Imperial College London
Alternate

ProfessorNeilAlford

Faculty of Engineering, Department of Materials

Professor of Materials
 
 
 
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Contact

 

+44 (0)20 7594 6724n.alford

 
 
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Assistant

 

Ms Karen Murphy +44 (0)20 7594 3330

 
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Location

 

2..05 (in RSM)Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

441 results found

Aupi X, Breeze J, Ljepojevic N, Dunne LJ, Malde N, Axelsson AK, Alford NMet al., 2004, Microwave dielectric loss in oxides: Theory and experiment, JOURNAL OF APPLIED PHYSICS, Vol: 95, Pages: 2639-2645, ISSN: 0021-8979

Journal article

Pullar RC, Vaughan C, Alford NM, 2004, The effects of sintering aids upon dielectric microwave properties of columbite niobates, M<SUP>2+</SUP>Nb<sub>2</sub>O<sub>6</sub>, Conference on Dielectrics for Emerging Technologies held at the IOP Physics Congress, Publisher: IOP PUBLISHING LTD, Pages: 348-352, ISSN: 0022-3727

Conference paper

Pullar RC, Vaughan C, Alford NMN, 2004, Effect of sintering aids upon dielectric microwave properties of ZnNb <inf>2</inf>O<inf>6</inf>, CoNb<inf>2</inf>O<inf>6</inf>, MgNb<inf>2</inf>O <inf>6</inf> and CaNb<inf>2</inf>O<inf>6</inf> columbite niobates, Pages: 1157-1160, ISSN: 1013-9826

Of the columbite niobate ceramics with the formula M2+Nb 2O6, several compounds (M2+ = Zn, Mg, Ca and Co) display dielectric losses at microwave (1-10 GHz) frequencies resulting in Qf values between 40,000 and 90,000 GHz, making them suitable materials for use in dielectric resonator applications. However, their temperature coefficient of resonant frequency (τf) values were high, at between -50 to -90 ppm, and the optimum sintering temperatures were found to be 1150°C, 1200°C, 1300°C and 1350°C for M = Co, Zn, Mg and Ca respectively. Doping with relatively large amounts of TiO2 and CaTiO3 was found to reduce τf in most cases, but with a large increase in dielectric losses (decrease in Q). This paper details the doping of these ceramics with sintering aids (<2 wt%) such as V2O5 and CuO, in an attempt to reduce the sintering temperature. It was found that in many cases the dopants also had an extremely beneficial effect upon microwave properties, decreasing τf considerably and substantially increasing the quality factor (Q).

Conference paper

Seabra MP, Avdeev M, Ferreira VM, Pullar RC, Alford NMN, Reaney IMet al., 2004, Structure-property relations in xBaTiO<inf>3</inf>-(1-x)La(Mg<inf>1/2</inf>Ti<inf>1/2</inf>)O<inf>3</inf> solid solutions, Journal of the American Ceramic Society, Vol: 87, Pages: 584-590, ISSN: 0002-7820

The microwave dielectric properties and microstructures of compounds in the solid solution series xBaTiO3-(1-x)La(Mg1/2-Ti1/2)O3 (BTLMT) have been investigated. The structural phase transitions that occur as a function of x have been studied and are related to changes in the dielectric properties. For compounds where x ≤ 0.1, X-ray diffraction (XRD) showed evidence of 1:1 ordering between Mg and Ti cations. For x ≤ 0.3, XRD and electron diffraction revealed that compounds were tilted in both antiphase and in-phase. However, for 0.3 < x < 0.7, only antiphase tilting was present. The temperature coefficient of resonant frequency (τf) vs the relative permittivity (εr) was linear until x = 0.5 at which point in the solid solution the transition to a nontilted structure resulted in nonlinear behavior. τf values close to zero (-2 ppm/°C) were achieved at x = 0.5 (εr ∼ 60), which had a quality factor (Q·fo) of 9600 GHz.

Journal article

Noujni D, Kamba S, Pashkin A, Bovtun V, Petzelt J, Axelsson AK, Alford NM, Wise PL, Reaney IMet al., 2004, Temperature dependence of microwave and THz dielectric response in Sr<sub>n+1</sub>Ti<sub>n</sub>O<sub>3n+1</sub> (n=1-4), 10th European Meeting on Ferroelectricity, Publisher: TAYLOR & FRANCIS LTD, Pages: 199-203, ISSN: 1058-4587

Conference paper

Sarma K, Farooq R, Jarman K, Pullar RC, Petrov PK, Alford NMet al., 2004, Sintering behaviour of Ba<sub>x</sub>Sr<sub>1-x</sub>TiO<sub>3</sub>, 10th European Meeting on Ferroelectricity, Publisher: TAYLOR & FRANCIS LTD, Pages: 249-252, ISSN: 1058-4587

Conference paper

Keith GM, Rampling MJ, Sarma K, Alford NM, Sinclair DCet al., 2004, Synthesis and characterisation of doped 6H-BaTiO<sub>3</sub> ceramics, 8th International Conference on Electronic Ceramics and Their Applications (ELECTROCERAMICS VIII), Publisher: ELSEVIER SCI LTD, Pages: 1721-1724, ISSN: 0955-2219

Conference paper

Petrov PK, Alford NM, Buslov O, Keis V, Kotelnikov I, Kulik P, Kozyrev Aet al., 2004, Tuneable two-pole one-dielectric-resonator filter with elliptic characteristics, 16th International Symposium on Integrated Ferroelectrics/5th Korean Workshop on High Dielectric Devices and Materials, Publisher: TAYLOR & FRANCIS LTD, Pages: 261-+, ISSN: 1058-4587

Conference paper

Pullar RC, Vaughan C, Alford NM, 2004, Effect of sintering aids upon dielectric microwave properties of ZnNb<sub>2</sub>O<sub>6</sub>, CoNb<sub>2</sub>O<sub>6</sub>, MgNb<sub>2</sub>O<sub>6</sub> and CaNb<sub>2</sub>O<sub>6</sub> columbite niobates, 8th Conference of the European-Ceramic-Society, Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 1157-1160, ISSN: 1013-9826

Conference paper

Petrov PK, Sarma K, Alford NM, 2004, Evaluation of residual stress in thin ferroelectric films using grazing incident X-ray diffraction, 10th European Meeting on Ferroelectricity, Publisher: TAYLOR & FRANCIS LTD, Pages: 183-189, ISSN: 1058-4587

Conference paper

Buslov OY, Keys VN, Kozyrev AB, Kotelnikov IV, Kulik PV, Alford NM, Petrov PKet al., 2004, Tuneable piezoelectric filter based on a dual-mode dielectric resonator, 14th International Crimean Conference on Microwave and Telecommunication Technology, Publisher: WEBER PUBLISHING CO, Pages: 410-411

Conference paper

Sarma K, Petrov PK, Alford NM, 2004, Single- and multi-target pulsed laser deposition of thin BSTO films: Preparation, microstructure and electrical properties, Symposium on Ferroelectric Thin Films XII held at the 2003 MRS Fall Meeting, Publisher: MATERIALS RESEARCH SOCIETY, Pages: 369-374, ISSN: 0272-9172

Conference paper

ALFORD NEIL MCNEILL, PENN STUART JAMES, 2003, Modified sintered materials, US6610623

Patent

ALFORD NEIL MCNEILL, PENN STUART JAMES, 2003, Sintered Materials, US2003013597

Patent

Feteira A, Sarma K, Alford NM, Reaney IM, Sinclair DCet al., 2003, Microwave dielectric properties of gallium-doped hexagonal barium titanate ceramics, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Vol: 86, Pages: 511-513, ISSN: 0002-7820

Journal article

Seabra MP, Avdeev M, Ferreira VM, Pullar RC, Alford NMet al., 2003, Structure and microwave dielectric properties of La(Mg<sub>0.5</sub>Ti<sub>0.5</sub>)O<sub>3</sub>-CaTiO<sub>3</sub> system, International Conference on Microwave Materials and Their Applications (MMA 2002), Publisher: ELSEVIER SCI LTD, Pages: 2403-2408, ISSN: 0955-2219

Conference paper

Petrov PK, Alford NM, Astafiev KF, Tagantsev AK, Setter N, Kaydanova T, Ginley DSet al., 2003, Structural investigation of thin SrTiO<sub>3</sub> films grown on MgO and LaAlO<sub>3</sub> substrates, 15th International Symposium on Integrated Ferroelectrics, Publisher: TAYLOR & FRANCIS LTD, Pages: 465-473, ISSN: 1058-4587

Conference paper

Pullar RC, Okeneme K, Alford NM, 2003, Temperature compensated niobate microwave ceramics with the columbite structure, M<SUP>2+Nb</SUP><sub>2</sub><SUP>O</SUP>6, International Conference on Microwave Materials and Their Applications (MMA 2002), Publisher: ELSEVIER SCI LTD, Pages: 2479-2483, ISSN: 0955-2219

Conference paper

Pullar RC, Axelsson AK, Alford NM, 2003, Near-zero τ<sub>f</sub> doped-niobate ceramics for dielectric resonator applications, Symposium on Dielectric Materials and Multilayer Electronic Devices/Symposium on Morphotropic Phase Boundary Phenomena and Peroviskite Materials, Publisher: AMER CERAMIC SOC, Pages: 287-304, ISSN: 1042-1122

Conference paper

Breeze JD, Aupi X, Alford NM, 2002, Ultralow loss polycrystalline alumina, APPLIED PHYSICS LETTERS, Vol: 81, Pages: 5021-5023, ISSN: 0003-6951

Journal article

Alford NM, Petrov PK, Breeze J, Sarma KSet al., 2002, Piezoelectrically tuned dielectric resonators, ELECTRONICS LETTERS, Vol: 38, Pages: 855-857, ISSN: 0013-5194

Journal article

Webb SJ, Breeze J, Scott RI, Cannell DS, Iddles DM, Alford NMet al., 2002, Raman spectroscopic study of gallium-doped Ba(Zn<sub>1/3</sub>Ta<sub>2/3</sub>)O<sub>3</sub>, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Vol: 85, Pages: 1753-1756, ISSN: 0002-7820

Journal article

Yates KA, Berenov AV, Sharma A, Driscoll JLM, Axelsson AK, Alford NM, Cohen LFet al., 2002, Comparison of DC resistivity and microwave transport properties of preferentially de-oxygenated polycrystalline La<sub>0.67</sub>Ca<sub>0.33</sub>MnO<sub>3</sub>, JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Vol: 247, Pages: 105-110, ISSN: 0304-8853

Journal article

Feteira A, Keith GM, Rampling MJ, Kirk CA, Reaney IM, Sarma K, Alford NM, Sinclair DCet al., 2002, Synthesis and characterisation of Ga-doped hexagonal BaTiO<sub>3</sub>, Symposium on Crystal Chemistry of Functional Materials held at the E-MRS Spring Meeting, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 439-448, ISSN: 1463-0184

Conference paper

Alford NM, Breeze J, Aupi X, 2002, Dielectric loss of oxide single crystals and polycrystalline analogues from 10 K to 300 K, 2nd China International Conference on High-Performance Ceramics (CICC-2), Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 17-22, ISSN: 1013-9826

Conference paper

Petrov PK, Sarma V, Poole M, Alford NMet al., 2002, Preparation and properties of BSTO thick films on metal substrates, Ferroelectrics UK 2001 Meeting, Publisher: MANEY PUBLISHING, Pages: 113-117

Conference paper

Pullar RC, Breeze JD, Alford NM, 2002, Microwave dielectric properties of columbite-structure niobate ceramics, M<SUP>2+</SUP>Nb<sub>2</sub>O<sub>6</sub>, 2nd China International Conference on High-Performance Ceramics (CICC-2), Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 1-4, ISSN: 1013-9826

Conference paper

GALLOP, JOHN CHARLES, ALFORD NEIL MCNEILL, 2001, POSITIONING METHOD FOR A MOBILE TELEPHONE RECEIVER, WO0163957

Patent

Petrov PK, Alford NM, 2001, Tunable dielectric resonator with ferroelectric element, ELECTRONICS LETTERS, Vol: 37, Pages: 1066-1067, ISSN: 0013-5194

Journal article

Alford NM, Penn SJ, Templeton A, Wang X, Webb Set al., 2001, Materials and processing developments in microwave ceramics, INDUSTRIAL CERAMICS, Vol: 21, Pages: 21-23, ISSN: 1121-7588

Journal article

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