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The purpose of this study was to investigate the influence of doping ions Mg²⁺, Zn²⁺, Al³⁺ to the structure of hydroxyapatite (HAP; Ca₁₀(PO₄)₆(OH)₂) and subsequently to evaluate their adaptation in structure and their anticorrosive properties.

The substituted hydroxyapatite was synthesized by precipitation method that included the addition of Mg²+, Zn²⁺ and Al³⁺ containing precursors to partially replace Ca²⁺ ions in the hydroxyapatite structure. For precipitation synthesis, three ratios of Ca/P = 1; 1.67; 3 and two values of pH = 7 and 12 were selected. Samples 1 (Ca/P = 1; pH = 7), 2 (Ca/P = 1.67; pH = 7), 3 (Ca/P = 3; pH = 7) and 5 (Ca/P = 1.67; pH = 12) were chosen to monitor the influence of doping ions Mg²⁺, Zn²⁺ and Al³⁺ to the structure of hydroxyapatite and its anticorrosive properties.

The chosen synthesis conditions are appropriate for the formation of crystalline HAP substituted by elements Mg, Zn and Al. Only for one sample (1-Mg), two different phases (hydroxyapatite and whitlockite) were identified in the phase composition. On the basis of preliminary corrosion tests, pigments were divided into three groups pursuant to their anticorrosion effectivity: pigments with high corrosion-inhibition efficiency; pigments without anticorrosive properties; and pigments that promote corrosion processes.

In addition, no doping effect can be observed except for the sample 1-Mg, which consists of two phases (hydroxyapatite and whitlockite). Preliminary corrosion tests prove that some samples of HAP have extremely high anticorrosive effectivity as effectivity of the commercial pigments. The accelerated corrosion test showed that HAP samples have insufficient corrosion-inhibition properties for coating applications compared with the commercial pigment.

The percentage of tourism revenues from the national income decreased during the period (2000: 2020) which necessitates diversification in tourism activity and tourism revenues through agricultural tourism as one of the types of tourism activities. On other hand, Al-Ahsa governorate is the largest governorate in Saudi Arabia, covering an area of about 2,500 square kilometers. Moreover, it includes an oasis that is the largest irrigated agricultural oases in the world. It is distinguished by its strategic geographical location, in addition to being one of the most famous palm oasis in the world. Although Al-Ahsa governorate has many ingredients for agricultural tourism; the number of farms approved in the Aryaf program reached about 101 farms at the level of Al-Ahsa with a rate that not exceed about 0.5% of farms in 2018 of the total farms. That means it still Agricultural tourism has not received sufficient attention from investors and farm owners.

The study targeted planning for agricultural tourism activities in Al-Ahsa Governorate using a long-term sustainable approach to achieve sustainable development and diversification of sources income in agriculture sector. The study depended on the sample size was determined from Al-Ahsa farms in light of the fact that the number of farm owners in Al-Ahsa. In addition the study relied on the use of descriptive and quantitative statistical analysis through the use of percentages, chi-square test and Likert's triple test.

The results of the study strategic plans of farms in Al-Ahsa points to the importance of enhancing agricultural tourism services in Al-Ahsa, including health, environmental, recreational and food services, which may have an impact on increasing the economic return of farms in a better way in order to gain competitive advantage by focusing on developing the farms themselves in line with the Aryaf program of the Ministry of Tourism in the Kingdom to ensure safe and sustainable growth of revenues Economic.

This study is concerned with Agricultural Tourism. The study is helpful in policy formation to target sustainable development and diversification of sources income in Saudi Arabia. The authors whose names are listed immediately below certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.