The new techniques of fine particle synthesis are shown to lead to better ceramic materials such as yttrium iron garnet (YIG) and ferroelectric lead zirconate titanate (PZT). The densities are greater than 99% of the theoretical density and the grain size can be easily controlled from 2 microns upwards. For YIG this means higher values of the nonlinear spin-wave excitation thresholdh_c. For PZT the result is higher values of the tensor componentd₃₃ and poling voltage. It is also shown that the fine particle systems and the fine-grain microstructure lead to interesting physics results. For PZT the lowering of the peak dielectric constant, the increasing transition temperatures and the decreasing values ofd₃₃ with decreasing grain size can be understood in terms of the changing low-frequency cut-off of the soft lattice vibration mode. Another interesting result is that for 2000 Å size particles of α-Fe₂O₃ the anisotropy constant is found to be 1·38 × 10² ergs/cm³ from Mössbauer measurements.

Properties of materials exhibiting cooperative phenomena are likely to be modified on restricting the lattice size. Several such microcrystalline materials have been studied to infer general underlying principles. Ferroelectricity, ferromagnetism, superconductivity, and superfluidity in limited lattice sometimes not only show modified behaviour but also new behaviour not present in bulk. Microcrystals are considered to be free, coupled, grain-boundary-separated, or domain-wall-separated.

Microparticles and micrograin ceramics show features distinct from the usual-sized polycrystalline materials. Amorphous state material combined with microparticle size for Pb(Zr_0.51 Ti_0.49)O₃ mimics the dielectric behaviour of crystalline ferroelectricity in ABO₃ compounds. Fine-grained Y₃Fe₅O₁₂ (yig) synthesized by pressure sintering ofyig microparticles exhibit spinwave relaxation due to transit time across grain diameter. Applying microemulsion techniques for microparticle synthesis,γ-Fe₂O₃ has been synthesized. The phase stability fractionγ-Fe₂O₃/α-Fe₂O₃ is found to be a function of particle size. At very small sizesγ-Fe₂O₃ becomes amorphous, leading to interesting Mössbauer studies.