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Papers by Biplab Paul
Journal of The Franklin Institute-engineering and Applied Mathematics, 1865
Journal of The Franklin Institute-engineering and Applied Mathematics, 1865
Journal of The Franklin Institute-engineering and Applied Mathematics, 1865
Journal of The Franklin Institute-engineering and Applied Mathematics, 1865
Journal of The Franklin Institute-engineering and Applied Mathematics, 1864
Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action... more Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action produced by various lighting agents. This property, no doubt, varied very much in the different agents used --some gave out more heat than others, and some evolved more carbonic acid gas than others. Coal gas produced less carbonic acid thari petroleum and other substances of that kind. This subject was important in connexion with the effect of artificial light upon health. No doubt in rooms where lights were burnt for a considerable time, unless proper regard were paid to ventilation, a large amount of noxious gases were evolved. These gases consisted of carbonic acid, sulphurous acid, and others of a more or less pernicious nature. In some cases in rooms where lights were burnt in which the combustion was not complete, there was a formation of carbonic oxide which was most poisonous. ~Vhen explosions took place in mines not only carbonic acid was formed, but also carbonic oxide, and these were both destructive of life in a very short time, but each separately had a different action in the destruction of life. Carbonic acid gas destroyed life comparatively slowly, while carbonic oxide immediately struck down any one who breathed it. In the case of the lamentable explosion at the Hartley colliery, which was attended with so largo a loss of life, he had no doubt that a mixture of carbonic acid and carbonic oxide was formed, and he hoped, for the sake of the victims themselves, that the latter predominated, inasmuch as their sufferings would be less protracted than under the influence of carbonic acid alone. The action of these gases produced such different appearances after death that it could be ascertained by which of them the death had been caused. Carbonic acid gas rendered the blood left in the veins of a dark color, while in cases of death from carbonic oxide the red color of the blood was heightened. The fact of these gases being generated by the combustion of ti~e agents used for lighting purposes made it necessary that the utmost attention should be paid to ventilation. He thought the plan of ligi~t-]ng adopted in the room in which they were assembled was so perl~:ct that it was impossible there could be any accumulation of noxi,)us gases, while the light itself, by being concentrated into one large foc~s, was of a very efficient character, and ventilation was greatly promo~ d. The subject of lighting by petroleum having been alluded to by ~;r. Paul, he could have wished that some further information had b(,m given with regard to the Rangoon petroleum. From that material 1.;~d been manufactured a very perfect lighting agent under the tith ~ of Belmontine, but he was afraid the supply of that petroleum, as ind,:ed of many other kinds, was considerably on the decrease, but he had ao doubt that other sources of supply would be obtained as the origilM ones failed.
Journal of The Franklin Institute-engineering and Applied Mathematics, 1864
Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action... more Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action produced by various lighting agents. This property, no doubt, varied very much in the different agents used --some gave out more heat than others, and some evolved more carbonic acid gas than others. Coal gas produced less carbonic acid thari petroleum and other substances of that kind. This subject was important in connexion with the effect of artificial light upon health. No doubt in rooms where lights were burnt for a considerable time, unless proper regard were paid to ventilation, a large amount of noxious gases were evolved. These gases consisted of carbonic acid, sulphurous acid, and others of a more or less pernicious nature. In some cases in rooms where lights were burnt in which the combustion was not complete, there was a formation of carbonic oxide which was most poisonous. ~Vhen explosions took place in mines not only carbonic acid was formed, but also carbonic oxide, and these were both destructive of life in a very short time, but each separately had a different action in the destruction of life. Carbonic acid gas destroyed life comparatively slowly, while carbonic oxide immediately struck down any one who breathed it. In the case of the lamentable explosion at the Hartley colliery, which was attended with so largo a loss of life, he had no doubt that a mixture of carbonic acid and carbonic oxide was formed, and he hoped, for the sake of the victims themselves, that the latter predominated, inasmuch as their sufferings would be less protracted than under the influence of carbonic acid alone. The action of these gases produced such different appearances after death that it could be ascertained by which of them the death had been caused. Carbonic acid gas rendered the blood left in the veins of a dark color, while in cases of death from carbonic oxide the red color of the blood was heightened. The fact of these gases being generated by the combustion of ti~e agents used for lighting purposes made it necessary that the utmost attention should be paid to ventilation. He thought the plan of ligi~t-]ng adopted in the room in which they were assembled was so perl~:ct that it was impossible there could be any accumulation of noxi,)us gases, while the light itself, by being concentrated into one large foc~s, was of a very efficient character, and ventilation was greatly promo~ d. The subject of lighting by petroleum having been alluded to by ~;r. Paul, he could have wished that some further information had b(,m given with regard to the Rangoon petroleum. From that material 1.;~d been manufactured a very perfect lighting agent under the tith ~ of Belmontine, but he was afraid the supply of that petroleum, as ind,:ed of many other kinds, was considerably on the decrease, but he had ao doubt that other sources of supply would be obtained as the origilM ones failed.
Journal of The Franklin Institute-engineering and Applied Mathematics, 1864
Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action... more Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action produced by various lighting agents. This property, no doubt, varied very much in the different agents used --some gave out more heat than others, and some evolved more carbonic acid gas than others. Coal gas produced less carbonic acid thari petroleum and other substances of that kind. This subject was important in connexion with the effect of artificial light upon health. No doubt in rooms where lights were burnt for a considerable time, unless proper regard were paid to ventilation, a large amount of noxious gases were evolved. These gases consisted of carbonic acid, sulphurous acid, and others of a more or less pernicious nature. In some cases in rooms where lights were burnt in which the combustion was not complete, there was a formation of carbonic oxide which was most poisonous. ~Vhen explosions took place in mines not only carbonic acid was formed, but also carbonic oxide, and these were both destructive of life in a very short time, but each separately had a different action in the destruction of life. Carbonic acid gas destroyed life comparatively slowly, while carbonic oxide immediately struck down any one who breathed it. In the case of the lamentable explosion at the Hartley colliery, which was attended with so largo a loss of life, he had no doubt that a mixture of carbonic acid and carbonic oxide was formed, and he hoped, for the sake of the victims themselves, that the latter predominated, inasmuch as their sufferings would be less protracted than under the influence of carbonic acid alone. The action of these gases produced such different appearances after death that it could be ascertained by which of them the death had been caused. Carbonic acid gas rendered the blood left in the veins of a dark color, while in cases of death from carbonic oxide the red color of the blood was heightened. The fact of these gases being generated by the combustion of ti~e agents used for lighting purposes made it necessary that the utmost attention should be paid to ventilation. He thought the plan of ligi~t-]ng adopted in the room in which they were assembled was so perl~:ct that it was impossible there could be any accumulation of noxi,)us gases, while the light itself, by being concentrated into one large foc~s, was of a very efficient character, and ventilation was greatly promo~ d. The subject of lighting by petroleum having been alluded to by ~;r. Paul, he could have wished that some further information had b(,m given with regard to the Rangoon petroleum. From that material 1.;~d been manufactured a very perfect lighting agent under the tith ~ of Belmontine, but he was afraid the supply of that petroleum, as ind,:ed of many other kinds, was considerably on the decrease, but he had ao doubt that other sources of supply would be obtained as the origilM ones failed.
Advanced Materials Research, 2009
Page 1. Controlled Synthesis of Lead Telluride Nanocrystals Biplab Paul 1, a , P. Banerji 2, b 1M... more Page 1. Controlled Synthesis of Lead Telluride Nanocrystals Biplab Paul 1, a , P. Banerji 2, b 1Materials Science Centre, Indian Institute of Technology, kharagpur 721302, India abiplabpaul2006@yahoo.co.in, bpallab@matsc.iitkgp.ernet.in ...
Journal of Applied Physics, 2010
The concept of energy filtering of the carriers to control the thermoelectric properties of PbTe ... more The concept of energy filtering of the carriers to control the thermoelectric properties of PbTe is experimentally applied in this present work. The energy barriers at the grain interfaces of the nanocomposites and the embedded Ag-rich nanodots within the grains are supposed to control the energy dependency of carrier scattering: that is what we mean by energy filtering of carriers. As a case study, vertical Bridgman grown bulk PbTe:undoped, PbTe:Ag crystals and nanocomposites of PbTe:Ag are used as samples.
The thermoelectric performance of PbTe:Cr nanocomposites with locally distorted density of states... more The thermoelectric performance of PbTe:Cr nanocomposites with locally distorted density of states is investigated. The sharpness and location of the localized states has been found to be an effective factor in tuning the transport properties of the system. The enhancement of electron effective mass and scattering parameter has been supposed to be the main cause of the remarkable enhancement of thermopower and power factor with room temperature values of -192 μV/K and 33.17×10-4 Wm-1 K-2 for the specimen with carrier concentration of 6.32×1018 cm-3.
Applied Physics Letters, 2011
ABSTRACT We report thermoelectric properties of PbTe doubly doped with chromium (Cr) and iodine (... more ABSTRACT We report thermoelectric properties of PbTe doubly doped with chromium (Cr) and iodine (I). Cr is found to create a local enhancement of density of states (DOS) in the conduction band of PbTe, and I is found to tune the position of the Fermi level. The coincidence of the Fermi level with the enhanced DOS is found to produce up to 135% enhancement in thermopower leading to a high power factor (PF) of 56.16 × 10-4 Wm-1K-2 at 500 K. Such high value of power factor can produce thermoelectric figure of merit (ZT) above 2.
Applied Surface Science, 2010
Journal of Crystal Growth, 2009
Single crystal of PbTe is grown by the simple vertical Bridgman method by using high purity Pb an... more Single crystal of PbTe is grown by the simple vertical Bridgman method by using high purity Pb and Te as source materials. Cone angle of the ampoule is optimized to obtain a preferred shape of the ingot. It is observed that the growth occurred in /2 2 0S direction. XRD analysis reveals the formation of rock salt structure with lattice constant 6.463 nm. Crystals were p-type with resitivity ranging from 3.97 Â 10 À3 to 4.07 Â 10 À3 O-cm. At room temperature, hole concentration is found to be $10 18 cm À3 throughout the crystal length and it is almost constant in the temperature range 130-300 K. At 300 K, the mobility is found to be in the range 842-856 cm 2 /V-s, lowest being at the higher end of the crystal. The indirect optical band gap and the corresponding absorption coefficients are determined by using FTIR spectrum.
Journal of Applied Physics, 2011
In this work we have investigated the effect of the chromium (Cr) impurity on the thermoelectric ... more In this work we have investigated the effect of the chromium (Cr) impurity on the thermoelectric properties of lead telluride (PbTe) bulk crystal with different Cr-content. The structural characterization of the crystals was done by x-ray diffraction and high-resolution transmission electron microscopic analyses. The incorporation of Cr in PbTe over the soluble limit has been found to replace Pb from the lattice site, forcing it to be precipitated into nanodots, with their dimensions in the range of 2-13 nm and their numbers increasing with the increase in Cr doping. The transport properties of the samples with different Cr-content have been evaluated through temperature dependent electrical resistivity, the Hall coefficient, and thermopower measurements in the temperature range of 100-600 K. The highest mobility is obtained as 1404 cm2/V s for a sample with a carrier concentration of 3.84 × 1018 cm-3 at 300 K. The high electron mobility and moderately higher value of the thermopower are expected to produce a high power factor of the samples with the highest value of 38.49 × 10-4 Wm-1K-2 in a specimen with a Cr-content of 1.45 at. % at room temperature. The power factor of the specimen with 1.3 at. % Cr-content is found to be above 29 × 10-4 Wm-1K-2 in the wide temperature range of 300-600 K.
Advanced Materials Research, 2009
Page 1. Controlled Synthesis of Lead Telluride Nanocrystals Biplab Paul 1, a , P. Banerji 2, b 1M... more Page 1. Controlled Synthesis of Lead Telluride Nanocrystals Biplab Paul 1, a , P. Banerji 2, b 1Materials Science Centre, Indian Institute of Technology, kharagpur 721302, India abiplabpaul2006@yahoo.co.in, bpallab@matsc.iitkgp.ernet.in ...
Journal of Applied Physics, 2010
The concept of energy filtering of the carriers to control the thermoelectric properties of PbTe ... more The concept of energy filtering of the carriers to control the thermoelectric properties of PbTe is experimentally applied in this present work. The energy barriers at the grain interfaces of the nanocomposites and the embedded Ag-rich nanodots within the grains are supposed to control the energy dependency of carrier scattering: that is what we mean by energy filtering of carriers. As a case study, vertical Bridgman grown bulk PbTe:undoped, PbTe:Ag crystals and nanocomposites of PbTe:Ag are used as samples.
The thermoelectric performance of PbTe:Cr nanocomposites with locally distorted density of states... more The thermoelectric performance of PbTe:Cr nanocomposites with locally distorted density of states is investigated. The sharpness and location of the localized states has been found to be an effective factor in tuning the transport properties of the system. The enhancement of electron effective mass and scattering parameter has been supposed to be the main cause of the remarkable enhancement of thermopower and power factor with room temperature values of -192 μV/K and 33.17×10-4 Wm-1 K-2 for the specimen with carrier concentration of 6.32×1018 cm-3.
Applied Physics Letters, 2011
ABSTRACT We report thermoelectric properties of PbTe doubly doped with chromium (Cr) and iodine (... more ABSTRACT We report thermoelectric properties of PbTe doubly doped with chromium (Cr) and iodine (I). Cr is found to create a local enhancement of density of states (DOS) in the conduction band of PbTe, and I is found to tune the position of the Fermi level. The coincidence of the Fermi level with the enhanced DOS is found to produce up to 135% enhancement in thermopower leading to a high power factor (PF) of 56.16 × 10-4 Wm-1K-2 at 500 K. Such high value of power factor can produce thermoelectric figure of merit (ZT) above 2.
Applied Surface Science, 2010
Journal of Crystal Growth, 2009
Single crystal of PbTe is grown by the simple vertical Bridgman method by using high purity Pb an... more Single crystal of PbTe is grown by the simple vertical Bridgman method by using high purity Pb and Te as source materials. Cone angle of the ampoule is optimized to obtain a preferred shape of the ingot. It is observed that the growth occurred in /2 2 0S direction. XRD analysis reveals the formation of rock salt structure with lattice constant 6.463 nm. Crystals were p-type with resitivity ranging from 3.97 Â 10 À3 to 4.07 Â 10 À3 O-cm. At room temperature, hole concentration is found to be $10 18 cm À3 throughout the crystal length and it is almost constant in the temperature range 130-300 K. At 300 K, the mobility is found to be in the range 842-856 cm 2 /V-s, lowest being at the higher end of the crystal. The indirect optical band gap and the corresponding absorption coefficients are determined by using FTIR spectrum.
Journal of The Franklin Institute-engineering and Applied Mathematics, 1865
Journal of The Franklin Institute-engineering and Applied Mathematics, 1865
Journal of The Franklin Institute-engineering and Applied Mathematics, 1865
Journal of The Franklin Institute-engineering and Applied Mathematics, 1865
Journal of The Franklin Institute-engineering and Applied Mathematics, 1864
Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action... more Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action produced by various lighting agents. This property, no doubt, varied very much in the different agents used --some gave out more heat than others, and some evolved more carbonic acid gas than others. Coal gas produced less carbonic acid thari petroleum and other substances of that kind. This subject was important in connexion with the effect of artificial light upon health. No doubt in rooms where lights were burnt for a considerable time, unless proper regard were paid to ventilation, a large amount of noxious gases were evolved. These gases consisted of carbonic acid, sulphurous acid, and others of a more or less pernicious nature. In some cases in rooms where lights were burnt in which the combustion was not complete, there was a formation of carbonic oxide which was most poisonous. ~Vhen explosions took place in mines not only carbonic acid was formed, but also carbonic oxide, and these were both destructive of life in a very short time, but each separately had a different action in the destruction of life. Carbonic acid gas destroyed life comparatively slowly, while carbonic oxide immediately struck down any one who breathed it. In the case of the lamentable explosion at the Hartley colliery, which was attended with so largo a loss of life, he had no doubt that a mixture of carbonic acid and carbonic oxide was formed, and he hoped, for the sake of the victims themselves, that the latter predominated, inasmuch as their sufferings would be less protracted than under the influence of carbonic acid alone. The action of these gases produced such different appearances after death that it could be ascertained by which of them the death had been caused. Carbonic acid gas rendered the blood left in the veins of a dark color, while in cases of death from carbonic oxide the red color of the blood was heightened. The fact of these gases being generated by the combustion of ti~e agents used for lighting purposes made it necessary that the utmost attention should be paid to ventilation. He thought the plan of ligi~t-]ng adopted in the room in which they were assembled was so perl~:ct that it was impossible there could be any accumulation of noxi,)us gases, while the light itself, by being concentrated into one large foc~s, was of a very efficient character, and ventilation was greatly promo~ d. The subject of lighting by petroleum having been alluded to by ~;r. Paul, he could have wished that some further information had b(,m given with regard to the Rangoon petroleum. From that material 1.;~d been manufactured a very perfect lighting agent under the tith ~ of Belmontine, but he was afraid the supply of that petroleum, as ind,:ed of many other kinds, was considerably on the decrease, but he had ao doubt that other sources of supply would be obtained as the origilM ones failed.
Journal of The Franklin Institute-engineering and Applied Mathematics, 1864
Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action... more Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action produced by various lighting agents. This property, no doubt, varied very much in the different agents used --some gave out more heat than others, and some evolved more carbonic acid gas than others. Coal gas produced less carbonic acid thari petroleum and other substances of that kind. This subject was important in connexion with the effect of artificial light upon health. No doubt in rooms where lights were burnt for a considerable time, unless proper regard were paid to ventilation, a large amount of noxious gases were evolved. These gases consisted of carbonic acid, sulphurous acid, and others of a more or less pernicious nature. In some cases in rooms where lights were burnt in which the combustion was not complete, there was a formation of carbonic oxide which was most poisonous. ~Vhen explosions took place in mines not only carbonic acid was formed, but also carbonic oxide, and these were both destructive of life in a very short time, but each separately had a different action in the destruction of life. Carbonic acid gas destroyed life comparatively slowly, while carbonic oxide immediately struck down any one who breathed it. In the case of the lamentable explosion at the Hartley colliery, which was attended with so largo a loss of life, he had no doubt that a mixture of carbonic acid and carbonic oxide was formed, and he hoped, for the sake of the victims themselves, that the latter predominated, inasmuch as their sufferings would be less protracted than under the influence of carbonic acid alone. The action of these gases produced such different appearances after death that it could be ascertained by which of them the death had been caused. Carbonic acid gas rendered the blood left in the veins of a dark color, while in cases of death from carbonic oxide the red color of the blood was heightened. The fact of these gases being generated by the combustion of ti~e agents used for lighting purposes made it necessary that the utmost attention should be paid to ventilation. He thought the plan of ligi~t-]ng adopted in the room in which they were assembled was so perl~:ct that it was impossible there could be any accumulation of noxi,)us gases, while the light itself, by being concentrated into one large foc~s, was of a very efficient character, and ventilation was greatly promo~ d. The subject of lighting by petroleum having been alluded to by ~;r. Paul, he could have wished that some further information had b(,m given with regard to the Rangoon petroleum. From that material 1.;~d been manufactured a very perfect lighting agent under the tith ~ of Belmontine, but he was afraid the supply of that petroleum, as ind,:ed of many other kinds, was considerably on the decrease, but he had ao doubt that other sources of supply would be obtained as the origilM ones failed.
Journal of The Franklin Institute-engineering and Applied Mathematics, 1864
Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action... more Discussion.--Dr. Marcct, F.R.S., understood Mr. Paul as directing attention to the heating action produced by various lighting agents. This property, no doubt, varied very much in the different agents used --some gave out more heat than others, and some evolved more carbonic acid gas than others. Coal gas produced less carbonic acid thari petroleum and other substances of that kind. This subject was important in connexion with the effect of artificial light upon health. No doubt in rooms where lights were burnt for a considerable time, unless proper regard were paid to ventilation, a large amount of noxious gases were evolved. These gases consisted of carbonic acid, sulphurous acid, and others of a more or less pernicious nature. In some cases in rooms where lights were burnt in which the combustion was not complete, there was a formation of carbonic oxide which was most poisonous. ~Vhen explosions took place in mines not only carbonic acid was formed, but also carbonic oxide, and these were both destructive of life in a very short time, but each separately had a different action in the destruction of life. Carbonic acid gas destroyed life comparatively slowly, while carbonic oxide immediately struck down any one who breathed it. In the case of the lamentable explosion at the Hartley colliery, which was attended with so largo a loss of life, he had no doubt that a mixture of carbonic acid and carbonic oxide was formed, and he hoped, for the sake of the victims themselves, that the latter predominated, inasmuch as their sufferings would be less protracted than under the influence of carbonic acid alone. The action of these gases produced such different appearances after death that it could be ascertained by which of them the death had been caused. Carbonic acid gas rendered the blood left in the veins of a dark color, while in cases of death from carbonic oxide the red color of the blood was heightened. The fact of these gases being generated by the combustion of ti~e agents used for lighting purposes made it necessary that the utmost attention should be paid to ventilation. He thought the plan of ligi~t-]ng adopted in the room in which they were assembled was so perl~:ct that it was impossible there could be any accumulation of noxi,)us gases, while the light itself, by being concentrated into one large foc~s, was of a very efficient character, and ventilation was greatly promo~ d. The subject of lighting by petroleum having been alluded to by ~;r. Paul, he could have wished that some further information had b(,m given with regard to the Rangoon petroleum. From that material 1.;~d been manufactured a very perfect lighting agent under the tith ~ of Belmontine, but he was afraid the supply of that petroleum, as ind,:ed of many other kinds, was considerably on the decrease, but he had ao doubt that other sources of supply would be obtained as the origilM ones failed.
Advanced Materials Research, 2009
Page 1. Controlled Synthesis of Lead Telluride Nanocrystals Biplab Paul 1, a , P. Banerji 2, b 1M... more Page 1. Controlled Synthesis of Lead Telluride Nanocrystals Biplab Paul 1, a , P. Banerji 2, b 1Materials Science Centre, Indian Institute of Technology, kharagpur 721302, India abiplabpaul2006@yahoo.co.in, bpallab@matsc.iitkgp.ernet.in ...
Journal of Applied Physics, 2010
The concept of energy filtering of the carriers to control the thermoelectric properties of PbTe ... more The concept of energy filtering of the carriers to control the thermoelectric properties of PbTe is experimentally applied in this present work. The energy barriers at the grain interfaces of the nanocomposites and the embedded Ag-rich nanodots within the grains are supposed to control the energy dependency of carrier scattering: that is what we mean by energy filtering of carriers. As a case study, vertical Bridgman grown bulk PbTe:undoped, PbTe:Ag crystals and nanocomposites of PbTe:Ag are used as samples.
The thermoelectric performance of PbTe:Cr nanocomposites with locally distorted density of states... more The thermoelectric performance of PbTe:Cr nanocomposites with locally distorted density of states is investigated. The sharpness and location of the localized states has been found to be an effective factor in tuning the transport properties of the system. The enhancement of electron effective mass and scattering parameter has been supposed to be the main cause of the remarkable enhancement of thermopower and power factor with room temperature values of -192 μV/K and 33.17×10-4 Wm-1 K-2 for the specimen with carrier concentration of 6.32×1018 cm-3.
Applied Physics Letters, 2011
ABSTRACT We report thermoelectric properties of PbTe doubly doped with chromium (Cr) and iodine (... more ABSTRACT We report thermoelectric properties of PbTe doubly doped with chromium (Cr) and iodine (I). Cr is found to create a local enhancement of density of states (DOS) in the conduction band of PbTe, and I is found to tune the position of the Fermi level. The coincidence of the Fermi level with the enhanced DOS is found to produce up to 135% enhancement in thermopower leading to a high power factor (PF) of 56.16 × 10-4 Wm-1K-2 at 500 K. Such high value of power factor can produce thermoelectric figure of merit (ZT) above 2.
Applied Surface Science, 2010
Journal of Crystal Growth, 2009
Single crystal of PbTe is grown by the simple vertical Bridgman method by using high purity Pb an... more Single crystal of PbTe is grown by the simple vertical Bridgman method by using high purity Pb and Te as source materials. Cone angle of the ampoule is optimized to obtain a preferred shape of the ingot. It is observed that the growth occurred in /2 2 0S direction. XRD analysis reveals the formation of rock salt structure with lattice constant 6.463 nm. Crystals were p-type with resitivity ranging from 3.97 Â 10 À3 to 4.07 Â 10 À3 O-cm. At room temperature, hole concentration is found to be $10 18 cm À3 throughout the crystal length and it is almost constant in the temperature range 130-300 K. At 300 K, the mobility is found to be in the range 842-856 cm 2 /V-s, lowest being at the higher end of the crystal. The indirect optical band gap and the corresponding absorption coefficients are determined by using FTIR spectrum.
Journal of Applied Physics, 2011
In this work we have investigated the effect of the chromium (Cr) impurity on the thermoelectric ... more In this work we have investigated the effect of the chromium (Cr) impurity on the thermoelectric properties of lead telluride (PbTe) bulk crystal with different Cr-content. The structural characterization of the crystals was done by x-ray diffraction and high-resolution transmission electron microscopic analyses. The incorporation of Cr in PbTe over the soluble limit has been found to replace Pb from the lattice site, forcing it to be precipitated into nanodots, with their dimensions in the range of 2-13 nm and their numbers increasing with the increase in Cr doping. The transport properties of the samples with different Cr-content have been evaluated through temperature dependent electrical resistivity, the Hall coefficient, and thermopower measurements in the temperature range of 100-600 K. The highest mobility is obtained as 1404 cm2/V s for a sample with a carrier concentration of 3.84 × 1018 cm-3 at 300 K. The high electron mobility and moderately higher value of the thermopower are expected to produce a high power factor of the samples with the highest value of 38.49 × 10-4 Wm-1K-2 in a specimen with a Cr-content of 1.45 at. % at room temperature. The power factor of the specimen with 1.3 at. % Cr-content is found to be above 29 × 10-4 Wm-1K-2 in the wide temperature range of 300-600 K.
Advanced Materials Research, 2009
Page 1. Controlled Synthesis of Lead Telluride Nanocrystals Biplab Paul 1, a , P. Banerji 2, b 1M... more Page 1. Controlled Synthesis of Lead Telluride Nanocrystals Biplab Paul 1, a , P. Banerji 2, b 1Materials Science Centre, Indian Institute of Technology, kharagpur 721302, India abiplabpaul2006@yahoo.co.in, bpallab@matsc.iitkgp.ernet.in ...
Journal of Applied Physics, 2010
The concept of energy filtering of the carriers to control the thermoelectric properties of PbTe ... more The concept of energy filtering of the carriers to control the thermoelectric properties of PbTe is experimentally applied in this present work. The energy barriers at the grain interfaces of the nanocomposites and the embedded Ag-rich nanodots within the grains are supposed to control the energy dependency of carrier scattering: that is what we mean by energy filtering of carriers. As a case study, vertical Bridgman grown bulk PbTe:undoped, PbTe:Ag crystals and nanocomposites of PbTe:Ag are used as samples.
The thermoelectric performance of PbTe:Cr nanocomposites with locally distorted density of states... more The thermoelectric performance of PbTe:Cr nanocomposites with locally distorted density of states is investigated. The sharpness and location of the localized states has been found to be an effective factor in tuning the transport properties of the system. The enhancement of electron effective mass and scattering parameter has been supposed to be the main cause of the remarkable enhancement of thermopower and power factor with room temperature values of -192 μV/K and 33.17×10-4 Wm-1 K-2 for the specimen with carrier concentration of 6.32×1018 cm-3.
Applied Physics Letters, 2011
ABSTRACT We report thermoelectric properties of PbTe doubly doped with chromium (Cr) and iodine (... more ABSTRACT We report thermoelectric properties of PbTe doubly doped with chromium (Cr) and iodine (I). Cr is found to create a local enhancement of density of states (DOS) in the conduction band of PbTe, and I is found to tune the position of the Fermi level. The coincidence of the Fermi level with the enhanced DOS is found to produce up to 135% enhancement in thermopower leading to a high power factor (PF) of 56.16 × 10-4 Wm-1K-2 at 500 K. Such high value of power factor can produce thermoelectric figure of merit (ZT) above 2.
Applied Surface Science, 2010
Journal of Crystal Growth, 2009
Single crystal of PbTe is grown by the simple vertical Bridgman method by using high purity Pb an... more Single crystal of PbTe is grown by the simple vertical Bridgman method by using high purity Pb and Te as source materials. Cone angle of the ampoule is optimized to obtain a preferred shape of the ingot. It is observed that the growth occurred in /2 2 0S direction. XRD analysis reveals the formation of rock salt structure with lattice constant 6.463 nm. Crystals were p-type with resitivity ranging from 3.97 Â 10 À3 to 4.07 Â 10 À3 O-cm. At room temperature, hole concentration is found to be $10 18 cm À3 throughout the crystal length and it is almost constant in the temperature range 130-300 K. At 300 K, the mobility is found to be in the range 842-856 cm 2 /V-s, lowest being at the higher end of the crystal. The indirect optical band gap and the corresponding absorption coefficients are determined by using FTIR spectrum.