## 1 Introduction  
Piezoelectric materials are used in a large number of applications, such as energy harvesting in traffic areas, ultrasonic imaging, and fine monitoring of structures, among others [1; 2; 3]. The choice of an optimum piezoelectric material is essential to enhance the effectiveness of electromechanical systems. The most significant and often-used materials for piezoelectric devices are lead titanate-zirconate (PZT) piezoceramics because of their high piezoelectric d\({}_{33}\) and k\({}_{\text{p}}\) associated with the possibility of altering the characteristics of \"soft\" and \"hard\" piezoelectric responses, as well as the presence of a morphotropic phase boundary (MPB) [4; 5; 6]. Lead-free piezoelectric materials have gained much interest lately owing to the substantial danger that the compound's toxicity poses to both human health and the environment [7; 8; 9; 10; 11].  
The creation of novel, environmentally friendly piezoelectric materials has been the subject of several investigations in recent years [12; 13; 14; 15]. In this way, potassium sodium niobate (KNN)-based ceramics should have good piezoelectric, ferroelectric, and dielectric properties near the MPB temperature [12; 13; 14]. [PERSON] et al. revealed (K,Na)NbO\({}_{3}\)-LiTaO\({}_{3}\)-LiSbO\({}_{3}\) to have incredibly high piezoelectric characteristics [16; 17; 18; 19]. This investigation was carried out using simultaneous, intricate chemical substitutions (near the MPB of KNN) in the A-(Li) and B- (Ta and Sb) sites of the perovskite lattice. A solid-state process was used to create nano-powders with high sinterability and intriguing piezoelectric capabilities for a KNN-based ceramic that contains 4 mol% lithium, 10 mol% tantalum, and 4 mol% antimony [20]. When Li ions were incorporated in the A-site and niobium ions (B-site) were partially substituted by Sb or Ta ions, the lattice parameters were changed. Consequently, the structure distortion shifts to the MPB region at room temperature [12; 17; 18]. In KNL\(-\)NTS ceramics, sintering improves with the addition of Li, which also has a significant effect on the final stabilized phase. Additionally, according to many publications,antimony enhances electrical characteristics by increasing \(\rm T_{R-O}\) and decreasing \(\rm T_{O-T}\) as it approaches room temperature [19; 20]. Furthermore, some researchers investigated the optimal Na:K ratio, finding a nominal composition of [(Na\({}_{0.535}\)K\({}_{0.480}\))\({}_{0.942}\)Li\({}_{0.058}\)]NbO\({}_{3}\). Although the effect of Sb on the dielectric properties and the morphotropic phase edge have not been extensively studied, in this nominal composition the orthorhombic phases are distinguished from the tetragonal and the highest electrical coefficient, \(\rm d_{33}\), was obtained (\(\sim\)314 pC/N).  
The influence of Sb on (K\({}_{0.44}\)Na\({}_{0.52}\)Li\({}_{0.04}\))(Nb\({}_{0.9-x}\)Ta\({}_{0.1}\)Sb\({}_{x}\))O\({}_{3}\) [KNL\(-\)(N\({}_{0.9-x}\)TS\({}_{x}\))] ceramics synthesized using a traditional solid-state reaction technique is the central issue of this work. Experimental results were examined considering the influence of Sb on structure, microstructure, and ferroelectric and piezoelectric capabilities and revealed that Sb plays a key role in the functional characteristics of the piezoceramic under study. The Sb concentration used in this work was chosen based on the Saito composition and the studies of [PERSON] et al. [9; 21; 22], who observed that 0.04 mol % of Sb showed the best properties. Here, we want to elucidate if it is possible to reduce the Sb concentration in these KNL\(-\)NTS piezoceramics.