Controllable preparation method of orthorhombic-phase rhombohedral-phase sodium niobate having high Curie point

The invention belongs to the field of preparing inorganic functional materials, in particular relates to a preparing process for controlled systemization of rhombohedral phase sodium niobate powders and orthorhombic sodium niobate powders in the micro-growing environment which is adjusted by dentate organic amine under hydrothermal condition. The method comprises steps of employing the most common niobium pentoxide and sodium hydroxide as raw materials, adjusting the mole ratio of the niobium pentoxide to the sodium hydroxide and systemizing the rhombohedral phase sodium niobate and the orthorhombic sodium niobate in hydrothermal reaction system of adding the organic amine. The method has the advantages that the process is simple and convenient in operation and low in preparing cost, the prepared products are uniform in morphology and good in dispersity. The prepared rhombohedral phase sodium niobate is better in thermal stability, higher in Curie temperature and sound in ferroelectric property, which can be