Relaxor ferroelectric compounds Sr(B1/3Nb2/3)O3, where (B Mg 2+ , Co 2+ , Cu 2+), synthesized by standard solid state reaction technique, exhibit strong correlation between structure, dielectric and transport behavior. The structure changes from highly distorted monoclinic structure in Mg 2+ and Co 2+ substituted samples to partially distorted Tetragonal structure in Cu substituted samples. In Cu 2+ based system significant Jahn-Teller distortion induced enhancements in dielectric properties

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... e also been observed. Further, weak Jahn-Teller distortion due to unevenly occupied t2g levels in Co 2+ produces intermediate rise in ε' as well as inbuilt flexibility to conduction electron movement enhances dielectric loss (tan δ). On the other hand, strong Jahn-Teller effects in Cu 2+ substituted compound, due to unevenly occupied eg levels, results in large enhancement in ε' and frequency exponent 's' (500 at 300 K temperature & at 10 KHz frequency). The UV-Vis studies give the wide energy band gap semi conducting values {Eg ≥ 3.00 eV}. The improved physical properties of Sr(Cu1/3Nb2/3)O3 compound makes it suitable for energy storage devices as well as microwave device applications at wide frequency range.