It entirely depends on what specific applications are focused on, and which frequency regime is associated. Generally, along with dielectric constant, other parameters such as breakdown strength, field dependence of dielectric constant, frequency dispersions of dielectric parameters need to be monitored altogether.

Generally for capacitor-based energy storage applications, dielectric constant of the order 103 is very satisfactory. But, sometimes a number of materials are admired even having dielectric constants of the order 50-500, provided the other parameters e.g., resistance, quality factor. dielectric loss, phase-shift and attenuation, capacitance, susceptance, dependence on frequency, dc field and temperature are suitable for particular applications.

Dear Babaji Ghule,

I agree with the excellent answer mentioned by Souvik Bhattacharjee.

He discussed the most parameters that affect the dielectric constant.

Best Wishes

Abdu Saeed and Souvik Bhattacharjee

Thank you for valuable guidance!

Puli, Venkata Sreenivas, Dhiren K. Pradhan, Douglas B. Chrisey, M. Tomozawa, G. L. Sharma, J. F. Scott, and Ram S. Katiyar. "Structure, dielectric, ferroelectric, and energy density properties of (1− x) BZT–xBCT ceramic capacitors for energy storage applications." Journal of Materials Science 48, no. 5 (2013): 2151-2157.

I agreed with Abdu Saeed and Souvik Bhattacharjee point of views. The dielectric constant value can help to reduce the dimension of electronic capacitor and maintain the performance.

@Dr Azeez Barzinjy and @Chian Heng Lee, thanks for your valuable guidance.