Electrical Conductivity of TTF-Hydrogen Uranyl Phosphate Composite

Moreno-Real, L.; Pozas-Tormo, R.; Bruque, S.; Martı́nez-Lara, M.; Ramos-Barrado, J.R.

doi:10.1557/proc-210-443

Cited by 2 publications

(2 citation statements)

References 10 publications

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“…Materials.--Samples of HUO2PO4 9 4H20 (HUP), NaUO2PO+. 3 H20 (NaUP), Mg(UO2PO4)2 9 9 H20 (Mg0 sUP), and (CsHsNH)UO=PO4 (pyHUP) were prepared as previously described (5,7,8), except for NaUP and Mg0 sUP, which were slurried in a more dilute 1M solution of the appropriate cation. After isolation, the samples were thoroughly air-dried before use in EL experiments.…”

Section: Methodsmentioning

confidence: 99%

Electroluminescence Cells Based on the Lamellar Solid Hydrogen Uranyl Phosphate

Dieckmann¹,

Ellis²,

Hellstrom³

1990

J. Electrochem. Soc.

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Electroluminescence (EL) cells have been constructed with the layered, ionically conducting solid, hydrogen uranyl phosphate, HUO2PO4 9 4 H20 (HUP), as the emissive medium. With ac excitation, both uranyl emission and molecular nitrogen plasma emission are observed, with the latter appearing to excite the former; the+ uranyl EL spectrum matches the photoluminescence spectrum of the solid. Similar results were obtained with fully substituted sodium (NaUP), magnesium (Mg0.sUP), and pyridinium (pyHUP) derivatives of HUP. For all of these solids, the dependence ~f the EL intensity on sample thickness, ac frequency, and applied voltage has been determined. Typical operating conditions are 1.5-3.0 kV at 0.2-4 kHz. Impedance measurements permitted acquisition of dielectric constants and ionic conductivities for these solids, both of which decrease in the order HUP > NaUP > Mg0.sUP > pyHUP. A model describing the dependence of EL intensity on cell parameters is presented.Display devices involving electroluminescence (EL) have traditionally been based on semiconductors (1, 2) and gas plasma discharges (3, 4). As part of an ongoing investigation of solid-state electro-optical properties, we have studied the photoluminescence (PL) of the lamellar solid, hydrogen uranyl phosphate, HUO2PO4-4H20 (HUP) (5). Since this highly emissive compound is also known to be a good proton conductor (6), we sought to determine whether HUP could serve as the basis for an EL cell.In this paper we report that ac-induced EL can be observed from cells containing HUP and several fully-substituted derivatives of HUP. Characteristic nitrogen plasma emission, arising from the gaseous ambient, is observed and appears to excite the uranyl emission; the uranyl EL spectrum matches its PL counterpart. The dependence of EL intensity on sample thickness, ac frequency, and applied voltage has been determined and impedance measurements have yielded dielectric constants and ionic conductivities for HUP and its derivatives. We present a model based on these data that accounts for the dependence of EL intensity on cell parameters. ExperimentalMaterials.--Samples of HUO2PO4 9 4H20 (HUP), NaUO2PO+. 3 H20 (NaUP), Mg(UO2PO4)2 9 9 H20 (Mg0 sUP), and (CsHsNH)UO=PO4 (pyHUP) were prepared as previously described (5,7,8), except for NaUP and Mg0 sUP, which were slurried in a more dilute 1M solution of the appropriate cation. After isolation, the samples were thoroughly air-dried before use in EL experiments. X-ray powder diffraction patterns were obtained for each solid, using a Nicolet I2/V powder diffractometer, to confirm the identity and single-phase nature of each material. Nitrogen gas ("boil off" from liquid N~) and helium (Badger Welding Supply, Incorporated, 99.99%) were used as received.EL experiments.--The cell shown in Fig. 1 was used for the majority of EL experiments. The cell consists of a cylindrical acrylic holder (3.8 cm diam x 2.8 cm) containing a 0.64 cm diam hole at its center. A cylindrical A1 rod (0.64 cm diam • 2.7 cm) can be inserted into the hol...

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Section: Methodsmentioning

confidence: 99%

Electroluminescence Cells Based on the Lamellar Solid Hydrogen Uranyl Phosphate

Dieckmann¹,

Ellis²,

Hellstrom³

1990

J. Electrochem. Soc.

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“…For other applications, and particularly for SiC-microelectromechanical systems ͑MEMS͒ devices, large-area substrates are essential. 1 The cubic polytype, namely, 3C-SiC but also known as ␤-SiC, is the only polytype with a cubic crystal structure which crystallizes in a ZnS lattice structure and hence it can be deposited on silicon substrates. This allows the growth of cubic silicon carbide layers on large-area silicon substrates and paves the way for this suitable and important material to be applied to MEMS or nanoelectromechanical systems.…”

mentioning

confidence: 99%

Low Stress Heteroepitaxial 3C-SiC Films Characterized by Microstructure Fabrication and Finite Elements Analysis

Anzalone

Camarda

Locke

et al. 2010

J. Electrochem. Soc.

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Chemical vapor deposition in the low pressure regime of a high quality 3C-SiC film on silicon ͑100͒-oriented substrates was carried out using silane ͑SiH 4 ͒, propane ͑C 3 H 8 ͒, and hydrogen ͑H 2 ͒ as the silicon supply, carbon supply, and gas carrier, respectively. The resulting bow in the freestanding cantilever structures was evaluated by an optical profilometer, and the residual gradient stress ͑ 1 ͒ in the films was calculated to be approximately between 15 and 20 MPa, which is significantly lower than the previously reported 3C-SiC on Si films. Finite element simulations of the stress field in the cantilever have been carried out to separate the uniform contribution ͑ 0 ͒, related to the SiC/Si interface, from the gradient one ͑ 1 ͒, related to the defects present in the SiC epilayer.There is an increasing demand for sensors that can operate at temperatures well above 300°C and in severe environments such as automotive and aerospace applications. In particular, combustion process and gas turbine control have stimulated the search for alternatives to silicon. Silicon carbide ͑SiC͒ is a material that has attracted much attention for a long time, particularly due to its wide bandgap, its ability to operate at high temperatures, its mechanical strength, and its inertness to exposure in corrosive environments. However, the difficulty in growing high quality crystalline material and processing electronic devices has limited its use to very specific application areas, such as high temperature, high power, and high frequency applications that are not suitable for Si-based devices. For other applications, and particularly for SiC-microelectromechanical systems ͑MEMS͒ devices, large-area substrates are essential. 1 The cubic polytype, namely, 3C-SiC but also known as ␤-SiC, is the only polytype with a cubic crystal structure which crystallizes in a ZnS lattice structure and hence it can be deposited on silicon substrates. This allows the growth of cubic silicon carbide layers on large-area silicon substrates and paves the way for this suitable and important material to be applied to MEMS or nanoelectromechanical systems. 2 The use of large-area substrates offers the possibility for economical and low cost batch processing, which makes SiC more attractive for sensors and device applications. The heteroepitaxy of SiC on Si substrates results in the heterostructure 3C-SiC/Si, which is a very interesting material system for MEMS and nanoelectromechanical systems.With respect to the mechanical properties of the silicon carbide films for use in sensors or freestanding MEMS structures, one important issue is the residual stress field, which is normally created during the growth process and which can result in the unwanted deformation or failure of these structures. Stress varies from point to point within the crystal lattice, altering the lattice spacing and consequently changing the properties of the material.For example, the built-in stress may change the mechanical response, the resonant frequency of the thin-film struc...

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Electrical Conductivity of TTF-Hydrogen Uranyl Phosphate Composite

Abstract: H3OUO2PO4.3H2O (HUP) undergoes intercalative reaction with tetrathiafulvalene (TTF) given a black solid with the next composition: (TTF)U02P04.0.6H2O. The electrical conductivity fall from 2.40.10−6 Ω−1 cm−1 (363K) to 8.8.10−8 Ω−1 cm−1(473K).

Cited by 2 publications

References 10 publications

Electroluminescence Cells Based on the Lamellar Solid Hydrogen Uranyl Phosphate

Electroluminescence Cells Based on the Lamellar Solid Hydrogen Uranyl Phosphate

Low Stress Heteroepitaxial 3C-SiC Films Characterized by Microstructure Fabrication and Finite Elements Analysis

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