skip to main content

Title: Temperature-induced structural change through the glass transition of silicate glass by neutron diffraction
Award ID(s):
Author(s) / Creator(s):
; ; ; ; ; ; ;
Date Published:
Journal Name:
Physical Review B
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Unconventional shale or tight oil/gas reservoirs that have micro-/nano-sized dual-scale matrix pore throats with micro-fractures may result in different fluid flow mechanisms compared with conventional oil/gas reservoirs. Microfluidic models, as a potential powerful tool, have been used for decades for investigating fluid flow at the pore-scale in the energy field. However, almost all microfluidic models were fabricated by using etching methods and very few had dual-scale micro-/nanofluidic channels. Herein, we developed a lab-based, quick-processing and cost-effective fabrication method using a lift-off process combined with the anodic bonding method, which avoids the use of any etching methods. A dual-porosity matrix/micro-fracture pattern, which can mimic the topology of shale with random irregular grain shapes, was designed with the Voronoi algorithm. The pore channel width range is 3 μm to 10 μm for matrices and 100–200 μm for micro-fractures. Silicon is used as the material evaporated and deposited onto a glass wafer and then bonded with another glass wafer. The channel depth is the same (250 nm) as the deposited silicon thickness. By using an advanced confocal laser scanning microscopy (CLSM) system, we directly visualized the pore level flow within micro/nano dual-scale channels with fluorescent-dyed water and oil phases. We found a serious fingering phenomenon when water displaced oil in the conduits even if water has higher viscosity and the residual oil was distributed as different forms in the matrices, micro-fractures and conduits. We demonstrated that different matrix/micro-fracture/macro-fracture geometries would cause different flow patterns that affect the oil recovery consequently. Taking advantage of such a micro/nano dual-scale ‘shale-like’ microfluidic model fabricated by a much simpler and lower-cost method, studies on complex fluid flow behavior within shale or other tight heterogeneous porous media would be significantly beneficial. 
    more » « less
  2. Strain glass is a new strain state discovered recently in ferroelastic systems that is characterized by nanoscale martensitic domains formed through a freezing transition. These nanodomains typically have mottled or tweed morphology depending on the elastic anisotropy of the system. Strain glass transition is a broadly smeared and high order–like transition, taking place within a wide temperature or stress range. It is accompanied by many unique properties, including linear superelasticity with high strength, low modulus, Invar and Elinvar anomalies, and large magnetostriction. In this review, we first discuss experimental characterization and testing that have led to the discovery of the strain glass transition and its unique properties. We then introduce theoretical models and computer simulations that have shed light on the origin and mechanisms underlying the unique characteristics and properties of strain glass transitions. Unresolved issues and challenges in strain glass study are also addressed. Strain glass transition can offer giant elastic strain and ultralow elastic modulus by well-controlled reversible structural phase transformations through defect engineering.

    more » « less
  3. null (Ed.)