  Self-resonance in the atomic vibration occurs when the average wavelength of
the phonon thermal vibration is equivalent or harmonic of the diameters of the
atoms. It is suggested that applying pressure at temperature corresponding to
the self-resonance should effectively reduce the number of vacancies. This
theoretical prediction is tested on Niobium by measuring the magnetic
susceptibility of the untreated and treated samples. The applied
pressure-temperature treatment increased the critical temperature of Niobium by
about 30 percent which was also accompanied with volume increase.
