Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userIncommensurately modulated twin structure of nyerereite Na1.64K0.36Ca(CO3)2
52
0
0.0
(
0
)
Added by
Pavel Gavryushkin dr
Publication date
2017
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Incommensurately modulated twin structure of nyerereite Na1.64K0.36Ca(CO3)2 has been first determined in the (3+1)D symmetry group Cmcm({alpha}00)00s with modulation vector q = 0.383a*. Unit-cell values are a = 5.062(1), b = 8.790(1), c = 12.744(1) {AA}. Three orthorhombic components are related by threefold rotation about [001]. Discontinuous crenel functions are used to describe occupation modulation of Ca and some CO3 groups. Strong displacive modulation of the oxygen atoms in vertexes of such CO3 groups is described using x-harmonics in crenel intervals. The Na, K atoms occupy mixed sites whose occupation modulation is described by two ways using either complementary harmonic functions or crenels. The nyerereite structure has been compared both with commensurately modulated structure of K-free Na2Ca(CO3)2 and with widely known incommensurately modulated structure of {gamma}-Na2CO3.
rate research
Read More
We report near room temperature ferromagnetic as well as low temperature antiferromagnetic correlations in Mn doped Cobalt Tellurate (CMTO) solid solutions using thorough magnetization studies. For all the composition the solid solutions show not only short range robust FM order at 185 K but also show long range enhanced AFM order less than or equal to 45 K. Scaling of inverse magnetic susceptibility data provide clear indication of Griffiths like FM phase extended over large thermal region and its robustness against magnetic field. Variations in both the phases as a function of Mn concentration also support our observation of anomalous behavior in the average bond distances and charge states (JAP 116: 074904 (2014)). Further an attempt towards the structural insight into the observed complex magnetic behavior by using network like structural analysis has been drawn. These observations make this an interesting magnetic system from fundamental and application perspective.
Twin domains are naturally present in the topological insulator BiSe{} and affect strongly its properties. While studies of its behavior for ideal BiSe{} structure exist, little is known about their possible interaction with other defects. Extra information are needed especially for the case of artificial perturbation of topological insulator states by magnetic doping, which has attracted a lot of attention recently. Employing ab initio calculations based on layered Greens function formalism, we study the interaction between twin planes in BiSe{}. We show the influence of various magnetic and non-magnetic chemical defects on the twin plane formation energy and discuss the related modification of their distribution. Furthermore, we examine the change of dopants magnetic properties at sites in the vicinity of a twin plane, and the dopants preference to occupy such sites. Our results suggest that twin planes repel each other at least over distance of $3-4$~nm. However, in the presence of magnetic Mn and Fe defects a close TP placement is preferred. Furthermore, calculated twin plane formation energies indicate that in this situation their formation becomes suppressed. Finally, we discuss the influence of twin planes on the surface band gap.
Secondary batteries are important energy storage devices for a mobile equipment, an electric car, and a large-scale energy storage. Nevertheless, variation of the local electronic state of the battery materials in the charge (or oxidization) process are still unclear. Here, we investigated the local electronic state of cobalt-hexacyanoferrate (Na$_x$Co[Fe(CN)$_6$]$_{0.9}$), by means of resonant inelastic X-ray scattering (RIXS) with high energy resolution (~100 meV). The L-edge RIXS is one of the most powerful spectroscopic technique with element- and valence-selectivity. We found that the local electronic state around Co$^{2+}$ in the partially-charged Na$_{1.1}$Co$^{2+}$$_{0.5}$Co$^{3+}$$_{0.5}$[Fe$^{2+}$(CN)$_6$]$_{0.9}$ film (x = 1.1) is the same as that of the discharged Na$_{1.6}$Co$^{2+}$[Fe$^{2+}$(CN)$_6$]$_{0.9}$ film (x = 1.6) within the energy resolution, indicating that the local electronic state around Co$^{2+}$ is invariant against the partial oxidization. In addition, the local electronic state around the oxidized Co$^{3+}$ is essentially the same as that of the fully-charged film Co$^{3+}$[Fe$^{2+}$(CN)$_6$]$_{0.3}$[Fe$^{3+}$(CN)$_6$]$_{0.6}$ (x = 0.0) film. Such a strong localization of the oxidized Co$^{3+}$ state is advantageous for the reversibility of the redox process, since the localization reduces extra reaction within the materials and resultant deterioration.
Incommensurate modulated structure (IMS) in Bi2Sr1.6La0.4CuO6+{delta} (BSLCO) has been studied by aberration corrected transmission electron microscopy in combination with high-dimensional (HD) space description. Two images in the negative Cs imaging (NCSI) and passive Cs imaging (PCSI) modes were deconvoluted, respectively. Similar results as to IMS have been obtained from two corresponding projected potential maps (PPMs), but meanwhile the size of dots representing atoms in the NCSI PPM is found to be smaller than that in PCSI one. Considering that size is one of influencing factors of precision, modulation functions for all unoverlapped atoms in BSLCO were determined based on the PPM obtained from the NCSI image in combination with HD space description.
High-energy (h$ u$ = 5.95 keV) synchrotron Photoemission spectroscopy (PES) is used to study bulk electronic structure of Na$_{0.35}$CoO$_{2}$.1.3H$_{2}$O, the layered superconductor. In contrast to 3-dimensional doped Co oxides, Co $it{2p}$ core level spectra show well-separated Co$^{3+}$ and Co$^{4+}$ ions. Cluster calculations suggest low spin Co$^{3+}$ and Co$^{4+}$ character, and a moderate on-site Coulomb correlation energy U$_{dd}sim$3-5.5 eV. Photon dependent valence band PES identifies Co $it{3d}$ and O $it{2p}$ derived states, in near agreement with band structure calculations.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
