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Development of high-performance flame detectors based on novel single crystal pmn-pt

The purpose of the project is to develop flame detectors with a much higher signal/noise-ratio by the application of novel magnesium-niobate-lead-titanate (pmn-pt) based single crystals instead of standard lithium tantalate (lt).

Modern infrared (IR) flame detectors are based on pyro-electric detectors that are equipped with narrowband IR filters. The filter characteristics are defined by the emission of specific infrared patterns from hot combustion gases like CO2 and CO, and pyro-electric detectors sense the infrared radiation reacting to the flame flicker in the frequency range of 5 to 20 Hz. To increase the detection range, false alarm immunity and to shorten the response time for rapid flame detection pyro-electric detectors with a higher Signal/Noise-Ratio (SNR) are necessary. PMN-PT-based ferroelectric single crystals (1-x) Pb(Mg1/3Nb2/3)O3-xPbTiO3 exhibit a range of extremely desirable physical properties, like a large piezoelectric coefficient. Until now PMN-PT have been used primarily in piezoelectric applications, for example precision actuators for HDD's (Hard Disk Drives), ultrasound devices, bio-sensors, optical communication devices, flat-panel speakers and vibrators for mobile handsets. Our previous studies have shown that PMN-PT can also exhibit an extremely high pyro-electric coefficient that is markedly superior to those of the conventional single crystals and ceramics. Prototypes of single crystal PMN-PT detectors excel by a doubled SNR compared with the conventional LT (Lithium Tantalate) based detectors. But the composition and crystal orientation for pyro-electric applications are different from those for piezoelectric applications. The objective of this proposal is not only to develop the technology to manufacture PMN-PT single crystals with extremely good pyro-electric properties, but also to design, manufacture and test prototypes of high performance, infrared flame detectors suited for harsh industrial environments. In order to satisfy the requirements of infrared flame detectors, it is necessary to establish an approach to control the variation, due mainly to segregation during crystal growth, of the pyro-electric coefficient and dielectric constant within a crystal boule and among the different crystal plates used for detector chips. In order to improve the integrated performance of PMN-PT single crystals, the influences of doping and solid-solution composition on the dielectric, pyro-electric and mechanical properties of such materials will be investigated. Based on these studies, the dielectric and pyro-electric properties of PMN-PT single crystals will be improved through adjusting the domain and phase structure for the composition range of 27%-29% PT, with a preferred crystal orientation of (111). A study will be carried out on the design of high performance pyro-electric detectors based on the characterisation of the dielectric, pyro-electric and mechanical properties of PMN-PT single crystals. The performance of a new generation of detectors will be investigated by optimising their device-structure, which are composed of pyro-electric chip, chip holder, wiring board and integrated preamplifier to achieve a better signal transduction performance. In addition to the study of signal to noise enhancement, the effects of temperatures in the range of -55 degrees C to +85 degrees Celsius on PMN-PT detectors will be studied based on the practical requirements of pyro-electric detectors for industrial use. Techniques related to grinding and polishing of the crystal, and enhancing the thermal resistance of the chip holder and the application of low-noise operational amplifiers will be investigated. The knowledge gained from the characterisation and evaluation of detector performance will enable us to develop high-performance pyro-electric detectors. GENERAL MONITORS will initially use the existing platform of lithium tantalite based flame detectors for a side by side comparison of the new PMN-PT pyro-electric detectors with lithium tantalite detectors from INFRATEC. The industry leader, FL4000 Multi-Spectral Flame Detector that uses neural network technology for identifying flame radiation from that generated by other IR radiating false alarm sources, will be used for laboratory blackbody measurements, hydrocarbon flame characterisation, and heat source and radiation discrimination (false alarm tests). Long range flame tests will be conducted, up to distances of 70 meters with open pans of burning gasoline and n-heptane, and the optical field of view (FOV) measured. The optical FOV is defined by the angle at which the maximum flame detection range is halved in each direction off-axis. Improvements in both detection distance and the optical FOV are expected with the superior PMN-PT detectors. Another important performance parameter for flame detectors is response time - a faster response time could result from the improved SNR of the PMN-PT detectors. Based on improvements in detection range, detection coverage (FOV), operating temperature and response time, a new generation of infrared flame detecting field devices could be designed to provide superior flame detection performance for industrial applications.
Acronym: 
FLAME
Project ID: 
5 421
Start date: 
01-04-2010
Project Duration: 
24months
Project costs: 
1 190 000.00€
Technological Area: 
Optical Technology related to measurements
Market Area: 
Oil and Gas Exploration and Production

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