THE CRYSTAL-STRUCTURE AND TWINNING OF NEODYMIUM GALLIUM PEROVSKITE SINGLE-CRYSTALS

By means of x-ray structure analysis, the crystal structure of neodymi um gallium perovskite (NGP) single crystals (NdGaO3) being used as a s ubstrate for HTSC film epitaxy has been refined and the position of at oms has been determined. The possibility of YBa2Cu3O7-x film epitaxy o n the plane {110} Of NGP Crystal as well as its advantages and pitfall s are analysed from structural data. The twinning types in the NGP cry stal were established. The twinning structure Of NGP substrates is fou nd to be stable up to a temperature of 1173 K, as differentiated from the LaGaO3 and LaAlO3 substrates. It is intimated that the twinning in the NGP substrates oriented as {001} can result in creation of 90-deg rees twin bonds in a film, and in the case of {110}-oriented plates it is possible to ignore the twinning presence in substrate completely.