This book focuses on the scientific research work in the field of solid state physics which was carried out in the physics laboratory of Kakatiya University (where the author has been working as a researcher cum faculty member) from the period 2008 to 2013. This book gives total information regarding the X-ray study on thermal properties such as Debye temperature, Debye-Waller factor, amplitude of vibrations and vacancy formation energy while focusing on ball milled copper, nickel, iron and chromium metal nanopowders. The X-ray diffraction technique has been adopted to determine the above said thermal properties.