The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The title compound [Fe (II)(L) 2][ClO 4] 2.C 7H 8 (L = 2-[3-(2&am... more The title compound [Fe (II)(L) 2][ClO 4] 2.C 7H 8 (L = 2-[3-(2'-pyridyl)pyrazol-1-ylmethyl]pyridine) has been isolated while attempting to grow single crystals of the spin-transition (continuous-type) compound [Fe (II)(L) 2][ClO 4] 2, published earlier ( Dalton Trans. 2003, 3392-3397). Magnetic susceptibility measurements, as well as Mossbauer and calorimetric investigations on polycrystalline samples of [Fe(L) 2][ClO 4] 2.C 7H 8 revealed the occurrence of an abrupt HS ( (5) T 2) <--> LS ( (1) A 1) transition with steep and narrow (2 K) hysteresis at approximately 232 K. The photomagnetic properties exhibit features typical for a broad distribution of activation energies, with relaxation curves in the shape of stretched exponentials. We performed a crystal structure determination of the compound at 120, 240, and 270 K. A noteworthy temperature-dependent behavior of the structural parameters was observed, in terms of disorder of both the anions and solvent molecules, leading to a strong thermal dependence of the strength and dimensionality of the interaction network. Additional data were obtained by diffuse reflectance measurements. We model and discuss the antagonistic effects of interactions and disorder by using a two-level cooperative mean-field approach which includes a distribution of barrier energies at the microscopic scale.
The relaxation of the metastable state of the spin-crossover compound [Fe(L) 2 ](ClO 4 ) 2 ‚H 2 O... more The relaxation of the metastable state of the spin-crossover compound [Fe(L) 2 ](ClO 4 ) 2 ‚H 2 O, with L ) 2,6-bis-(pyrazol-1-ylmethyl)pyridine, populated by the LIESST (light induced excited spin state trapping) effect, has been investigated by magnetic measurements. The time dependence of the relaxation curve at several temperatures, starting from different initial states, is in the shape of stretched exponentials, and the thermal variation of the photostationary state under constant photoexcitation is progressive and reversible. These features are satisfactorily modeled by considering noninteracting two-level systems with a distribution of activation energies. A suggested origin for the distribution is the conformational flexibility of the nonplanar heterocyclic ligands. The effect of the intensity distribution during the LIESST process is also accounted for in a simple way.
We investigate the thermal hysteresis of spin-crossover compounds by using the first-order revers... more We investigate the thermal hysteresis of spin-crossover compounds by using the first-order reversal curve ͑FORC͒ method. By magnetic measurements we have recorded the FORC data for the pure Fe-and Zn-diluted spin transition system ͓Fe x Zn 1−x ͑btr͒ 2 ͑NCS͒ 2 ͔ .H 2 O, where x governs, through cooperative interactions, the width of the thermal hysteresis loop. The wiping-out and congruency properties are obeyed and support the description of the system by independent spin-like domains. The FORC analysis show, for increasing dilution parameter 1 − x, almost monotonous trends: ͑i͒ increasing width of the bias distribution, ͑ii͒ decreasing width of the coercivity distribution, ͑iii͒ increasing correlation between the bias and coercivity distribution. The Preisach distributions finally are expressed in terms of P͑⌬ , J͒, where ⌬ = energy gap and J = intra-domain interaction parameter are the major physical parameter quantities involved in the two-level ͑e.g., Ising-like͒ standard description of interacting spin-crossover units. The physical origin of the distributions is discussed and the eventual ⌬ − J correlation is determined. The pure compound exhibits a negligible ⌬ − J correlation and therefore can be considered as made of independent spin domains. The diluted compounds exhibit a sizeable ⌬ − J correlation, which can merely be explained by a small spreading of the composition parameter.
Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2006
Investigation on solvent-induced polymorphism in X-ray structures of 2-hydroxy-1,4-naphthoquinone... more Investigation on solvent-induced polymorphism in X-ray structures of 2-hydroxy-1,4-naphthoquinone (Lawsone) 1, is carried out. In protic methanol, 1 crystallizes in monoclinic space group P2 1 /c (1a) comprising of 2D hydrogen bonded network via cyclic dimers. In aprotic solvent such as acetone on the other hand, 1 exhibits orthorhombic space group Pna 2 1 (1b) and emerges with 1D catemeric chain. Solvent-induced topological isomerism of cyclic dimers and helical catemeric chains arising from (i) bifurcated intra-and inter molecular hydrogen bondings viz. O H· · ·O C interactions between C(2) hydroxyl and C(1), C(4) carbonyls, (ii) C H· · ·O interactions viz. C(3) H· · ·O(1)C(1) have been discussed. A signal for radical in 1 at g = 2.0058 is signatured by EPR spectrum and it's oxime derivative viz. 2-hydroxy-4-naphthoquinone-1-oxime 2, in solid state shows biradical and monoradical formation with aggregation of dimer and monomer due to non-covalent hydrogen bonds. Zero field split parameters for 2 are estimated to be D = 215 G, E x = 13 G, E y = 47 G at 298 K. A half field signal at 77 K indicates triplet ground state. Frozen glass EPR of 2 resolves as regioregular dimeric-monomeric species showing hyperfine interactions with 1-oximino nitrogen in dimerĀ( 14 N) = 15.5 G].
Spectrometric studies were carried out on samples of tourmaline (schörl-dravite series) from geol... more Spectrometric studies were carried out on samples of tourmaline (schörl-dravite series) from geological environments where first-phase-formed tourmaline underwent influence of geochemically different fluids. Samples are from a differentiated magmatic complex of Trento-Alto Adige, Italy, and from hydrothermal gold and silver deposits of the Humboldt Range, Nevada, USA. Chemical data were obtained from electron microprobes. The results of Mössbauer measurements suggest three to five doublets. Fe occurs in two valence states. The Z-site, usually fulfilled with Al3+ and Fe3+, is assigned only to Al3+ and Fe2+. This location was found in nearly all samples studied. In the Y-site Fe2+ and Fe3+ are obviously present. Isomer shifts with intermediate values can be assumed to be related to intervalence charge transfer (IVCT). Optical spectroscopy reveals absorption bands at 9 000 and 14000 cm−1, which are assigned to a charge transfer between Fe2+ and Fe3+, the 23 000 cm−1 absorption band is supposed to be due to Fe2+ → Ti4+ charge transfer. The occupation of the Z-site only by Fe2+ and the coexistence of divalent and trivalent Fe in the Y-site could be explained by selective oxidation in Y-site through a late process.
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The authors present the concept and design of a parallel resonant converter for induction heating... more The authors present the concept and design of a parallel resonant converter for induction heating applications. The generators have a power range up to 200 kW. The inverter bridge, implemented with MOSFET transistors, can work to frequencies up to 200 kHz. The inverter is controlled by an automatic tracking circuit that makes certain that the resonant and inverter frequency are
The title compound [Fe (II)(L) 2][ClO 4] 2.C 7H 8 (L = 2-[3-(2&am... more The title compound [Fe (II)(L) 2][ClO 4] 2.C 7H 8 (L = 2-[3-(2'-pyridyl)pyrazol-1-ylmethyl]pyridine) has been isolated while attempting to grow single crystals of the spin-transition (continuous-type) compound [Fe (II)(L) 2][ClO 4] 2, published earlier ( Dalton Trans. 2003, 3392-3397). Magnetic susceptibility measurements, as well as Mossbauer and calorimetric investigations on polycrystalline samples of [Fe(L) 2][ClO 4] 2.C 7H 8 revealed the occurrence of an abrupt HS ( (5) T 2) <--> LS ( (1) A 1) transition with steep and narrow (2 K) hysteresis at approximately 232 K. The photomagnetic properties exhibit features typical for a broad distribution of activation energies, with relaxation curves in the shape of stretched exponentials. We performed a crystal structure determination of the compound at 120, 240, and 270 K. A noteworthy temperature-dependent behavior of the structural parameters was observed, in terms of disorder of both the anions and solvent molecules, leading to a strong thermal dependence of the strength and dimensionality of the interaction network. Additional data were obtained by diffuse reflectance measurements. We model and discuss the antagonistic effects of interactions and disorder by using a two-level cooperative mean-field approach which includes a distribution of barrier energies at the microscopic scale.
The relaxation of the metastable state of the spin-crossover compound [Fe(L) 2 ](ClO 4 ) 2 ‚H 2 O... more The relaxation of the metastable state of the spin-crossover compound [Fe(L) 2 ](ClO 4 ) 2 ‚H 2 O, with L ) 2,6-bis-(pyrazol-1-ylmethyl)pyridine, populated by the LIESST (light induced excited spin state trapping) effect, has been investigated by magnetic measurements. The time dependence of the relaxation curve at several temperatures, starting from different initial states, is in the shape of stretched exponentials, and the thermal variation of the photostationary state under constant photoexcitation is progressive and reversible. These features are satisfactorily modeled by considering noninteracting two-level systems with a distribution of activation energies. A suggested origin for the distribution is the conformational flexibility of the nonplanar heterocyclic ligands. The effect of the intensity distribution during the LIESST process is also accounted for in a simple way.
We investigate the thermal hysteresis of spin-crossover compounds by using the first-order revers... more We investigate the thermal hysteresis of spin-crossover compounds by using the first-order reversal curve ͑FORC͒ method. By magnetic measurements we have recorded the FORC data for the pure Fe-and Zn-diluted spin transition system ͓Fe x Zn 1−x ͑btr͒ 2 ͑NCS͒ 2 ͔ .H 2 O, where x governs, through cooperative interactions, the width of the thermal hysteresis loop. The wiping-out and congruency properties are obeyed and support the description of the system by independent spin-like domains. The FORC analysis show, for increasing dilution parameter 1 − x, almost monotonous trends: ͑i͒ increasing width of the bias distribution, ͑ii͒ decreasing width of the coercivity distribution, ͑iii͒ increasing correlation between the bias and coercivity distribution. The Preisach distributions finally are expressed in terms of P͑⌬ , J͒, where ⌬ = energy gap and J = intra-domain interaction parameter are the major physical parameter quantities involved in the two-level ͑e.g., Ising-like͒ standard description of interacting spin-crossover units. The physical origin of the distributions is discussed and the eventual ⌬ − J correlation is determined. The pure compound exhibits a negligible ⌬ − J correlation and therefore can be considered as made of independent spin domains. The diluted compounds exhibit a sizeable ⌬ − J correlation, which can merely be explained by a small spreading of the composition parameter.
Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2006
Investigation on solvent-induced polymorphism in X-ray structures of 2-hydroxy-1,4-naphthoquinone... more Investigation on solvent-induced polymorphism in X-ray structures of 2-hydroxy-1,4-naphthoquinone (Lawsone) 1, is carried out. In protic methanol, 1 crystallizes in monoclinic space group P2 1 /c (1a) comprising of 2D hydrogen bonded network via cyclic dimers. In aprotic solvent such as acetone on the other hand, 1 exhibits orthorhombic space group Pna 2 1 (1b) and emerges with 1D catemeric chain. Solvent-induced topological isomerism of cyclic dimers and helical catemeric chains arising from (i) bifurcated intra-and inter molecular hydrogen bondings viz. O H· · ·O C interactions between C(2) hydroxyl and C(1), C(4) carbonyls, (ii) C H· · ·O interactions viz. C(3) H· · ·O(1)C(1) have been discussed. A signal for radical in 1 at g = 2.0058 is signatured by EPR spectrum and it's oxime derivative viz. 2-hydroxy-4-naphthoquinone-1-oxime 2, in solid state shows biradical and monoradical formation with aggregation of dimer and monomer due to non-covalent hydrogen bonds. Zero field split parameters for 2 are estimated to be D = 215 G, E x = 13 G, E y = 47 G at 298 K. A half field signal at 77 K indicates triplet ground state. Frozen glass EPR of 2 resolves as regioregular dimeric-monomeric species showing hyperfine interactions with 1-oximino nitrogen in dimerĀ( 14 N) = 15.5 G].
Spectrometric studies were carried out on samples of tourmaline (schörl-dravite series) from geol... more Spectrometric studies were carried out on samples of tourmaline (schörl-dravite series) from geological environments where first-phase-formed tourmaline underwent influence of geochemically different fluids. Samples are from a differentiated magmatic complex of Trento-Alto Adige, Italy, and from hydrothermal gold and silver deposits of the Humboldt Range, Nevada, USA. Chemical data were obtained from electron microprobes. The results of Mössbauer measurements suggest three to five doublets. Fe occurs in two valence states. The Z-site, usually fulfilled with Al3+ and Fe3+, is assigned only to Al3+ and Fe2+. This location was found in nearly all samples studied. In the Y-site Fe2+ and Fe3+ are obviously present. Isomer shifts with intermediate values can be assumed to be related to intervalence charge transfer (IVCT). Optical spectroscopy reveals absorption bands at 9 000 and 14000 cm−1, which are assigned to a charge transfer between Fe2+ and Fe3+, the 23 000 cm−1 absorption band is supposed to be due to Fe2+ → Ti4+ charge transfer. The occupation of the Z-site only by Fe2+ and the coexistence of divalent and trivalent Fe in the Y-site could be explained by selective oxidation in Y-site through a late process.
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Papers by Jorge Linares