Stabilized Yttrium Oxyfluoride Powder for Plasma Resistance
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Solution Overview
Problem
Yttrium oxyfluoride undergoes phase transitions between cubic and rhombohedral crystal structures with temperature changes, causing stress and potential fracture or cracking, especially in shaped forms like films or bulk materials.
Innovation Solution
Stabilization of yttrium oxyfluoride using calcium fluoride (CaF2) to suppress crystal phase transitions during heating and cooling, achieved through a powder mixture of CaF2, yttrium oxyfluoride (YOF), and yttrium oxide (Y2O3) fired in an inert atmosphere or vacuum at specific temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If yttrium oxyfluoride is used in shaped forms (film or bulk), then it can be applied in various applications, but phase transition during heating or cooling causes stress and fracture/cracking
Solution Approach 1:
The invention creates a composite material system consisting of yttrium oxyfluoride (YOF) and calcium fluoride (CaF2). The CaF2 acts as a stabilizing phase that suppresses the harmful phase transitions of YOF during thermal cycling, while maintaining the functional properties of YOF. This composite approach allows the material to retain application versatility while dramatically improving reliability by preventing fracture and cracking.
2Stability of the object's composition
If yttrium oxyfluoride undergoes phase transition during heating or cooling, then crystal structure changes occur, but this causes volumetric change and stress leading to fracture
Solution Approach 1:
The invention utilizes the phase transition properties of calcium fluoride (CaF2) to stabilize yttrium oxyfluoride. The CaF2 undergoes its own phase transitions at different temperatures, and these transitions are harnessed to counteract and suppress the harmful phase transitions of YOF. By controlling and utilizing phase transitions of the additive material, the invention prevents the unwanted crystal structure changes in YOF that would otherwise cause volumetric expansion and fracture.
3Reliability
If calcium fluoride is added to stabilize yttrium oxyfluoride, then phase transition is suppressed, but the material composition becomes more complex
Solution Approach 1:
The invention changes the compositional parameters of the yttrium oxyfluoride system by adding calcium fluoride in controlled amounts (5-50 wt%). This parameter change transforms the material from a single-phase system prone to harmful transitions to a two-phase composite system where the CaF2 stabilizes the YOF. The simplicity of this compositional adjustment—adding a single common ceramic material—makes the solution practically implementable despite the increased material complexity.
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
Prevents phase transition-induced fracture and cracking, ensuring durability and improved resistance to halogen-based plasma, suitable for semiconductor manufacturing and thermal spray applications.
Implementation Method 1
the use of calcium fluoride represented by CaF2 to stabilize yttrium oxyfluoride effectively suppresses crystal phase transition in the yttrium oxyfluoride in relation to temperature change
Implementation Method 2
firing, in an inert atmosphere or in a vacuum at a temperature from 800° C. to 1700° C., a molded product of a powder mixture including a calcium fluoride powder represented by CaF2 and an yttrium oxyfluoride powder represented by YOF
Data Source
AI summary
An yttrium oxyfluoride is represented by YOF and is stabilized by a fluoride represented by CaF2. Preferably, the number of moles of Ca with respect to 100 mol of yttrium is from 8 to 40 mol. A powder material is made of a first powder mixture including a calcium fluoride powder represented by CaF2 and an yttrium oxyfluoride powder represented by YOF, or a second powder mixture including a calcium fluoride powder represented by CaF2, an yttrium fluoride powder represented by YF3, and an yttrium oxide powder represented by Y2O3. A production method involves firing a molded product of the first or second powder mixture under predetermined conditions.