TY  - JOUR
AU  - Davidovic, A
AU  - Cajkovski, T
AU  - Colomban, P
AU  - Mioč, Ubavka B.
AU  - Likar-Smiljanic, V
AU  - Cajkovski, D
AU  - Biljic, R
AU  - Nedić, Zoran
PY  - 2005
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6559
AB  - The effect of monovalent and bivalent cations on some electrical properties of 12-tungstophosphoric acid (WPA) salts were studied. The charge carriers in this acid are protonic entities such as H+, OH- and various forms of hydrated proton H(H2O)(n)(+). Conductivity, dielectric relaxations and activation energies of WPA were investigated. Permittivity measurements were performed on pressed polycrystalline pellets at lower frequencies (5 Hz-500 kHz) and in the X-band microwave range (8-12 GHz); the temperature interval was from room temperature to 360 K. In the microwave region, WPA hexahydrate (WPA-6) and some IATA salts exhibit one, two or three relaxations of the Debye type. Their relaxation times of the order of 10(-11) s are attributed to the fast reorientation of water molecules and/or fast reorientation of oxonium ions (H3O+). In the lower frequency interval, dielectric relaxations of WPA-6 and some IATA salts with longer relaxation times of the order of 10(-7)-10(-5) s were registered and assigned to ion (H+ and/or H3O+) and cation jumps. (c) 2005 Elsevier B.V. All rights reserved.
T2  - Solid State Ionics
T1  - The influence of monovalent and bivalent cations on the electrical properties of 12-Tungstophosphoric acid salts
VL  - 176
IS  - 39-40
SP  - 2881
EP  - 2885
DO  - 10.1016/j.ssi.2005.09.020
ER  - 

@article{
author = "Davidovic, A and Cajkovski, T and Colomban, P and Mioč, Ubavka B. and Likar-Smiljanic, V and Cajkovski, D and Biljic, R and Nedić, Zoran",
year = "2005",
abstract = "The effect of monovalent and bivalent cations on some electrical properties of 12-tungstophosphoric acid (WPA) salts were studied. The charge carriers in this acid are protonic entities such as H+, OH- and various forms of hydrated proton H(H2O)(n)(+). Conductivity, dielectric relaxations and activation energies of WPA were investigated. Permittivity measurements were performed on pressed polycrystalline pellets at lower frequencies (5 Hz-500 kHz) and in the X-band microwave range (8-12 GHz); the temperature interval was from room temperature to 360 K. In the microwave region, WPA hexahydrate (WPA-6) and some IATA salts exhibit one, two or three relaxations of the Debye type. Their relaxation times of the order of 10(-11) s are attributed to the fast reorientation of water molecules and/or fast reorientation of oxonium ions (H3O+). In the lower frequency interval, dielectric relaxations of WPA-6 and some IATA salts with longer relaxation times of the order of 10(-7)-10(-5) s were registered and assigned to ion (H+ and/or H3O+) and cation jumps. (c) 2005 Elsevier B.V. All rights reserved.",
journal = "Solid State Ionics",
title = "The influence of monovalent and bivalent cations on the electrical properties of 12-Tungstophosphoric acid salts",
volume = "176",
number = "39-40",
pages = "2881-2885",
doi = "10.1016/j.ssi.2005.09.020"
}

Davidovic, A., Cajkovski, T., Colomban, P., Mioč, U. B., Likar-Smiljanic, V., Cajkovski, D., Biljic, R.,& Nedić, Z.. (2005). The influence of monovalent and bivalent cations on the electrical properties of 12-Tungstophosphoric acid salts. in Solid State Ionics, 176(39-40), 2881-2885.
https://doi.org/10.1016/j.ssi.2005.09.020

Davidovic A, Cajkovski T, Colomban P, Mioč UB, Likar-Smiljanic V, Cajkovski D, Biljic R, Nedić Z. The influence of monovalent and bivalent cations on the electrical properties of 12-Tungstophosphoric acid salts. in Solid State Ionics. 2005;176(39-40):2881-2885.
doi:10.1016/j.ssi.2005.09.020 .

Davidovic, A, Cajkovski, T, Colomban, P, Mioč, Ubavka B., Likar-Smiljanic, V, Cajkovski, D, Biljic, R, Nedić, Zoran, "The influence of monovalent and bivalent cations on the electrical properties of 12-Tungstophosphoric acid salts" in Solid State Ionics, 176, no. 39-40 (2005):2881-2885,
https://doi.org/10.1016/j.ssi.2005.09.020 . .

TY  - JOUR
AU  - Sredic, S
AU  - Cajkovski, T
AU  - Davidović, Miloš D.
AU  - Cajkovski, D
AU  - Likar-Smiljanic, V
AU  - Marinović-Cincović, Milena
AU  - Mioč, Ubavka B.
AU  - Nedić, Zoran
AU  - Biljic, R
PY  - 2004
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6422
AB  - Bentonite a natural raw material from the Sipovo mining deposits (Republic of Srpska), which contains a high percentage of montmorillonite, was treated to obtain montmorillonite clay ready for further investigations. Al-pillared montmorillonite was doped with 12-tungstophosphoric acid (WPA) by the sol-gel method. Substantial increase in proton conductivity of this new material was achieved. Different physicochemical methods were used to characterize new materials such as X-ray powder diffraction (XRD), thermogravimetric (TG) analysis, porosity measurements, scanning electron microscopy (SEM), and infrared measurements (IR). Impedance spectroscopy technique was applied in order to study the proton conductivity and its dependence on the frequency and tungstophosphoric acid concentration.
T2  - Materials Science Forum
T1  - Physicochemical properties of Al-pillared montmorillonite doped with 12-tungstophosphoric acid
VL  - 453-454
SP  - 157
EP  - 162
DO  - 10.4028/www.scientific.net/MSF.453-454.157
ER  - 

@article{
author = "Sredic, S and Cajkovski, T and Davidović, Miloš D. and Cajkovski, D and Likar-Smiljanic, V and Marinović-Cincović, Milena and Mioč, Ubavka B. and Nedić, Zoran and Biljic, R",
year = "2004",
abstract = "Bentonite a natural raw material from the Sipovo mining deposits (Republic of Srpska), which contains a high percentage of montmorillonite, was treated to obtain montmorillonite clay ready for further investigations. Al-pillared montmorillonite was doped with 12-tungstophosphoric acid (WPA) by the sol-gel method. Substantial increase in proton conductivity of this new material was achieved. Different physicochemical methods were used to characterize new materials such as X-ray powder diffraction (XRD), thermogravimetric (TG) analysis, porosity measurements, scanning electron microscopy (SEM), and infrared measurements (IR). Impedance spectroscopy technique was applied in order to study the proton conductivity and its dependence on the frequency and tungstophosphoric acid concentration.",
journal = "Materials Science Forum",
title = "Physicochemical properties of Al-pillared montmorillonite doped with 12-tungstophosphoric acid",
volume = "453-454",
pages = "157-162",
doi = "10.4028/www.scientific.net/MSF.453-454.157"
}

Sredic, S., Cajkovski, T., Davidović, M. D., Cajkovski, D., Likar-Smiljanic, V., Marinović-Cincović, M., Mioč, U. B., Nedić, Z.,& Biljic, R.. (2004). Physicochemical properties of Al-pillared montmorillonite doped with 12-tungstophosphoric acid. in Materials Science Forum, 453-454, 157-162.
https://doi.org/10.4028/www.scientific.net/MSF.453-454.157

Sredic S, Cajkovski T, Davidović MD, Cajkovski D, Likar-Smiljanic V, Marinović-Cincović M, Mioč UB, Nedić Z, Biljic R. Physicochemical properties of Al-pillared montmorillonite doped with 12-tungstophosphoric acid. in Materials Science Forum. 2004;453-454:157-162.
doi:10.4028/www.scientific.net/MSF.453-454.157 .

Sredic, S, Cajkovski, T, Davidović, Miloš D., Cajkovski, D, Likar-Smiljanic, V, Marinović-Cincović, Milena, Mioč, Ubavka B., Nedić, Zoran, Biljic, R, "Physicochemical properties of Al-pillared montmorillonite doped with 12-tungstophosphoric acid" in Materials Science Forum, 453-454 (2004):157-162,
https://doi.org/10.4028/www.scientific.net/MSF.453-454.157 . .

TY  - JOUR
AU  - Nikolić, Aleksandar S.
AU  - Likar-Smiljanic, V
AU  - Jovalekić, Čedomir
AU  - Cajkovski, T
AU  - Biljic, R
AU  - Lazarević, Zorica Ž.
AU  - Pavlović, Miodrag B.
PY  - 2004
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6437
AB  - Nickel and nickel-zinc ferrites are ones of the most abundant members of the soft magnetic materials. In the last few years, the interest in new methods of their preparation increases, because it is well known that the physical and chemical properties of these materials strongly depend on the preparing conditions. Powder samples of soft ferrites of NiFe2O4 and NixZn1-xFC2O4 were synthesized by a classical sintering procedure, planetary mill synthesis, and by a chemical procedure from complex compounds with acetylacetonato-ligands. Average particle sizes were 1 mum, 40 nm and 20x20x4 nm (slabs), respectively. All of the obtained materials were measured ill the frequency range of 7 - 12 GHz for the real and the imaginary part of permittivity and permeability, and the absorption coefficients were calculated. A concurrent analysis of the obtained values showed the influence of the method of synthesis, as well as the particle size on the absorption coefficients in the applied frequency range.
T2  - Materials Science Forum
T1  - Nicolson-Ross analysis of absorption coefficients of nickel and nickel-zinc ferrite powders prepared using a novel method
VL  - 453-454
SP  - 405
EP  - 410
DO  - 10.4028/www.scientific.net/MSF.453-454.405
ER  - 

@article{
author = "Nikolić, Aleksandar S. and Likar-Smiljanic, V and Jovalekić, Čedomir and Cajkovski, T and Biljic, R and Lazarević, Zorica Ž. and Pavlović, Miodrag B.",
year = "2004",
abstract = "Nickel and nickel-zinc ferrites are ones of the most abundant members of the soft magnetic materials. In the last few years, the interest in new methods of their preparation increases, because it is well known that the physical and chemical properties of these materials strongly depend on the preparing conditions. Powder samples of soft ferrites of NiFe2O4 and NixZn1-xFC2O4 were synthesized by a classical sintering procedure, planetary mill synthesis, and by a chemical procedure from complex compounds with acetylacetonato-ligands. Average particle sizes were 1 mum, 40 nm and 20x20x4 nm (slabs), respectively. All of the obtained materials were measured ill the frequency range of 7 - 12 GHz for the real and the imaginary part of permittivity and permeability, and the absorption coefficients were calculated. A concurrent analysis of the obtained values showed the influence of the method of synthesis, as well as the particle size on the absorption coefficients in the applied frequency range.",
journal = "Materials Science Forum",
title = "Nicolson-Ross analysis of absorption coefficients of nickel and nickel-zinc ferrite powders prepared using a novel method",
volume = "453-454",
pages = "405-410",
doi = "10.4028/www.scientific.net/MSF.453-454.405"
}

Nikolić, A. S., Likar-Smiljanic, V., Jovalekić, Č., Cajkovski, T., Biljic, R., Lazarević, Z. Ž.,& Pavlović, M. B.. (2004). Nicolson-Ross analysis of absorption coefficients of nickel and nickel-zinc ferrite powders prepared using a novel method. in Materials Science Forum, 453-454, 405-410.
https://doi.org/10.4028/www.scientific.net/MSF.453-454.405

Nikolić AS, Likar-Smiljanic V, Jovalekić Č, Cajkovski T, Biljic R, Lazarević ZŽ, Pavlović MB. Nicolson-Ross analysis of absorption coefficients of nickel and nickel-zinc ferrite powders prepared using a novel method. in Materials Science Forum. 2004;453-454:405-410.
doi:10.4028/www.scientific.net/MSF.453-454.405 .

Nikolić, Aleksandar S., Likar-Smiljanic, V, Jovalekić, Čedomir, Cajkovski, T, Biljic, R, Lazarević, Zorica Ž., Pavlović, Miodrag B., "Nicolson-Ross analysis of absorption coefficients of nickel and nickel-zinc ferrite powders prepared using a novel method" in Materials Science Forum, 453-454 (2004):405-410,
https://doi.org/10.4028/www.scientific.net/MSF.453-454.405 . .

TY  - JOUR
AU  - Cajkovski, T
AU  - Davidović, Miloš D.
AU  - Pissis, P
AU  - Polizos, G
AU  - Cajkovski, D
AU  - Likar-Smiljanic, V
AU  - Biljic, R
AU  - Nedić, Zoran
AU  - Mioč, Ubavka B.
PY  - 2003
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6383
AB  - The electrical and dielectric properties of the copper salt of 12-tungstophosphoric acid (WPA) hydrate have been investigated by broadband dielectric relaxation spectroscopy (DRS). This work is a continuation of our previous investigations on the influence of monovalent and bivalent cations on the dielectric properties of WPA hydrates salts. Measurements were made in the frequency range 10 mHz-1 MHz in order to explore the long-range dynamics, following recent microwave measurements aiming at the local dynamics properties. Experiments were done in the temperature interval 293-350 K. Data treatment included complex permittivity epsilon*, complex electric modulus M* and complex impedance Z* formalism, Arrhenius diagram and Cole-Cole diagrams. The results are discussed in terms of conductivity relaxation and conductivity current relaxation. Rather long conductivity relaxation times measured seem to correspond to ion jumping processes. A phase transition was observed at 323 K. (C) 2003 Elsevier B.V. All rights reserved.
T2  - Solid State Ionics
T1  - Dielectric investigation of electrical conductivity in the copper salt of the 12-tungstophosphoric acid hydrate
VL  - 162
SP  - 203
EP  - 208
DO  - 10.1016/S0167-2738(03)00233-9
ER  - 

@article{
author = "Cajkovski, T and Davidović, Miloš D. and Pissis, P and Polizos, G and Cajkovski, D and Likar-Smiljanic, V and Biljic, R and Nedić, Zoran and Mioč, Ubavka B.",
year = "2003",
abstract = "The electrical and dielectric properties of the copper salt of 12-tungstophosphoric acid (WPA) hydrate have been investigated by broadband dielectric relaxation spectroscopy (DRS). This work is a continuation of our previous investigations on the influence of monovalent and bivalent cations on the dielectric properties of WPA hydrates salts. Measurements were made in the frequency range 10 mHz-1 MHz in order to explore the long-range dynamics, following recent microwave measurements aiming at the local dynamics properties. Experiments were done in the temperature interval 293-350 K. Data treatment included complex permittivity epsilon*, complex electric modulus M* and complex impedance Z* formalism, Arrhenius diagram and Cole-Cole diagrams. The results are discussed in terms of conductivity relaxation and conductivity current relaxation. Rather long conductivity relaxation times measured seem to correspond to ion jumping processes. A phase transition was observed at 323 K. (C) 2003 Elsevier B.V. All rights reserved.",
journal = "Solid State Ionics",
title = "Dielectric investigation of electrical conductivity in the copper salt of the 12-tungstophosphoric acid hydrate",
volume = "162",
pages = "203-208",
doi = "10.1016/S0167-2738(03)00233-9"
}

Cajkovski, T., Davidović, M. D., Pissis, P., Polizos, G., Cajkovski, D., Likar-Smiljanic, V., Biljic, R., Nedić, Z.,& Mioč, U. B.. (2003). Dielectric investigation of electrical conductivity in the copper salt of the 12-tungstophosphoric acid hydrate. in Solid State Ionics, 162, 203-208.
https://doi.org/10.1016/S0167-2738(03)00233-9

Cajkovski T, Davidović MD, Pissis P, Polizos G, Cajkovski D, Likar-Smiljanic V, Biljic R, Nedić Z, Mioč UB. Dielectric investigation of electrical conductivity in the copper salt of the 12-tungstophosphoric acid hydrate. in Solid State Ionics. 2003;162:203-208.
doi:10.1016/S0167-2738(03)00233-9 .

Cajkovski, T, Davidović, Miloš D., Pissis, P, Polizos, G, Cajkovski, D, Likar-Smiljanic, V, Biljic, R, Nedić, Zoran, Mioč, Ubavka B., "Dielectric investigation of electrical conductivity in the copper salt of the 12-tungstophosphoric acid hydrate" in Solid State Ionics, 162 (2003):203-208,
https://doi.org/10.1016/S0167-2738(03)00233-9 . .

TY  - JOUR
AU  - Mioč, Ubavka B.
AU  - Todorovic, MR
AU  - Uskoković-Marković, SM
AU  - Davidović, Milorad P.
AU  - Kremenović, Aleksandar S.
AU  - Spasojević-de Bire, Anne
AU  - Cajkovski, T
AU  - Likar-Smiljanic, V
AU  - Biljic, R
PY  - 2003
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6384
AB  - Some structural properties of a magnesium salt of 12-tungstophosphoric acid, MgHPW12O40.nH(2)O (MgHVvTA-n), are reported. The influence of the Mg2+ ion on the structure, dynamics of the protonic species, and dielectric and conductive characteristics of the salt have been studied. The interaction of protonic species with Keggin anion was discussed. Preliminary results of the crystal structure indicate that the structure is composed of Keggin anions and Mg(OH2)(6) aqua-complexes. Some comparisons are made with other alkaline-earth and alkaline salts of WPA. The results of thermal analysis (TGA and DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), conductivity and permittivity measurements of MgHWPA-n are reported and discussed. (C) 2003 Elsevier B.V. All rights reserved.
T2  - Solid State Ionics
T1  - Structure and proton conductivity in a magnesium salt of 12-tungstophosphoric acid
VL  - 162
SP  - 217
EP  - 223
DO  - 10.1016/S0167-2738(03)00257-1
ER  - 

@article{
author = "Mioč, Ubavka B. and Todorovic, MR and Uskoković-Marković, SM and Davidović, Milorad P. and Kremenović, Aleksandar S. and Spasojević-de Bire, Anne and Cajkovski, T and Likar-Smiljanic, V and Biljic, R",
year = "2003",
abstract = "Some structural properties of a magnesium salt of 12-tungstophosphoric acid, MgHPW12O40.nH(2)O (MgHVvTA-n), are reported. The influence of the Mg2+ ion on the structure, dynamics of the protonic species, and dielectric and conductive characteristics of the salt have been studied. The interaction of protonic species with Keggin anion was discussed. Preliminary results of the crystal structure indicate that the structure is composed of Keggin anions and Mg(OH2)(6) aqua-complexes. Some comparisons are made with other alkaline-earth and alkaline salts of WPA. The results of thermal analysis (TGA and DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), conductivity and permittivity measurements of MgHWPA-n are reported and discussed. (C) 2003 Elsevier B.V. All rights reserved.",
journal = "Solid State Ionics",
title = "Structure and proton conductivity in a magnesium salt of 12-tungstophosphoric acid",
volume = "162",
pages = "217-223",
doi = "10.1016/S0167-2738(03)00257-1"
}

Mioč, U. B., Todorovic, M., Uskoković-Marković, S., Davidović, M. P., Kremenović, A. S., Spasojević-de Bire, A., Cajkovski, T., Likar-Smiljanic, V.,& Biljic, R.. (2003). Structure and proton conductivity in a magnesium salt of 12-tungstophosphoric acid. in Solid State Ionics, 162, 217-223.
https://doi.org/10.1016/S0167-2738(03)00257-1

Mioč UB, Todorovic M, Uskoković-Marković S, Davidović MP, Kremenović AS, Spasojević-de Bire A, Cajkovski T, Likar-Smiljanic V, Biljic R. Structure and proton conductivity in a magnesium salt of 12-tungstophosphoric acid. in Solid State Ionics. 2003;162:217-223.
doi:10.1016/S0167-2738(03)00257-1 .

Mioč, Ubavka B., Todorovic, MR, Uskoković-Marković, SM, Davidović, Milorad P., Kremenović, Aleksandar S., Spasojević-de Bire, Anne, Cajkovski, T, Likar-Smiljanic, V, Biljic, R, "Structure and proton conductivity in a magnesium salt of 12-tungstophosphoric acid" in Solid State Ionics, 162 (2003):217-223,
https://doi.org/10.1016/S0167-2738(03)00257-1 . .

TY  - JOUR
AU  - Cajkovski, T
AU  - Davidović, Milorad P.
AU  - Cajkovski, D
AU  - Likar-Smiljanic, V
AU  - Biljic, R
AU  - Mioč, Ubavka B.
AU  - Todorović, M
PY  - 2003
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6349
AB  - The main aim of this paper is to investigate the effects of gamma-irradiation on dielectric properties of barium salt of 12-tungstophosphoric acid (WPA) hydrate BaHPW12O40-7H(2)O (BaHWPA(.)7). Irradiation was carried out with two doses. Permittivity measurements have been performed in microwave X-band, at room temperature. After the irradiation (the absorbed dose 940 kGy) visible effect is the slight yellow color of the specimen and both real part epsilon and imaginary p I art epsilon of permittivity curves are shifted along the frequency axis. By measuring permittivity several days in succession gradual recovery of the specimen was observed. After five days epsilon and epsilon curves returned to their initial values on the frequency axis, and the color also disappeared. The second irradiation of the same specimen (1880 kGy) resulted in somewhat larger shift of epsilon and epsilon towards lower frequencies. This time, with larger absorbed dose there was no recovery effect and no-coloration. IR spectra of unirradiated and irradiated specimens were recorded and obtained data used for explanation of the observed phenomena.
T2  - Materials Science Forum
T1  - Effects of gamma-irradiation on the dielectric properties of the barium salt of 12-tungstophosphoric acid hydrate
VL  - 413
SP  - 141
EP  - 145
UR  - https://hdl.handle.net/21.15107/rcub_vinar_6349
ER  - 

@article{
author = "Cajkovski, T and Davidović, Milorad P. and Cajkovski, D and Likar-Smiljanic, V and Biljic, R and Mioč, Ubavka B. and Todorović, M",
year = "2003",
abstract = "The main aim of this paper is to investigate the effects of gamma-irradiation on dielectric properties of barium salt of 12-tungstophosphoric acid (WPA) hydrate BaHPW12O40-7H(2)O (BaHWPA(.)7). Irradiation was carried out with two doses. Permittivity measurements have been performed in microwave X-band, at room temperature. After the irradiation (the absorbed dose 940 kGy) visible effect is the slight yellow color of the specimen and both real part epsilon and imaginary p I art epsilon of permittivity curves are shifted along the frequency axis. By measuring permittivity several days in succession gradual recovery of the specimen was observed. After five days epsilon and epsilon curves returned to their initial values on the frequency axis, and the color also disappeared. The second irradiation of the same specimen (1880 kGy) resulted in somewhat larger shift of epsilon and epsilon towards lower frequencies. This time, with larger absorbed dose there was no recovery effect and no-coloration. IR spectra of unirradiated and irradiated specimens were recorded and obtained data used for explanation of the observed phenomena.",
journal = "Materials Science Forum",
title = "Effects of gamma-irradiation on the dielectric properties of the barium salt of 12-tungstophosphoric acid hydrate",
volume = "413",
pages = "141-145",
url = "https://hdl.handle.net/21.15107/rcub_vinar_6349"
}

Cajkovski, T., Davidović, M. P., Cajkovski, D., Likar-Smiljanic, V., Biljic, R., Mioč, U. B.,& Todorović, M.. (2003). Effects of gamma-irradiation on the dielectric properties of the barium salt of 12-tungstophosphoric acid hydrate. in Materials Science Forum, 413, 141-145.
https://hdl.handle.net/21.15107/rcub_vinar_6349

Cajkovski T, Davidović MP, Cajkovski D, Likar-Smiljanic V, Biljic R, Mioč UB, Todorović M. Effects of gamma-irradiation on the dielectric properties of the barium salt of 12-tungstophosphoric acid hydrate. in Materials Science Forum. 2003;413:141-145.
https://hdl.handle.net/21.15107/rcub_vinar_6349 .

Cajkovski, T, Davidović, Milorad P., Cajkovski, D, Likar-Smiljanic, V, Biljic, R, Mioč, Ubavka B., Todorović, M, "Effects of gamma-irradiation on the dielectric properties of the barium salt of 12-tungstophosphoric acid hydrate" in Materials Science Forum, 413 (2003):141-145,
https://hdl.handle.net/21.15107/rcub_vinar_6349 .

TY  - JOUR
AU  - Davidović, Miloš D.
AU  - Cajkovski, T
AU  - Cajkovski, D
AU  - Likar-Smiljanic, V
AU  - Biljic, R
AU  - Mioč, Ubavka B.
AU  - Nedić, Zoran
PY  - 2002
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2509
AB  - Barium salt of 12-tungstophosphoric acid (WPA) hydrate BaHPW12O40.7H(2)O (BaHWPA-7H20) has been investigated both in the microwave (X-band) region and in the lower frequency (5 Hz-500 kHz) region. This work is a continuation of our previous investigations on the influence of monovalent and bivalent cations on the dielectric properties of WPA hydrate salts. The real and imaginary parts of the permittivity (epsilon, epsilon) as a function of frequency and temperature, were determined in both frequency regions. The observed relaxations were attributed to specific relaxation processes. In the lower frequency range, the relaxation time tau=1.0 x 10(-6) s was assigned to barium ion jumps. In the microwave region, the dielectric relaxation time tau =1.7 x 10(-11) s was attributed to polyatomic ions (H3O+) and/or H2O molecules reorientations. A phase transition was observed at 330 K. The low value of the activation energy for reorientation in the microwave frequency region is discussed. The d.c. conductivity and its temperature dependence were determined. Measurements were made in the temperature interval from 286 to 353 K. In the upper part of this temperature interval a PTCR effect was observed. (C) 2002 Published by Elsevier Science B.V.
T2  - Solid State Ionics
T1  - Dielectric relaxation and conductivity in barium salt of 12-tungstophosphoric acid hydrate
VL  - 147
IS  - 1-2
SP  - 123
EP  - 128
DO  - 10.1016/S0167-2738(02)00003-6
ER  - 

@article{
author = "Davidović, Miloš D. and Cajkovski, T and Cajkovski, D and Likar-Smiljanic, V and Biljic, R and Mioč, Ubavka B. and Nedić, Zoran",
year = "2002",
abstract = "Barium salt of 12-tungstophosphoric acid (WPA) hydrate BaHPW12O40.7H(2)O (BaHWPA-7H20) has been investigated both in the microwave (X-band) region and in the lower frequency (5 Hz-500 kHz) region. This work is a continuation of our previous investigations on the influence of monovalent and bivalent cations on the dielectric properties of WPA hydrate salts. The real and imaginary parts of the permittivity (epsilon, epsilon) as a function of frequency and temperature, were determined in both frequency regions. The observed relaxations were attributed to specific relaxation processes. In the lower frequency range, the relaxation time tau=1.0 x 10(-6) s was assigned to barium ion jumps. In the microwave region, the dielectric relaxation time tau =1.7 x 10(-11) s was attributed to polyatomic ions (H3O+) and/or H2O molecules reorientations. A phase transition was observed at 330 K. The low value of the activation energy for reorientation in the microwave frequency region is discussed. The d.c. conductivity and its temperature dependence were determined. Measurements were made in the temperature interval from 286 to 353 K. In the upper part of this temperature interval a PTCR effect was observed. (C) 2002 Published by Elsevier Science B.V.",
journal = "Solid State Ionics",
title = "Dielectric relaxation and conductivity in barium salt of 12-tungstophosphoric acid hydrate",
volume = "147",
number = "1-2",
pages = "123-128",
doi = "10.1016/S0167-2738(02)00003-6"
}

Davidović, M. D., Cajkovski, T., Cajkovski, D., Likar-Smiljanic, V., Biljic, R., Mioč, U. B.,& Nedić, Z.. (2002). Dielectric relaxation and conductivity in barium salt of 12-tungstophosphoric acid hydrate. in Solid State Ionics, 147(1-2), 123-128.
https://doi.org/10.1016/S0167-2738(02)00003-6

Davidović MD, Cajkovski T, Cajkovski D, Likar-Smiljanic V, Biljic R, Mioč UB, Nedić Z. Dielectric relaxation and conductivity in barium salt of 12-tungstophosphoric acid hydrate. in Solid State Ionics. 2002;147(1-2):123-128.
doi:10.1016/S0167-2738(02)00003-6 .

Davidović, Miloš D., Cajkovski, T, Cajkovski, D, Likar-Smiljanic, V, Biljic, R, Mioč, Ubavka B., Nedić, Zoran, "Dielectric relaxation and conductivity in barium salt of 12-tungstophosphoric acid hydrate" in Solid State Ionics, 147, no. 1-2 (2002):123-128,
https://doi.org/10.1016/S0167-2738(02)00003-6 . .

TY  - JOUR
AU  - Cajkovski, T
AU  - Davidović, Milorad P.
AU  - Cajkovski, D
AU  - Likar-Smiljanic, V
AU  - Biljic, R
AU  - Mioč, Ubavka B.
AU  - Nedić, Zoran
PY  - 2000
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6312
AB  - Complex permittivity of 12-tungstophosphoric acid hexahydrate (H3PW12O40 6H(2)O), 6-WPA has been measured at microwave frequencies (X-band) in the temperature interval from 296 K to 350 K. From 296 K to 328 K 6-WPA displays dipolar relaxation of the Debye type at the frequency f(1)=9.30 GHz which corresponds to the relaxation time tau (1)=1.7x10(11) s. From 328 K to 350 K large changes of epsilon (f) and epsilon (f) take place. Two additional relaxations appear at frequencies f(2)=8.25 GHz and f(3)=10.80 GHz. These additional relaxations could be due to protonic entities that become excited at higher temperatures. An assignation of these relaxations to specific proton entities is proposed.
T2  - Materials Science Forum
T1  - Temperature dependence of dielectric relaxation in 12-tungstophosphoric acid hexahydrate at microwave frequencies
VL  - 352
SP  - 251
EP  - 254
UR  - https://hdl.handle.net/21.15107/rcub_vinar_6312
ER  - 

@article{
author = "Cajkovski, T and Davidović, Milorad P. and Cajkovski, D and Likar-Smiljanic, V and Biljic, R and Mioč, Ubavka B. and Nedić, Zoran",
year = "2000",
abstract = "Complex permittivity of 12-tungstophosphoric acid hexahydrate (H3PW12O40 6H(2)O), 6-WPA has been measured at microwave frequencies (X-band) in the temperature interval from 296 K to 350 K. From 296 K to 328 K 6-WPA displays dipolar relaxation of the Debye type at the frequency f(1)=9.30 GHz which corresponds to the relaxation time tau (1)=1.7x10(11) s. From 328 K to 350 K large changes of epsilon (f) and epsilon (f) take place. Two additional relaxations appear at frequencies f(2)=8.25 GHz and f(3)=10.80 GHz. These additional relaxations could be due to protonic entities that become excited at higher temperatures. An assignation of these relaxations to specific proton entities is proposed.",
journal = "Materials Science Forum",
title = "Temperature dependence of dielectric relaxation in 12-tungstophosphoric acid hexahydrate at microwave frequencies",
volume = "352",
pages = "251-254",
url = "https://hdl.handle.net/21.15107/rcub_vinar_6312"
}

Cajkovski, T., Davidović, M. P., Cajkovski, D., Likar-Smiljanic, V., Biljic, R., Mioč, U. B.,& Nedić, Z.. (2000). Temperature dependence of dielectric relaxation in 12-tungstophosphoric acid hexahydrate at microwave frequencies. in Materials Science Forum, 352, 251-254.
https://hdl.handle.net/21.15107/rcub_vinar_6312

Cajkovski T, Davidović MP, Cajkovski D, Likar-Smiljanic V, Biljic R, Mioč UB, Nedić Z. Temperature dependence of dielectric relaxation in 12-tungstophosphoric acid hexahydrate at microwave frequencies. in Materials Science Forum. 2000;352:251-254.
https://hdl.handle.net/21.15107/rcub_vinar_6312 .

Cajkovski, T, Davidović, Milorad P., Cajkovski, D, Likar-Smiljanic, V, Biljic, R, Mioč, Ubavka B., Nedić, Zoran, "Temperature dependence of dielectric relaxation in 12-tungstophosphoric acid hexahydrate at microwave frequencies" in Materials Science Forum, 352 (2000):251-254,
https://hdl.handle.net/21.15107/rcub_vinar_6312 .

TY  - JOUR
AU  - Davidović, Miloš D.
AU  - Cajkovski, T
AU  - Cajkovski, D
AU  - Likar-Smiljanic, V
AU  - Biljic, R
AU  - Mioč, Ubavka B.
AU  - Nedić, Zoran
PY  - 1999
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6283
AB  - Magnesium salt of 12-tungstophosphoric acid (WPA) hydrate MgHPW12O40-14H(2)O has been investigated in the microwave (X-band) and in the lower frequency (5 Hz-500 kHz) region. The specimens were obtained by pressing powder. Real and imaginary parts of permittivity were obtained for the specimens in both frequency regions. In the microwave region dipolar relaxation was observed with the relaxation time tau = 1.6 X 10(-11) s. This relaxation is attributed to the fast reorientation of H2O molecules. In the lower frequency region ionic jump relaxation was observed with the relaxation time tau = 3.9 X 10(-7) s. Results on ac and dc conductivity are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.
T2  - Solid State Ionics
T1  - Dielectric investigation of magnesium salt of 12-tungstophosphoric acid hydrate
VL  - 125
IS  - 1-4
SP  - 411
EP  - 415
DO  - 10.1016/S0167-2738(99)00203-9
ER  - 

@article{
author = "Davidović, Miloš D. and Cajkovski, T and Cajkovski, D and Likar-Smiljanic, V and Biljic, R and Mioč, Ubavka B. and Nedić, Zoran",
year = "1999",
abstract = "Magnesium salt of 12-tungstophosphoric acid (WPA) hydrate MgHPW12O40-14H(2)O has been investigated in the microwave (X-band) and in the lower frequency (5 Hz-500 kHz) region. The specimens were obtained by pressing powder. Real and imaginary parts of permittivity were obtained for the specimens in both frequency regions. In the microwave region dipolar relaxation was observed with the relaxation time tau = 1.6 X 10(-11) s. This relaxation is attributed to the fast reorientation of H2O molecules. In the lower frequency region ionic jump relaxation was observed with the relaxation time tau = 3.9 X 10(-7) s. Results on ac and dc conductivity are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.",
journal = "Solid State Ionics",
title = "Dielectric investigation of magnesium salt of 12-tungstophosphoric acid hydrate",
volume = "125",
number = "1-4",
pages = "411-415",
doi = "10.1016/S0167-2738(99)00203-9"
}

Davidović, M. D., Cajkovski, T., Cajkovski, D., Likar-Smiljanic, V., Biljic, R., Mioč, U. B.,& Nedić, Z.. (1999). Dielectric investigation of magnesium salt of 12-tungstophosphoric acid hydrate. in Solid State Ionics, 125(1-4), 411-415.
https://doi.org/10.1016/S0167-2738(99)00203-9

Davidović MD, Cajkovski T, Cajkovski D, Likar-Smiljanic V, Biljic R, Mioč UB, Nedić Z. Dielectric investigation of magnesium salt of 12-tungstophosphoric acid hydrate. in Solid State Ionics. 1999;125(1-4):411-415.
doi:10.1016/S0167-2738(99)00203-9 .

Davidović, Miloš D., Cajkovski, T, Cajkovski, D, Likar-Smiljanic, V, Biljic, R, Mioč, Ubavka B., Nedić, Zoran, "Dielectric investigation of magnesium salt of 12-tungstophosphoric acid hydrate" in Solid State Ionics, 125, no. 1-4 (1999):411-415,
https://doi.org/10.1016/S0167-2738(99)00203-9 . .

TY  - JOUR
AU  - Čajkovski, Tamara
AU  - Davidović, Milorad P.
AU  - Čajkovski, D.
AU  - Likar-Smiljanić, Vladana D.
AU  - Biljić, Radivoje M.
AU  - Mioč, Ubavka B.
AU  - Stamenković, Vojislav R.
PY  - 1998
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/2180
AB  - Heteropolyacids hydrates as superionic conductors have been intensely investigated during the last fifteen years. By using various experimental techniques such as IR and Raman spectroscopy, neutron scattering, impedance measurements, X-ray diffraction and others, informations have been obtained on the properties of protonic entities and conductivity mechanisms. The salts of heteropolyacids have been less investigated although there is a steady growth of activities in this field too. In this work the results of permittivity measurements are presented on copper and calcium salts of 12-tungstophosphoric acid hydrates (CuHPW12O40. 15H(2)O and CaHPW12O40. 13H(2)O). Measurements have been done in the region of microwaves, at room temperature and in a room ambient. The aim of this work was to study the influence of copper and calcium ions on dielectric relaxation processes in these salts. Dielectric relaxations have been found for both salts. Contributions of fast reorientations of H2O molecules and oxonium ions (H3O+) to these relaxations are discussed as well as, their influence on dynamic conductivity.
T2  - Solid State Phenomena
T1  - Dielectric properties of metal salts of heteropolyacid hydrates
VL  - 61-2
SP  - 279
EP  - 283
DO  - 10.4028/www.scientific.net/ssp.61-62.279
UR  - https://hdl.handle.net/21.15107/rcub_vinar_2180
ER  - 

@article{
author = "Čajkovski, Tamara and Davidović, Milorad P. and Čajkovski, D. and Likar-Smiljanić, Vladana D. and Biljić, Radivoje M. and Mioč, Ubavka B. and Stamenković, Vojislav R.",
year = "1998",
abstract = "Heteropolyacids hydrates as superionic conductors have been intensely investigated during the last fifteen years. By using various experimental techniques such as IR and Raman spectroscopy, neutron scattering, impedance measurements, X-ray diffraction and others, informations have been obtained on the properties of protonic entities and conductivity mechanisms. The salts of heteropolyacids have been less investigated although there is a steady growth of activities in this field too. In this work the results of permittivity measurements are presented on copper and calcium salts of 12-tungstophosphoric acid hydrates (CuHPW12O40. 15H(2)O and CaHPW12O40. 13H(2)O). Measurements have been done in the region of microwaves, at room temperature and in a room ambient. The aim of this work was to study the influence of copper and calcium ions on dielectric relaxation processes in these salts. Dielectric relaxations have been found for both salts. Contributions of fast reorientations of H2O molecules and oxonium ions (H3O+) to these relaxations are discussed as well as, their influence on dynamic conductivity.",
journal = "Solid State Phenomena",
title = "Dielectric properties of metal salts of heteropolyacid hydrates",
volume = "61-2",
pages = "279-283",
doi = "10.4028/www.scientific.net/ssp.61-62.279",
url = "https://hdl.handle.net/21.15107/rcub_vinar_2180"
}

Čajkovski, T., Davidović, M. P., Čajkovski, D., Likar-Smiljanić, V. D., Biljić, R. M., Mioč, U. B.,& Stamenković, V. R.. (1998). Dielectric properties of metal salts of heteropolyacid hydrates. in Solid State Phenomena, 61-2, 279-283.
https://doi.org/10.4028/www.scientific.net/ssp.61-62.279
https://hdl.handle.net/21.15107/rcub_vinar_2180

Čajkovski T, Davidović MP, Čajkovski D, Likar-Smiljanić VD, Biljić RM, Mioč UB, Stamenković VR. Dielectric properties of metal salts of heteropolyacid hydrates. in Solid State Phenomena. 1998;61-2:279-283.
doi:10.4028/www.scientific.net/ssp.61-62.279
https://hdl.handle.net/21.15107/rcub_vinar_2180 .

Čajkovski, Tamara, Davidović, Milorad P., Čajkovski, D., Likar-Smiljanić, Vladana D., Biljić, Radivoje M., Mioč, Ubavka B., Stamenković, Vojislav R., "Dielectric properties of metal salts of heteropolyacid hydrates" in Solid State Phenomena, 61-2 (1998):279-283,
https://doi.org/10.4028/www.scientific.net/ssp.61-62.279 .,
https://hdl.handle.net/21.15107/rcub_vinar_2180 .

TY  - JOUR
AU  - Cajkovski, T
AU  - Davidović, Milorad P.
AU  - Cajkovski, D
AU  - Likar-Smiljanic, V
AU  - Biljic, R
AU  - Mioč, Ubavka B.
AU  - Nedić, Zoran
PY  - 1998
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6251
AB  - Complex permittivity measurements have been performed on lithium and cesium salts of 12-tungstophosphoric acid hydrates (H3PW12O40.nH(2)O) within the frequency region of the microwave X-band (8 - 12 GHz) and at room temperature. Dielectric relaxation spectra have been observed for both salts. For the lithium salt (Li3PW12O40.11H(2)O) one dipolar relaxation has been recorded, whereas for the cesium salt (CS3PW12O40.10H(2)O) two dipolar relaxations have been registered. The results are discussed by assuming that the fast reorientation of H2O molecules and oxonium ions (H3O+) contribute to the observed relaxations. Dynamical conductivity results exhibit frequency dependence with a waviness reflecting the observed dipolar relaxations.
T2  - Materials Science Forum
T1  - X-band microwave permittivity measurements on lithium and cesium salts of 12-tunstophosphoric acid
VL  - 282-2
SP  - 193
EP  - 197
UR  - https://hdl.handle.net/21.15107/rcub_vinar_6251
ER  - 

@article{
author = "Cajkovski, T and Davidović, Milorad P. and Cajkovski, D and Likar-Smiljanic, V and Biljic, R and Mioč, Ubavka B. and Nedić, Zoran",
year = "1998",
abstract = "Complex permittivity measurements have been performed on lithium and cesium salts of 12-tungstophosphoric acid hydrates (H3PW12O40.nH(2)O) within the frequency region of the microwave X-band (8 - 12 GHz) and at room temperature. Dielectric relaxation spectra have been observed for both salts. For the lithium salt (Li3PW12O40.11H(2)O) one dipolar relaxation has been recorded, whereas for the cesium salt (CS3PW12O40.10H(2)O) two dipolar relaxations have been registered. The results are discussed by assuming that the fast reorientation of H2O molecules and oxonium ions (H3O+) contribute to the observed relaxations. Dynamical conductivity results exhibit frequency dependence with a waviness reflecting the observed dipolar relaxations.",
journal = "Materials Science Forum",
title = "X-band microwave permittivity measurements on lithium and cesium salts of 12-tunstophosphoric acid",
volume = "282-2",
pages = "193-197",
url = "https://hdl.handle.net/21.15107/rcub_vinar_6251"
}

Cajkovski, T., Davidović, M. P., Cajkovski, D., Likar-Smiljanic, V., Biljic, R., Mioč, U. B.,& Nedić, Z.. (1998). X-band microwave permittivity measurements on lithium and cesium salts of 12-tunstophosphoric acid. in Materials Science Forum, 282-2, 193-197.
https://hdl.handle.net/21.15107/rcub_vinar_6251

Cajkovski T, Davidović MP, Cajkovski D, Likar-Smiljanic V, Biljic R, Mioč UB, Nedić Z. X-band microwave permittivity measurements on lithium and cesium salts of 12-tunstophosphoric acid. in Materials Science Forum. 1998;282-2:193-197.
https://hdl.handle.net/21.15107/rcub_vinar_6251 .

Cajkovski, T, Davidović, Milorad P., Cajkovski, D, Likar-Smiljanic, V, Biljic, R, Mioč, Ubavka B., Nedić, Zoran, "X-band microwave permittivity measurements on lithium and cesium salts of 12-tunstophosphoric acid" in Materials Science Forum, 282-2 (1998):193-197,
https://hdl.handle.net/21.15107/rcub_vinar_6251 .

TY  - JOUR
AU  - Davidović, Miloš D.
AU  - Cajkovski, T
AU  - Cajkovski, D
AU  - Likar-Smiljanic, V
AU  - Biljic, R
AU  - Mioč, Ubavka B.
PY  - 1997
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7234
AB  - Complex permittivity measurements of 12-tungstophosphoric acid hexahydrate (WPA . 6H(2)O) have been performed in the X-band region at room temperature. Permittivity data were obtained by measuring reflection (S-11) and transmission (S-21) parameters with a network analyzer and also by using a short-circuited-waveguide. Results on powder samples are compared with the results on compressed samples using the model of mixtures. From Cole-Cole plots, a dipole relaxation lime tau = 1.9 x 10(-11) s was determined and attributed to polyatomic ion reorientation.
T2  - Solid State Ionics
T1  - Microwave X-band permittivity measurements on 12-tungstophosphoric acid hexahydrate
VL  - 97
IS  - 1-4
SP  - 233
EP  - 238
DO  - 10.1016/S0167-2738(97)00041-6
ER  - 

@article{
author = "Davidović, Miloš D. and Cajkovski, T and Cajkovski, D and Likar-Smiljanic, V and Biljic, R and Mioč, Ubavka B.",
year = "1997",
abstract = "Complex permittivity measurements of 12-tungstophosphoric acid hexahydrate (WPA . 6H(2)O) have been performed in the X-band region at room temperature. Permittivity data were obtained by measuring reflection (S-11) and transmission (S-21) parameters with a network analyzer and also by using a short-circuited-waveguide. Results on powder samples are compared with the results on compressed samples using the model of mixtures. From Cole-Cole plots, a dipole relaxation lime tau = 1.9 x 10(-11) s was determined and attributed to polyatomic ion reorientation.",
journal = "Solid State Ionics",
title = "Microwave X-band permittivity measurements on 12-tungstophosphoric acid hexahydrate",
volume = "97",
number = "1-4",
pages = "233-238",
doi = "10.1016/S0167-2738(97)00041-6"
}

Davidović, M. D., Cajkovski, T., Cajkovski, D., Likar-Smiljanic, V., Biljic, R.,& Mioč, U. B.. (1997). Microwave X-band permittivity measurements on 12-tungstophosphoric acid hexahydrate. in Solid State Ionics, 97(1-4), 233-238.
https://doi.org/10.1016/S0167-2738(97)00041-6

Davidović MD, Cajkovski T, Cajkovski D, Likar-Smiljanic V, Biljic R, Mioč UB. Microwave X-band permittivity measurements on 12-tungstophosphoric acid hexahydrate. in Solid State Ionics. 1997;97(1-4):233-238.
doi:10.1016/S0167-2738(97)00041-6 .

Davidović, Miloš D., Cajkovski, T, Cajkovski, D, Likar-Smiljanic, V, Biljic, R, Mioč, Ubavka B., "Microwave X-band permittivity measurements on 12-tungstophosphoric acid hexahydrate" in Solid State Ionics, 97, no. 1-4 (1997):233-238,
https://doi.org/10.1016/S0167-2738(97)00041-6 . .