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Dielectric characteristics of neodymium heptamolybdate crystals grown by gel encapsulation technique
Author(s) -
Bhat Sushma,
Khosa S. K.,
Kotru Dr. P. N.,
Tandon R. P.
Publication year - 1995
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170300225
Subject(s) - dielectric , neodymium , conductivity , dielectric loss , space charge , materials science , analytical chemistry (journal) , electrical resistivity and conductivity , polarization (electrochemistry) , chemistry , optics , organic chemistry , laser , optoelectronics , electrical engineering , physics , quantum mechanics , engineering , electron
Results obtained from the dielectric studies of neodymium heptamolybdate crystals grown in the system Nd(NO 3 ) 3 –MoO 3 –NH 4 OH– HNO 3 —Na 2 SiO 3 by gel encapsulation technique are presented. The variation of dielectric constant (ε′), dielectric loss (tanδ) and conductivity (σ) with frequency at different temperatures is studied. The dielectric constant of the material increases sharply, attains a peak value and then decreases rapidly, as material's temperature rises from room temperature to higher degrees. The temperature at which the peak value is attained is the transition temperature of the material. Dielectric loss (tan δ) follows almost a similar behaviour. The conductivity (σ) is also found to be temperature‐and frequency‐dependent. This sharp rise in ε′ is attributed to the contribution from space charge polarization. Theoretically obtained data using the expression ε′ = a 0 + a 1 T 2 and —In σ = a + b ( T — T 0 ) 2 for T < T 0 ) fits very well with the experimentally obtained data indicating that space charge polarization increases as some power of temperature larger than one.