Spontaneous anion-exchange synthesis of optically active mixed-valence Cs2Au2I6 perovskite from layered CsAuCl4 perovskite

2021 ◽  
Author(s):  
Bhawna Bhawna ◽  
Mrinmoy Roy ◽  
Vikram . ◽  
Hitesh Borkar ◽  
Aftab Alam ◽  
...  
Keyword(s):  
Anion Exchange ◽  
Mixed Valence ◽  
Optically Active ◽  
Lead Free ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydroiodic Acid ◽  
Photovoltaic Material

Cs2Au2I6, a lead-free photovoltaic material, has been synthesised via a controlled and systematic addition of hydroiodic acid (HI) in CsAuCl4. X-ray diffraction studies suggest the formation of Cs2Au2I6 when a...

scholarly journals A novel and potentially scalable CVD-based route towards SnO2:Mo thin films as transparent conducting oxides

2021 ◽  
Author(s):  
Tianlei Ma ◽  
Marek Nikiel ◽  
Andrew G. Thomas ◽  
Mohamed Missous ◽  
David J. Lewis
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Mixed Valence ◽  
Chemical Vapour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conducting Oxides ◽  
Valence States ◽  
3 Omega ◽  
First Time

AbstractIn this report, we prepared transparent and conducting undoped and molybdenum-doped tin oxide (Mo–SnO2) thin films by aerosol-assisted chemical vapour deposition (AACVD). The relationship between the precursor concentration in the feed and in the resulting films was studied by energy-dispersive X-ray spectroscopy, suggesting that the efficiency of doping is quantitative and that this method could potentially impart exquisite control over dopant levels. All SnO2 films were in tetragonal structure as confirmed by powder X-ray diffraction measurements. X-ray photoelectron spectroscopy characterisation indicated for the first time that Mo ions were in mixed valence states of Mo(VI) and Mo(V) on the surface. Incorporation of Mo6+ resulted in the lowest resistivity of $$7.3 \times 10^{{ - 3}} \Omega \,{\text{cm}}$$ 7.3 × 10 - 3 Ω cm , compared to pure SnO2 films with resistivities of $$4.3\left( 0 \right) \times 10^{{ - 2}} \Omega \,{\text{cm}}$$ 4.3 0 × 10 - 2 Ω cm . Meanwhile, a high transmittance of 83% in the visible light range was also acquired. This work presents a comprehensive investigation into impact of Mo doping on SnO2 films synthesised by AACVD for the first time and establishes the potential for scalable deposition of SnO2:Mo thin films in TCO manufacturing. Graphical abstract

Solid-state Thermoelectric Characteristics of NiII, FeII, CoII, and CuII Borohydrides

2021 ◽  
Author(s):  
Isam M. Arafa ◽  
Mazin Y. Shatnawi ◽  
Yousef N. Obeidallah ◽  
Ahmed K. Hijazi ◽  
Yaser A . Yousef
Keyword(s):  
Energy Transport ◽  
Waste Heat ◽  
Mixed Valence ◽  
Small Scale ◽  
X Ray Diffraction ◽  
Promising Candidate ◽  
X Ray ◽  
Cold Pressed ◽  
Thermal Energy Transport ◽  
Body Heat

Abstract Four transition metal borohydrides (MTBHs, MT = Ni, Fe, Co, and Cu) were prepared by sonicating a mixture of the desired MT salt with excess NaBH4 in a nonaqueous DMF/CH3OH media. The process afforded bimetallic (Ni-BH4), trimetallic (Fe-BH4, Co-BH4), and mixed-valence (Cu-H, Cu-BH4) amorphous, ferromagnetic nanoparticles as identified by thermal, ATR-IR, X-Ray diffraction, and magnetic susceptibility techniques. The electrical conductivity (σ) of cold-pressed discs of these MTBHs shows a nonlinear increase while their thermal conductivity (κ) decreases in the temperature range of 303 ≤ T ≤ 373 K. The thermal energy transport occurs through phonon lattice dynamics rather than electronic. The σ/κ ratio shows a nonlinear steep increase from 9.4 to 270 KV-2 in Ni-BH4, while a moderate-weak increase is observed for Fe-BH4, Co-BH4, and Cu-BH4. Accordingly, the corresponding thermoelectric (TE) parameters S, PF, ZT, and η were evaluated. All TE data shows that the bimetallic Ni-BH4 (S, 80 μVK-1; PF, 259 μWm-1K-2; ZT 0.64; η, 2.56%) is a better TE semiconductor than the other three MT-BHs investigated in this study. Our findings show that Ni-BH4 is a promising candidate to exploit low-temperature waste heat from body heat, sunshine, and small domestic devices for small-scale TE applications.

scholarly journals Effect of pressure on a mixed valence FeiiFeiii2complex

2014 ◽  
Vol 70 (a1) ◽  
pp. C901-C901
Author(s):  
Solveig Madsen ◽  
Jacob Overgaard ◽  
Bo Iversen
Keyword(s):  
Phase Transition ◽  
Hydrogen Bond ◽  
Mixed Valence ◽  
Hydrogen Bond Network ◽  
X Ray Diffraction ◽  
X Ray ◽  
Effect Of Pressure ◽  
Bond Network ◽  
Fe Sites ◽  
Cyano Groups

Intramolecular electron transfer (ET) in mixed valence (MV) oxo-centered [FeiiFeiii2O(carboxylate)6(ligand)3]·solvent complexes is highly dependent on temperature, on the nature of the ligands, and on the presence of crystal solvent molecules [1]. Whereas the effects of temperature, crystal solvent, and ligand variation on the details of the ET have been explored thoroughly, the effect of pressure is less well described [2]. The effect of pressure on the ET in MV Fe3O(cyanoacetate)6(water)3has been investigated with single crystal X-ray diffraction and Mössbauer spectroscopy. Previous multi-temperature studies have shown that at room temperature the ET between the three Fe sites is fast and the observed structure of the Fe3core is a perfectly equilateral triangle [3]. Cooling the complex below 130 K induces a phase transition as the ET slows down. Below 120 K the Fe3core is distorted due to the localization of the itinerant electron on one of the three Fe sites in the triangle (the complex is then in the valence trapped state). The valence trapping is complete within a temperature interval of just 10 K. The abruptness of the transition has been attributed to the extended hydrogen bond network involving water ligands and cyano groups, promoting intermolecular cooperative effects. The high-pressure X-ray diffraction data show that there is a 900flip of half the cyano groups at 3.5 GPa, which dramatically changes the hydrogen bond network. At a slightly higher pressure, a phase transition is found to occur. The five single crystals investigated all broke into minor fragments at the transition; however triclinic unit cells, similar to the low temperature unit cell, could be indexed from selected spots. Additional evidence that the complex is valence trapped comes from high pressure Mössbauer spectra measured above the phase transition (4 GPa). The relationship between valence trapping and the structural changes will in this work be highlighted using void space and Hirshfeld surface analysis.

Die neuen Oxobismutate(III) Cs6Bi4O9, K9Bi5O13 und A2Bi4O7 (A = Rb, Cs) / The New Oxobismutates(III) Cs6Bi4O9, K9Bi5O13 and A2Bi4O7 (A = Rb, Cs)

2002 ◽  
Vol 57 (10) ◽  
pp. 1090-1100
Author(s):  
Franziska Emmerling ◽  
Caroline Röhr
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Alkali Metals ◽  
Mixed Valence ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Mixed Valence Compound

AbstractThe title compounds were synthesized at a temperature of 700 °C via oxidation of elemental Bi with the hyperoxides AO2 or via reaction of the elemental alkali metals A with Bi2O3. Their crystal structures have been determined by single crystal x-ray diffraction. They are dominated by two possible surroundings of Bi by O, the ψ-trigonal-bipyramidal three (B) and the ψ-tetrahedral four (T) coordination. Cs6Bi4O9 (triclinic, spacegroup P1̄, a = 813.82(12), b = 991.60(14), c = 1213.83(18) pm, α = 103.658(2), β = 93.694(3), γ = 91.662(3)°, Z = 2) contains centrosymmetric chain segmentes [Bi8O18]12- with six three- (T) and two four-coordinated (B) Bi(III) centers. K9Bi5O13 (monoclinic, spacegroup P21/c, a = 1510.98(14), b = 567.59(5), c = 2685.6(2) pm, β = 111.190(2)°, Z = 4) is a mixed valence compound with isolated [BivO4]3- tetrahedra and chains [BiIII4O9]6- of two T and two B coordinated Bi. In the compounds A2Bi4O7 (A = Rb/Cs: monoclinic, C2/c, a = 2037.0(3) / 2130.6(12), b = 1285.5(2) / 1301.9(7), c = 1566.6(2) / 1605.6(9) pm, β = 94.783(3) / 95.725(9)°, Z = 8) ribbons [Bi4O6O2/2]2- are formed, which are condensed to form a three-dimensional framework.

scholarly journals Dielectric and Raman studies of Ba0.06(Na1/2Bi1/2)0.94TiO3–NaNbO3 ceramics

2016 ◽  
Vol 34 (2) ◽  
pp. 437-445 ◽  
Author(s):  
Sumit K. Roy ◽  
S. Chaudhuri ◽  
R.K. Kotnala ◽  
D.K. Singh ◽  
B.P. Singh ◽  
...  
Keyword(s):  
Single Phase ◽  
Solid State Reaction Method ◽  
Lead Free ◽  
Orthorhombic Symmetry ◽  
Dielectric Studies ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
New Phase ◽  
Diffusivity Parameter

AbstractIn this work the X-ray diffraction, scanning electron microscopy, Raman and dielectric studies of lead free perovskite (1 – x)Ba0.06(Na1/2Bi1/2)0.94TiO3–xNaNbO3 (0 ⩽ x ⩽ 1.0) ceramics, prepared using a standard solid state reaction method, were investigated. X-ray diffraction studies of all the ceramics suggested the formation of single phase with crystal structure transforming from rhombohedral-tetragonal to orthorhombic symmetry with the increase in NaNbO3 content. Raman spectra also confirmed the formation of solid solution without any new phase. Dielectric studies showed that the phase transition is of diffusive character and diffusivity parameter decreases with increasing NaNbO3 content. The compositional fluctuation was considered to be the main cause of diffusivity.

The crystal structures of the mixed-valence tellurium oxysalts tlapallite, (Ca,Pb)3CaCu6[Te4+3Te6+O12]2(Te4+O3)2(SO4)2·3H2O, and carlfriesite, CaTe4+2Te6+O8

2019 ◽  
Vol 83 (4) ◽  
pp. 539-549 ◽  
Author(s):  
Owen P. Missen ◽  
Anthony R. Kampf ◽  
Stuart J. Mills ◽  
Robert M. Housley ◽  
John Spratt ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Mixed Valence ◽  
Oxidation States ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
The One ◽  
Micro Analysis ◽  
Secondary Bonding

ABSTRACTThe crystal structure of tlapallite has been determined using single-crystal X-ray diffraction and supported by electron probe micro-analysis, powder diffraction and Raman spectroscopy. Tlapallite is trigonal, space groupP321, witha= 9.1219(17) Å,c= 11.9320(9) Å andV= 859.8(3) Å3, and was refined toR1= 0.0296 for 786 reflections withI> 2σ(I). This study resulted from the discovery of well-crystallised tlapallite at the Wildcat prospect, Utah, USA. The chemical formula of tlapallite has been revised to (Ca,Pb)3CaCu6[Te4+3Te6+O12]2(Te4+O3)2(SO4)2·3H2O, or more simply (Ca,Pb)3CaCu6Te4+8Te6+2O30(SO4)2·3H2O, from H6(Ca,Pb)2(Cu,Zn)3(TeO3)4(TeO6)(SO4). The tlapallite structure consists of layers containing distorted Cu2+O6octahedra, Te6+O6octahedra and Te4+O4disphenoids (which together form the new mixed-valence phyllotellurate anion [Te4+3Te6+O12]12−), Te4+O3trigonal pyramids and CaO8polyhedra. SO4tetrahedra, Ca(H2O)3O6polyhedra and H2O groups fill the space between the layers. Tlapallite is only the second naturally occurring compound containing tellurium in both the 4+and 6+oxidation states with a known crystal structure, the other being carlfriesite, CaTe4+2Te6+O8. Carlfriesite is the predominant secondary tellurium mineral at the Wildcat prospect. We also present an updated structure for carlfriesite, which has been refined toR1= 0.0230 for 874 reflections withI> 2σ(I). This updated structural refinement improves upon the one reported previously by refining all atoms anisotropically and presenting models of bond valence and Te4+secondary bonding.

Intermetallic phase detection in lead-free solders using synchrotron x-ray diffraction

2004 ◽  
Vol 33 (12) ◽  
pp. 1524-1529 ◽  
Author(s):  
Gavin J. Jackson ◽  
Hua Lu ◽  
Raj Durairaj ◽  
Nick Hoo ◽  
Chris Bailey ◽  
...  
Keyword(s):  
Intermetallic Phase ◽  
Lead Free ◽  
Phase Detection ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lead Free Solders
Sign in / Sign up

Export Citation Format

Share Document