The linear temperature dependence of the paramagnetic resonance linewidth in the manganate perovskites and

1996 ◽  
Vol 8 (50) ◽  
pp. 11283-11289 ◽  
Author(s):  
Mohindar S Seehra ◽  
Manjula M Ibrahim ◽  
V Suresh Babu ◽  
G Srinivasan
Keyword(s):  
Temperature Dependence ◽  
Linear Temperature Dependence ◽  
Paramagnetic Resonance ◽  
Linear Temperature ◽  
Resonance Linewidth

Parametric Models of Ultrasonic Piezoelectric Transducers over a Wide Temperature Range

2015 ◽  
Vol 2015 (HiTEN) ◽  
pp. 000266-000272 ◽  
Author(s):  
Steven A. Morris ◽  
Jeremy Townsend
Keyword(s):  
Dielectric Constant ◽  
Temperature Dependence ◽  
Coupling Coefficient ◽  
Thin Disk ◽  
Piezoelectric Transducers ◽  
Parametric Models ◽  
Model Parameters ◽  
Linear Temperature Dependence ◽  
Linear Temperature ◽  
Wide Range

Piezoelectric ultrasonic transducers are used extensively in well logging and logging-while-drilling applications for pulse-echo operation. We present a method of modeling the operation of ultrasonic thin-disk piezoelectric transducers over a wide range of temperatures. The model is based on using Redwood's version of Mason's model of thin-disk transducers. Laboratory measurements in the oven of non-backed transducers in air are used to extract the Mason model parameters as a function of temperature. Derived parameters are frequency-thickness constant, dielectric constant, and thickness mode coupling coefficient. A fourth parameter, bulk density, is measured independently and assumed constant over temperature. Temperature dependence of frequency thickness constant and coupling coefficient are modeled as linear temperature coefficients. Temperature dependence of the dielectric constant must be specified as a table because of the non-linear temperature dependence of that parameter.

scholarly journals Uniform excitations in magnetic nanoparticles

2010 ◽  
Vol 1 ◽  
pp. 48-54 ◽  
Author(s):  
Steen Mørup ◽  
Cathrine Frandsen ◽  
Mikkel Fougt Hansen
Keyword(s):  
Magnetic Nanoparticles ◽  
Temperature Dependence ◽  
Inelastic Neutron Scattering ◽  
Magnetic Hyperfine Field ◽  
Short Review ◽  
Inelastic Neutron ◽  
Blocking Temperature ◽  
Linear Temperature Dependence ◽  
Linear Temperature ◽  
Average Magnetization

We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T 3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering.

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