Though many, if not most, scientists are familiar with the effect of size on the electronic properties of nanoparticles, fewer are familiar with the effect of size on constituent properties such as cohesive energy, melting points, and congruent vapor pressures, for example. These properties are, of course, very important in the synthesis, manipulation and utilization of nanoparticles and are often difficult to determine experimentally, particularly in the range below 5 nm. Therefore, in order to supplement these experimental results, a simple, “back of the envelope” model for calculating such properties based solely on the size of the nanoparticle and knowledge of the enthalpy of the bulk materials has been developed. While some phenomena, such as sintering, require somewhat more computational space than an envelope, others, such as dissolution, can actually be described with that degree of simplicity.
Helen Farrell has recently retired as a Directorate Fellow in the Department of Materials Sciences and Engineering at Idaho National Laboratory (INL). She earned B.S. and M.S. Degrees in Chemistry at the University of Massachusetts and a Ph.D. in Chemistry at the University of California at Berkeley in 1969. She has since worked at Brookhaven National Laboratory, Bell Telephone laboratories, the University of Illinois and Idaho National Laboratory. After many years of experimental research in the areas of the physics, chemistry and materials science of surfaces and interfaces, she became a density functional theory (DFT) modeler when she moved to INL and has expanded her interests to include nanoparticles.
