**4. Conclusions**

In the present work the SAW propagation properties of TeO3/BeO/128◦ YX LiNbO<sup>3</sup> multi-layered SAW structure have been investigated theoretically. The optimized thickness values of TeO<sup>3</sup> and BeO thin films are obtained. It is established that with the integration of (0.026 λ) TeO<sup>3</sup> and (0.08 λ) BeO layer on 128◦ YX LiNbO<sup>3</sup> single crystal, an efficient, temperature stable, high velocity (∼4266 ms−<sup>1</sup> ) multi-layered SAW structure can be made. Because the proposed device is based upon sturdy wurtzite BeO layer, it can work efficiently in the severe environment conditions. The proposed temperature stable SAW structure can be conceived effortlessly for possible applications in both high, as well as low, frequency regions.

**Author Contributions:** Conceptualization, N.D.S.; Formal analysis, N.D.S.; Investigation, N.D.S.; Methodology, N.D.S.; Software, J.B.; Writing—original draft, N.D.S.; Writing—review & editing, J.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
