Characteristic Mechanical Properties and Phase Stability of L12 Intermetallic Compounds

1984 ◽  
Vol 39 ◽  
Author(s):  
Yoshinao Mishima ◽  
Yoshihiro Oya ◽  
Tomoo Suzuki
Keyword(s):  
Crystal Structure ◽  
Intermetallic Compounds ◽  
Phase Stability ◽  
Close Relation ◽  
Relative Magnitude ◽  
Plastic Behavior ◽  
Alloy Chemistry ◽  
The Stability ◽  
Crystallographic Planes ◽  
Anti Phase Boundary

ABSTRACTThe present paper deals with the occurence and magnitude of characteristic mechanical anomalies observed in many L12 intermetallic compounds and their relation to the phase stability of the crystal structure against other geometrically closed packed(GCP) phases. The dislocation configurations in the crystal structure and resultant plastic behavior are in close relation with anti-phase boundary(APB) and stacking fault(SF) energies in the compounds, while the relative magnitude of these energies on various crystallographic planes actually determines the phase stability of the L12 crystal structure. It is shown here, based on our series of investigations carried out over the past decade, that the general tendencies for particular deformation modes to occur can be systematically interpreted in terms of alloy chemistry of the compounds, including variables such as combination of component species, nonstoichiometry and ternary additions in the compounds, all of which affect the stability of the phase.

scholarly journals Explainable machine learning for materials discovery: predicting the potentially formable Nd–Fe–B crystal structures and extracting the structure–stability relationship

IUCrJ ◽  
2020 ◽  
Vol 7 (6) ◽  
pp. 1036-1047
Author(s):  
Tien-Lam Pham ◽  
Duong-Nguyen Nguyen ◽  
Minh-Quyet Ha ◽  
Hiori Kino ◽  
Takashi Miyake ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Unsupervised Learning ◽  
Crystal Structures ◽  
Coordination Number ◽  
Phase Stability ◽  
Learning Model ◽  
Structure Stability ◽  
Host Crystal ◽  
The Stability ◽  
Relationship Of

New Nd–Fe–B crystal structures can be formed via the elemental substitution of LA–T–X host structures, including lanthanides (LA), transition metals (T) and light elements, X = B, C, N and O. The 5967 samples of ternary LA–T–X materials that are collected are then used as the host structures. For each host crystal structure, a substituted crystal structure is created by substituting all lanthanide sites with Nd, all transition metal sites with Fe and all light-element sites with B. High-throughput first-principles calculations are applied to evaluate the phase stability of the newly created crystal structures, and 20 of them are found to be potentially formable. A data-driven approach based on supervised and unsupervised learning techniques is applied to estimate the stability and analyze the structure–stability relationship of the newly created Nd–Fe–B crystal structures. For predicting the stability for the newly created Nd–Fe–B structures, three supervised learning models: kernel ridge regression, logistic classification and decision tree model, are learned from the LA–T–X host crystal structures; the models achieved maximum accuracy and recall scores of 70.4 and 68.7%, respectively. On the other hand, our proposed unsupervised learning model based on the integration of descriptor-relevance analysis and a Gaussian mixture model achieved an accuracy and recall score of 72.9 and 82.1%, respectively, which are significantly better than those of the supervised models. While capturing and interpreting the structure–stability relationship of the Nd–Fe–B crystal structures, the unsupervised learning model indicates that the average atomic coordination number and coordination number of the Fe sites are the most important factors in determining the phase stability of the new substituted Nd–Fe–B crystal structures.

Tuning the phase stability and surface HER activity of 1T′-MoS2 by covalent chemical functionalization

2020 ◽  
Vol 8 (44) ◽  
pp. 15852-15859
Author(s):  
Jiu Chen ◽  
Fuhua Li ◽  
Yurong Tang ◽  
Qing Tang
Keyword(s):  
Phase Stability ◽  
Chemical Functionalization ◽  
The Stability

Chemical functionalization can significantly improve the stability of meta-stable 1T′-MoS2 and tune the surface HER activity.

scholarly journals Phase stability and elasticity of C15 transition-metal intermetallic compounds

1997 ◽  
Vol 18 (6) ◽  
pp. 536-543 ◽  
Author(s):  
F. Chu ◽  
T. E. Mitchell ◽  
S. P. Chen ◽  
M. Sob ◽  
R. Siegl ◽  
...  
Keyword(s):  
Transition Metal ◽  
Intermetallic Compounds ◽  
Phase Stability

Crystal structure, phase stability, and magnetism inNi3V

1987 ◽  
Vol 35 (13) ◽  
pp. 6940-6943 ◽  
Author(s):  
J. -H. Xu ◽  
T. Oguchi ◽  
A. J. Freeman
Keyword(s):  
Crystal Structure ◽  
Phase Stability ◽  
Structure Phase

Crystal structure, chemical expansion and phase stability of HoMnO3 at high temperature

2012 ◽  
Vol 196 ◽  
pp. 528-535 ◽  
Author(s):  
Sverre M. Selbach ◽  
Amund Nordli Løvik ◽  
Kristin Bergum ◽  
Julian R. Tolchard ◽  
Mari-Ann Einarsrud ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Phase Stability ◽  
Chemical Expansion

The search for formal electrostatic effects on molecular conformation and crystal packing: crystal structure of 2,2′′-disubstituted (HversusPPh2) 1,1′-(1,2-phenylene)bis(3-methyl-1H-imidazol-3-ium) bis(trifluoromethanesulfonate)

2016 ◽  
Vol 72 (3) ◽  
pp. 198-202
Author(s):  
Carine Duhayon ◽  
Yves Canac ◽  
Laurent Dubrulle ◽  
Carine Maaliki ◽  
Remi Chauvin
Keyword(s):  
Crystal Structure ◽  
Electrostatic Interactions ◽  
Molecular Conformation ◽  
Crystal Packing ◽  
Relative Orientation ◽  
Electron Delocalization ◽  
Electrostatic Effects ◽  
Conformational Freedom ◽  
The Stability ◽  
Bond Character

Electrostatic interactions between localized integral charges make the stability and structure of highly charged small and rigid organics intriguing. Can σ/π-electron delocalization compensate reduced conformational freedom by lowering the repulsion between identical charges? The crystal structure of the title salt, C14H16N42+·2CF3SO3−, (2), is described and compared with that of the 2,2′′-bis(diphenylphosphanyl) derivative, (4). The conformations of the dications and their interactions with neighbouring trifluoromethanesulfonate anions are first analyzed from the standpoint of formal electrostatic effects. Neither cation exhibits any geometrical strain induced by the intrinsic repulsion between the positive charges. In contrast, the relative orientation of the imidazolium rings [i.e. antifor (2) andsynfor (4)] is controlled by different configurations of the interactions with the closest trifluoromethanesulfonate anions. The long-range arrangement is also found to be specific: beyond the formal electrostatic packing, C—H...O and C—H...F contacts have no definite `hydrogen-bond' character but allow the delineation of layers, which are either pleated or flat in the packing of (2) or (4), respectively.

Polycarboxylate crown ethers from meso-tartaric acid

1991 ◽  
Vol 69 (1) ◽  
pp. 12-19 ◽  
Author(s):  
Frank R. Fronczek ◽  
Richard D. Gandour ◽  
Thomas M. Fyles ◽  
Philippa J. Hocking ◽  
Susan J. McDermid ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crown Ether ◽  
Tartaric Acid ◽  
Crown Ethers ◽  
Nmr Spectra ◽  
Product Distribution ◽  
Complexing Agents ◽  
Triclinic Space Group ◽  
The Stability ◽  
Ether Synthesis

The synthesis of crown ethers derived from meso-tartaric acid was investigated. The sodium salt of the bis(dimethylamide) of meso-tartaric acid reacted with diethylene glycol ditosylate to give a mixture of 18-crown-6 tetraamide and 27-crown-9 hexaamide crown ethers. The 2R,3S,11S,12R 18-crown-6 isomer crystallized in triclinic space group [Formula: see text] (a = 7.557(2), b = 8.866(2), c = 10.4133(13) Å, α = 94.13(2), β = 95.86(2), γ = 99.26(2)°, R = 0.040 for 2090 observed of 3129 unique reflections). The structures of the remaining products were then assigned from the NMR spectra. The solution conformations of the amide crown ethers were examined by NMR, and provide a rationale for the product distribution obtained. One of the 18-crown-6 isomers and a mixture of the two 27-crown-9 isomers were hydrolyzed to the respective crown ether carboxylic acids, and the stability constants for complexation of cations were determined by potentiometric titration. The meso tetra- and hexacarboxylates are remarkably nonselective and inefficient cation complexing agents, compared to related crown ethers from R,R-(+)-tartaric acid, due to the unfavorable conformational control exerted by the tartaro units. Key words: crown ether synthesis, complexation, crown ether conformation, meso-tartaric acid, crystal structure.

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