Ordering and Energetics of Hg Overlayers on Cu(O01)

1989 ◽  
Vol 159 ◽  
Author(s):  
C.W. Hutchings ◽  
P.A. Dowben ◽  
Y.J. Kime ◽  
W. Li ◽  
M. Karimi ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Diffraction Data ◽  
Isosteric Heat ◽  
The Other ◽  
Square Lattice ◽  
Atom Beam ◽  
Ordered Phases ◽  
Beam Scattering ◽  
Two Phases ◽  
Beam Diffraction

ABSTRACTThe growth, ordering, and energetics of Hg overlayers on Cu(O01) have been studied using atom beam scattering, LEED and angle-resolved photoemission. Two stable ordered phases have been identified: one phase is a c(2↑2) and the other phase is a higher density square lattice which has a coincidence c(4↑4) structure. A phase diagram has been determined using LEED and atom beam diffraction data for surface temperatures between 180 and 330 K. ABS data suggest out that there is a narrow coexistance region between these two phases. The isosteric heat of adsorption has been determined as a function of coverage.

scholarly journals Bicritical Central Point of Ising Model Phase Diagram

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Yahia Boughaleb ◽  
Mohammed Nouredine ◽  
Mohamed Snina ◽  
Rachid Nassif ◽  
Mohamed Bennai
Keyword(s):  
Phase Diagram ◽  
Order Parameter ◽  
Present Model ◽  
Central Point ◽  
Square Lattice ◽  
Ordered Structures ◽  
Ordered Phases ◽  
Algebraic Order ◽  
Pure Phases ◽  
Model Phase

We deal with a 2D half occupied square lattice with repulsive interactions between first and second neighboring particles. Despite the intensive studies of the present model the central point of the phase diagram for which the ratio of the two interaction strengths is still open. In the present paper we show, using standard Monte Carlo calculations, that the situation corresponds to a phase of mixed ordered structures quantified by an “algebraic” order parameter defined as the sum of densities of the existing ordered clusters. The introduced grandeur also characterizes the transitions towards the known pure ordered phases for the other values of as mentioned by the agreement of our results with those of the literature. The computation of the Cowley short range order parameter against suggests that the central point is bicritical and is a state to cross when passing between the two pure phases.

scholarly journals New insights on the crystalline forms in binary systems of n-alkanes: Characterization of the solid ordered phases in the phase diagram tricosane + pentacosane

1999 ◽  
Vol 14 (6) ◽  
pp. 2644-2654 ◽  
Author(s):  
F. Rajabalee ◽  
V. Métivaud ◽  
D. Mondieig ◽  
Y. Haget ◽  
M. A. Cuevas-Diarte
Keyword(s):  
Phase Diagram ◽  
Binary Systems ◽  
The Other ◽  
Structural Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ordered Phases ◽  
Crystalline Forms ◽  
Mixed Samples

X-ray diffraction analyses of the pure components n-tricosane and n-pentacosane and of their binary mixed samples have enabled us to characterize the crystalline phases observed at “low temperature.” Contrary to what was announced in literature on the structural behavior of mixed samples in odd-odd binary systems with Δn = 2, the three domains are not all orthorhombic. This work has enabled us to show that two of the domains are, in fact, monoclinic (Aa, Z = 4), and the other one is orthorhombic (Pca21, Z = 4). The conclusions drawn in this work can easily be transposed to other binary systems of n-alkanes.

Structural and Electronic Changes in the Growth of Mercury Overlayers on Cu(001): A Helium Beam Scattering, Leed and Arpes Study

1990 ◽  
Vol 187 ◽  
Author(s):  
G. Vidali ◽  
W. Li ◽  
P. A. Dowben ◽  
M. Karimi ◽  
C.W. Hutchings ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Surface Temperature ◽  
Electron Spectroscopy ◽  
High Density ◽  
Atom Beam ◽  
Preliminary Results ◽  
Bilayer Films ◽  
Ordered Phases ◽  
Beam Scattering ◽  
Arpes Data

AbstractWe used atom beam scattering (ABS), LEED and angle-resolved photo-electron spectroscopy (ARPES) to study bilayer films of Hg on Cu(001). In the surface temperature range of 180 to 330 K, the first Hg layer forms two ordered phases, a c(2×2) (with coverage=0.5 of Cu(001)) and a high density (partially commensurate) c(4×4) (coverage=0.62 ). ARPES data show that there is little or no dispersion of the 5d band of Hg. ABS data show that this layer is not flat, with in-registry Hg atoms lying about 0.15 below the not-in-registry Hg atoms. From ABS we find that the second layer forms a completely registered c(4times;4) phase. From ARPES we obtain that the second layer has an electronic structure, particularly the 5d levels, characteristic of bulk mercury.Preliminary results of calculations of the structure of the bilayer are given.

scholarly journals Ground state and stability of the fractional plateau phase in metallic Shastry–Sutherland system TmB4

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matúš Orendáč ◽  
Slavomír Gabáni ◽  
Pavol Farkašovský ◽  
Emil Gažo ◽  
Jozef Kačmarčík ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Diagram ◽  
Ground State ◽  
Constant Magnetic Field ◽  
Paramagnetic Phase ◽  
The Other ◽  
Zero Field ◽  
Plateau Phase ◽  
Low Field ◽  
Zero Field Cooling

AbstractWe present a study of the ground state and stability of the fractional plateau phase (FPP) with M/Msat = 1/8 in the metallic Shastry–Sutherland system TmB4. Magnetization (M) measurements show that the FPP states are thermodynamically stable when the sample is cooled in constant magnetic field from the paramagnetic phase to the ordered one at 2 K. On the other hand, after zero-field cooling and subsequent magnetization these states appear to be of dynamic origin. In this case the FPP states are closely associated with the half plateau phase (HPP, M/Msat = ½), mediate the HPP to the low-field antiferromagnetic (AF) phase and depend on the thermodynamic history. Thus, in the same place of the phase diagram both, the stable and the metastable (dynamic) fractional plateau (FP) states, can be observed, depending on the way they are reached. In case of metastable FP states thermodynamic paths are identified that lead to very flat fractional plateaus in the FPP. Moreover, with a further decrease of magnetic field also the low-field AF phase becomes influenced and exhibits a plateau of the order of 1/1000 Msat.

scholarly journals Quasi-1D XY antiferromagnet Sr2Ni(SeO3)2Cl2 at Sakai-Takahashi phase diagram

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. S. Kozlyakova ◽  
A. V. Moskin ◽  
P. S. Berdonosov ◽  
V. V. Gapontsev ◽  
S. V. Streltsov ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Long Range ◽  
Density Functional ◽  
Uniaxial Anisotropy ◽  
Exchange Interactions ◽  
Spin Liquid ◽  
Functional Theory ◽  
One Dimensional ◽  
Ordered Phases ◽  
Experimental Findings

AbstractUniform quasi-one-dimensional integer spin compounds are of interest as a potential realization of the Haldane conjecture of a gapped spin liquid. This phase, however, has to compete with magnetic anisotropy and long-range ordered phases, the implementation of which depends on the ratio of interchain J′ and intrachain J exchange interactions and both uniaxial D and rhombic E single-ion anisotropies. Strontium nickel selenite chloride, Sr2Ni(SeO3)2Cl2, is a spin-1 chain system which passes through a correlations regime at Tmax ~ 12 K to long-range order at TN = 6 K. Under external magnetic field it experiences the sequence of spin-flop at Bc1 = 9.0 T and spin-flip transitions Bc2 = 23.7 T prior to full saturation at Bsat = 31.0 T. Density functional theory provides values of the main exchange interactions and uniaxial anisotropy which corroborate the experimental findings. The values of J′/J = 0.083 and D/J = 0.357 place this compound into a hitherto unoccupied sector of the Sakai-Takahashi phase diagram.

Phase diagram of ordered phases with L10 and L12 superlattices

1972 ◽  
Vol 15 (1) ◽  
pp. 138-140 ◽  
Author(s):  
N. S. Golosov ◽  
G. S. Golosova ◽  
L. E. Popov
Keyword(s):  
Phase Diagram ◽  
Ordered Phases

CHANGES IN THE COMPOSITION AND YIELD OF THE MAMMARY SECRETION OF COWS DURING THE INITIATION OF LACTATION

1973 ◽  
Vol 59 (2) ◽  
pp. 231-247 ◽  
Author(s):  
P. E. HARTMANN
Keyword(s):  
Mammary Gland ◽  
Late Pregnancy ◽  
The Other ◽  
Small Samples ◽  
Dry Period ◽  
Abrupt Increase ◽  
Milk Samples ◽  
Casein Protein ◽  
Two Phases

SUMMARY Mammary secretion (1·2–2·0 ml) was collected from the milk sinus of each mammary gland (quarter) of two pregnant heifers and eight pregnant cows (dry period 49–229 days), first at weekly intervals from 40 days before parturition, then with increasing frequency as parturition approached. The progressive changes in the concentration of lactose, glucose, casein, non-casein protein and fat in the mammary secretion were determined. Calves were separated from the cows immediately after birth and the yield and composition of milk from individual quarters were determined for 5 days after parturition. Two quarters (milked quarters) of each of a further five cows were milked throughout pregnancy, while the other two quarters (unmilked quarters) of each cow were allowed to involute (dry off) 63– 104 days before parturition. Small samples (5–10 ml) of secretion were collected from the unmilked quarters, first at weekly intervals after drying off and then every second day from 10 to 15 days before parturition. On the days that the unmilked quarters were sampled, corresponding composite milk samples were collected from the milked quarters and the progressive changes in the yield of milk, lactose and fat were determined. The changes in the concentration of lactose and glucose in the mammary secretion, during drying off in late lactation, were determined in an additional five cows. In most cows allowed a usual dry period, and in the unmilked quarters of cows in which two quarters were milked throughout pregnancy, the concentration of lactose gradually increased from about 8 to 12 days before parturition to reach levels of about half those found in normal milk just before parturition. However, in some cows the concentration of lactose was low until 1–2 days before parturition and then increased abruptly, whereas in others the concentration of lactose increased slowly from as early as 32 days before parturition. A further rapid increase in the concentration of lactose in the mammary secretion occurred between 0 and 4 days before parturition in all cows. This latter increase was accompanied by an abrupt increase in the yield of milk, lactose and fat in the milked quarters of the cows in which two quarters were milked throughout pregnancy. These observations suggest that the initiation of lactation in the cow develops in two phases, a limited secretion of milk constituents occurs in late pregnancy and then 0–4 days before parturition copious secretion (lactogenesis) occurs.

scholarly journals Multicritical Nishimori point in the phase diagram of the±JIsing model on a square lattice

2008 ◽  
Vol 77 (5) ◽  
Author(s):  
Martin Hasenbusch ◽  
Francesco Parisen Toldin ◽  
Andrea Pelissetto ◽  
Ettore Vicari
Keyword(s):  
Phase Diagram ◽  
Square Lattice

Resistive transition broadening in two-phase polycrystalline YBaCuO

1993 ◽  
Vol 8 (5) ◽  
pp. 957-961 ◽  
Author(s):  
J.C. Abele ◽  
R.L. Bristol ◽  
T.C. Nguyen ◽  
M.W. Ohmer ◽  
L.S. Wood
Keyword(s):  
Magnetic Fields ◽  
Computer Models ◽  
Structured Data ◽  
The Other ◽  
Critical Ratio ◽  
Resistive Transition ◽  
Two Phase ◽  
Two Phases

A model proposed by Tinkham1to explain the resistance versus temperature broadening found in highTcsuperconductors in applied magnetic fields is extended to “foot and knee”-structured data taken on polycrystalline YBa2Cu3O6+δ. The proposed extension involves a series combination of two types of superconductors. For this series combination to result, a critical ratio of the two types of superconductors must be met—a result common to both percolation and randomized cellular autonoma theory. This critical ratio is investigated via statistical computer models of a polycrystalline superconductor having two phases of crystallites—one with substantially lowerJcthan the other.

scholarly journals Logros de niños y niñas de educación inicial mediante el juego con bloques de Lego (Achievements of Early Childhood Education children through play with Lego blocks)

Retos ◽  
2020 ◽  
pp. 241-249
Author(s):  
Alix María Casadiego ◽  
Karina Avendaño Casadiego ◽  
Leidy Carolina Cuervo ◽  
Gabriel Avendaño Casadiego ◽  
Alvaro Avendaño Rodríguez
Keyword(s):  
Early Childhood ◽  
Early Childhood Education ◽  
Temporal Relationship ◽  
Free Play ◽  
The Other ◽  
Pedagogical Practices ◽  
Childhood Education ◽  
Didactic Engineering ◽  
Two Phases ◽  
Observation Code

 El juego, además de ser una de las experiencias que más disfrutan niños y niñas durante su etapa en educación inicial, les permite aprender y desarrollarse en forma integral. De acuerdo con ello, el presente estudio tiene como objetivo indagar en cuáles logros en relaciones espaciales, temporales y socioafectivas son más exitosos los niños y las niñas de educación inicial e identificar su evolución durante 10 semanas de observación. La metodología tuvo dos fases: inicialmente, mediante la ingeniería didáctica, se construyó un código de observación y una vez construido se realizaron las observaciones durante 10 semanas de trabajo. Las actividades fueron realizadas, durante las horas de juego libre, en las escuelas donde la Facultad de Educación de la Universidad Surcolombiana realiza sus prácticas pedagógicas. Los resultados mostraron que es en la actividad socio afectiva donde se obtienen mayores logros desde el comienzo de la experiencia; por otro lado, el principal logro se obtiene en la característica relación temporal, relacionada con la capacidad para anticiparse a los acontecimientos o predecir resultados, específicamente en la capacidad de organizar un plan para llevar a cabo una idea, que se logra en un 87%. Abstract. Playing, in addition to being one of the experiences that children enjoy the most during their stage of early childhood education, allows them to learn and develop in an integral way. In accordance with this, the present study aims to investigate which achievements in spatial, temporal and socio-affective relationships are more successful in early childhood education children and to identify their evolution during 10 weeks of observation. The methodology had two phases: initially, through didactic engineering, an observation code was constructed and once it was ready, observations were made during 10 weeks of work. The activities were carried out, during free play hours, in the schools where the Education Faculty of the Surcolombiana University carries out its pedagogical practices. The results showed that it is in the socio-affective activity where the greatest achievements are obtained from the beginning of the experience; on the other hand, the main achievement is obtained in the characteristic temporal relationship, related to the ability to anticipate events or predict results, specifically in the ability to organize a plan to carry out an idea, is achieved 87%.

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