Dielectric Spectroscopy
Dr. A.M. Awasthi

  • Frequency Bandwidth--- 3x10-5 to 2x107 Hz.
  • Impedance Range--- 10-3 to 1015 ? (18 decades) covers conductors to best insulators.
  • Capacity Range--- 10-15F to 1F allows broadband measurement of capacitances.
  • Absolute Accuracy for Phase (2x10-3 degrees) and Loss-Tangent (3x10-5).
  • Nonlinear Dielectric, Conductivity, and Impedance Spectroscopy.
  • Time-Domain Response Functions and Distributions of Relaxation Timescales.
  • Widest Sample-Temperature Windows--- LHe to RT and RT to 800 C. Sample Size--- t ~ 2-4mm x   ~ 8-10mm pellets.
UGC-DAE Consortium for Scientific Research
( An Autonomous Institute of University Grants Commission, New Delhi )

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Relevant Publications -

  • Fractional power-law spectral response of CaCu3Ti4O12 dielectric: many-body effects, Jitender Kumar and A.M. Awasthi, Appl. Phys. Lett. 101, 062908 (2012).

  • Discovery of strange kinetics in bulk material: correlated dipoles in CaCu3Ti4O12, A.M. Awasthi and Jitender Kumar, J. Appl. Phys. 112, 054108 (2012).

  • Dielectric relaxation spectroscopy of phlogopite mica, Navjeet Kaur, Mohan Singh, Anupinder Singh, A.M. Awasthi, Lakhwant Singh, Physica B: Condensed Matter 407, 4489 (2012).

  • Electrical properties of KTiOPO4 at low temperatures, Jitender Kumarand A.M. Awasthi, AIP Conf. Proc. 1447, 119 (2012).

  • Novel Studies of Ferroelectric Domain-Wall Dynamics, Jitender Kumar, S. Bhardwaj, and A.M. Awasthi, AIP Conf. Proc. 1349, 1235 (2011).

  • Correlated Magnetic and Electrical Orders in YMn1?xFexO3 Multiferroics, Sonu Namdeo and A.M. Awasthi, International Conference on Physics of Emerging Functional Materials, AIP Conf. Proc. 1313, 239 (2010).
Dielectric spectroscopy provides the short-time (AC) behaviour of insulators and semiconductors. It measures the electrical susceptibility of the material with intrinsic (ionic/dipolar/atomic/electronic) and proximity (grain-boundary/space-charge) contributions, which are affected by its structural/order-disorder/kinetic transitions, as well as by various relaxations/arrests. Our broadband impedance analyzer (NovoControl) enables probing the electrical response at extreme timescales, covering a rather wide range of conductivities and dielectric losses, alongwith the dispersive/non-activated behaviour.