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Formation of Lead Magnesium Niobate Perovskite from Niobate Precursors Having Varying Magnesium Content
Author(s) -
Joy Pattayil Alias,
Sreedhar Krishnan
Publication year - 1997
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1997.tb02896.x
Subject(s) - columbite , stoichiometry , pyrochlore , magnesium , perovskite (structure) , materials science , inorganic chemistry , phase (matter) , mineralogy , chemistry , crystallography , metallurgy , organic chemistry
Formation of lead magnesium niobate (PMN) perovskite phase using a columbite type of precursor together with the addition of excess MgO has been investigated. When MgO and Nb 2 O 5 are reacted with 1:1 stoichiometry, a minor amount (}2%) of Mg 4 Nb 2 O 9 is formed along with the columbite‐type phase which in turn could lead to the formation of a minor amount of “free Nb 2 O 5 ” in the precursor. This may be the reason for the formation of small amounts of pyrochlore phase during the synthesis of PMN perovskite from the stoichiometric 1:1 precursor. However, it has been found that the perovskite phase can easily be stabilized by the addition of a large excess of MgO in the precursor, although this leads to additional Mg‐Nb‐O phase Mg 4 Nb 2 O 9 , besides the columbite‐type phase MgNb 2 O 6 . It has been shown that, after this precursor reacts with PbO to form the PMN perovskite, the excess Mg present in the Mg‐rich niobate precursor separates out as MgO, as evidenced by X‐ray diffraction, which can be removed by leaching with dilute nitric acid, thus forming pure PMN.