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Structural and Electrical Properties of the NH 4 DyHP 3 O 10 Compound
Author(s) -
Zouari N.,
Khemakhem H.,
Gargouri M.,
Mnif M.,
Mhiri T.,
Daoud A.
Publication year - 1999
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(199905)213:1<219::aid-pssb219>3.0.co;2-q
Subject(s) - dielectric , ferroelectricity , permittivity , condensed matter physics , dielectric spectroscopy , materials science , phase transition , charge carrier , chemistry , physics , optoelectronics , electrode , electrochemistry
Low‐frequency dielectric dispersion phenomena in NH 4 DyHP 3 O 10 (ammonium dysprosium hydrogen phosphate type) polycrystalline compounds have been analyzed by impedance spectroscopy. The thermal evolution of the dielectric constant shows a phase transition at 305 K which is ferroelectric–paraelectric type. The ferroelectric phase is isotypic with KDyHP 3 O 10 triclinic symmetry P1 (at room temperature: a = 6.820 Å, b = 7.583 Å, c = 8.467 Å, α = 104.396°, β = 103.545°, γ = 90.349°, Z = 2). An empirical expression has been deduced for the complex permittivity ε ( ω ), ε *( ω ) = ε ∞ + ε s ‐ ε ∞ /1 + ( i ω / ω 1 ) m + σ 0 / ε 0 ω [1 + ( i ω / ω 2 ) n ], where the ( ω 1 , m ) and ( ω 2 , n ) couples characterize the lattice and the charge carriers responses, respectively. This relation may be considered as a generalisation of the Cole‐Cole dielectric expression. The influence of the charge carrier contribution on the dielectric permittivity at low frequency is significant, as shown when both lattice and carrier polarization mechanisms are simultaneously considered.