Imperial College London
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ProfessorRogerWhatmore

Faculty of Engineering, Department of Materials

Visiting Professor
 
 
 
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Contact

 

r.whatmore

 
 
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Location

 

Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

343 results found

Whatmore RW, 2005, Uncooled pyroelectric detector arrays using ferroelectric ceramics and thin films, Pages: 121-129, ISSN: 0537-9989

Pyroelectric infra-red detectors have been of-interest for many years because of their wide wavelength response, good sensitivity and lack of need for cooling. They have achieved a wide market acceptance for such applications as people sensing, IR speetrometry (especially for environmental protection) and flame/fire protection. Arrays of such detectors, comprising a pyroelectric material interfaced to an application specific integrated circuit for signal amplification and read out, provide an attractive solution to the problem of collecting spatial information on the IR distribution in a scene. Pyroelectric arrays have the property that they are only sensitive to changes in the IR flux. This means that they are particularly-well suited to the monitoring of movements of people in applications such as retail outlets and in safety and healthcare applications. The applications of low cost arrays with limited (few hundred elements) for people sensing and imaging radiometry are illustrated. The performances and costs of uncooled pyroelectric arrays are ultimately driven by the materials used. For this reason, continuous improvements in materials technology are important. In the area of bulk ceramics, it is possible to obtain significant improvements in both production costs and performance though the use of tape-cast, functionally-gradient materials. The use of directly-deposited ferroelectric thin films on silicon ASIC's offers considerable potential for low cost high performance pyroelectric arrays. The challenges involved in developing such materials are discussed. Sol gel deposition provides an excellent technique for thin film growth and will be illustrated with an example of a Mn-doped PZT film that can be grown at 560°C with a FoM FD exceeding that of many bulk materials. The ability to grow such high-performance thin films onto silicon brings with it the ability to fabricate novel MEMS-based pyroelectric device structures. A new concept that is presented here

Conference paper

Sanson A, Whatmore RW, 2005, Phase diagram of the Bi<sub>4</sub>Ti<sub>3</sub>O<sub>12</sub>-BaTiO<sub>3</sub>-(Na<sub>1/2</sub>Bi<sub>1/2</sub>)TiO<sub>3</sub> system, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Vol: 88, Pages: 3147-3153, ISSN: 0002-7820

Journal article

Zhang Q, Corkovic S, Shaw CP, Huang Z, Whatmore RWet al., 2005, Effect of porosity on the ferroelectric properties of sol-gel prepared lead zirconate titanate thin films, THIN SOLID FILMS, Vol: 488, Pages: 258-264, ISSN: 0040-6090

Journal article

Sixsmith A, Johnson N, Whatmore R, 2005, Pyroelectric IR sensor arrays for fall detection in the older population, Meeting on Electro-Active Materials and Sustainable Growth, Publisher: EDP SCIENCES S A, Pages: 153-160, ISSN: 1155-4339

Conference paper

Munasinghe C, Heikenfeld J, Dorey R, Whatmore R, Bender JP, Wager JF, Steckl AJet al., 2005, High brightness ZnS and GaN electroluminescent devices using PZT thick dielectric layers, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol: 52, Pages: 194-203, ISSN: 0018-9383

Journal article

Wilson SA, Maistros GM, Whatmore RW, 2005, Structure modification of 0-3 piezoelectric ceramic/polymer composites through dielectrophoresis, Conference on Cluster on Dielectrics at Meso and Nano Scales, Publisher: IOP PUBLISHING LTD, Pages: 175-182, ISSN: 0022-3727

Conference paper

Marshall JM, Zhang Q, Huang Z, Whatmore RWet al., 2005, Orientation control of low temperature deposited sol-gel PZT52/48 films, 7th European Conference on Applications of Polar Dielectrics (ECAPD-7), Publisher: TAYLOR & FRANCIS LTD, Pages: 41-48, ISSN: 0015-0193

Conference paper

Chima-Okereke C, Reece MJ, Bushby AJ, Whatmore RW, Zhang Qet al., 2005, Nanoindentation of multilayer PZT/Pt/SiO<sub>2</sub> thin film systems on silicon wafers for MEMS applications., Symposium on Fundamentals of Nanoindentation and Nanotribology III held at the 2004 MRS Fall Meeting, Publisher: MATERIALS RESEARCH SOC, Pages: 351-356, ISSN: 0272-9172

Conference paper

Whatmore RW, 2005, Pyroelectric Ceramics and Thin Films: Characterization, Properties and Selection, POLAR OXIDES: PROPERTIES, CHARACTERIZATION, AND IMAGING, Editors: Waser, Bottger, Tiedke, Publisher: BLACKWELL SCIENCE PUBL, Pages: 221-240

Book chapter

Dorey RA, Whatmore RW, 2005, Pyroelectric PZT/PMNZTU composite thick films, 9th Electroceramics Congress, Publisher: ELSEVIER SCI LTD, Pages: 2379-2382, ISSN: 0955-2219

Conference paper

Whatmore RW, Landi S, Shaw CP, Kirby PBet al., 2005, Pyroelectric arrays using ceramics and thin films integrated radiation collectors: Design fabrication and testing, 7th European Conference on Applications of Polar Dielectrics (ECAPD-7), Publisher: TAYLOR & FRANCIS LTD, Pages: 11-22, ISSN: 0015-0193

Conference paper

Dunn S, Cullen D, Abad-Garcia E, Bertoni C, Carter R, Howorth D, Whatmore RWet al., 2004, Using the surface spontaneous depolarization field of ferroelectrics to direct the assembly of virus particles, APPLIED PHYSICS LETTERS, Vol: 85, Pages: 3537-3539, ISSN: 0003-6951

Journal article

Duval FFC, Dorey RA, Wright RW, Huang ZR, Whatmore RWet al., 2004, Fabrication and modeling of high-frequency PZT composite thick film membrane resonators, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, Vol: 51, Pages: 1255-1261, ISSN: 0885-3010

Journal article

Leinvuo JT, Wilson SA, Whatmore RW, 2004, Flextensional ultrasonic motor using the contour mode of a square piezoelectric plate, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, Vol: 51, Pages: 929-936, ISSN: 0885-3010

Journal article

Duval FFC, Dorey RA, Wright RW, Huang Z, Whatmore RWet al., 2004, Fabrication of PZT composite thick films for high frequency membrane resonators, International Conference on Electroceramics (ICE 2003), Publisher: SPRINGER, Pages: 267-270, ISSN: 1385-3449

Conference paper

Whatmore RW, 2004, Pyroelectric arrays: Ceramics and thin films, International Conference on Electroceramics (ICE 2003), Publisher: SPRINGER, Pages: 139-147, ISSN: 1385-3449

Conference paper

Navarro A, Whatmore RW, Alcock JR, 2004, Preparation of functionally graded PZT ceramics using tape casting, International Conference on Electroceramics (ICE 2003), Publisher: KLUWER ACADEMIC PUBL, Pages: 413-415, ISSN: 1385-3449

Conference paper

Zhang Q, Whatmore RW, 2004, Low fatigue lead zirconate titanate-based capacitors modified by manganese for nonvolatile memories, Symposium on Functional Metal Oxides - Semiconductor Structures held at the E-MRS 2003 Meeting, Publisher: ELSEVIER SCIENCE SA, Pages: 136-140, ISSN: 0921-5107

Conference paper

Southin JEA, Whatmore RW, 2004, Finite element modelling of nanostructured piezoelectric resonators (NAPIERs)., IEEE Trans Ultrason Ferroelectr Freq Control, Vol: 51, Pages: 654-662, ISSN: 0885-3010

A new modification to the traditional piezoelectric thin film bulk acoustic wave resonator (FBAR) and solidly mounted acoustic wave resonator (SMR) is proven to significantly improve their performances. The proposed design involves the surface micro/nano structuring of planar piezoelectric thin films to realize an array of a large number of rod-like structures. In contrast to the plate-like thickness extensional resonance in traditional FBAR and SMR devices, the rod-like structures can be excited in their length extensional resonance, yielding a higher electromechanical coupling factor and effectively eliminating the spurious resonances from lateral modes of vibration. The designs have been investigated by two and three-dimensional finite element analyses and one-dimensional transmissionline modelling. The results show that significant increases in the electromechanical coupling factor of ca. 40% can be achieved by using the rod-like length extensional resonances as compared with the plate-like thickness extensional resonances in traditional devices. Simulations show that rod width-to-thickness aspect ratios of less than 0.5 could result in an electromechanical coupling factor (k2eff) of over 10% for a zinc oxide device, compared with approximately 7% for a conventional design.

Journal article

Dorey RA, Whatmore RW, 2004, Pyroelectric properties of PZT/PMNZTU composite thick films, JOURNAL OF ELECTROCERAMICS, Vol: 12, Pages: 191-196, ISSN: 1385-3449

Journal article

Dorey RA, Whatmore RW, 2004, Electroceramic thick film fabrication for MEMS, JOURNAL OF ELECTROCERAMICS, Vol: 12, Pages: 19-32, ISSN: 1385-3449

Journal article

Zhang Q, Whatmore RR, 2004, Hysteretic properties of Mn-doped Pb(Zr,Ti)O<inf>3</inf> thin films, Journal of the European Ceramic Society, Vol: 24, Pages: 277-282, ISSN: 0955-2219

Pb(Zr,Ti)O3 (PZT 30/70) and Mn-doped Pb(Zr,Ti)O3 (PMZT 30/70) thin films have been fabricated on Pt/Ti/SiO2/Si substrates by a chemical solution deposition technique. The experiments found that the addition of Mn in PZT thin films greatly improves the ferroelectric properties of thin films. It is demonstrated that the Mn-doped (1 mol%) PZT showed fatigue-free characteristics at least up to 1010 switching bipolar pulse cycles under 10 V and excellent retention properties. The Mn-doped PZT thin films also exhibited well-defined hysteresis loops with a remnant polarization (Pr) of 34 μC/cm2 and a coercive field (Ec) of 100 kV/cm for the thickness of 300 nm. Dielectric constant and loss (tanδ) for Mn doped PZT thin films are 214 and 0.008, respectively. These figures compare well with or exceed the values reported previously. In this paper, the mechanism by which Mn influences on the ferroelectric properties of PZT thin films has also been discussed. © 2003 Elsevier Ltd. All rights reserved.

Journal article

Marshall JM, Dunn S, Whatmore RW, 2004, FIB milled PZT nanocapacitors tested using PFM, 10th European Meeting on Ferroelectricity, Publisher: TAYLOR & FRANCIS LTD, Pages: 223-230, ISSN: 1058-4587

Conference paper

Duval FFC, Dorey RA, Wright RW, Huang Z, Whatmore RWet al., 2004, High frequency PZT composite thick film resonators, 10th European Meeting on Ferroelectricity, Publisher: TAYLOR & FRANCIS LTD, Pages: 27-33, ISSN: 1058-4587

Conference paper

Sanson A, Whatmore RW, 2004, Influence of MgO on the structural and electrical properties of Bi<sub>4</sub>Ti<sub>3</sub>O<sub>12</sub>, 10th European Meeting on Ferroelectricity, Publisher: TAYLOR & FRANCIS LTD, Pages: 193-197, ISSN: 1058-4587

Conference paper

Battat J, Huang Z, Donohue PP, Todd MA, Whatmore RWet al., 2004, Kinetics of phase transformations in lead scandium tantalate thin films, 10th European Meeting on Ferroelectricity, Publisher: TAYLOR & FRANCIS LTD, Pages: 87-94, ISSN: 1058-4587

Conference paper

Leinvuo JT, Wilson SA, Almond HJA, Whatmore RWet al., 2004, Experimental design and construction of a flextensional ultrasonic piezoelectric micro-motor, 10th European Meeting on Ferroelectricity, Publisher: TAYLOR & FRANCIS LTD, Pages: 165-169, ISSN: 1058-4587

Conference paper

Marson S, Dorey RA, Zhang Q, Whatmore RW, Hardy A, Mullens Jet al., 2004, Direct patterning of photosensitive chemical solution deposition PZT layers, 8th International Conference on Electronic Ceramics and Their Applications (ELECTROCERAMICS VIII), Publisher: ELSEVIER SCI LTD, Pages: 1925-1928, ISSN: 0955-2219

Conference paper

Mortara L, Navarro A, Whatmore RW, Alcock JRet al., 2004, Steps towards ceramic process scale-up: analysis of a laboratory process, 8th International Conference on Electronic Ceramics and Their Applications (ELECTROCERAMICS VIII), Publisher: ELSEVIER SCI LTD, Pages: 1117-1120, ISSN: 0955-2219

Conference paper

Dorey RA, Whatmore RW, 2004, Electrical properties of high density PZT and PMN-PT/PZT thick films produced using ComFi technology, 8th International Conference on Electronic Ceramics and Their Applications (ELECTROCERAMICS VIII), Publisher: ELSEVIER SCI LTD, Pages: 1091-1094, ISSN: 0955-2219

Conference paper

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