No abstract

Thermal transport is a key performance metric for thorium dioxide in many applications where defect-generating radiation fields are present. An understanding of the effect of nanoscale lattice defects on thermal transport in this material is currently unavailable due to the lack of a single crystal material from which unit processes may be investigated. In this work, a series of high-quality thorium dioxide single crystals are exposed to 2 MeV proton irradiation at room temperature and 600 °C to create microscale regions with varying densities and types of point and extended defects. Defected regions are investigated using spatial domain thermoreflectance to quantify the change in thermal conductivity as a function of ion fluence as well as transmission electron microscopy and Raman spectroscopy to interrogate the structure of the generated defects. Together, this combination of methods provides important initial insight into defect formation, recombination, and clustering in thorium dioxide and the effect of those defects on thermal transport. These methods also provide a promising pathway for the quantification of the smallest-scale defects that cannot be captured using traditional microscopy techniques and play an outsized role in degrading thermal performance.

Hot electron mediated enhancement in the decay rates of persistent photocurrent in gold nanoparticles embedded indium oxide films

This IUTAM Symposium, dedicated to the memory of Jean Mandel, was held in the first week of September 1986, covering topics: thermodynamics of irreversible process, dissipative phenomena in plasticity and viscoplasticity in fracture and damage, behaviors of heterogeneous or complex media such as composites, woods and geomaterials, phase transformation, experimental techniques based on infrared thermography, cyclic leads, large deformation, numerical methods for coupled problems, etc. The topics are heterogeneous but unified in terms of thermomechanical couplings. Some of the papers presented in this proceeding will be briefly reviewed here. I. Muller simulated thermomechanical properties of materials with shape memory and proposed a model with the potential energy under a shear load and interfacial energy. Statistical mechanics of the model is discussed. J. Kestin presented his recent work on metal plasticity as a problem in thermodynamics. He is interested in the fact that Volterra and Somigliana dislocations can be produced by fictitiously reversible processes of changing the internal state created by plastic deformation. In turn, this makes it possible to calculate entropy and Gibbs equations. G. J. Dvorak's paper is "Thermomechanical deformation and coupling in elastic-plastic composite materials." He presented his recent discovery that spatially uniform stress and strain fields can be caused in certain heterogeneous media by simultaneous application of a uniform thermal change and uniform overall stress. J. L. Lataillade presented the use of a standard infrared camera to measure the temperature evolution of a polymetric material during its dynamic plastic deformation. M. P. Luong used infrared vibrothermography as a nondestructive technique to analyze the unstable crack propagation in concrete. J. R. Barber and M. Comninou reviewed thermoelastic effects in fracture and discussed crack closure and thermal contact resistance. P. Perzyna's paper concerns the influence of thermomechanical coupling on dynamic fracture of ductile solids. M. Taya and T. Mori used the Eshelby method to evaluate dimensional change in metal matrix composites subjected to thermal cycling. At high temperature, the thermal stress relaxation occurs by first matrix creep and followed by the diffu