Lattice variation as a function of concentration and grain size in MgO-NiO solid solution system

Area of Science:

• Materials Science
• Solid State Chemistry
• Nanotechnology

Background:

• Understanding the relationship between crystal size and material properties is crucial for developing advanced materials.
• The Mg1-xNixO solid solution system is of interest due to its potential applications, but its structural behavior at the nanoscale is not fully understood.

Purpose of the Study:

• To investigate the effect of crystal grain size on the lattice parameters and crystal structure of Mg1-xNixO solid solutions.
• To analyze the influence of synthesis methods and calcination temperatures on grain size and subsequent lattice variations.
• To elucidate the interplay between surface stress and ionic bonding in nanocrystalline materials.

Main Methods:

• Synthesis of Mg1-xNixO solid solutions using sol-gel and microwave hydrothermal methods.
• Calcination at temperatures ranging from 673 K to 1473 K to control grain size.
• Characterization using X-ray diffraction (XRD) for lattice parameters and grain size analysis.
• Scanning electron microscopy (SEM) for morphological observations.

Main Results:

• A wide range of grain sizes, from nanometric to micrometric, were achieved by varying calcination temperatures.
• A non-monotonic variation in lattice parameters with grain size was observed for all concentrations.
• Nanocrystalline Mg1-xNixO showed significant lattice expansion, while larger grains exhibited contraction.

Conclusions:

• Crystal grain size is a critical factor influencing the lattice parameters of Mg1-xNixO solid solutions.
• Surface stress and weakened ionic bonding in nanocrystalline particles are key mechanisms driving lattice expansion.
• This study provides a comprehensive understanding of lattice variations in the MgO-NiO system as a function of concentration and grain size.