Structural evolution and dopant occupancy preference of yttrium-doped potassium sodium niobate thin films

Mohd Hatta, Maziati Akmal and Abd Rashid, Mohd Warikh M. and Azlan, Umar Al Amani and Azam, Mohd Asyadi and Anand, T. Joseph Sahaya and Moriga, Toshihiro (2016) Structural evolution and dopant occupancy preference of yttrium-doped potassium sodium niobate thin films. Journal of Electroceramics, 37 (1-4). pp. 50-57. ISSN 1385-3449 E-ISSN 1573-8663

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Abstract

Sodium potassium niobate (KNN) is the most promising candidate for lead-free piezoelectric material, owing to its high Curie temperature and piezoelectric coefficients among the non-lead piezoelectric. Numerous studies have been carried out to enhance piezoelectric properties of KNN through composition design. This research studied the effects of yttrium concentrations and lattice site occupancy preference in KNN films. For this research, the yttrium-doped KNN thin films (mol% = 0, 0.1, 0.3, 0.5, 0.7 and 0.9) were fabricated using the sol-gel spin coating technique and had revealed the orthorhombic perovskite structures. Based on the replacement of Y3+ ions for K+/ Na+ ions, it was found that the films doped with 0.1 to 0.5 mol% of yttrium had less lattice strain, while films with more than 0.5 mol% of Y3+ ions had increased strain due to the tendency of Y3+ to occupy the B-site in the perovskite lattice. Furthermore, by analysing the vibrational attributes of octahedron bonding, the dopant occupancy at A-site and B-site lattices could be identified. O-Nb-O bonding was asymmetric and became distorted due to the B-site occupancy of yttrium dopants at high dopant concentrations of >0.5 mol%. Extra conduction electrons had resulted in better resistivity of 2.153× 106 Ω at 0.5 mol%, while higher resistivity was recorded for films prepared with higher concentration of more than 0.5 mol%. The introduction of Y3+ improved the grain distribution of KNN structure. Further investigations indicated that yttrium enhances the surface smoothness of the films. However, at high concentrations (0.9 mol%), the yttrium increases the roughness of the surface. Within the studied range of Y3+ , the film with 0.5 mol% Y3+ represented a relatively desirable improvement in dielectric loss, tan δ and quality factor, Qm.

Item Type:	Article (Journal)
Additional Information:	8252/67745
Uncontrolled Keywords:	KNN . Yttrium . Thin film . Doped . Structural . Lattice . Occupancy
Subjects:	Q Science > Q Science (General)
Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button):	Kulliyyah of Engineering Kulliyyah of Engineering > Department of Mechanical Engineering
Depositing User:	Dr Maziati Akmal
Date Deposited:	24 May 2019 08:59
Last Modified:	24 May 2019 08:59
URI:	http://irep.iium.edu.my/id/eprint/67745

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