symmetrical dibenzoquinone derivatives were isolated from solid cultures of the fungus Acremonium cavaraeanum. Compound 1 was new and identified as 2,7-dihydroxy-3,6,9-trimethyl-9 H-xanthene-1,4,5,8-tetraone. Compound 2 was 3,3’,6,6’-tetrahydroxy-4,4’-dimethyl-1,1’-bi- p-benzoquinone, i.e. oosporein, which was reported from A. cavaraeanum for the first time. The structure of the dibenzoquinone (1) was unambiguously elucidated using a combination of MS, IR, 1D- and 2D-NMR, and the dibenzoquinone (2) was further determined by single-crystal X-ray diffraction.

O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate: structural evidence of the decomposition product and its oxalate salt

2019 ◽  
Vol 234 (9) ◽  
pp. 613-621
Author(s):  
Marc André Althoff ◽  
Jörn Frederik Martens ◽  
Marco Reichel ◽  
Manfred Metzulat ◽  
Thomas Matthias Klapötke ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Title Compound ◽  
Analytical Methods ◽  
Decomposition Product ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rearrangement Process ◽  
Study Support ◽  
First Time

Abstract The molecular and single crystal structure of O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate oxalate, as determined by single crystal X-ray diffraction studies, is described for the first time; although this compound is well-known by industry and research from the mid-20th century. The known decomposition product of pure O,O-diethyl O-[2-(dimethylamino)ethyl] phosphorothioate could also be structurally characterized. Additionally, the compounds are characterized by recent analytical methods e.g. NMR. The findings of our study support the thesis that the isolated decomposition product must be a by-product of the thiono-thiolo rearrangement process of the title compound.

Superhyperfine structure of 25Mg in the EPR spectrum of Ir2+ in MgO

Physica B+C ◽  
1977 ◽  
Vol 86-88 ◽  
pp. 1229-1230
Author(s):  
A. Raizman ◽  
J.T. Suss ◽  
W. Low
Keyword(s):  
Epr Spectrum ◽  
Superhyperfine Structure

Indirect Coupling Constants in a Thallium Single Crystal

1974 ◽  
Vol 52 (8) ◽  
pp. 687-693
Author(s):  
J. Schratter ◽  
D. Llewelyn Williams
Keyword(s):  
Single Crystal ◽  
Angular Dependence ◽  
Line Width ◽  
Orientation Dependence ◽  
Coupling Constants ◽  
Second Moment ◽  
Indirect Coupling ◽  
First Time

We have measured the angular dependence of the line width in thallium and related it to the second moment to estimate the pseudodipolar and pseudoexchange contributions for the first two shells of neighbors. These values are very different, despite the fact that both shells have nearly the same radius, and this establishes experimentally for the first time an orientation dependence of the indirect coupling constants.

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