ИСТИНА

The ZnO-based materials are attractive for the fabrication of optoelectronic devices operating in the blue and ultraviolet spectral regions. The high-pressure rock salt polymorph of ZnO (rs-ZnO) is of particular interest because of the wider opportunities for bandgap engineering as compared to the low-pressure wurtzite phase. However, rs-ZnO could not be quenched down to ambient pressure to the beginning of this work. The main objective of the work was to synthesize various rs ZnO-based phases at high pressure (up to 7.7 GPa) and high temperature (up to 2000 K) and then recover them at ambient conditions. Three different chemical routes to the rs-ZnO stabilization at ambient conditions have been developed i.e. by preparing nanostructured rs-ZnO phase [1]; by the use of isostructural MgO or NaCl matrix [2,3]; and by alloying ZnO with the rs-MeIIO (MeII – Mg2+, Ni2+, Fe2+, Co2+, Mn2+) [4,5] and LiMeIIIO2 (MeIII – Sc3+, Ti3+, Fe3+, In3+) oxides [6]. Thus, a number of materials with advanced electronic and optical properties has been synthesized; and their structural, thermodynamic, luminescent, magnetic and transport properties have been studied. The data obtained shed light on the factors responsible for formation of rs-ZnO under pressure and its recovery down to ambient conditions, which will help to develop the principles of producing new advanced ZnO-based materials. Finally, it has been shown that the synthesized rs-ZnO materials are the materials of choice for the advanced optoelectronic applications. The use of high pressure and high temperature is the key factor for the formation of such materials with high (up to 0.8 mol. fr.) ZnO content.