Theoretical investigation of ferroelectric and dielectric properties of Rochelle salt colemanite type crystals

Abstract

Studies of Rochelle salt crystals such as colemanite (Ca₂B₆O₁₁.5H₂O), which exhibits ferroelectricity below −7 °C, are performed using a modified two-sublattice pseudospin model Hamiltonian. This Hamiltonian model includes terms for phonon anharmonic interactions up to the fourth order. Using this and the dual thermal Green’s function, formulations for ferroelectric mode frequencies, permittivity, and loss tangent for colemanite crystals were derived. The model values were fitted to the derivation to obtain the above quantities of thermal variation. The theoretical variations in these quantities were compared with the experimental variations reported by Gavrilova et al. reported to be in good agreement.

KEYWORDS:

• Green function
• decoupling
• tan $\left(\delta \right)$
• permittivity
• response function

Acknowledgment

The authors are thankful Prof. S. C. Bhatt, Prof. P. D. Semalty, Prof. Mahavir Singh (Shimla), Prof. L. P. Purohit (Haridwar), Prof. R. K. Shukla (Lucknow), Prof. N. S. Negi (Shimla), and Dr. Vinay Kumar (JIC, Saudi Arabia) for their kind encouragement, Mr. Aman Sharma, Maharaj Singh College, Saharanpur, Mr. Nitin Bahuguna, and Ms. Riya Upadhyay (Research Scholar) for help.

Disclosure statement

No potential conflict of interest was reported by the authors.