Permanently Polarized Hydroxyapatite via DC-Field Sintering
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Solution Overview
Problem
Current methods for obtaining permanently polarized hydroxyapatite fail to achieve stable polarization at room temperature, leading to limited applications in biomedical and electrochemical processes due to thermal phase transitions and short-lived polarization effects.
Innovation Solution
A process involving sintering hydroxyapatite at 700-1200°C under a constant DC voltage of 250-2500V or equivalent electric field, followed by cooling while maintaining the electric field, results in a permanently polarized hydroxyapatite with enhanced crystallinity and electrochemical activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydroxyapatite is polarized at high temperature (above 1000°C) or high electric field (above 100,000 V/cm), then polarization effect is achieved, but energy is not stored and polarization is not permanent
Solution Approach 1:
The patent changes the temperature parameter to a specific range (900-1200°C) and electric field parameter (250-2500V) to achieve optimal polarization. By optimizing these parameters within specific ranges rather than using extreme values, the patent achieves both permanent polarization and energy storage capability, resolving the contradiction between polarization stability and energy storage
Solution Approach 2:
The patent applies electric field during the sintering process itself (before final cooling) to induce permanent polarization. This preliminary application of electric field during the phase transition period creates stable polarized centers that persist after cooling, achieving both permanent polarization and energy storage without requiring subsequent high-field treatment
2Manufacturing precision
If hydroxyapatite is sintered at high temperature (1200-1250°C), then crystallinity is improved, but polarization becomes unstable at room temperature
Solution Approach 1:
The patent applies electric field during the sintering process itself (before final cooling) to induce permanent polarization. This preliminary application of electric field during the phase transition period creates stable polarized centers that persist after cooling, achieving both permanent polarization and energy storage without requiring subsequent high-field treatment
Solution Approach 2:
The patent optimizes the sintering temperature to a specific range (900-1200°C) and applies electric field within specific parameters (250-2500V) to achieve optimal polarization. By optimizing these parameters within specific ranges rather than using extreme values, the patent achieves both permanent polarization and energy storage capability
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
The process achieves a high degree of crystallinity and prolonged electrochemical activity, enabling stable and efficient use in biomedical applications and electrochemical processes, such as drug delivery and tissue regeneration.
Implementation Method 1
the polarization was consequence of the electrical dipoles associated to the formation of defects inside crystal grains and of the space charge polarization originated in the grain boundaries
Implementation Method 2
applying a constant or variable DC voltage between 250 V and 2500 V or an equivalent electric field between 1.49 kV/cm and 15 kV/cm
Implementation Method 3
The monoclinic cHAp changes to hexagonal phase at about 210° C., which means a change from an ordered to a disordered distribution of OH− ions along the c-axis
Implementation Method 4
heating the samples obtained in (a) at a temperature between 900° C. and 1200° C.
Data Source
AI summary
The present invention relates to a permanently polarized hydroxyapatite and a composition or material comprising thereof. The present invention further relates to a process for obtaining a permanently polarized hydroxyapatite and to different uses of the permanently polarized hydroxyapatite or the composition or material comprising thereof.