M. Quintero

University of the Andes

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P. Grima

University of the Andes

R. Tovar

University of the Andes

J. C. Woolley

University of Ottawa

E. Quintero

University of the Andes

M. Morocoima

University of the Andes

Gerzón E. Delgado

University of the Andes

P. Bocaranda

University of the Andes

E. Moreno

University of the Andes

G. Lamarche

New York Chiropractic College

José Antonio Henao

Industrial University of Santander

Cooperative Institutions

University of the Andes

Universidad de Los Andes

University of Ottawa

Carleton University

Centre National de la Recherche Scientifique

Universidad Nacional Autónoma de México

Instituto Politécnico Nacional

University of Zulia

Industrial University of Santander

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Lattice parameter values and phase transitions for the Cu2Cd1−zMnzSnSe4 and Cu2Cd1−zFezSnSe4 alloys

Journal of Alloys and Compounds (2009)

E. Moreno M. Quintero M. Morocoima E. Quintero P. Grima

Tetragonal crystal system

Rietveld Refinement

Orthorhombic crystal system

Lattice constant

Powder Diffraction

Differential thermal analysis

10.1016/j.jallcom.2009.07.066

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Citations (14)

Magnetic properties of Zn1−zMnzGa2Se4 alloy system in the temperature range from 2to300K

Journal of Applied Physics (2006)

M. Morocoima M. Quintero E. Quintero P. Bocaranda J. Ruiz

Measurements of low field static magnetic susceptibility and of magnetization with pulsed magnetic fields up to 32T have been made as a function of temperature on polycrystalline samples of the Zn1−zMnzGa2Se4 alloy system, which has a defect tetragonal chalcopyrite structure in the whole composition range. The resulting data have been used to give information on the magnetic spin-flop and magnetic saturation transitions, and details of the magnetic B-T phase diagrams were determined for the phases. The zero-field Néel temperatures TN and triple points, for the Zn1−zMnzGa2Se4 alloy system, have been found to be 8.1K and (7.8K, 2.2T) for z=1, 5.8K and (5.6K, 1.7T) for z=0.85, 4.5K and (4.35K, 1.0T) for z=0.075, and 3.9K and (3.85K, 0.5T) for z=0.7. The susceptibility χ(T) curves for B=3 and 5T show magnetothermal effects below 4.5K.

Tetragonal crystal system

Magnetic shape-memory alloy

Atmospheric temperature range

Saturation (graph theory)

10.1063/1.2354324

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Citations (2)

T(z) diagram and optical energy gap values of Cd1−zMnzGa2Se4 alloys

Journal of Electronic Materials (1993)

E. Guerrero M. Quintero R. Tovar T. Tinoco J. González

Solidus

Tetragonal crystal system

Classification of discontinuities

Phase boundary

10.1007/bf02661380

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Citations (14)

The (AgInSe ₂ ) _{1– x} (VSe) _x system (0 ≤ x ≤ 0.5): X‐ray diffraction and differential thermal analysis measurements

Physica status solidi. C, Conferences and critical reviews/Physica status solidi. C, Current topics in solid state physics (2005)

S. Durán P. Grima M.A. Morris M. Quintero J. Ruiz

Polycrystalline samples of the (AgInSe2)1–x(VSe)x system were prepared by the melt and anneal method. The anneal temperature was 900 K and the anneal time one month. The step composition was 0.1 and the weight of each sample approximately 1 g. Additionally, the composition x = 1/3 was also prepared, since these alloys have been reported as electronic, i.e. definite compounds exist in the diagram at precise values of composition, one of them x = 1/3. The stoichiometric relation of the samples was investigated by SEM technique. The experimental values, in average, are very close to the nominal values, all of them lying inside the interval of the experimental error (±5%). X-Ray Diffraction (XRD) and Differential Thermal Analysis (DTA) techniques were used for characterization of the alloy samples. Guinier photographs were obtained for all the samples and unit cell parameters were calculated using the available software for indexation. The diffraction patterns show sharp lines indicating good thermal equilibrium of the samples. Transition temperatures obtained from DTA measurements were manually obtained from the (T vs. T graph with the criteria that the transition occurs at the intersection of the base line with the slope of the thermal transition peak, as usually. From the analysis of the experimental results it was observed that the solid solubility of VSe in AgInSe2 is approximately 20%, i.e. the single-phase region exists in the composition range 0 ≤ x < 0.2, whereas for x > 0.2 at least two phases coexist. A schematic T-x phase diagram is proposed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Differential thermal analysis

10.1002/pssc.200461821

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Citations (3)

T(z) diagram and optical energy gap values of Cu2(1−z)MnzIn2Te4 alloys

Journal of Alloys and Compounds (1995)

A. Rivero M. Quintero M. Morocoima J. C. Woolley

Tetragonal crystal system

Differential thermal analysis

10.1016/0925-8388(94)01511-2

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Citations (5)

Low temperature magnetic behaviour of CuFeS2 from neutron diffraction data

Journal of Magnetism and Magnetic Materials (1996)

J. C. Woolley A.-M. Lamarche G. Lamarche M. Quintero I. P. Swainson

Rietveld Refinement

Magnetic structure

10.1016/s0304-8853(96)00252-1

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Citations (44)

PHASE DIAGRAM OF (CuInTe 2 ) 1-x (FeTe) x ALLOYS (0 ≤ x ≤ 0.6) ( DIAGRAMA DE FASES DEL SISTEMA DE ALEACIONES (CuInTe 2 ) 1-x (FeTe) x (0 ≤ x ≤ 0.6)

P. Grima M. Quintero Luis Nieves Humberto Cabrera Eduardo Pérez Cappe

Polycrystalline samples of the (CuInTe2)1-x (FeTe)x alloy system where prepared by the melt and anneal technique and the products characterized by X-Ray Diffraction (XRD), Differential Thermal Analysis (DTA) and Optical Diffuse Reflectance Spectroscopy (ODRS) techniques. A first sight, samples were composed by a tetragonal phase with traces of a secondary phase identified as Fe1.125Te. Under exhaustive examination, it was found that the tetragonal phase, at the same time, is composed by two phases, with the same crystal structure and close lattice parameters, typical of spinodal decomposition. From ODRS measurements, optical absorption vs energy curves was obtained. These curves show how the addition of Fe produces a disordering-reordering process in the cationic sublattice suggesting that composition x=0.5 (CuFeInTe3) could be an intermediate compound in the diagram. Using the obtained information, a preliminary T-x phase diagram is proposed. Se prepararon muestras policristalinas del sistema de aleaciones (CuInTe2)1-x (FeTe)x por la tecnica de fusion y recocido; los productos fueron caracterizados por las tecnicas de Difraccion de Rayos X (DRX), Analisis Termico Diferencial (ATD) y Reflectancia por Espectroscopia de Optica Difusa (REOD). A primera vista, las muestras se componen de una fase tetragonal con trazas de una fase secundaria identificada como Fe1.125Te. Bajo un examen mas exhaustivo, se encontro que la fase tetragonal se compone a su vez de dos fases, con la misma estructura cristalina y parametros de red cercanos, tipico de una descomposicion espinodal. A partir de mediciones REOD, se obtuvieron las curvas de absorcion optica vs energia. Estas curvas muestran como la adicion de Fe produce un proceso de desorden-reorden en la subred cationica que sugiere que la composicion x = 0,5 (CuFeInTe3) podria ser un compuesto intermediario en el diagrama. Con la informacion obtenida, se propone un diagrama de fases T-x.

Tetragonal crystal system

Differential thermal analysis

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Phase diagram, optical energy gap, and magnetic susceptibility of (CuIn)1−zMn2zSe2 alloys

physica status solidi (a) (1988)

M. Quintero P. Grima Julie E. Avon G. Lamarche J. C. Woolley

Polycrystalline samples of (CuIn)1−zMn2zSe2 alloys are prepared by the melt and anneal technique and are used in differential thermal analysis, lattice parameter, optical energy gap, and magnetic susceptibility measurements. It is found that the range of single phase solid solution in CuInSe2 extends to z = 0.32 and that the transition temperature from chalcopyrite to zinc blende decreases from 810 °C at z = 0 to 510 °C at the limit of single phase behaviour. Measurements of optical energy gap and magnetic susceptibility as a function of temperature show that in all of the chalcopyrite samples ordering of the manganese on the cation sublattice occurs, while for the zincblende samples, the manganese may be ordered or disordered depending upon the heat treatment used. The magnetic data indicates that the ordering is the same as that observed previously in similar telluride alloys. Polykristalline (CuIn)1−zMn2zSe2-Legierungsproben werden in der Schmelze und mittels Temperung hergestellt und in der differentiellen Thermoanalyse sowie bei Messungen der optischen Bandlücke, Gitterparameter und der magnetischen Suszeptibilität benutzt. Es wird gefunden, daß sich der Bereich der Einphasen-Festkörperlösung in CuInS2 bis zu z = 0,32 ausdehnt und daß die Übergangstemperatur von Chalkopyrit zu Zinkblende von 810 °C bei z = 0 auf 510 °C an der Grenze des Einphasenverhaltens abnimmt. Meassungen der optischen Bandlücke und der magnetischen Suszeptibilität also Funktion der Temperatur zeigen, daß in allen Chalkopyritproben Ordnungsprozesse von Mangan im Kationensubgitter auftreten, während für Zinkblendeproben, Mangan geordnet oder fehlgeordnet sein kann, in Abhägigkeit von der benutzten Wärmebehandlung. Die magnetischen Werte zeigen, daß der Ordnungsvorgang der gleiche ist, der kürzlich in ähnlichen Telluridlegierungen beobachtet wurde.

Telluride

Atmospheric temperature range

10.1002/pssa.2211080214

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Citations (21)

On the crystal structure of the defective ternary compound

Solid State Communications (2010)

D. Caldera M. Morocoima M. Quintero Carlos Rincón R. Casanova

10.1016/j.ssc.2010.11.031

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Citations (14)

Enzymatic determination of N-methylcarbamate pesticides at the nanomolar level by the stopped-flow technique