Rafael Espinlsa - Academia.edu (original) (raw)

Papers by Rafael Espinlsa

Economia Mexicana, Nueva Epoca

A Cournot oligopolistic setting model of trade is characterized by local and foreign firms compet... more A Cournot oligopolistic setting model of trade is characterized by local and foreign firms competing in the presence of pollution quota and tax. Local firms are foreign-owned (FDI) and repatriate their profits. First, we analyze the impact on welfare given by the merger of the local firms, as a response to external firms’ competition and pollution abatement costs. Second, when merger is welfare decreasing, we study the best response of the government in order to compensate this negative externality. Finally, we compare the pollution quota and tax in order to determine their efficiency as a policy instrument.

Revista de análisis económico, 2021

Carta Economica Regional, 2002

EconoQuantum, 2004

Una buena compilación puede ser encontrada en Klein (1999). 5. Algunos ejemplos son los admirable... more Una buena compilación puede ser encontrada en Klein (1999). 5. Algunos ejemplos son los admirables y acertados artículos escritos por Rodrik (2000), Willliamson (1996) y Bardhan (1989), entre otros. Corrupción, inversión extranjera directa y reformas institucionales  19

In view of the demographic changes which are taking and will take place in Spain, as well as the ... more In view of the demographic changes which are taking and will take place in Spain, as well as the uncertainty about the ability of the public social security system to meet the obligations it has acquired, mutual provident societies are offering complementary services within a mixed social security system. Due to the limited attention that the literature has paid to these societies, the aim of this paper is to acquire a deeper knowledge of these companies by drawing multiple comparisons between these organisations and another type of mutual called industrial accident and occupational illness mutual insurance companies, using the Scheffé test. Special attention will be paid to the regions of Catalonia and the Basque Country, which are the most active Spanish regions in developing mutualism.

In recent years it has carried out a policy of decentralization of education in our country assum... more In recent years it has carried out a policy of decentralization of education in our country assuming the CCAA and the trade unions and employers' new skills. In this context, the analysis of the territorial dimension of the transfer of the execution of these policies is of great interest in Spain as it is one of the EU countries with the highest willingness to promote a decentralized model. The article analyzes the evolution of the decentralization of training for employment in our country and its economic conditions, administrative and organizational. The issues set out to design a model that allows conceptualize what parameters need to be addressed in any process of decentralization of the current system of job training under the current reform proposals for the work of March 2012.

El trabajo pretende realizar un análisis descriptivo sobre las causas y motivaciones de los proce... more El trabajo pretende realizar un análisis descriptivo sobre las causas y motivaciones de los procesos de colaboración establecidos por las principales ONGs españolas (44 de las 100 mayores de nuestro país por presupuesto). Sobre todo se centra en procesos de colaboración intrasectorial, ONG-ONG, pero también se describen los aspectos más generales de colaboraciones de tipo intersectorial, ONG-empresa y en menor medida ONG-Sector Público. El escenario descrito nos dibuja un sector muy proclive a la colaboración, a la cual está acostumbrada desde hace un mayor número de años que la empresa, y la cual se articulo con objetivos muy diferentes en función de quien sea el partner elegido. Esta discriminación entre formas y modelos de actuación nos hace pensar que existe una dirección cada vez más cualificada y formada en el campo del management dentro de las ONGs, la cual traerá, a nuestro juicio, un desarrollo importante de las colaboraciones y el trabajo en red durante los próximos años.

Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions With Materials and Atoms, 2010

Undoped and Mg-doped α-Al2O3 single crystals were implanted with Mg ions, with an energy of 90keV... more Undoped and Mg-doped α-Al2O3 single crystals were implanted with Mg ions, with an energy of 90keV and a fluence of 1017ions/cm2. DC electrical measurements using the four-point probe method, between 295 and 428K, were used to characterize the electrical conductivity of the implanted area. Measurements in this temperature range indicate that the electrical conductivity after implantation is thermally activated with

Physical Review B, 2002

The phenomenally large enhancement in conductivity observed when Li-doped MgO crystals are oxidiz... more The phenomenally large enhancement in conductivity observed when Li-doped MgO crystals are oxidized at elevated temperatures was investigated by dc and ac electrical measurements in the temperature interval 250-673 K. The concentration of [Li] 0 centers (Li + ions each with a trapped hole) resulting from oxidation was monitored by optical absorption measurements. At low electric fields, dc measurements reveal blocking contacts. At high fields, the I − V characteristic is similar to that of a diode connected in series with the bulk resistance of the sample. Low voltage ac measurements show that the equivalent circuit for the sample consists of the bulk resistance in series with the junction capacitance connected in parallel with a capacitance, which represents the dielectric constant of the sample. Both dc and ac experiments provide consistent values for the bulk resistance. The electrical conductivity of oxidized MgO:Li crystals increases linearly with the concentration of [Li] 0 centers. The conductivity is thermally activated with an activation energy of (0.70 ± 0.01) eV, which is independent of the [Li] 0 content. The standard semiconducting mechanism satisfactorily explains these results. Free holes are the main contribution to band conduction as they are trapped at or released from the [Li] 0-acceptor centers. In as-grown MgO:Li crystals, electrical current increases dramatically with time due to the formation of [Li] 0 centers. The activation energy values between 1.3 and 0.7 eV are likely a combination of the activation energy for the creation of [Li] 0 centers and the activation energy of ionization of these centers. Destruction of [Li] 0 centers can be induced in oxidized crystals by application of an electric field due to Joule heating up to temperatures at which [Li] 0 centers are not stable.

Materials Science Forum, 1997

ABSTRACT

Organic Field-Effect Transistors VIII, 2009

The search of new organic molecules with improved properties is of fundamental relevance for hybr... more The search of new organic molecules with improved properties is of fundamental relevance for hybrid organic-inorganic based devices (OLED, FET, PV, injection layers, flexible large area devices, lasers, etc.). Triindole based materials present extended aromatic cores with disk-like geometry that allow tailoring their electronic properties through chemical functionalization. In this work we present an optical and electronic study of new triindole based single crystals. Pistacking gives rise to highly ordered columnar structures yielding to high mobilities, around 0.4 cm2V-1s-1. External oxidation is found to increase orders of magnitude the conductivity. Slight modifications of this platform modify substantially the crystallization dynamics and therefore the quality of the thin films obtained by spin coating from solutions with different solvents. The morphology, stability and properties of the optimized films are found to be promising for device fabrication. A comparative study of the absorption and emission efficiency of solutions and thin films of the different derivatives is presented. The first tests for OLED and OFET devices are under way.

Radiation Effects and Defects in Solids, 2001

AC and DC electrical measurements between 273 and 800 K were used to characterize the electrical ... more AC and DC electrical measurements between 273 and 800 K were used to characterize the electrical conductivity of Al 2 O 3 :Mg single crystals containing [Mg] 0 center. At low fields contacts are blocking. At high fields, electrical current flows steadily through the sample and the I-V characteristic corresponds to a directly biased barrier whit a series resistance (bulk resistance). AC measurements yield values for the junction capacitance as well as for the sample resistance, and provide perfectly reproducible conductivity values. The conductivity varies linearly whit the [Mg] 0 concentration and a thermal activation energy of 0.68 eV was obtained, which agrees very well with the activation energy previously reported for motion of free holes.

Radiation Effects and Defects in Solids, 2001

Hydrogen and deuterium are observed in alpha-Al2O3 crystals in the form of OH- and OD- radicals, ... more Hydrogen and deuterium are observed in alpha-Al2O3 crystals in the form of OH- and OD- radicals, respectively, which absorb in the infrared region. Infrared-absorption measurements were used to monitor diffusion of deuterons and protons in alpha-Al2O3 single crystals under the application of a moderate electric field parallel to the crystallographic c-axis, in the temperature range of 973-1333K. A linear dependence

Radiation Effects and Defects in Solids, 2001

Electroluminescence (EL) was investigated in Al2O3:Mg single crystals containing thermally genera... more Electroluminescence (EL) was investigated in Al2O3:Mg single crystals containing thermally generated [Mg]0 centers when a current in excess of 10 muA was passed through the samples in the temperature interval 323-673 K. The EL is emitted from a narrow region at the negative electrode suggesting an electron-hole recombination process due to the injection of electrons which recombine with holes. EL

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2012

With the aim to study the effects of heavy ion implantation on the morphology of a-Al 2 O 3 singl... more With the aim to study the effects of heavy ion implantation on the morphology of a-Al 2 O 3 single crystals with c, m and r orientations, ion implantation at room temperature, with Au or Ag ions, energy of 160 keV and fluences ranging from 5 Â 10 15 to 1 Â 10 17 ions cm À2 was performed. The microstructure and morphology of irradiated surfaces were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The presence of metal precipitates was explored by AFM and monitored by the variation of the intensity of the extinction bands associated with Mie scattering from Au and Ag colloids located at about 2.2 eV (563 nm) and 2.8 eV (443 nm), respectively. The results show a dependence on the surface roughness with the ion fluence and the implantation orientation. The dependence of thermal conductivity with the implanted conditions was studied by scanning thermal microscopy. Thermal images indicate that thermal conductivity of Al 2 O 3 is higher in samples implanted with Ag ions at a fluence of 6 Â 10 16 ions cm À2 than in samples implanted with Au at a higher fluence. Successive etchings of an Ag implanted sample reveal a dependence of the thermal conductivity with the distance to the surface due to the layered damage structure produced by the implantation. The DC electrical measurements, between 273 and 445 K, using the four and two-point probe methods were used to characterize the electrical conductivity of the implanted area. The I-V characteristic of the electrical contacts reveals an ohmic behavior, independent of the ions implanted and the crystallographic orientation. Measurements of the electrical conductivity at different temperatures in the investigated range predominantly suggest a band conduction mechanism thermally activated, with energies of about 0.09 and 0.07 eV, in samples implanted with Au or Ag ions, respectively. We conclude that the enhancement in conductivity observed in the implanted regions is related to the intrinsic defects created by the implantation, rather than to the implanted Au and Ag ions.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2008

Undoped a-Al 2 O 3 single crystals with the c axis either perpendicular or parallel to the broad ... more Undoped a-Al 2 O 3 single crystals with the c axis either perpendicular or parallel to the broad face were implanted with Mg ions. The concentrations of defects induced by implantation were monitored by optical absorption measurements. In the Mg-implanted region, direct current electrical measurements were made between 296 and 445 K. At room temperature, an increase in the electrical conductivity of about 15 orders of magnitude relative to the unimplanted region was observed only in crystals with the c axis perpendicular to the broad face of the samples. The I-V characteristics reveal an ohmic behavior of the electrical contact on the implanted area. Measurements at different temperatures suggest that the electrical conductivity is thermally activated with an activation energy of about 0.02 eV. We relate the enhancement in conductivity observed in the implanted regions to intrinsic defects created by the implantation, rather than with the implanted Mg ions.

Materials Science and Engineering: C, 2006

Iron thin films have been grown by DC magnetron sputtering using Si(100) wafers as substrates, an... more Iron thin films have been grown by DC magnetron sputtering using Si(100) wafers as substrates, and then oxidized in a well-controlled oxygen atmosphere in the vacuum chamber. Film thickness is about 50 nm, and grains forming these samples do not exceed 20 nm. In order to control structural properties such as size and shape of these grains, growth conditions can be modified, like deposition rate or substrate temperature, varying from 150 to 300 K. Two sets of samples have been prepared considering deposition rate: (i) films grown at 0.6 nm/min and (ii) at 1.2 nm/min. In order to prevent iron films from natural oxidation, all the sample series were covered with a gold layer. Analysis of their magnetic behaviour shows a strong dependence on grain size and temperature, resulting in a more effective oxidation for samples prepared at higher deposition rates and lower substrate temperatures, which behaves as a Fe/Fe oxide granular system.

Economia Mexicana, Nueva Epoca

A Cournot oligopolistic setting model of trade is characterized by local and foreign firms compet... more A Cournot oligopolistic setting model of trade is characterized by local and foreign firms competing in the presence of pollution quota and tax. Local firms are foreign-owned (FDI) and repatriate their profits. First, we analyze the impact on welfare given by the merger of the local firms, as a response to external firms’ competition and pollution abatement costs. Second, when merger is welfare decreasing, we study the best response of the government in order to compensate this negative externality. Finally, we compare the pollution quota and tax in order to determine their efficiency as a policy instrument.

Revista de análisis económico, 2021

Carta Economica Regional, 2002

EconoQuantum, 2004

Una buena compilación puede ser encontrada en Klein (1999). 5. Algunos ejemplos son los admirable... more Una buena compilación puede ser encontrada en Klein (1999). 5. Algunos ejemplos son los admirables y acertados artículos escritos por Rodrik (2000), Willliamson (1996) y Bardhan (1989), entre otros. Corrupción, inversión extranjera directa y reformas institucionales  19

In view of the demographic changes which are taking and will take place in Spain, as well as the ... more In view of the demographic changes which are taking and will take place in Spain, as well as the uncertainty about the ability of the public social security system to meet the obligations it has acquired, mutual provident societies are offering complementary services within a mixed social security system. Due to the limited attention that the literature has paid to these societies, the aim of this paper is to acquire a deeper knowledge of these companies by drawing multiple comparisons between these organisations and another type of mutual called industrial accident and occupational illness mutual insurance companies, using the Scheffé test. Special attention will be paid to the regions of Catalonia and the Basque Country, which are the most active Spanish regions in developing mutualism.

In recent years it has carried out a policy of decentralization of education in our country assum... more In recent years it has carried out a policy of decentralization of education in our country assuming the CCAA and the trade unions and employers' new skills. In this context, the analysis of the territorial dimension of the transfer of the execution of these policies is of great interest in Spain as it is one of the EU countries with the highest willingness to promote a decentralized model. The article analyzes the evolution of the decentralization of training for employment in our country and its economic conditions, administrative and organizational. The issues set out to design a model that allows conceptualize what parameters need to be addressed in any process of decentralization of the current system of job training under the current reform proposals for the work of March 2012.

El trabajo pretende realizar un análisis descriptivo sobre las causas y motivaciones de los proce... more El trabajo pretende realizar un análisis descriptivo sobre las causas y motivaciones de los procesos de colaboración establecidos por las principales ONGs españolas (44 de las 100 mayores de nuestro país por presupuesto). Sobre todo se centra en procesos de colaboración intrasectorial, ONG-ONG, pero también se describen los aspectos más generales de colaboraciones de tipo intersectorial, ONG-empresa y en menor medida ONG-Sector Público. El escenario descrito nos dibuja un sector muy proclive a la colaboración, a la cual está acostumbrada desde hace un mayor número de años que la empresa, y la cual se articulo con objetivos muy diferentes en función de quien sea el partner elegido. Esta discriminación entre formas y modelos de actuación nos hace pensar que existe una dirección cada vez más cualificada y formada en el campo del management dentro de las ONGs, la cual traerá, a nuestro juicio, un desarrollo importante de las colaboraciones y el trabajo en red durante los próximos años.

Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions With Materials and Atoms, 2010

Undoped and Mg-doped α-Al2O3 single crystals were implanted with Mg ions, with an energy of 90keV... more Undoped and Mg-doped α-Al2O3 single crystals were implanted with Mg ions, with an energy of 90keV and a fluence of 1017ions/cm2. DC electrical measurements using the four-point probe method, between 295 and 428K, were used to characterize the electrical conductivity of the implanted area. Measurements in this temperature range indicate that the electrical conductivity after implantation is thermally activated with

Physical Review B, 2002

The phenomenally large enhancement in conductivity observed when Li-doped MgO crystals are oxidiz... more The phenomenally large enhancement in conductivity observed when Li-doped MgO crystals are oxidized at elevated temperatures was investigated by dc and ac electrical measurements in the temperature interval 250-673 K. The concentration of [Li] 0 centers (Li + ions each with a trapped hole) resulting from oxidation was monitored by optical absorption measurements. At low electric fields, dc measurements reveal blocking contacts. At high fields, the I − V characteristic is similar to that of a diode connected in series with the bulk resistance of the sample. Low voltage ac measurements show that the equivalent circuit for the sample consists of the bulk resistance in series with the junction capacitance connected in parallel with a capacitance, which represents the dielectric constant of the sample. Both dc and ac experiments provide consistent values for the bulk resistance. The electrical conductivity of oxidized MgO:Li crystals increases linearly with the concentration of [Li] 0 centers. The conductivity is thermally activated with an activation energy of (0.70 ± 0.01) eV, which is independent of the [Li] 0 content. The standard semiconducting mechanism satisfactorily explains these results. Free holes are the main contribution to band conduction as they are trapped at or released from the [Li] 0-acceptor centers. In as-grown MgO:Li crystals, electrical current increases dramatically with time due to the formation of [Li] 0 centers. The activation energy values between 1.3 and 0.7 eV are likely a combination of the activation energy for the creation of [Li] 0 centers and the activation energy of ionization of these centers. Destruction of [Li] 0 centers can be induced in oxidized crystals by application of an electric field due to Joule heating up to temperatures at which [Li] 0 centers are not stable.

Materials Science Forum, 1997

ABSTRACT

Organic Field-Effect Transistors VIII, 2009

The search of new organic molecules with improved properties is of fundamental relevance for hybr... more The search of new organic molecules with improved properties is of fundamental relevance for hybrid organic-inorganic based devices (OLED, FET, PV, injection layers, flexible large area devices, lasers, etc.). Triindole based materials present extended aromatic cores with disk-like geometry that allow tailoring their electronic properties through chemical functionalization. In this work we present an optical and electronic study of new triindole based single crystals. Pistacking gives rise to highly ordered columnar structures yielding to high mobilities, around 0.4 cm2V-1s-1. External oxidation is found to increase orders of magnitude the conductivity. Slight modifications of this platform modify substantially the crystallization dynamics and therefore the quality of the thin films obtained by spin coating from solutions with different solvents. The morphology, stability and properties of the optimized films are found to be promising for device fabrication. A comparative study of the absorption and emission efficiency of solutions and thin films of the different derivatives is presented. The first tests for OLED and OFET devices are under way.

Radiation Effects and Defects in Solids, 2001

AC and DC electrical measurements between 273 and 800 K were used to characterize the electrical ... more AC and DC electrical measurements between 273 and 800 K were used to characterize the electrical conductivity of Al 2 O 3 :Mg single crystals containing [Mg] 0 center. At low fields contacts are blocking. At high fields, electrical current flows steadily through the sample and the I-V characteristic corresponds to a directly biased barrier whit a series resistance (bulk resistance). AC measurements yield values for the junction capacitance as well as for the sample resistance, and provide perfectly reproducible conductivity values. The conductivity varies linearly whit the [Mg] 0 concentration and a thermal activation energy of 0.68 eV was obtained, which agrees very well with the activation energy previously reported for motion of free holes.

Radiation Effects and Defects in Solids, 2001

Hydrogen and deuterium are observed in alpha-Al2O3 crystals in the form of OH- and OD- radicals, ... more Hydrogen and deuterium are observed in alpha-Al2O3 crystals in the form of OH- and OD- radicals, respectively, which absorb in the infrared region. Infrared-absorption measurements were used to monitor diffusion of deuterons and protons in alpha-Al2O3 single crystals under the application of a moderate electric field parallel to the crystallographic c-axis, in the temperature range of 973-1333K. A linear dependence

Radiation Effects and Defects in Solids, 2001

Electroluminescence (EL) was investigated in Al2O3:Mg single crystals containing thermally genera... more Electroluminescence (EL) was investigated in Al2O3:Mg single crystals containing thermally generated [Mg]0 centers when a current in excess of 10 muA was passed through the samples in the temperature interval 323-673 K. The EL is emitted from a narrow region at the negative electrode suggesting an electron-hole recombination process due to the injection of electrons which recombine with holes. EL

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2012

With the aim to study the effects of heavy ion implantation on the morphology of a-Al 2 O 3 singl... more With the aim to study the effects of heavy ion implantation on the morphology of a-Al 2 O 3 single crystals with c, m and r orientations, ion implantation at room temperature, with Au or Ag ions, energy of 160 keV and fluences ranging from 5 Â 10 15 to 1 Â 10 17 ions cm À2 was performed. The microstructure and morphology of irradiated surfaces were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The presence of metal precipitates was explored by AFM and monitored by the variation of the intensity of the extinction bands associated with Mie scattering from Au and Ag colloids located at about 2.2 eV (563 nm) and 2.8 eV (443 nm), respectively. The results show a dependence on the surface roughness with the ion fluence and the implantation orientation. The dependence of thermal conductivity with the implanted conditions was studied by scanning thermal microscopy. Thermal images indicate that thermal conductivity of Al 2 O 3 is higher in samples implanted with Ag ions at a fluence of 6 Â 10 16 ions cm À2 than in samples implanted with Au at a higher fluence. Successive etchings of an Ag implanted sample reveal a dependence of the thermal conductivity with the distance to the surface due to the layered damage structure produced by the implantation. The DC electrical measurements, between 273 and 445 K, using the four and two-point probe methods were used to characterize the electrical conductivity of the implanted area. The I-V characteristic of the electrical contacts reveals an ohmic behavior, independent of the ions implanted and the crystallographic orientation. Measurements of the electrical conductivity at different temperatures in the investigated range predominantly suggest a band conduction mechanism thermally activated, with energies of about 0.09 and 0.07 eV, in samples implanted with Au or Ag ions, respectively. We conclude that the enhancement in conductivity observed in the implanted regions is related to the intrinsic defects created by the implantation, rather than to the implanted Au and Ag ions.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2008

Undoped a-Al 2 O 3 single crystals with the c axis either perpendicular or parallel to the broad ... more Undoped a-Al 2 O 3 single crystals with the c axis either perpendicular or parallel to the broad face were implanted with Mg ions. The concentrations of defects induced by implantation were monitored by optical absorption measurements. In the Mg-implanted region, direct current electrical measurements were made between 296 and 445 K. At room temperature, an increase in the electrical conductivity of about 15 orders of magnitude relative to the unimplanted region was observed only in crystals with the c axis perpendicular to the broad face of the samples. The I-V characteristics reveal an ohmic behavior of the electrical contact on the implanted area. Measurements at different temperatures suggest that the electrical conductivity is thermally activated with an activation energy of about 0.02 eV. We relate the enhancement in conductivity observed in the implanted regions to intrinsic defects created by the implantation, rather than with the implanted Mg ions.

Materials Science and Engineering: C, 2006

Iron thin films have been grown by DC magnetron sputtering using Si(100) wafers as substrates, an... more Iron thin films have been grown by DC magnetron sputtering using Si(100) wafers as substrates, and then oxidized in a well-controlled oxygen atmosphere in the vacuum chamber. Film thickness is about 50 nm, and grains forming these samples do not exceed 20 nm. In order to control structural properties such as size and shape of these grains, growth conditions can be modified, like deposition rate or substrate temperature, varying from 150 to 300 K. Two sets of samples have been prepared considering deposition rate: (i) films grown at 0.6 nm/min and (ii) at 1.2 nm/min. In order to prevent iron films from natural oxidation, all the sample series were covered with a gold layer. Analysis of their magnetic behaviour shows a strong dependence on grain size and temperature, resulting in a more effective oxidation for samples prepared at higher deposition rates and lower substrate temperatures, which behaves as a Fe/Fe oxide granular system.