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Growth studies of YVO 4 crystals (II). Changes in YVO‐stoichiometry
Author(s) -
Erdei S.,
Johnson G. G.,
Ainger F. W.
Publication year - 1994
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170290610
Subject(s) - yttrium , stoichiometry , vanadium , electron microprobe , analytical chemistry (journal) , oxygen , materials science , phase diagram , solid solution , crystal (programming language) , oxide , ternary operation , crystal growth , inorganic chemistry , chemistry , phase (matter) , crystallography , mineralogy , metallurgy , organic chemistry , chromatography , computer science , programming language
Incongruent vanadium oxide vaporization of yttrium orthovanadate (YVO 4 ) melt generates changes in both oxygen and yttrium‐vanadium (YV) stoichiometry. Slightly modified YVO 4 or YVO 4 + Y 8 V 2 O 17 phases are formed from continuously changing melt systems depending on their starting compositions. The occurrence of Y 8 V 2 O 17 in yttrium orthovanadate crystal fibers grown by laser heated pedestal growth (LHPC) technique can be simply eliminated by utilization of suitable V 2 O 5 ‐excess starting compositions. In contrast, the oxygen‐deficient YVO 4– x black phase is an inherently oxygen deficient phase with limited solid solution in the YVO 4 YVO 3 subsystem of Y 2 O 3 V 2 O 5 V 2 O 3 complex ternary phase diagram close to the congruent YVO 4 composition (49.3 mol% V 2 O 5 –50.7 mol% Y 2 O 3 ). The greater oxygen deficiency YVO 4– x specimens have smaller lattice parameters as determined from detailed XRD data. Ceramic feed rod and fiber crystal grown from the feed rod with slight yttrium oxide excess starting composition were characterized by electron microprobe analysis. Changes in both YV and oxygen stoichiometry were observed along the fiber, due to double limited solid solution system of three dimensional ternary phase diagram. Consequently, both the presence of Y 8 V 2 O 17 phase and change of YV stoichiometry over oxygen deficiency cause difficulties for YVO 4 crystal growth from yttrium oxide excess melt.