Intermediate Range Structure in Ion-Conducting Tellurite Glasses

We present ac conductivity spectra of tellurite glasses at several temperatures. For the first time, we report oscillatory modulations at frequencies around MHz. This effect is more pronounced the lower the temperature, and washes out when approaching the glass transition temperature $T_g$. We show, by using a minimal model, how this modulation may be attributed to the fractal structure of the glass at intermediate mesoscopic length scales

Structure and electrical behavior relationship of a magnesium–tellurite glass using Raman and impedance spectroscopy

In this paperwe present the study of the glassy systems of formula: xMgO(1−x)(0.5V2O5·0.5MoO3)2TeO2,with (0 b x b 1). The aim of the work is to understand the relationship between in the induced changes in the glassy matrix by the incorporation of MgO in a vanadium–tellurite glass and the electrical response of the material. It has been found that the incorporation of MgO in the glassy matrix raises the glass transition temperature. The whole system's electrical behavior is explained by the small polaron hopping, in good agreement with the variable range polaron hopping model. In this matrix, an ionic transport by Mg2+ is not allowed. The study gives an opportunity to understand how to tune in the middle-range glassy structural order and, as a direct implication, how to control the electrical conduction process.Instituto de Física La Plat

Structure and electrical behavior relationship of a magnesium–tellurite glass using Raman and impedance spectroscopy

In this paperwe present the study of the glassy systems of formula: xMgO(1−x)(0.5V2O5·0.5MoO3)2TeO2,with (0 b x b 1). The aim of the work is to understand the relationship between in the induced changes in the glassy matrix by the incorporation of MgO in a vanadium–tellurite glass and the electrical response of the material. It has been found that the incorporation of MgO in the glassy matrix raises the glass transition temperature. The whole system's electrical behavior is explained by the small polaron hopping, in good agreement with the variable range polaron hopping model. In this matrix, an ionic transport by Mg2+ is not allowed. The study gives an opportunity to understand how to tune in the middle-range glassy structural order and, as a direct implication, how to control the electrical conduction process.Instituto de Física La Plat

Ep-CAM (MOC-31) expression in tooth germ and ameloblastoma

Ep-CAM, a transmembrane glycoprotein expressed in most epithelium in normal conditions, has diverse roles in these tissues, including in cell adhesion, proliferation, differentiation, cell cycle regulation, migration and intracellular signaling. It is also over-expressed in most malignant neoplasia, participating in the initiation, progression, and metastatic dissemination of the tumor. The expression and roles of this protein in oral neoplasia, particularly in odontogenic tumors, remain unestablished. The objective of this study consisted in analyzing the expression of this protein in ameloblastoma and tooth germ

Electric behavior of functional glasses based on TeO2

In this paper we study the structural and electrical behavior of glass-ceramic material of general formula: xMgO (1-x) (0.5V2O 5.0.5MoO3)2TeO2 (0≤x≤0.9) through measurements of density, molar volume, oxygen packing density (OPD), differential scanning calorimetry (DSC) and Raman spectroscopy: electric behavior was studied by impedance spectroscopy. We found that magnesium cation induces the growth of slightly crystallized areas inside the material. Those nanocrystallizations were detected to a greater extent by atomic force microscopy (AFM) and in lesser extent by X-ray diffraction (XRD). Regarding the electrical measurements, it can be established that magnesium cation does not act as good ionic conductor in this material.En este trabajo estudiamos la estructura de un material vítreo cuya fórmula general es: xMgO(1-x)(0.5V2 O5 .0.5MoO3)2TeO2 (0≤x≤0.9), mediante medidas de densidad, volumen molar, empaquetamiento denso de oxigeno (OPD), calorimetría diferencial de barrido (DSC) y espectroscopia Raman; el comportamiento eléctrico se estudió por medio de espectroscopia de impedancia. Encontramos que el catión magnesio induce el crecimiento de zonas levemente cristalizadas dentro del material. Dichas nanocristalizaciones pudieron ser detectadas en mayor medida por microscopia de fuerzas atómicas (AFM) y en menor medida se pudo observar en los patrones de difracción de Rayos X (DRX). Con respecto a las propiedades eléctricas, se puede establecer que el catión magnesio no actúa como buen conductor iónico en este material.Instituto de Física La Plat

Electric behavior of functional glasses based on TeO2

In this paper we study the structural and electrical behavior of glass-ceramic material of general formula: xMgO (1-x) (0.5V2O 5.0.5MoO3)2TeO2 (0≤x≤0.9) through measurements of density, molar volume, oxygen packing density (OPD), differential scanning calorimetry (DSC) and Raman spectroscopy: electric behavior was studied by impedance spectroscopy. We found that magnesium cation induces the growth of slightly crystallized areas inside the material. Those nanocrystallizations were detected to a greater extent by atomic force microscopy (AFM) and in lesser extent by X-ray diffraction (XRD). Regarding the electrical measurements, it can be established that magnesium cation does not act as good ionic conductor in this material.En este trabajo estudiamos la estructura de un material vítreo cuya fórmula general es: xMgO(1-x)(0.5V2 O5 .0.5MoO3)2TeO2 (0≤x≤0.9), mediante medidas de densidad, volumen molar, empaquetamiento denso de oxigeno (OPD), calorimetría diferencial de barrido (DSC) y espectroscopia Raman; el comportamiento eléctrico se estudió por medio de espectroscopia de impedancia. Encontramos que el catión magnesio induce el crecimiento de zonas levemente cristalizadas dentro del material. Dichas nanocristalizaciones pudieron ser detectadas en mayor medida por microscopia de fuerzas atómicas (AFM) y en menor medida se pudo observar en los patrones de difracción de Rayos X (DRX). Con respecto a las propiedades eléctricas, se puede establecer que el catión magnesio no actúa como buen conductor iónico en este material.Instituto de Física La Plat

Caracterización eléctrica de fronteras de grano en conductores iónicos mediante medidas de espectroscopia de impedancias en un bicristal

En este trabajo se presentan resultados de medidas de espectroscopia de impedancias realizadas en un bicristal del conductor iónico zirconia estabilizada con itria (YSZ). Utilizando electrodos de tamaño micrométrico se ha podido medir el transporte iónico a través, perpendicularmente, de una única frontera de grano, caracterizando eléctricamente las propiedades de dicha frontera. De este modo se han obtenido los parámetros microscópicos que determinan la distribución de carga en la frontera y por lo tanto el transporte iónico a través de ella, como son la barrera de potencial en la frontera DF = 0.35±0.01 V a 275 ºC, y el espesor de la zona de carga espacial l* = 5±1 Å. Estos valores son significativamente diferentes a los obtenidos anteriormente en muestras cerámicas policristalinas del mismo material, y muestran mejor acuerdo con los valores que predice el modelo de Mott-Schottky para la distribución de carga y el transporte iónico a través de la frontera de granoPeer reviewe