In this work, we provide an exhaustive analysis of the ferroelectric and thermal properties, as well as the phase diagrams of a nanoparticle with antiferroelectric core/ferroelectric shell described by the effective field theory. Our strategy relies on the use of the suitability core–shell structure, which allows tuning of interface at various scales. For this purpose, several physical quantities were systematically investigated including the longitudinal polarization, pyroelectric coefficient, internal energy, specific heat, and entropy. The influences of the core exchange interaction Jc/Js and transverse field Ω/Js on the aforementioned properties and phase diagrams are discussed in detail, which both have a considerable implications regarding the critical temperature (Tc), and could represent an important step towards better understanding of this aspect. Through a detailed analysis, the results indicate that Jc/Js affects substantially the physical quantities, however, the internal energy exhibits an inflection point in the vicinity of Tc. Interestingly, our results showed that a variation of Jc/Js and Ω/Js could lead to diverse results pertained to the critical behavior. The phase diagrams in the (Tc/Js,J1/Js),(Tc/Js,Ω/Js), and (Tc/Js,Ωc/Js) coordinates are constructed. Consequently, the increase of |Jc/Js| enlarges noticeably the magnitude of the ordered state. Besides, the increase of Ω/Js shrinks the ordered state and thus Tc. Our study implies the important role played by Jc/Js to appropriately controlling the transition temperature, which may provide a further insight into the effect ofJc/Js on the critical properties. Typical ferroelectric hysteresis behaviors were probed detailedly to confirm the order–disorder character. Our approach could provide a guidance to design ferroelectric nanomaterials while controlling the exchange couplings.