scholarly journals Metastable Materials Accessed under Moderate Pressure Conditions (P ≤ 3.5 GPa) in a Piston-Cylinder Press

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1946
Author(s):  
Javier Gainza ◽  
Federico Serrano-Sánchez ◽  
João Elias F. S. Rodrigues ◽  
Norbert Marcel Nemes ◽  
José Luis Martínez ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Colossal Magnetoresistance ◽  
Alkali Metals ◽  
Complete Characterization ◽  
Moderate Pressure ◽  
X Ray Diffraction ◽  
Soft Chemistry ◽  
Piston Cylinder ◽  
Jahn Teller

In this review, we describe different families of metastable materials, some of them with relevant technological applications, which can be stabilized at moderate pressures 2–3.5 GPa in a piston-cylinder press. The synthesis of some of these systems had been previously reported under higher hydrostatic pressures (6–10 GPa), but can be accessed under milder conditions in combination with reactive precursors prepared by soft-chemistry techniques. These systems include perovskites with transition metals in unusual oxidation states (e.g., RNiO3 with Ni3+, R = rare earths); double perovskites such as RCu3Mn4O12 with Jahn–Teller Cu2+ ions at A sites, pyrochlores derived from Tl2Mn2O7 with colossal magnetoresistance, pnictide skutterudites MxCo4Sb12 (M = La, Yb, Ce, Sr, K) with thermoelectric properties, or metal hydrides Mg2MHx (M = Fe, Co, Ni) and AMgH3 (A: alkali metals) with applications in hydrogen storage. The availability of substantial amounts of sample (0.5–1.5 g) allows a complete characterization of the properties of interest, including magnetic, transport, thermoelectric properties and so on, and the structural characterization by neutron or synchrotron X-ray diffraction techniques.

Kenoplumbomicrolite, (Pb,□)2Ta2O6[□,(OH),O], a new mineral from Ploskaya, Kola Peninsula, Russia

2018 ◽  
Vol 82 (5) ◽  
pp. 1049-1055 ◽  
Author(s):  
Daniel Atencio ◽  
Marcelo B. Andrade ◽  
Luca Bindi ◽  
Paola Bonazzi ◽  
Matteo Zoppi ◽  
...  
Keyword(s):  
Kola Peninsula ◽  
Northern Region ◽  
Complete Characterization ◽  
New Mineral ◽  
X Ray Diffraction ◽  
International Mineralogical Association ◽  
Cell Parameters ◽  
Mohs Hardness

ABSTRACTThis study presents a complete characterization of kenoplumbomicrolite, (Pb,□)2Ta2O6[□,(OH),O], occurring in an amazonite pegmatite from Ploskaya Mountain, Western Keivy Massif, Kola Peninsula, Murmanskaja Oblast, Northern Region, Russia.Kenoplumbomicrolite occurs in yellowish brown octahedral, cuboctahedral and massive crystals, up to 20 cm, has a white streak, a greasy lustre and is translucent. The Mohs hardness is ~6. Attempts to measure density (7.310–7.832 g/cm3) were affected by the ubiquitous presence of uraninite inclusions. Reflectance values were measured in air and immersed in oil. Kenoplumbocrolite is optically isotropic. The empirical formula is (Pb1.30□0.30Ca0.29Na0.08U0.03)Σ2.00(Ta0.82Nb0.62Si0.23Sn4+0.15Ti0.07Fe3+0.10Al0.01)Σ2.00O6[□0.52(OH)0.25O0.23]Σ1.00 (from the crystal used for the structural study) and (Pb1.33□0.66Mn0.01)Σ2.00(Ta0.87Nb0.72Sn4+0.18Fe3+0.11W0.08Ti0.04)Σ2.00O6[□0.80(OH)0.10O0.10]Σ1.00 (average including additional fragments). The mineral is cubic, space group Fd$\overline 3 $m. The unit-cell parameters refined from powder X-ray diffraction data are a = 10.575(2) Å and V = 1182.6(8) Å3, which are in accord with those obtained previously from a single crystal of a = 10.571(1) Å, V = 1181.3(2) Å3 and Z = 8. The mineral description and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2015-007a).

Thermoelectric Characterization of Ti and In Double-Doped Cobalt Antimony Thin Films

2016 ◽  
Vol 847 ◽  
pp. 143-147
Author(s):  
Ya Dan Li ◽  
Zhuang Hao Zheng ◽  
Ping Fan ◽  
Jing Ting Luo ◽  
Guang Xing Liang ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermoelectric Properties ◽  
Flexible Substrate ◽  
Rf Magnetron Sputtering ◽  
X Ray Diffraction ◽  
Alloy Target ◽  
Diffraction Peaks ◽  
Thermoelectric Thin Films ◽  
Antimony Alloy

CoSb3 thermoelectric thin films were prepared on polyimide flexible substrate by radio frequency (RF) magnetron sputtering technology using a cobalt antimony alloy target. Ti and In were added into CoSb3 thin films by co-sputtering. The influence of Ti and In on the thermoelectric properties of CoSb3 thin films was investigated. X-ray diffraction result shows that the major diffraction peaks of all the thin films match the standard peaks related to the CoSb3 phase. The sample has best thermoelectric properties when the Ti sputtering time was 1min and In sputtering time was 30 seconds.

Synthesis and Characterization of Large Single Crystals of Silicon and Germanium Clathrate-II Compounds and a New Tin Compound with Clathrate Layers

2000 ◽  
Vol 626 ◽  
Author(s):  
Svilen Bobev ◽  
Slavi C. Sevov
Keyword(s):  
Alkali Metal ◽  
Single Crystals ◽  
Alkali Metals ◽  
Measured Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mixed Alkali ◽  
Pauli Paramagnetism ◽  
Silicon And Germanium

ABSTRACTWe have synthesized large single crystals of clathrate-II compounds with frameworks of silicon and germanium by employing mixed alkali metal countercations. The combinations of alkali metals are rationally selected in order to fit the different cages of the clathrate-II structure. This approach leads to the following stoichiometric and fully “stuffed” compounds: Cs8Na16Si136, Cs8Na16Ge136, Rb8Na16Si136 and Rb8Na16Ge136. The structures and the corresponding Si-Si and Ge-Ge distances are elucidated and established with high accuracy from extensive single crystal X-ray diffraction work. The compounds are stoichiometric, metallic, and are very stable at a variety of extreme conditions such as heat, concentrated acids, hydrothermal treatment etc. No evidence was found for vacancies in the silicon and germanium networks or partial occupancies of the alkali metal sites. The stoichiometry of these fully “stuffed” clathrates is consistent with the measured temperature independent Pauli paramagnetism, supported also by the conductivity measurements on single crystals and thermopower measurements on pellets. A new compound with novel clathrate-like structure forms when small and large cations are combined with tin. The new materials, A6Na18Sn46 (A = K, Rb, Cs), are made of clathrate layers and the interlayer space filled with Sn4-tetrahedra and alkali-metal cations. Its formula can be rationalized as A6Na6Sn34 + 3·Na4Sn4 (one clathrate layer and three tin tetrahedra). The compound is stable in air and is being currently tested at other conditions. Detailed measurements of its transport properties are under way.

Bioceramic Production from Giant Purple Barnacle (Megabalanus tintinnabulum)

2014 ◽  
Vol 631 ◽  
pp. 137-142 ◽  
Author(s):  
F.N. Oktar ◽  
H. Gokce ◽  
O. Gunduz ◽  
Y.M. Sahin ◽  
D. Agaogullari ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Complete Characterization ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Hot Plate ◽  
X Ray ◽  
Fine Powders ◽  
Simple Economic ◽  
And Chemical Properties

In this study the structural and chemical properties of barnacle shell based bioceramic materials (i.e. hydroxyapatite, whitlockite, monetite and other phases) were produced by using mechano-chemical (hot-plate) conversion method. Cleaned barnacle shells were ball milled down to <75µm in diameter. Differential thermal and gravimetric analyses (DTA/TGA) were performed to determine the exact CaCO3 content. Sample batches of 2g were prepared from the fine powders produced. For each batch, the required volume of an aqueous H3PO4 solution was calculated in order to set the stoichiometric molar ratio of Ca/P equal to 1.5 for ß-tricalcium phosphate (ß-TCP) or to 1.667 for hydroxyapatite (HA). The temperature was set to 80°C for 15 minutes to complete the process. After the titration of the equivalent amount of H3PO4 into the prepared solution, agitation was carried out on a hot-plate (i.e. mechano-chemical processing) for 8 hours. The sediments formed were dried and the resulting TCP and HA powders were calcined at 400°C and 800°C respectively. For complete characterization of the bioceramics produced, scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) analyses were carried out. The current study proposes a simple, economic and time efficient method for nano-bioceramic production.

Cu0.8Mg1.2Si2O6 : a copper-bearing silicate with the low-clinopyroxene structure

2016 ◽  
Vol 80 (2) ◽  
pp. 325-335 ◽  
Author(s):  
Lei Ding ◽  
Céline Darie ◽  
Claire V. Colin ◽  
Pierre Bordet
Keyword(s):  
X Ray Diffraction ◽  
Soft Chemistry ◽  
X Ray ◽  
Cu Content ◽  
Distorted Structure ◽  
Mechanisms Of Formation ◽  
Jahn Teller ◽  
The Stability ◽  
Insight Into

AbstractThe Cu0.8Mg1.2Si2O6 pyroxene has been synthesized using a soft chemistry method. Its crystal structure was determined from powder X-ray diffraction data. Cu0.8Mg1.2Si2O6 crystallizes with the lowclinopyroxene monoclinic structure (space group P21/c). The role of the Jahn-Teller-distorted Cu2+ cation on the stability of this strongly distorted structure is investigated. Cu2+ shows a strong preference for the M2 site, attributed to a better adaptation of its JT-distorted coordination polyhedron to this already distorted and more flexible site. Comparison with previously reported compounds indicates that increasing the Cu content enhances the M2 site distortion, eventually leading to symmetry lowering from orthorhombic Pbca to monoclinic P21/c. These observations bring new insight into the mechanisms of formation and chemical composition of pyroxene minerals in the presence of JT cations.

Epitaxial La0.67(Sr,Ca)0.33MnO3 Films on Si for IR Bolometer Applications

2004 ◽  
Vol 811 ◽  
Author(s):  
A.M. Grishin ◽  
S.I. Khartsev ◽  
J.-H. Kim ◽  
Jun Lu
Keyword(s):  
Colossal Magnetoresistance ◽  
Buffer Layers ◽  
Maximum Temperature ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
High Resolution Tem ◽  
Noise Equivalent Temperature Difference ◽  
Sharp Interfaces ◽  
Heteroepitaxial Layers

ABSTRACTWe report on processing and properties of La0.67(Sr,Ca)0.33MnO3(LSCMO) films grown by pulsed laser deposition technique on Si(001) substrates buffered with Bi4Ti3O12/CeO2/YSZ heteroepitaxial layers. X-ray diffraction shows cube-on-cube growth of epitaxial Bi4Ti3O12/CeO2/YSZ/Si heterostructure whereas the LSCMO layer grows in the “diagonal-on-side” manner onto the Bi4Ti3O12 (BTO) template. High resolution TEM images demonstrate sharp interfaces between the buffer layers and LSCMO film as well as rare misfit dislocations on the CeO2/YSZ interface. LSCMO film processing conditions have been optimized to get maximum temperature coefficient of resistivity TCR = 4.4%K-1 and colossal magnetoresistance(CMR) ‘Delta;ρ/ρ ∼ 2.9%kOe-1 @ 294K. Almost ultimate CMR performance at room temperature has been achieved due to successive improvement of c-axisorientation of layers: full widths at half-maximum (FWHM) 0.65, 0.58, 0.65, 1.13 and 0.18 degrees in LSCMO/BTO/CeO2/YSZ/Si stack, respectively. Characterization of electrical noise in CMR film yields noise equivalent temperature difference (NETD) as low as 1.2 ‘mu;K/√Hz @ 30Hz and 294K.

Synthesis and characterization of N-silylated, C1-symmetric benzamidinates of lithium, sodium, and tin(II)

2006 ◽  
Vol 84 (2) ◽  
pp. 269-276 ◽  
Author(s):  
Floria Antolini ◽  
Peter B Hitchcock ◽  
Alexei V Khvostov ◽  
Michael F Lappert
Keyword(s):  
Nmr Spectra ◽  
Alkali Metals ◽  
Membered Ring ◽  
Molecular Structures ◽  
Synthesis And Characterization ◽  
Neutral Ligand ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ligand Free

The synthesis and characterization of complexes obtained from the reactions between Li[N-t-Bu(SiMe3)] (A) or the sodium analogue Na[N-t-Bu(SiMe3)] (B) and the cyanoarene RCN (R = Ph or 4-MeOC6H4) are discussed. These are the THF adduct [Li{µ-cis-N(t-Bu)C(Ph)N(SiMe3)}(THF)]2 (1), the TMEDA adduct Li[N(t-Bu)C(Ph)N(SiMe3)](TMEDA) (2), the neutral ligand-free lithium benzamidinate Li[N(t-Bu)C(C6H4OMe-4)N(SiMe3)] (3), and the THF adduct Li[N(t-Bu)C(C6H4OMe-4)N(SiMe3)](THF) (3a). The preparation and structure of the crystalline compound [Na{µ-cis-N(t-Bu)C(Ph)N(SiMe3)}(OEt2)]2 (4) is described. From the lithium benzamidinate 1 and Sn(II) chloride the tin(II) complex [Sn{N(t-Bu)C(Ph)N(SiMe3)}2] (5) was obtained. The molecular structures of the crystalline compounds 1, 4, and 5 were established by X-ray diffraction. In 1 and 4 the benzamidinato ligand is both chelating and bridging, with the Me3Si-substituted nitrogen atom as the bridging site. The central planar (MN)2 four-membered ring is a rhombus in 1, with almost equal Li—N bond lengths, whereas in 4 the bonds to Na(1) are significantly longer than those to Na(2). In 5, the ligand is N,N′-chelating. Key words: alkali metals, tin(II), benzamidinates, NMR spectra, X-ray structures.

Characterization of Ancient Dolomitic Binding Materials from Zamarce, in Navarre (Spain)

2002 ◽  
Vol 712 ◽  
Author(s):  
C. Montoya ◽  
J. Lanas ◽  
M. Arandigoyen ◽  
I. Navarro ◽  
P.J. García Casado ◽  
...  
Keyword(s):  
Raw Materials ◽  
Thermal Studies ◽  
Complete Characterization ◽  
X Ray Diffraction ◽  
Morphological Examination ◽  
X Ray ◽  
Main Components ◽  
Santa Maria ◽  
The Church

ABSTRACTTen ancient mortars of dolomitic origin, used in the construction of the church of Santa María de Zamarce in Navarre, Spain, have been studied in order to define their composition and to characterize the type of binder employed. A complete characterization has been carried out including: morphological examination (visually and using optical microscopy); mineralogical studies (X-ray diffraction, XRD); chemical analysis (main components and soluble salts); grain size distribution and thermal studies (thermogravimetric and thermodifferential simultaneous analysis, TGA-DTA). Dolomite and calcite, as binders, and quartz, as aggregate, have been found as the main phases. The important variability of the studied samples has confirmed that the choice of the raw materials and their preparation were not taken carefully. Thermal behavior of the samples has shown the endothermic peaks related to calcite and dolomite decarbonations. No hydromagnesite phases have been detected. Finally, the approximate indications of the original composition of the raw materials mixtures are presented.

Hydrothermal Synthesis and Characterization of Zeolite A Using Amorphous Gel from Industrial Reagents

2017 ◽  
Vol 899 ◽  
pp. 60-64
Author(s):  
Jarina Costa Moreira ◽  
Luciano André Koslowski ◽  
Rozineide A. Antunes Boca Santa ◽  
Domingos Lusitâneo Pier Macuvele ◽  
Humberto Gracher Riella
Keyword(s):  
Alkali Metals ◽  
Chemical Properties ◽  
Sodium Aluminate ◽  
Commercial Application ◽  
Zeolite A ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
Good Crystallinity ◽  
Physical And Chemical

Zeolites are crystalline microporous aluminosilicate of alkali metals and alkaline-earth metals. These materials have large commercial application due to their physical and chemical properties. The synthesis of zeolite A was carried out based on procedures described by International Zeolite Association (IZA), the sodium silicate was used as a source of silicon and the sodium aluminate as a source of aluminum for the produced zeolite. The synthesis occurred at hydrothermal conditions through static autoclaving. The material formed was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results obtained from the characterization analysis were satisfactory and the method of synthesis showed to have high reproducibility in the production of zeolite A with good crystallinity as predominant phase. This result is very interesting because this method is simple and did not use toxic organic compounds as templates.

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