Oriented Apatite Oxide Ion Conductor Composition
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Solution Overview
Problem
Conventional oriented apatite-type oxide ion conductors face challenges in achieving high oxide ion conductivity due to difficulties in controlling the composition and excessive introduction of element M, leading to decreased conductivity.
Innovation Solution
The development of an oriented apatite-type oxide ion conductor with a specific composition formula A 9.33+x [T 6.00-y M y ]O 26.0+z, where A represents lanthanoids or alkaline earth metals, T includes Si or Ge, and M is selected from B, Zn, Sn, and Mo, with controlled x, y, and z values to enhance conductivity, produced through a method involving a gas phase-solid phase diffusion step and annealing to achieve high orientation and reduced M content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the amount of element M is increased to obtain oriented apatite-type oxide ion conductor, then the crystal structure is formed, but the oxide ion conductivity decreases
Solution Approach 1:
The invention optimizes the compositional parameters by precisely controlling the amount of element M to be 0.40 ≤ y < 1.00 in the formula A9.33+x[T6.00-yMy]O26.00+z, and controlling stoichiometric deviations x and z within specific ranges. This parameter optimization ensures sufficient M content for apatite structure formation while preventing excessive M content that would harm oxide ion conductivity, thus resolving the contradiction between structure stability and conductivity.
2Stability of the object's composition
If conventional gas phase method is used to introduce element M, then oriented apatite-type structure is obtained, but excessive M content is introduced
Solution Approach 1:
The invention performs preliminary action by first forming the oriented apatite-type crystal structure with controlled M content during the gas phase heating process, then subsequently performing annealing treatment. This two-step approach allows precise control of M content introduction in the first step, and further optimization through annealing in the second step, preventing excessive M content while ensuring proper structure formation.
Solution Approach 2:
The invention implements feedback control by using annealing treatment as a secondary step to adjust and optimize the M content and crystal structure after the initial gas phase formation. The annealing process provides feedback adjustment to the composition and structure, ensuring that M content remains within the optimal range (0.40 ≤ y < 1.00) and correcting any deviations from the desired stoichiometry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in an oxide ion conductor with improved conductivity, measured as 10^-4 S/cm or greater at 500°C, and a transference number of 0.8 or greater, with a Lotgering degree of orientation of 0.60 or greater, effectively addressing the limitations of previous technologies.
Implementation Method 1
a step of converting a precursor expressed as A 2.00+x TO 5.00+z into an oriented apatite-type crystal structure by heating the precursor in a gas phase containing an element M, where M represents one or two or more elements selected from the group consisting of B, Zn, Sn, W, and Mo, and thereby reacting the element M with the precursor
Implementation Method 2
an annealing step
Data Source
AI summary
An oriented apatite-type oxide ion conductor of the present invention includes a composite oxide expressed as A9.33+x[T6.00-yMy]O26.0+z, where A represents one or two or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Be, Mg, Ca, Sr, and Ba, T represents an element including Si or Ge or both, and M represents one or two or more elements selected from the group consisting of B, Ge, Zn, Sn, W, and Mo, and where x is from -1.00 to 1.00, y is from 0.40 to less than 1.00, and z is from -3.00 to 2.00.