Relaxation Due to Incoherent Tunnelling in Dielectric Glasses
نویسندگان
چکیده
A new relaxation mechanism is shown to arise from overdamped two-level systems above a critical temperature T ∗ ≈ 5 K, thus yielding an explanation for experimental observations in dielectric glasses in the temperature range between T ∗ and the relaxation peak at 50 K. Using the distribution function of the tunnelling model for the parameters of the two-level systems, both the linear decrease of the sound velocity and the linear increase of the absorption up to the relaxation maximum, are quantitatively accounted for by our theory. PACS. 61.40– amorphous and polymeric materials PACS. 63.50 – disordered solids, vibrational states PACS. 77.22G – relaxation phenomena, dielectrics
منابع مشابه
Multilevel Tunnelling Systems and Fractal Clustering in the Low-Temperature Mixed Alkali-Silicate Glasses
The thermal and dielectric anomalies of window-type glasses at low temperatures (T < 1 K) are rather successfully explained by the two-level systems (2LS) standard tunneling model (STM). However, the magnetic effects discovered in the multisilicate glasses in recent times, magnetic effects in the organic glasses, and also some older data from mixed (SiO₂)(1-x) (K₂O)(x) and (SiO₂)(1-x) (Na₂O)(x)...
متن کاملTemperature cycling during the aging of a polymer glass
– Temperature cycling is used to study aging properties of plexiglass (PMMA) dielectric constant. If a negative temperature cycle is applied during the aging time the relaxation dynamics is just delayed for a time equal to the cycle period. In contrast this time shifting procedure cannot be applied to positive temperature cycles. The analogies and differences with similar experiments done in ot...
متن کاملInfluence of Interface Thermal Resistance on Relaxation Dynamics of Metal-Dielectric Nanocomposite Materials under Ultrafast Pulse Laser Excitation
Nanocomposite materials, including noble metal nanoparticles embedded in a dielectric host medium, are interesting because of their optical properties linked to surface plasmon resonance phenomena. For studding of nonlinear optical properties and/or energy transfer process, these materials may be excited by ultrashort pulse laser with a temporal width varying from some femtoseconds to some hund...
متن کاملDielectric and Electric Modulus Behavior of Chlorinated Poly(Vinyl Chloride) Stabilized with Phenyl Maleimide
Dielectric constant, ε', dielectric loss factor, ε", electric modulus, M, and ac conductivity, σac, of pure CPVC and that stabilized with 10 wt% of phenyl maleimide, PM, have been carried out. The dielectric properties have been studied in the temperature and frequency ranges; 310 K 450 K and 1 kHz4 MHz, respectively. The incorporation of 10 wt% of PM as stabilizer for CPVC leads to reduce its ...
متن کاملEvidence of secondary relaxations in the dielectric spectra of ionic liquids
We investigated the dynamics of a series of room temperature ionic liquids based on the same 1-butyl-3-methyl imidazolium cation and different anions by means of broadband dielectric spectroscopy covering 15 decades in frequency (10-10Hz), and in the temperature range from 400 K down to 35 K. An ionic conductivity is observed above the glass transition temperature Tg with a relaxation in the el...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 1994