Single Crystal Charge Density Studies of Thermoelectric Material Indium Antimonide

2011 ◽  
Vol 66 (8-9) ◽  
pp. 562-568 ◽  
Author(s):  
Charles Robert Muthaian ◽  
Bandarinathan Subha ◽  
Ramachandran Saravanan
Keyword(s):  
Single Crystal ◽  
Charge Density ◽  
Thermoelectric Material ◽  
Indium Antimonide ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Covalent Character ◽  
X Ray ◽  
Density Analysis ◽  
Experimental Electron Density

Abstract density distribution using the single crystal X-ray intensity data. The charge density of this material has been studied including and excluding the quasi-forbidden h+k +l = 4n+2 type reflections using the maximum entropy method (MEM). Both the pictorial and numerical results of the experimental electron density show mixed ionic and covalent character in InSb. The use of InSb as a thermoelectric material is supported through charge density analysis.

Charge density studies utilizing powder diffraction and MEM. Exploring of high Tc superconductors, C60 superconductors and manganites

2001 ◽  
Vol 216 (2) ◽  
Author(s):  
M. Takata ◽  
E. Nishibori ◽  
M. Sakata
Keyword(s):  
Charge Density ◽  
Maximum Entropy ◽  
Powder Diffraction ◽  
Recent Progress ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
High Tc Superconductors ◽  
High Tc ◽  
X Ray

AbstractThe recent progress of the accurate charge density studies by the Maximum Entropy Method(MEM) utilizing X-ray powder diffraction is reviewed with some examples. Results for PrBCO (PrBa

Nuclear-weighted X-ray maximum entropy method – NXMEM

2015 ◽  
Vol 71 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Sebastian Christensen ◽  
Niels Bindzus ◽  
Mogens Christensen ◽  
Bo Brummerstedt Iversen
Keyword(s):  
Single Crystal ◽  
Maximum Entropy ◽  
Diffraction Data ◽  
Maximum Entropy Method ◽  
Functional Materials ◽  
Structural Features ◽  
Entropy Method ◽  
Nuclear Density ◽  
Single Crystal Diffraction ◽  
X Ray

Subtle structural features such as disorder and anharmonic motion may be accurately characterized from nuclear density distributions (NDDs). As a viable alternative to neutron diffraction, this paper introduces a new approach named the nuclear-weighted X-ray maximum entropy method (NXMEM) for reconstructing pseudo NDDs. It calculates an electron-weighted nuclear density distribution (eNDD), exploiting that X-ray diffraction delivers data of superior quality, requires smaller sample volumes and has higher availability. NXMEM is tested on two widely different systems: PbTe and Ba8Ga16Sn30. The first compound, PbTe, possesses a deceptively simple crystal structure on the macroscopic level that is unable to account for its excellent thermoelectric properties. The key mechanism involves local distortions, and the capability of NXMEM to probe this intriguing feature is established with simulated powder diffraction data. In the second compound, Ba8Ga16Sn30, disorder among the Ba guest atoms is analysed with both experimental and simulated single-crystal diffraction data. In all cases, NXMEM outperforms the maximum entropy method by substantially enhancing the nuclear resolution. The induced improvements correlate with the amount of available data, rendering NXMEM especially powerful for powder and low-resolution single-crystal diffraction. The NXMEM procedure can be implemented in existing software and facilitates widespread characterization of disorder in functional materials.

scholarly journals Structural and Charge Density Properties of Manganese Sulfide

2019 ◽  
Vol 9 (2S2) ◽  
pp. 313-315
Keyword(s):  
Charge Density ◽  
Maximum Entropy Method ◽  
Manganese Sulfide ◽  
Entropy Method ◽  
Data Sets ◽  
X Ray Diffraction ◽  
Structure Factors ◽  
Density Analysis ◽  
Distribution Studies ◽  
Profile Refinement

Single phased Manganese Sulfide was analyzed by powder X-ray diffraction (PXRD) data sets with cubic structure. The simulated XRD data sets were used to analyze the structure of manganese sulfide. The powder profile refinements were done by Rietveld profile refinement technique. The refinement results were subjected to analyze the charge density analysis using structure factors. The chemical bonding nature between Mn and S were analyzed by charge density distribution studies through maximum entropy method. From MEM analsysis, it found that the bonding between Mn and S atoms is ionic in nature.

Maximum Entropy Method Charge Density Distributions of Novel Thermoelectric Clathrates

1999 ◽  
Vol 590 ◽  
Author(s):  
B. Iversen ◽  
A. Bentien ◽  
A. Palmqvist ◽  
D. Bryan ◽  
S. Latturner ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Charge Density ◽  
Maximum Entropy ◽  
Maximum Entropy Method ◽  
Mixed Valence ◽  
Entropy Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Distributions ◽  
Positively Charged

ABSTRACTRecently materials with promising thermoelectric properties were discovered among the clathrates. Transport data has indicated that these materials have some of the characteristics of a good thermoelectric, namely a low thermal conductivity and a high electrical conductivity. Based on synchrotron powder and conventional single crystal x-ray diffraction data we have determined the charge density distribution in Sr8Ga16Ge3O using the Maximum Entropy Method. The MEM density shows clear evidence of guest atom rattling, and this contributes to the reduction of the thermal conductivity. Analysis of the charge distribution reveals that Sr8Ga16Ge30 contains mixed valence alkaline earth guest atoms. The Sr atoms in the small cavities are, as expected, doubly positively charged, whereas the Sr atoms in the large cavities appear negatively charged. The MEM density furthermore suggests that the Ga and Ge atoms may not be randomly disordered on the framework sites as found in the conventional leastsquares refinements.

Synthesis and Electron Density Analysis of SnO2 Nano Particles

2011 ◽  
Vol 671 ◽  
pp. 121-129
Author(s):  
S. Saravanakumar ◽  
M. Jeya Priya ◽  
R. Saravanan
Keyword(s):  
Electron Density ◽  
Maximum Entropy Method ◽  
Three Dimensional ◽  
Entropy Method ◽  
Nano Particles ◽  
Oxide Material ◽  
X Ray ◽  
Scale Range ◽  
Density Analysis ◽  
Electron Density Analysis

Tin oxide material (SnO2) is synthesized in nano scale range and is characterized. The refined X-ray intensity data was obtained from the Reitveld method. The electron density of nano SnO2 is determined using MEM (Maximum Entropy Method). Using one, two and three dimensional MEM maps, the bonding within the atoms is clearly understood. The particle size of SnO2 is also analyzed using XRD and SEM.

Charge-density analysis of hydrogen-bonded complexes of glycine by the maximum entropy method

2009 ◽  
Vol 938 (1-3) ◽  
pp. 229-237 ◽  
Author(s):  
Rajul Ranjan Choudhury ◽  
Pascal Roussel ◽  
Frederic Capet ◽  
R. Chitra
Keyword(s):  
Charge Density ◽  
Maximum Entropy ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Density Analysis ◽  
Bonded Complexes ◽  
Hydrogen Bonded

Nuclear and charge density distributions in ferroelectric PbTiO3: maximum entropy method analysis of neutron and X-ray diffraction data

2013 ◽  
Vol 28 (4) ◽  
pp. 276-280 ◽  
Author(s):  
Jinlong Zhu ◽  
Wei Han ◽  
Jianzhong Zhang ◽  
Hongwu Xu ◽  
Sven C. Vogel ◽  
...  
Keyword(s):  
Charge Density ◽  
Maximum Entropy ◽  
Maximum Entropy Method ◽  
Rietveld Analysis ◽  
Entropy Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Distributions ◽  
Increasing Temperature ◽  
Ionic States

We conducted in-situ high-temperature neutron and X-ray diffraction studies on tetragonal PbTiO3. Using a combination of Rietveld analysis and Maximum Entropy Method, the nuclear and charge density distributions were determined as a function of temperature up to 460 °C. The ionic states obtained from charge density distributions reveal that the covalency of Pb–O2 bonds gradually weakens with increasing temperature. The spontaneous polarizations calculated from the contributions of ionic state, ionic displacement, and nuclear polarization, are in good agreement with the experimental measurements. This method provides an effective approach to determine spontaneous polarizations in multiferroics with high-current leakage and low resistance.

Nuclear Density Analysis in Solids. The Case of Ba8Ga16Si30

2001 ◽  
Vol 691 ◽  
Author(s):  
B. B. Iversen ◽  
A. Bentien ◽  
A. E. C. Palmqvist ◽  
D. Bryan ◽  
G. D. Stucky ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Diffraction Data ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Type I ◽  
Nuclear Density ◽  
Neutron Diffraction Data ◽  
Temperature Dependent ◽  
Density Analysis

ABSTRACTMulti-temperature (15, 100, 150, 200, 300, 450, 600, 900 K) single crystal neutron diffraction data on the type I clathrate Ba8Ga16Si30 are analyzed with the maximum entropy method to obtain direct space nuclear densities. The nuclear densities suggest that the guest atoms are structurally disordered, and the disorder appears to be temperature dependent with increased host-guest interaction at high temperatures.

Molecular tapes in the structure of isoguaninium chloride

2017 ◽  
Vol 74 (1) ◽  
pp. 108-112 ◽  
Author(s):  
Urszula Anna Budniak ◽  
Paulina Maria Dominiak
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Charge Density ◽  
Interaction Energy ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Structure

Isoguanine, an analogue of guanine, is of intrinsic interest as a noncanonical nucleobase. The crystal structure of isoguaninium chloride (systematic name: 6-amino-2-oxo-1H,7H-purin-3-ium chloride), C5H6N5O+·Cl−, has been determined by single-crystal X-ray diffraction. Structure analysis was supported by electrostatic interaction energy (E es) calculations based on charge density reconstructed with the UBDB databank. In the structure, two kinds of molecular tapes are observed, one parallel to (010) and the other parallel to (50\overline{4}). The tapes are formed by dimers of isoguaninium cations interacting with chloride anions. E es analysis indicates that cations in one kind of tape are oriented so as to minimize repulsive electrostatic interactions.

Sign in / Sign up

Export Citation Format

Share Document