A quantity measuring the ability of a substance to store electrical energy in an electric field is dielectric constant. it is gain of energy. 

Dielectric loss is the dissipation of energy through the movement of charges in an alternating electromagnetic field as polarization switches direction. it is loss of energy.

Hi Faseeh ur Raheem. If there is a increase in the dielectric constant of composition as we changes x=0 to x=1.Does it means that its dielectric loss should decrease as we move from x=0 to x=1.