Ferroelectric single crystals Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) are promising full materials for non resonant or large bandwidth transducers due to the large values of their piezoelectric properties (d ij , k ij ) and ...Ferroelectric single crystals Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) are promising full materials for non resonant or large bandwidth transducers due to the large values of their piezoelectric properties (d ij , k ij ) and their low mechanical quality factor (Q ij ). Many studies on oriented PZN-4.5PT single crystals were carried out but it is very difficult to find research findings on oriented Mn doped PZN-PT. Thus, investigations were made using XRD, Raman and EPR characterization for oriented PZN-4.5PT grown through the Flux method. Mn doping effect on structural, dielectric, mechanical and piezoelectric properties with two values of Mn percentage (1 and 2 mol%) are also reported in this paper. Through the XRD study, the lattice parameters of doped PZN-PT crystals are slightly increased compared to the undoped one but the Mn didn’t change its structure. The room temperature dielectric permittivity along direction is about 1572 and 1626 (respectively 1% and 2% Mn doped crystals) which are much lower than that of the undoped PZN-4.5PT (2553). The remnant polarization and coercive field of oriented doped crystal measured at 1 KHz are respectively 30 μC/cm2 and 4.30 kV/cm (PZN-4.5PT), 32 μC/cm2 and 6.10 kV/cm (PZN-4.5PT + 1% Mn) and 28 μC/cm2 and 7.30 kV/cm (for the 2% Mn doped crystal). The mechanical quality factor Qm changed from 139 to 441 respectively for the pure and 1% Mn doped single crystals at room temperature while it decreases slightly to 336 for the 2 mol% Mn doped.展开更多
In this paper, we have declined the formalism of the method of the Modified Atomic Orbital Theory (MAOT) applied to the calculations of energies of doubly excited states 2<em>snp</em>, 3<em>snp</e...In this paper, we have declined the formalism of the method of the Modified Atomic Orbital Theory (MAOT) applied to the calculations of energies of doubly excited states 2<em>snp</em>, 3<em>snp</em>, and 4<em>snp</em> Helium-like systems. Then we also applied the variational procedure of the Modified Atomic Orbital Theory to the computations of total energies, excitation energies of doubly-excited states 2<em>snp</em>, 3<em>snp</em>, 4<em>snp</em> types of Helium-like systems. The results obtained in this work are in good agreement with the experimental and theoretical values available.展开更多
Historically, the LiCoO2 is the most used as active material for battery positive electrode because of its great potential (3.7 - 4.2 V), its interesting specific capacity (150 mA·h·g-1) and its excellent li...Historically, the LiCoO2 is the most used as active material for battery positive electrode because of its great potential (3.7 - 4.2 V), its interesting specific capacity (150 mA·h·g-1) and its excellent life cycle [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003300390038003500370036003700340032000000 . However, its toxicity, the cobalt cost and its structural instability oriented research towards new materials more stable that can replace it. In another context, hybrid, electrical vehicles and communication (computers and mobile phones...) have increased the scientific and technological research for new materials capable of storing and return energy through a system called accumulator. And research has identified the phosphate olivine structure as the most prolific ceramic material for positive electrode. LiFePO4 is a promising cathode material for Lithium-ion batteries. It provides high thermal stability and is synthesized using low cost materials. Unfortunately LiFePO4 suffers from a low electrical conductivity, which is harmful to its electrochemical performance. Decreasing the particle size, coating the particles with carbon or doping with metal atoms can increase the conductivity of the material. In this paper, we present the synthesis, physico-chemical and electrical characterization of lithium and iron doped Al-phosphorrus-based ceramic. The NPK Fertiliser was used as Al and phosphorus precursors. The powder XRD spectrum shows a possible presence of LiFePO4 and Fe2(PO)3 in theheterostrcture. An important quantity of Al is found by EDX spectra which supposed that the most important based atom is Aluminum and not Phosphorus. This can explain the increase of the conductivity value 102 times more important than those found in the literature for LiFePO4.展开更多
In the first part of this paper, an analysis of the high-resolution spectrum of the HTO molecule ν1(ν3) band, from 3630 to3950 cm–1, was undertaken. The rotational transition of this band was assigned using combina...In the first part of this paper, an analysis of the high-resolution spectrum of the HTO molecule ν1(ν3) band, from 3630 to3950 cm–1, was undertaken. The rotational transition of this band was assigned using combination differences. Their wavenumbers were analyzed with a least squares fit program in order to obtain spectroscopic constants. A perturbed state has been evidenced. In the second part, with a view towards building a spectroscopic data base, a calculation of the dipolar momentum function was undertaken.展开更多
文摘Ferroelectric single crystals Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) are promising full materials for non resonant or large bandwidth transducers due to the large values of their piezoelectric properties (d ij , k ij ) and their low mechanical quality factor (Q ij ). Many studies on oriented PZN-4.5PT single crystals were carried out but it is very difficult to find research findings on oriented Mn doped PZN-PT. Thus, investigations were made using XRD, Raman and EPR characterization for oriented PZN-4.5PT grown through the Flux method. Mn doping effect on structural, dielectric, mechanical and piezoelectric properties with two values of Mn percentage (1 and 2 mol%) are also reported in this paper. Through the XRD study, the lattice parameters of doped PZN-PT crystals are slightly increased compared to the undoped one but the Mn didn’t change its structure. The room temperature dielectric permittivity along direction is about 1572 and 1626 (respectively 1% and 2% Mn doped crystals) which are much lower than that of the undoped PZN-4.5PT (2553). The remnant polarization and coercive field of oriented doped crystal measured at 1 KHz are respectively 30 μC/cm2 and 4.30 kV/cm (PZN-4.5PT), 32 μC/cm2 and 6.10 kV/cm (PZN-4.5PT + 1% Mn) and 28 μC/cm2 and 7.30 kV/cm (for the 2% Mn doped crystal). The mechanical quality factor Qm changed from 139 to 441 respectively for the pure and 1% Mn doped single crystals at room temperature while it decreases slightly to 336 for the 2 mol% Mn doped.
文摘In this paper, we have declined the formalism of the method of the Modified Atomic Orbital Theory (MAOT) applied to the calculations of energies of doubly excited states 2<em>snp</em>, 3<em>snp</em>, and 4<em>snp</em> Helium-like systems. Then we also applied the variational procedure of the Modified Atomic Orbital Theory to the computations of total energies, excitation energies of doubly-excited states 2<em>snp</em>, 3<em>snp</em>, 4<em>snp</em> types of Helium-like systems. The results obtained in this work are in good agreement with the experimental and theoretical values available.
文摘Historically, the LiCoO2 is the most used as active material for battery positive electrode because of its great potential (3.7 - 4.2 V), its interesting specific capacity (150 mA·h·g-1) and its excellent life cycle [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003300390038003500370036003700340032000000 . However, its toxicity, the cobalt cost and its structural instability oriented research towards new materials more stable that can replace it. In another context, hybrid, electrical vehicles and communication (computers and mobile phones...) have increased the scientific and technological research for new materials capable of storing and return energy through a system called accumulator. And research has identified the phosphate olivine structure as the most prolific ceramic material for positive electrode. LiFePO4 is a promising cathode material for Lithium-ion batteries. It provides high thermal stability and is synthesized using low cost materials. Unfortunately LiFePO4 suffers from a low electrical conductivity, which is harmful to its electrochemical performance. Decreasing the particle size, coating the particles with carbon or doping with metal atoms can increase the conductivity of the material. In this paper, we present the synthesis, physico-chemical and electrical characterization of lithium and iron doped Al-phosphorrus-based ceramic. The NPK Fertiliser was used as Al and phosphorus precursors. The powder XRD spectrum shows a possible presence of LiFePO4 and Fe2(PO)3 in theheterostrcture. An important quantity of Al is found by EDX spectra which supposed that the most important based atom is Aluminum and not Phosphorus. This can explain the increase of the conductivity value 102 times more important than those found in the literature for LiFePO4.
文摘In the first part of this paper, an analysis of the high-resolution spectrum of the HTO molecule ν1(ν3) band, from 3630 to3950 cm–1, was undertaken. The rotational transition of this band was assigned using combination differences. Their wavenumbers were analyzed with a least squares fit program in order to obtain spectroscopic constants. A perturbed state has been evidenced. In the second part, with a view towards building a spectroscopic data base, a calculation of the dipolar momentum function was undertaken.
